CCAMLR SCIENTIFIC ABSTRACTS 1994 · Surveys of Antarctic fur seals entangled in man-made marine debris were carried out for the fourth consecutive winter and sixth consecutive summer

CCAMLR SCIENTIFIC ABSTRACTS1994

Commission for the Conservation ofAntarctic Marine Living Resources

PO Box 213, North Hobart 7002, Tasmania, AustraliaTelephone – 61 3 6231 0366; Facsimile – 61 3 6234 9965

Email – [email protected] – www.ccamlr.org

Copies of this publication are available from the CCAMLR Secretariat at the above address.

Published in April 1999

PREFACE

CCAMLR Scientific Abstracts provides a comprehensive record of all scientific paperspresented for the consideration of the annual meetings of the CCAMLR Commission andScientific Committee and of their subsidiary bodies.

This volume contains abstracts of scientific papers presented in 1994. It corresponds tothe Thirteenth Meetings of the CCAMLR Commission and Scientific Committee and ispublished only in English.

There are four categories of papers:

(i) Scientific papers published elsewhere, for which the full reference and publishedabstract are given;

(ii) Scientific papers submitted for publication, i.e., in CCAMLR Science or elsewhere,which are listed as ‘in press’ with details of the publisher, if known;

(iii) Scientific papers not intended for publication, which are listed as ‘unpublished’;and

(iv) Supplementary scientific papers (i.e., listing of data submitted, summary ofanalyses performed, etc.) not intended for publication, for which the title alone islisted.

All abstracts are listed in groups by respective CCAMLR bodies at meetings of whichthese papers were submitted. Each abstract is preceded with a unique CCAMLRdocument number, e.g. SC-CAMLR-XII/BG/11 (background document number 11submitted at the Twelfth Meeting of the Scientific Committee); or WG-Krill-92/8(document number 8 submitted at the 1992 meeting of the Working Group on Krill).

Unpublished papers must not be cited without written permission of the author(s).Addresses of principal authors are given for this purpose.

TABLE OF CONTENTS

Page

Abstracts of papers submitted at the 1994 meetings of the:

Scientific Committee................................................ 1

Workshop on Evaluating Krill Flux Factors (WS-FLUX) ...................................... 2

Working Group on Krill (WG-Krill).................................. 3

Working Group for the CCAMLR Ecosystem Monitoring Program (WG-CEMP) ................................... 11

Joint Meeting of WG-Krill and WG-CEMP ............................. 20

Working Group on Fish Stock Assessment (WG-FSA)................. 24

Ad Hoc Working Group on Incidental Mortality Arising from Longline Fishing ..................................... 31

Author Index ............................................................ 37

CCAMLR Scientific Abstracts, 1994_________________________________________________________________________________________

Scientific Committeeadults and of severe injury yet reported,grounds still remain for concern.

SC-CAMLR-XIII/BG/4Fishing gear, oil and marine debrisassociated with seabirds at BirdIsland, South Georgia, 1993/94.N. Huin and J.P. Croxall (British AntarcticSurvey, High Cross, Madingley Road,Cambridge CB3 0ET, Untied Kingdom),18 pp. (English, unpublished).

SC-CAMLR-XIII/8WG-CEMP-94/20Antarctic pack ice seals: indicatorsof environmental change andcontributors to carbon flux. Aninternational research program coordinatedby the SCAR Group of Specialists on Seals,mimeo: 7 pp. (English). We record the first observations of oiled

albatrosses at South Georgia, provide dataon ingestion of plastics by albatrosses andgiant petrels and report a 6-fold increaseover the previous year of the incidence offishing line and hooks associated with,regurgitated by and impaled in seabirds.Although the ingestion of oil, plastics andfishing gear are probably causing onlyminor problems for South Georgia seabirdsat present, the increase in number andvariety of environmental threats is a causefor concern. Members of CCAMLR areurged to do everything possible to eliminateor minimise these problems.

SC-CAMLR-XIII/BG/1 Rev. 1Status of catches in the ConventionArea 1993/94 season. CCAMLRSecretariat, 10 pp. (English).

SC-CAMLR-XIII/BG/3Entanglement of Antarctic fur seals(Arctocephalus gazella) inman-made debris at Bird Island,South Georgia during the 1993winter and 1993/94 pup-rearingseason. J.P. Croxall, K. Reid, A. Walkerand J.P.Y. Arnould (British AntarcticSurvey, High Cross, Madingley Road,Cambridge CB3 0ET, Untied Kingdom),24 pp. (English, unpublished).

SC-CAMLR-XIII/BG/5Report on CCAMLR’s participationat the FAO ad hoc consultation onthe role of regional fisheriesagencies in relation to high seasstatistics. CCAMLR Secretariat, 4 pp.(English, unpublished).

Surveys of Antarctic fur seals entangledin man-made marine debris were carried outfor the fourth consecutive winter and sixthconsecutive summer at Bird Island, SouthGeorgia. In the 1993 winter the number ofentangled seals was only 39% of the record1992 total, but still 5-times the numbers in1990 and 1991. Nearly all animals werejuveniles, half with severe injuries and theproportion of females (40%) was thehighest yet reported. The proportion ofanimals entangled in packaging bands wasthe lowest ever (24%) and less thanone-half that in 1992. Fishing netfragments and especially string and bagswere important as entangling materials. Inthe 1993/94 summer the number of sealsentangled (23) was the lowest ever and a70% reduction on the previous year,thereby reversing the upward trend since1990. For the first time more animals wereentangled in net fragments (35%) than inpackaging bands (30%), the decrease in thelatter mirroring the records of the precedingwinter. However, 68% of animals affectedwere female (previous highest 40%);combined with the highest proportion of

SC-CAMLR-XIII/BG/6Observer’s report from the 1994meeting of the Scientific Committeeof the International WhalingCommission. CCAMLR Observer’sreport (W.K. de la Mare), Australia, 2 pp.(English, unpublished).

SC-CAMLR-XIII/BG/7Report on CCAMLR’s participationat the SCAR Sixth BiologySymposium ‘Antarctic communities,structure and survival’. CCAMLRSecretariat, 2 pp. (English, unpublished).

SC-CAMLR-XIII/BG/9 Rev. 1CCAMLR scheme of InternationalScientific Observation: preliminaryreport of the scientific observer FVMaksheevo, 7 February to 18 April1994. (USA designated scientific

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observer) USA, 18 pp. (English,unpublished).

(CCAMLR Secretariat, 25 Old Wharf,Hobart, Tasmania, 7000 Australia), 13 pp.(English, unpublished).

SC-CAMLR-XIII/BG/10 A methodology is described which,when applied to data from an acousticsurvey, will yield mean krill density alongan arbitrary section through the survey area,giving results compatible with thespecifications given in SC-CAMLR-XII,Annex 4, Appendix D. A program writtento calculate such sections is also describedand example output displayed. A similarprogram calculates current speeds normal toa section given an oceanographic dataset ofcurrent direction and speed. The twoprograms produce compatible vectors ofkrill density and current speed alongspecified sections.

CCAMLR sea ice data project.CCAMLR Secretariat, 5 pp. (English,unpublished).

SC-CAMLR-XIII/BG/11Revision of the Statistical Bulletin.CCAMLR Secretariat, 5 pp. (English,unpublished).

SC-CAMLR-XIII/BG/12Report on fishery and scientificactivity of Ukraine in the Antarcticin 1993/94. Observer’s report (Ukraine),7 pp. (English, unpublished).

SC-CAMLR-XIII/BG/13 WS-Flux-94/5Ob and Lena Banks. Observer’s report(Ukraine), 9 pp. (English, unpublished).

Use of current velocity data fromFRAM to investigate the large-scaletransport of krill in the Scotia Sea.E.J. Murphy (British Antarctic Survey,High Cross, Madingley Road, Cambridge,CB3 0ET, United Kingdom), 10 pp.(English, unpublished).

SC-CAMLR-XIII/BG/14Summary report of theUK nominated scientific observerson FV Ihn Sung 66, 15 December1993 to 7 February 1994. (C. Jones,M. Wharton and I. Liggett) UK, 10 pp.(English, unpublished).

Current velocity data from a single timerealisation of the FRAM model are presentedfor particular areas of the Scotia Sea. Theregions are based on the CCAMLR subareasand also include a more detailed area aroundSouth Georgia. Mean current velocitieshave been calculated for region boundariesover the upper 250 m of the water column.These have been combined with estimatesof krill density and standing stock in orderto study the large-scale flux of krill throughthe regions and to estimate residence times.

SC-CAMLR-XIII/BG/15Information on squid relevant toCCAMLR area, 1993/94.P.G. Rodhouse (British Antarctic Survey,High Cross, Madingley Road, CambridgeCB3 0ET, United Kingdom), 4 pp. (English,unpublished).

SC-CAMLR-XIII/BG/16International data management.CCAMLR Secretariat, 5 pp. (English,unpublished).

WS-Flux-94/6Large-scale circulation in the SouthAtlantic: estimates from gianticeberg drift rates. P.N. Trathan andC. Symon (British Antarctic Survey, HighCross, Madingley Road, Cambridge, CB30ET, United Kingdom), 11 pp. (English,unpublished).

Workshop on EvaluatingKrill Flux Factors

The paper reports work currently inprogress and presents estimates of oceancirculation in the Scotia Sea. The estimatesare derived from the drift rates of gianticebergs calved in the Weddell Sea since1974. Comparison with other estimates is

WS-Flux-94/4Analysis of acoustic andoceanographic data for the 1994krill flux workshop. D.J. Agnew,

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limited by the lack of studies reported in theliterature; however, efforts to make thesecomparisons are in hand.

a run of 100 days. Some of the trajectoriesare extremely complex. Particles to thenorth of the shelf can be transported uponto the shelf. Only those particles releasedvery close to the shelf break in the south aretransported up onto the shelf. Furthersouth, particles are transported to the westalong the shelf.

WS-Flux-94/7Comparison of geostrophicvelocities from Subarea 48 .1 .W. de la Mare (Australian AntarcticDivision, Channel Highway, Kingston,Tasmania 7050, Australia), 4 pp. (English,unpublished).

Working Group on KrillWS-Flux-94/8Reference materials on StatisticalArea 48 for krill flux workshop.M. Naganobu (National Research Instituteof Far Seas Fisheries, Orido 5-7-1,Shimizu, Shizuoka, 424 Japan), 9 pp.(English, unpublished).

WG-Krill-94/4Parameters for the stochastic krilldynamics model (SKDM): selectivityand maturity. D.J. Agnew (CCAMLRData Manager, 25 Old Wharf, Hobart,Tasmania 7000, Australia), 3 pp. (English,unpublished).WS-Flux-94/9

Stream lines in the FRAM velocityfield: speeds and directions frompassive tracers. E.J. Murphy (BritishAntarctic Survey, High Cross, MadingleyRoad, Cambridge, CB3 0ET, UnitedKingdom), 4 pp. (English, unpublished).

The parameters used to model gearselectivity and maturity at length in theSKDM were derived from data available atthe CCAMLR Data Centre or in documentssubmitted to past meetings of the ScientificCommittee. In the SKDM, if l50 forselectivity and maturity is to be sampledfrom a uniform distribution and applied to astandard function width, then these shouldbe:

A single time realisation of the FRAMmodel has been used to obtain trajectoriesof passive tracers. This note presents someof the analyses undertaken in order toprovide background information on thepotential transfers of krill in the Scotia Sea.A more detailed presentation of the streamlines in the South Georgia region is alsogiven.

lr 50 = U[30,39] wr = 9 mm(for gear selectivity)

lm 50 = U[32,37] wm = 6 mm(for maturity).

WS-Flux-94/10Tracer trajectories from the westernshelf of South Georgia: shipdisplacement data. E.J. Murphy,I. Everson and C. Goss (British AntarcticSurvey, High Cross, Madingley Road,Cambridge, CB3 0ET, United Kingdom),5 pp. (English, unpublished).

WG-Krill-94/5Incorporation of a model of krillrecruitment into the Butterworth etal. stochastic krill dynamics model(SKDM) . D.J. Agnew (CCAMLR DataManager, 25 Old Wharf, Hobart, Tasmania7000, Australia), 6 pp. (English,unpublished).Corrected ship’s heading data were used

to calculate drift data for the shelf area to thewest of South Georgia. The data werecollected over a six-week period during1986. A distance-weighted interpolationwas used to obtain tracer trajectories in thisirregular data grid. The vector field iscomplex with no simple flow field. Thesedata include a lot of complex processinteractions. Particles getting onto the shelfare retained with little chance of escape after

The method of simulating recruitmentvariability using observed ratios of 0-yearkrill to the total population is validated andtested. The method links natural mortalityto krill recruitment. Incorporation of thekrill dynamics model into the SKDMincreases the variability of the krillpopulation dynamics predicted by the lattermodel, although median escapement is

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similar to the previous formulation of theSKDM model.

were calculated. The results of biologicalinvestigations of krill on the fishinggrounds of the South Orkney and SouthGeorgia subareas are also given.WG-Krill-94/6

Fine-scale catches of krill inArea 48 reported to CCAMLR for the1992/93 fishing season. CCAMLRSecretariat, 37 pp. (English, unpublished).

WG-Krill-94/10 Rev. 1Analysis of krill fishing by Sovietfishing vessels in the CooperationSea (Division 58.4.2) in 1978 byfine-scale data. V.N. Yakovlev andV.A. Bibik (YugNIRO, 2 Sverdlov Street,Kerch 334500, Crimea, Ukraine), 3 pp.(English, unpublished).

WG-Krill-94/7 Rev. 1Assessing the probability ofdetecting krill concentrations inDivision 58.4.2. V.N. Yakovlev,V.A. Bibik and L.M. Kokoz (SouthernScientific Research Institute of MarineFisheries and Oceanography (YugNIRO),2 Sverdlov Street, Kerch 334500, CrimeaUkraine), 17 pp. (English, unpublished).

WG-Krill-94/11Towards a distribution of M/K forkrill (Euphausia superba) requiredfor the stochastic krill yield model.M. Basson (Northeast Fisheries Center,Water Street, Woods Hole, Ma. 02543,USA), 16 pp. (English, unpublished).

In 1994 the first stage was completed onthe creation of a model describing krilldistribution and the process of searching forkrill concentrations in the area of Antarcticabetween 30° and 80°E. During the courseof this work several tasks were performed,including the analysis and classification ofkrill echograms according to the primarycharacteristics of aggregations (length,volume, frequency of occurrence andtemporal stability). In addition, algorithmshave been developed for the automaticprocessing of data on the distribution ofkrill concentrations, as well as catch data.Data have been obtained on the frequencyof occurrence of krill swarms - these dataare discussed in detail for large spatialscales. A series of algorithms has beencalculated and approaches to theconstruction of the model are presented.

WG-Krill-94/12In situ target strength measurementsof Antarctic zooplankton (Euphausiasuperba and Salpa thompsoni) at120 kHz and 200 kHz,corroboration of scattering models,and a statistical technique fordelineating species. D.A. Demer andR.P. Hewitt (Scripps Institution ofOceanography, University of Ca. at SanDiego, La Jolla, California 92038-0203,USA), 35 pp. (English, unpublished).

In situ measurements of target strength(TS) were made of Antarctic zooplankton(Euphausia superba and Salpa thompsoni)at 120 kHz and 200 kHz. Concurrently, atwo-metre Isaacs-Kidd midwater trawl wasused to sample the zooplankton populationsand animal length-frequency data wererecorded. The TS and length-frequencydata were combined to corroboratetheoretical scattering models for bothspecies. The individual TS measurementswere collected at 120 kHz with a split-beamechosounder and a single-target detectionalgorithm. Because the two transducerswere essentially collocated, range-bin andoff-axis angles from the 120 kHz detectionswere used to extract the corresponding TSfrom the 200 kHz single-beam data. Thebackscattering cross-sectional areas σbs( )of salps are shown to fit a fluid spheremodel [V.C. Anderson, (1950) J. Acoust.Soc. Am., 22: 426-431]; presumably,

WG-Krill-94/9Polish krill fishery in the 1991/92and 1992/93 seasons: catches andresults of biological investigations.J. Sosinski and Z. Cielniaszek (SeaFisheries Institute, ul. Kollataja 1, 81-332Gdynia, Poland), 15 pp. (English,unpublished).

Poland began krill fishing operations inthe 1976/77 season. It has been engaged inthe commercial krill fishery since the1986/87 season. A maximum catch of 15.9thousand tonnes was taken in the 1992/93season. This paper presents an analysis ofPolish krill catches in the 1991/92 and1992/93 seasons. CPUEs by month andsubarea of the Atlantic sector of Antarctica

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predominant scattering is from eachanimal’s spheroidal nucleus. Consistentwith the measurements of encaged krill[K.G. Foote et al. (1990) J. Acoust. Soc.Am., 87(1): 16-24 and D. Chu et al.(1993) J. Acoust. Soc. Am., 93(5):2985-2988], the TS of in situ krill areshown to fit a deformed cylinder model[T.K. Stanton et al. (1993a) J. Acoust.Soc. Am., 94(6): 3454-3462 andT.K. Stanton et al. (1993b) J. Acoust.Soc. Am., 94(6): 3463-3472]. Byutilising these scattering models andempirically derived distributions of animalsizes, a technique is developed foracoustically delineating the two species.The method uses non-parametricKolmogorov-Smirnov fitness tests toevaluate cumulative distribution frequencies(CDFs) of ∆σbs derived from thedifferences in σbs measurements at twofrequencies. About 15% of the testsindicated the presence of salps without krill,and about 3% revealed krill without salps.The salp/no krill echograms werecharacterised by diffuse scattering layerswhich were much higher in volumebackscattering strength (Sv) at 200 kHzthan at 120 kHz. Conversely, the krill/nosalp echograms included dense swarmswith virtually equivalent Sv at the twofrequencies. The ability of this method todelineate salps from krill is highlydependent on the degree to which the twoCDFs differ. A simulated combination of200 kHz and 38 kHz resulted in highlydistinguishable CDFs, indicating that thesefrequencies may be more useful fordistinguishing salps from krill. Data werecollected near Elephant Island, Antarctica,during the austral summer of 1994, as partof the United States Antarctic Marine LivingResources Program.

420 kHz and 1 MHz, and the dependenceof these data on animal volume versuscross-sectional area was explored. The420 kHz and 1 MHz data were collectedwith a dual-beam sonar system and the200 kHz data with a split-beam system.Experiments were conducted with live,tethered individuals in an enclosure filledwith filtered seawater. The data werecompared to both empirical and theoreticalmodels of reduced target strength (TSnormalised by the square of the animallength) versus ka (the product of wavenumber and equivalent cylindrical radius).The theoretical models chosen for thiscomparison were two versions of ahigh-pass bent-cylinder model (Stanton,1989b) that indicate TS is dependent onanimal volume, and the ray bent-cylindermodel (Stanton, 1993a) which implies TS isdependent on the cross-sectional area. Thedependence of acoustic backscattering onanimal volume or area was tested by fittingregression lines for TS versus the logs ofka, length (L), wet weight (WW) and dryweight (DW). Contrary to an empiricalmodel derived from similar experiments(Wiebe et al., 1990), and to the high-passmodels, the regressions indicated that TS isproportional to the cross-sectional area ofthe animal. However, neither Wiebe et al.(1990) nor this experiment directlyaccounted for animal orientations.Simulations using a Distorted Wave BornApproximation Model (Chu et al., 1993)indicated that animal behaviour is animportant factor in the scatteringcharacteristics of zooplankton. Moreover,because scattering from individualzooplankton is highly non-linear, especiallyin the geometric scattering region (ka>1),linear regressions of TS versus the log ofka, L, WW or DW are inappropriate andmisleading.

WG-Krill-94/13 WG-Krill-94/14Zooplankton target strength:volumetric or areal dependence?D.A. Demer and L.V. Martin (ScrippsInstitution of Oceanography, University ofCalifornia at San Diego, La Jolla, Ca.92038-0203, USA), 21 pp. (English,unpublished).

An attempt to derive a compositeindex of abundance from acousticsurveys and fishery data.R.P. Hewitt, V. Marín and D.A. Demer(Southwest Fisheries Science Center,La Jolla, Ca. 92038, USA). CCAMLRScience, (in press): 13 pp. (English).

Target strengths (TS) of variouszooplankton were measured at 200 kHz,

Maps of krill (Euphausia superba)density derived from acoustic survey data,as well as the distribution of fishing effort

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in the Chilean krill fishery, indicate an areaof high krill density wrapping around thenorthwestern end of Elephant Island duringthe austral summer of 1992. In this area,the distribution of catch-per-fishing-timeand krill density (measured acoustically)show similar forms. Search time could notbe used to estimate other aspects of thepattern of krill distribution because fishingoperations are limited by processingefficiency rather than the availability ofkrill. Analysis of the acoustic survey datasuggested characteristic distribution patternscales of 1.7 and 4 n miles. Estimates of acomposite index of krill abundance(SC-CAMLR-VIII, 1989) were derived usingthese data sets for two surveys. Inaddition, the data suggest that theabundance of krill in the Elephant Islandarea can change rapidly, and when krill docome into the area they are most oftenfound in water 100 m to 500 m deep alongthe shelf break north of Elephant Island,particularly in the area where it wrapsaround the western end of the island.

fifth year. Von Bertalanffy growth curvescalculated for different areas are similar tothose obtained by Australian researchers inthe Prydz Bay region for the period 1981 to1985. In mid-summer, E. superba of age2+ to 4+ were predominant in all haulsmade south of the Antarctic Divergence,while north of the Divergence the krill stockwas clearly dominated by individuals ofage 4+. The coefficients of naturalmortality (M) of E. superba in the Indiansector of the Southern Ocean, calculatedusing the methods of Alverson and Carney,Richter and Efanov and Beverton and Holt,varied from 0.72 to 0.87, from 0.52 to0.57 and from 0.76 to 2.92 respectively.The value of age-dependent naturalmortality of E. superba derived usingZikov and Slepokurov’s method rangedfrom 0.52 during the maturation period, to1.1 to 2.41 during the first and last years oflife. The relationship between agecomposition and spawning success ofE. superba is examined based on longtermobservations made in the coastal areas ofthe Sodruzhestva and Kosmonavtov Seas.

WG-Krill-94/15Comments on WG-Krill-93/12 and93/13. K. Hiramatsu (National ResearchInstitute of Far Seas Fisheries 7-1, Orido5 Chome, Shimizu-Shi, Shizuoka, 424,Japan), 3 pp. (English, unpublished).

WG-Krill-94/17Towards a new method for agedetermination in Antarctic krill, andevidence that krill shrink undernatural conditions. S. Sun,W. de la Mare and S. Nicol (Institute ofOceanology, Academia Sinica, 7 NanhaiRd, Qingdao, 266071, People’s Republicof China), 12 pp. (English, unpublished).

WG-Krill-94/16Demographic studies of Antarctickrill (Euphausia superba Dana) inthe Sodruzhestva and KosmonavtovSeas (Indian sector of the SouthernOcean). E.A. Pakhomov (SouthernOcean Group, Department of Zoology andEntomology, Rhodes University,PO Box 94, Grahamstown, 6140 SouthAfrica), 31 pp. (English, unpublished).

Laboratory studies have shown thatAntarctic krill (Euphausia superba) shrink ifmaintained in conditions of low foodavailability. Recent studies have alsodemonstrated that E. superba individualsmay be shrinking in the field during winter.If krill shrink during winter, conclusionsreached by length/frequency analysis maybe unreliable. In this study, the correlationbetween the body length and the crystallinecone number of the compound eye wasexamined. Samples collected in latesummer show an apparent linearrelationship between crystalline conenumber and body length. From alaboratory population, it appears that whenkrill shrink, the crystalline cone numberremains relatively unchanged. If thecrystalline cone number is little affected byshrinking, then this may be a more reliable

The reproductive state and sizecomposition of Euphausia superbaspecimens collected in the Indian sector ofthe Southern Ocean from 1985 to 1990were analysed to estimate growth, life spanand mortality rates of this species. The lifecycle of E. superba exceeded five years inthe Kosmonavtov Sea and six years in theSodruzhestva Sea. Assuming that growthtakes place for only 180 days per year,growth rates ranged from 0.120 to0.133 mm.day-1 during the first year oflife, to 0.019 to 0.022 mm.day-1 during the

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indicator of age than body length alone.The ratio of crystalline cone number tobody length offers a method for detectingthe effect of shrinking in naturalpopulations of krill. On the basis of thecrystalline cone number count, it appearsthat E. superba shrink during winter.

January/February 1993 using echointegration. T. Pauly andI. Higginbottom (Australian AntarcticDivision, Channel Highway, Kingston,Tasmania 7050, Australia), 25 pp.(English, unpublished).

Hydroacoustic surveys of krill(Euphausia superba) abundance in thePrydz Bay region were undertaken inJanuary/February 1991, February/March1992 and January/February 1993. Thesurveys indicated some association of krillwith the shelf break in the western part ofthe survey area and the centre of the PrydzBay region, but also found that the shelfbreak was in general not a region ofrelatively high krill abundance. The meansurface density estimates of krill in 1991,1992 and 1993 were 16.6, 10.3 and7.7 g/m2 respectively. These densities arelarge compared to estimates of 1.95, 3.45and 1.78 g/m2 for Statistical Subareas 48.1,48.2 and 48.3 (SC-CAMLR 1991, p47), butsmall compared to the 20.2 g/m2 estimatedfor January 1985 from the SIBEX-II data.The Australian SIBEX-II estimate falls in themiddle of the range of densities estimatedfrom seven surveys conducted between1981 and 1985 (Higginbottom et al.,1988). The distribution of the Sa values forthe lower-biomass years 1992 and 1993were similar and distinctly different fromthe higher-biomass year of 1991. Thedifference is characterised by the highpercentage of lower Sa values(60%<10 m2/n miles2) for 1992 and 1993compared with the relatively evendistribution of medium Sa values (10 to200 m2/n miles2) over the survey region in1991. The extent of bias in these resultsdue to the presence of substantial biomassesof species other than Euphausia superba inthe survey areas (Williams et al., 1983;Ikeda et al., 1984, 1986; Hosie et al. ,1988) could not be determined.

WG-Krill-94/18Hydroacoustic survey of Antarctickrill populations in CCAMLRDivision 58.4.1 during 1995/96summer season. W. de la Mare(Australian Antarctic Division, ChannelHighway, Kingston, Tasmania 7050,Australia), 4 pp. (English, unpublished).

In the past, CCAMLR has used the resultsof hydroacoustic surveys to setprecautionary limits on the krill fishery inall of the South Atlantic (Area 48) and inpart of the South Indian Ocean (Division58.4.2). Division 58.4.1 is the only area ofthe Southern Ocean that has been regularlyfished for krill which has not been surveyedto obtain krill distribution and abundanceestimates and thus there is no basis forsetting a precautionary catch limit. In 1993the CCAMLR Working Group on Krill,Scientific Committee and the Commissiongave high priority to the conduct of asurvey of Division 58.4.1, and theAustralian Antarctic Division is planning toconduct such a survey with a jointoceanographic program inJanuary/February 1996.

WG-Krill-94/19Access to and use of data withinCCAMLR. D.G.M. Miller, ConvenerWG-Krill (Sea Fisheries Research Institute,Private Bag X2, Roggebaai, South Africa),2 pp. (English, unpublished).

WG-Krill-94/20Suggested outline for the designand implementation of futurenear-synoptic krill surveys.D.G.M. Miller, Convener WG-Krill (SeaFisheries Research Institute, PrivateBag X2, Roggebaai, South Africa), 12 pp.(English, unpublished).

WG-Krill-94/22Recruitment variability of Antarctickrill (Euphausia superba) . V. Siegeland V. Loeb (Institut für Seefischerei,Bundesforschungsanstalt für Fischerei,Palmaille 9, 22767 Hamburg, Germany),5 pp. (English, unpublished).WG-Krill-94/21

Estimation of the biomass of krill inPrydz Bay during January/February1991, February/March 1992 and

Between-year variability of krillyear-class success and recruitment duringthe period 1975 to 1994 is described, based

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on data from German expeditions and USAMLR cruises to the Elephant Island area.Recruitment indices based on the relativeabundance of the 1+ year class during eachyear indicate good recruitment for the1980/81, 1985/86, 1987/88 and 1990/91year classes; exceedingly poor recruitmentoccurred for the 1976/77, 1982/83,1983/84, 1988/89, 1991/92 and 1992/93year classes.

black-browed albatross suggests that theseother factors result in yet lesser resilience ofthe albatross population to the effects of akrill fishery. An approach for estimatingthe parameters of functional relationshipsbetween survival rates and krill biomass (oravailability) is introduced. This is based onthe method of moments, and is applied to anumber of survival rate estimates providedby WG-CEMP members for theblack-browed albatross and Antarctic furseal. Attempts are made to estimate thelevels of krill harvesting which would resultin halving the sizes of various krill predatorpopulations, and the precision androbustness to model-misspecification of theassociated estimator are investigated.Results in those regards are not tooencouraging. Estimates of the functionalrelationships for the black-browed albatrossand Antarctic fur seal indicate a surprisinglylow resilience of these populations to theeffects of a krill fishery. Discussion isneeded as to whether this reflects aninappropriate modelling approach or resultsfrom possible negative bias in estimates ofsurvival rates from field data.

WG-Krill-94/23Yet further krill yield computations.R.B. Thomson and D.S. Butterworth(Department of Applied Mathematics,University of Cape Town, Rondebosch7700, South Africa), 28 pp. (English,unpublished).

Preliminary computations are carried outfor the krill yield model of Butterworth etal. (1993), adjusted as requested by thefifth meeting of WG-Krill. This involvesmodifying the input distributions for thelengths at recruitment and maturity, naturalmortality and the extent of recruitmentvariability. Sensitivity tests are carried outto assess the consequences of avoidance ofgravid females by the fishery, and highernatural mortality for younger ages of krill.Results do not differ greatly from those ofcomparative calculations in Butterworthet al. (1993), except at higher harvestingintensities for which greater resourcedepletion is indicated. Comparativelygreater depletion is also evident for maleswhen gravid females are avoided, and ifnatural mortality is higher for younger ages.

WG-Krill-94/25Fishes incidentally caught byJapanese commercial Antarctic krillfishery in the vicinity of the SouthShetland Islands during the australsummer months of 1994. T. Iwami(Laboratory of Biology, Tokyo KaseiGakuin University, 2600 Aihara, Machida,Tokyo 194-02, Japan), 5 pp. (English,unpublished).

WG-Krill-94/24 Observations of the abundance ofby-catch fishes were made from 12 Januaryto 18 February 1994 on board theFV Niitaka Maru to the north of the SouthShetland Islands. A total of 77 specimensof fishes belonging to 13 species werefound in 25 out of 99 krill trawl hauls.Among by-catch fishes, juvenileLepidonotothen larseni was the mostabundant (26 individuals) and mostcommon (found in 11 hauls) species.Juvenile and postlarval Chaenocephalusaceratus (13 individuals from four hauls)and Chaenodraco wilsoni (10 individualsfrom six hauls) were also fairly abundant.To compare the abundance of each fishspecies, an index of its occurrence per100 kg of krill was calculated. Fish

Further calculations of the effects ofkrill fishing on predators.D.S. Butterworth and R.B. Thomson(Department of Applied Mathematics,University of Cape Town, Rondebosch7700, South Africa), 29 pp. (English,unpublished).

Earlier initial modelling attempts by theauthors are extended to consider thesituation where predator survival ratesdepend on factors other than krill biomass.This is achieved by making the survivalrates depend instead on krill ‘availability’,where there is a random component in therelationship between krill biomass andavailability. An examination of theconsequences of this in the case of the

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abundance could have been dependent onthe density of krill concentrations. Thelarge incidental catch of fishes occurred inhauls with low krill catch rates (haulNos. 36 and 47), and fishes were notfound or were scarce in hauls conducted onkrill swarms of high density.

WG-Krill-94/28CPUEs and body length of Antarctickrill in Japanese commercial fisheryduring 1992/93 season in thefishing grounds north of LivingstonIsland. S. Kawaguchi, T. Ichii andM. Naganobu (National Research Instituteof Far Seas Fisheries, 5-7-1, Orido,Shimizu, Shizuoka 424, Japan), 15 pp.(English, unpublished).

WG-Krill-94/26Numerical model of ecosystemincluding Euphausia superba Danaas a key species in circumpolarregion. M.J. Kishi and M. Naganobu(Ocean Research Institute, University ofTokyo, Minamidai 1-15-1, Nakano-ku,Tokyo 164, Japan), 4 pp. (English,unpublished).

This paper summarises Japanesecommercial krill catch data pertaining to the1992/93 austral summer season. As inprevious years, the main fishing groundswere located to the north of LivingstonIsland. The highest values of CPUEoccurred in the middle of summer (lateFebruary to late March). Krill with a modallength of 45 mm were dominant in catches,which is almost the same as in the previousseason.

A research plan for developing a modelof the processes governing the biochemicalcycle in the Southern Ocean comprises thefollowing elements: (i) an Ocean GeneralCirculation Model (OGCM); (ii) aone-dimensional ecosystem model that canbe applied to primary production in theSouthern Ocean; (iii) an ecosystem modelable to describe krill ecology; (iv) anumerical model to combine the OGCM andecosystem models; (v) the development of anumerical model which incorporates effectsof marine mammal consumption and krillcatch; and (vi) an integrated model of theabove component models. This year anOGCM and a one-dimensional ecosystemmodel for the Southern Ocean have beendeveloped. The OGCM was originallydeveloped by the Center for Climate SystemResearch (CCSR), University of Tokyo.The one-dimensional ecosystem model byKawamiya et al. (1994) with sevencomponent parts is combined with aone-dimensional mixed-layer model forcalculating the diffusion coefficient.

WG-Krill-94/29Hydrographic flux in StatisticalArea 88 of CCAMLR in the pacificsector of the Southern Ocean.M. Naganobu (National Research Instituteof Far Seas Fisheries, 5-7-1, Orido,Shimizu, Shizuoka 424, Japan), 18 pp.(English, unpublished).

This document presents basicinformation on the hydrographic flux inStatistical Area 88 (Pacific Ocean sector),including data on the surface geostrophiccurrent across the area and verticaldistributions of geostrophic velocity andtemperature along 90°W, 120°W, 170°Wand 175°E.

WG-Krill-94/30Change of sex ratio of krill(Euphausia superba) from australearly summer to midsummer in1983/84 in the vicinity of PrydzBay, Antarctica. M. Naganobu andS. Kawaguchi (National Research Instituteof Far Seas Fisheries, 5-7-1, Orido,Shimizu, Shizuoka 424, Japan), 13 pp.(English, unpublished).

WG-Krill-94/27The plan for the 7th Antarcticresearch cruise by the RV KaiyoMaru of the Japanese FisheriesAgency in 1994/95. M. Naganobu,T. Ichii, S. Kawaguchi, T. Ogishima andY. Takao (National Research Institute ofFar Seas Fisheries 7-1, Orido 5 Chome,Shimizu-Shi, Shizuoka, 424, Japan), 5 pp.(English, unpublished).

Changes in the distribution of Antarctickrill in the vicinity of Prydz Bay fromDecember 1983 to January/February 1984were analysed. The results showed notable

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changes in sex ratio and the coefficient offatness which took place from early tomid-summer. The high proportion offemale krill having a high coefficient offatness was considered to be an indicatorthat the study area was suitable for krillspawning. This area is characterised by(well-distinguished) shelf slope watersoriginating from cold winter waters.

Krill biomass density varied from a mean of42 gm-2 during the first survey phase to19.6 gm-2 on the second survey phase. Thenumber of small swarms detected duringthe second phase was greater than duringthe first phase. On this first survey a largeswarm (2.8 km in extent) had a potentialbiomass of 3.7 x 104 tonnes. Somecalculations are presented to show thepotential impact of krill on the flux ofcarbon in the area of the survey.WG-Krill-94/31

Modelling the spatial distribution ofAntarctic krill (Euphausia superbaDana). A.W.A. Murray andD.G.M. Miller (British Antarctic Survey,High Cross, Madingley Road, CambridgeCB3 0ET, United Kingdom) 53 pp.(English, unpublished).

WG-Krill-94/33Operation results of Ukrainianvessels at Antarctic krill fishery inSubareas 48.2 and 48.3 in March toJune 1994: krill size composition.V.A. Bibik and V.N. Yakovlev (SouthernScientific Research Institute of MarineFisheries and Oceanography (YugNIRO),2 Sverdlov Street, Kerch 334500, CrimeaUkraine), 4 pp. (English, unpublished).

Various simple probability models havebeen applied to describe the spatialdistribution of krill (Euphausia superba)from acoustic data collected in theSouthwest Atlantic and Indian Oceans.None of the 12 models applied provided awholly satisfactory fit to the data. Resultstend to support current thinking whichinterlinks krill aggregation with physicaland biological processes on a number ofscales. It is suggested that atwo-component Weibull mixture model or aback-transformed Extreme Value approachappear to offer improvement on currentefforts to simulate krill distribution. Theefficacy of alternative stochastic modellingmethods requires investigation.

In 1994 Ukraine resumed krill fishingafter a one-year hiatus in the 1992/93season. Fishing was conducted by twovessels, BAT Grigory Kovtun and RKTSGeneral Petrov. A scientific observer fromYugNIRO was on board one of the vessels.The fishery and scientific information givenin this paper is preliminary, and someclarification of data might be required afterthe observer returns from the cruise.

WG-Krill-94/34A review of the Antarctic krill(Euphausia superba Dana) biomassin the Sodruzhestva Sea (=PrydzBay region, Division 58.4.2).E.A. Pakhomov (Southern Ocean Group,Department of Zoology and Entomology,Rhodes University, PO Box 94,Grahamstown, 6140 South Africa), 8 pp.(English, unpublished).

WG-Krill-94/32A biological acoustic survey in themarginal ice edge zone on theBellingshausen Sea. A.W.A. Murray,J. L. Watkins and D. G. Bone. Deep SeaResearch (in press): 29 pp. (English).

An acoustic survey at 38 and 120 kHzwas carried out from RRS Discovery in theBellingshausen Sea from 23 November to7 December 1992 as part of the UK JointGlobal Ocean Flux Study (JGOFS) SouthernOcean investigations (Turner and Owens,1994). A total of 285 targets was identifiedand described from the chart record of theechosounder. Mean Volume BackscatteringStrength data were collected using an echointegration system. These data are used todescribe the spatial and temporal variabilityof krill (Euphausia superba) distributionand biomass in the marginal ice edge zone.

In this paper the levels of Antarctic krillbiomass estimated using different methodsin the Indian sector of the Southern Ocean(Division 58.4.2), are reviewed. Annualestimates of krill biomass made by fivecountries (Australia, Japan, France, SouthAfrica and Ukraine) from 1977 to 1992 areavailable in the current literature. The mostcomprehensive longterm estimates areavailable for the area south of 65°S between60 and 80°E. Preliminary analysis of thesedata has shown that in this area six yearsvariability in krill biomass may be detected,

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when high levels of total krill biomass wereobserved during the austral summers of1978, 1984 and 1990.

WG-CEMP-94/7CCAMLR Ecosystem MonitoringProgram Standard Methods: revisionof Method A4 for penguins.W.Z. Trivelpiece (Department of Biology,Montana State University, Bozeman,Mt. 59717, USA), 2 pp. (English,unpublished).

WG-Krill-94/35Conditions for the precisemeasurement of fish target strengthin situ. K. Sawada, M. Furusawa andN. J. Williamson. Journal of MarineAcoustics, Society of Japan, 20(2): 73-79,1993 (English).

WG-CEMP-94/8CCAMLR Ecosystem MonitoringProgram Standard Methods:determination of sex of Adéliepenguins. K. Kerry, J. Clarke andG. Else. Wildl. Res., 20: 725-32, 1993(English).

Conditions for the precise measurementof in situ fish target strength (TS) areempirically studied and two indices areproposed for this purpose. One is thenumber of fish in the effective reverberationvolume which contributes to the formationof an echo at a certain time, and the other isa percentage of the multiple echoes which isderived from a residual of the single echoextraction. As both indices decrease, targetstrength approaches a certain asymptoticvalue which previous studies have shownto be reliable. This shows the existence ofsome threshold values below which TSmeasurement will be reliable. Theeffectiveness of both indices is confirmedby a set of data obtained from one largeschool of fish in the eastern shelf of theBering Sea during an inter-calibrationexercise conducted by Japanese and USvessels on 15 and 16 August 1991.

The suggestion that sex of Adéliepenguins, Pygoscelis adeliae, might beassigned by observing which member ofthe pair (the male) takes the first longincubation shift (Anon., 1991) wasexamined for each of the 1990/91, 1991/92and 1992/93 breeding seasons. There wasan 8- or 9-day period when more than 90%of the incubating birds were male and a6- or 7-day period when more than 90% ofthe birds were female. The dates of thesepeak periods of male or female presenceoverlapped by only two to five daysbetween the three seasons but were constantto within two days relative to thecommencement of egg laying. Peakpresence of males occurred 15 to 21 daysafter the appearance of the first egg in thecolony and peak presence of females after33 to 36 days from this date. In all threeseasons male birds could be identified with91.8 to 98.6% accuracy within 15 to21 days after the first sighting of an egg.The method provides, therefore, a means ofidentifying the sex of Adélie penguins withan accuracy greater than 90% and isapplicable to whole colonies containingseveral hundred pairs without recourse tocontinuous observations or capturing thebirds.

Working Group for the CCAMLREcosystem Monitoring Program

WG-CEMP-94/4TDR-derived foraging performanceindices. J.P. Croxall (British AntarcticSurvey, Natural Environment ResearchCouncil, High Cross, Madingley Road,Cambridge CB3 0ET, United Kingdom),4 pp. (English, unpublished).

WG-CEMP-94/9 Rev. 1WG-CEMP-94/6Coordination of CEMP siteprotection within the AntarcticTreaty System. CCAMLR Secretariat,9 pp. (English, unpublished).

CCAMLR Ecosystem MonitoringProgram Standard Methods: revisionof methods for black-browedalbatrosses. J.P. Croxall (BritishAntarctic Survey, Natural EnvironmentResearch Council, High Cross, MadingleyRoad, Cambridge CB3 0ET, UnitedKingdom), 5 pp. (English, unpublished).

WG-CEMP-94/10Spatial structure of the SouthernOcean ecosystem: predator-prey

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linkages in Southern Ocean foodwebs. E.J. Murphy. Journal of AnimalEcology, (in press): 43 pp. (English).

WG-CEMP-94/11Temporal patterns of milkproduction in Antarctic furseals (Arctocephalus gazella) .J.P.Y. Arnould and I.L. Boyd. J. Zool.,Lond., (in press): 25 pp. (English).

The food chain of the Southern Oceanhas often been characterised as simple andhomogeneous. However, the populationprocesses of a key prey organism, krill(Euphausia superba Dana), operate overocean basin scales and are stronglyinfluenced by large-scale abiotic factors. Amodel was developed in which the localprey abundance is regulated by acontinuous, hydrodynamically mediated,rate of prey intake into the area and theconcentrating effects of abiotic-bioticinteractions. This model was used withestimates of annual predator demands andprey concentration for the South Georgiaarea to investigate the relationship betweenflow rate and depletion in preyconcentration as a function of distance froma predator colony. The model resultsindicate that concentrating factors need to belarge to produce the build up of krilldensities of the order estimated to occur inthe South Georgia area, with the peakretention rates required to occur somedistance offshore. It was found, however,that in order to maintain the estimatedsupply rates the region need not be an areaof particularly high prey concentration tosupport the estimated predator impact.Differential predator foraging rangesproduce a more complex response to thereduction in the abundance of particularpredators by harvesting than in the situationwhere foraging ranges overlap completely.In such a system, predators which foragecloser to shore encounter the greatestchanges in prey abundance. Randomfluctuations in the interannual preyavailability were introduced into thesimulation of the flow system. This canlead to apparent cycle changes in predatorand prey abundance due to the interactiveform of the system even though the preypopulation dynamics are not taken intoaccount. The system enhances variabilitysuch that inshore foraging predatorsencounter greater variation in prey supply.The model results emphasise the importanceof investigating the magnitude and timing ofthe horizontal fluxes of secondaryproduction in this spatially distributedecosystem.

The timing of milk production inAntarctic fur seals was studied at BirdIsland, South Georgia. Like all lactatingotariid seals (Pinnipedia: Otariidae), femaleAntarctic fur seals alternate between shortnursing periods ashore and regular foragingtrips to sea. Females do not necessarilyreturn to the colony with full mammae,indicating that mammary volume capacityis unlikely to limit foraging trip duration.Upon arrival at the colony, milk fat(r2 = 0.33, P <0.04) and protein (r2 =0.60, P <0.002) content were positivelycorrelated to the time spent at sea. A similartrend was observed in the milk producedon land. The rate of milk energyproduction was much lower at sea (5.02 ±0.5 MJ•day-1) than on land (23.66 ±4.41 MJ•day-1). The rate of milk energyproduction during the foraging trip wasnegatively correlated to the time spent at sea(r2 = 0.29, P < 0.05), whereas the rate ofmilk energy production on land waspositively correlated (r2 = 0.61, P < 0.001)to the duration of the preceding foragingtrip. The total amount of milk energydelivered to the pup during each two-daynursing period was positively correlated(r2 = 0.60, P < 0.002) to the duration ofthe previous foraging trip. The overall rateof milk energy delivery, however, wasindependent of foraging trip duration. Thisaccords with Antarctic fur seal pup growthrates being unaffected by maternal foragingtrip duration patterns.

WG-CEMP-94/12Foraging behaviour of Antarctic furseals during periods of contrastingprey abundance. I.L. Boyd,J.P.Y. Arnould, T. Barton andJ.P. Croxall. Journal of Animal Ecology.63: 703-713, 1994 (English).

Foraging behaviour of Antarctic fur sealsrearing pups at Bird Island, South Georgia,was assessed using at-sea activity patternsmeasured by electronic time-depthrecorders. Information was obtained for a

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total of 75 individuals and 191 foragingtrips to sea over five reproductive seasonsfrom 1988/89 to 1992/93; this included oneseason (1990/91) of low prey abundance.A method was developed to divide thediving record up into logical units or boutswhich differed from past methods used fordefining bouts of behaviour. Foraging tripswere significantly longer in 1990/91 than inthe other years. There were significantdifferences between years in the proportionof time spent foraging when at sea and inthe distribution of foraging through the dayand night. These differences probablyrepresent behavioural responses to changesin prey distribution and abundance andwere reflected in the frequency ofoccurrence of different types of foragingbehaviour. Four types of foraging boutwere recognised using a cluster analysis.Type I (short) bouts were of short duration(17 minutes) and occurred mainly duringdaytime and at dusk. They probablyrepresented exploratory behaviour. Type II(long) bouts occurred mainly at night andwere of long duration (80 minutes). Theyincreased in frequency in 1990/91 whenfood was scarce and 61 to 73% of timespent foraging was in these bouts. Type III(shallow) bouts occurred mainly at night,were of short duration (12 minutes) andrepresented feeding close to the surface,possibly in association with other,surface-feeding krill predators. Shallowbouts accounted for 8 to 14% of time spentforaging. Type IV (deep) bouts were ofmedium duration (19 minutes) andrepresented feeding at greater depth (40 to50 m) than other bout types. They weremost abundant around dawn. Mean diveduration during bouts exceeded thetheoretical aerobic dive limit on >50% ofoccasions for short, long and deep bouts.There were positive correlations betweenmean dive duration and surface intervalduration for most of these bout types inmost years. This suggested that long divesincurred a cost in terms of the amount oftime spent at the surface between dives.The study demonstrated that female furseals invest a significantly greater effort inforaging during periods of low preyabundance by both increasing the time spentforaging and by increasing activity duringforaging. This could represent a 30 to 50%

increase in the costs of foraging duringyears of low food abundance.

WG-CEMP-94/13The use of heart rate to estimateoxygen consumption of free-rangingblack-browed albatrosses (Diomedeamelanophrys) . R.M. Bevan,A.J. Woakes, P.J. Butler and I.L. Boyd.Phil. Trans. Roy. Soc. Lond., Ser. B. (inpress): 19 pp. (English).

Heart rates fH( ) and rates of oxygenconsumption Vo2( ) were measured in eightblack-browed albatrosses (Diomedeamelanophrys) when walking on a treadmill,with the aim of using fH to predict Vo2 infree-ranging albatrosses. The resultingrelationship between the variables was: Vo2

(ml min-1) = [0.0157 fH (beats min-1)]1.60,r=0.80, P<0.001. In addition to thecalibration procedure, six of the albatrosseswere injected with doubly-labelled water(DLW), and fH and Vo2 were monitoredcontinuously over a three-day period whilethe birds were held in a respirometer.During the three-day period, the birds werewalked for up to three to four hours day-1 inbouts lasting approximately 0.5 hours. Theheart rate data were used to estimate themetabolic rates of these birds using theabove regression. Estimates of metabolicrate derived from fH , DLW andrespirometry did not differ (ANOVA;P=0.94), primarily because of the variancebetween individual birds. There was alsono significant difference between thedifferent estimates obtained from thedifferent equations used to calculate energyexpenditure from the DLW technique(ANOVA; P=0.95). Mean estimates ofVo2 from fH under active and inactiveconditions differed from measured valuesof Vo2 by -5.9% and -1.7% respectively.In addition, the estimates of Vo2 from fH atdifferent walking speeds did not differsignificantly from the measured values. Itappears that, in the black-browed albatross,fH is as good a predictor of the meanmetabolic rate of free-ranging birds as DLWor time-energy budgets combined witheither respirometry or DLW. However, themethod should be applied to as manyindividuals and as many instances of a

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particular behaviour as possible. The heartrate technique offers potential for muchmore detailed analyses of the daily energybudgets of these birds, and over muchlonger periods, than has previously beenpossible.

These provisioning rates, and theproportion of krill in the diet, are higherthan those recorded previously at SouthGeorgia and Indian Ocean sites, probablyreflecting high local availability of krill atSouth Georgia in 1986. In many respectswhite-chinned petrels at South Georgia areintermediate ecologically between prionsand albatrosses, although specialised intheir extensive consumption of myctophids.Because krill and all their main fish prey arecurrently the targets of substantialcommercial fishing and the main squid prey(Martialia) is a potential fisheries target, therole and status of white-chinned petrels isof additional importance.

WG-CEMP-94/14The food and feeding ecology of thewhite-chinned petrel (Procellariaaequinoctialis) at South Georgia.J.P. Croxall, A.J. Hall, H.J. Hill,A.W. North and P.G. Rodhouse.J. Zool., Lond., (in press): 44 pp.(English).

The diet of the white-chinned petrel atBird Island, South Georgia, was studiedduring the chick-rearing period in 1986 byquantitative analysis (by weight, frequencyof occurrence and number of individuals) ofregurgitated or lavaged adult stomachcontents. Antarctic krill was the mostimportant constituent of the diet,comprising over 90% of prey items andforming 47% of the diet by weight; fish andsquid occurred in 67% and 35% of samplesand formed 33% and 19%, respectively, ofthe diet by weight. Decapods, amphipodsand salps occurred in a few samples. Thefish were mainly lanternfish (Myctophidae)of eight species (chiefly of the generaElectrona and Gymnoscopelus), forming80% by numbers and 52% by mass of fishprey, and the notothenioid Patagonotothenguntheri (14% by number and 35% bymass). Of the squid species taken, theommastrephid Martialia hyadesi comprised57% by number and 52% by mass, and thegonatid Gonatus antarcticus 14% bynumber and 42% by mass. These dietarydata confirm white-chinned petrel as themost important avian consumer of fish andsquid at South Georgia (and the third mostimportant consumer of krill). In 1986 thenotothenioid fish were probably obtainedvia commercial fishing operations, but themyctophids and squid were probablylive-caught, most likely at night. Meal sizeincreased rapidly until chicks were threeweeks old and then remained constant untilthe chicks were within 10 days of fledging,when it decreased. Meal delivery rate washigh (one per day) for young chicks (1 to10 days old) and thereafter fluctuatedbetween 0.56 and 0.88 meals per day untilclose to fledging, when it was halved.

WG-CEMP-94/15Interannual variation in the breedingbiology of the Antarctic prion(Pachyptila desolata) at Bird Island,South Georgia. G.M. Liddle. J. Zool.,Lond., 234: 125-139, 1994 (English).

Interannual variation in aspects of thebreeding biology of Antarctic prions wasstudied for three summers (1989 to 1992) atBird Island, South Georgia. Egg size andmass and incubation period remainedconstant. Laying, hatching and fledgingwere significantly delayed and lesssynchronous in 1991/92 (the range oflaying dates was 51 days compared to 10 to15 days in the two other seasons). Thiswas due to an unusually cold and protractedwinter, with ice blocking burrows into thespring, restricting the availability of nestsites. Brooding lasted longer in 1991/92,but the overall fledging period wasunchanged. Skeletal growth rates did notvary amongst years; growth in mass wasslower in 1989/90 but fledging mass wassimilar in all three years. In 1989/90 and1991/92 later-hatched chicks grew (inmass) faster. The survival of chicks fromhatching to fledging did not vary amongstyears or with hatching date. Feedingfrequency was similar between years, onceallowance had been made for starlit nights.Thus late and asynchronous breeding in1991/92 did not result in reduced breedingsuccess, either through predation orstarvation. Crustaceans formed 98 to 99%of the mass of the identifiable portion ofregurgitated food samples. Significantannual variation was found within thesecrustaceans, with the presence of krill (least

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in 1990/91) being inversely related to thatof amphipods and copepods. There was norelationship between diet composition andchick growth or survival. Other species,lacking the morphological specialisation forfeeding on copepods and amphipods, hadvery low breeding success in 1990/91,when krill was scarce.

Way NE, Seattle, Wa. 98115, USA), 4 pp.(English, unpublished).

WG-CEMP-94/21Annual variation in fledging sizeand breeding success of cape petrelsat Seal Island, Antarctica.M.K. Schwartz and J.L. Bengtson(National Marine Mammal Laboratory,National Marine Fisheries Service, 7600Sand Point Way NE, Seattle, Wa. 98115,USA), 5 pp. (English, unpublished).

WG-CEMP-94/16 Rev. 1CEMP indices and trends. CCAMLRSecretariat, 28 pp. (English, unpublished).

Indices of predator reproductive statusare calculated for CEMP parameters such asadult weight on arrival at breeding colony,duration of foraging trips, breedingpopulation size and success, chick weightand diet, and fur seal pup growth rates(Methods A1 to A9, B1 and B2 and C1 andC2) using data held at the CCAMLR DataCentre. Preliminary statistical and graphicalanalyses of the trends shown by indices arepresented. Information on the ice-coverwithin CEMP study regions is also provided(Method F2).

Cape petrels (Daption capensis) arewidely distributed, abundant Antarcticprocellariids which utilise near-surface,marine prey. This species has been selectedfor inclusion in the CCAMLR EcosystemMonitoring Program (CEMP), which seeksto detect and quantify various aspects ofecological change in selected components ofthe Antarctic marine ecosystem.Information about the relationship betweenthe growth and reproductive performance ofcape petrels and its prey availability wouldprovide a useful complement to similarinformation on penguins, which utilise preyover a range of depths and, being solelyreliant upon their swimming ability, mustforage near breeding colonies. To evaluatethe potential utility of incorporating capepetrel studies into the longterm CEMPmonitoring and directed research beingconducted at Seal Island, Antarctica(60°59’S 55°23’W), a low-intensity effortto collect relevant cape petrel data wasinitiated during the 1989/90 australsummer. The main objectives of this effortwere to assess the feasibility of collectingdata on parameters of growth andreproduction, and to determine theinterannual variability of these parameters.

WG-CEMP-94/17Data on crabeater seal reproductionand demography: modellingfunctional relationships in theAntarctic marine ecosystem.J.L. Bengtson and P.L. Boveng (NationalMarine Mammal Laboratory, NationalMarine Fisheries Service, 7600 Sand PointWay NE, Seattle, Wa. 98115, USA), 3 pp.(English, unpublished).

WG-CEMP-94/18Compilation of informationconcerning the at-sea behaviour ofmarine mammals and birds and theprospects for a workshop onTDR-related data. P.L. Boveng(National Marine Mammal Laboratory,National Marine Fisheries Service, 7600Sand Point Way NE, Seattle, Wa. 98115,USA), 8 pp. (English, unpublished).

WG-CEMP-94/22Effects of time-depth recorders onforaging behaviour of lactatingAntarctic fur seals. B.G. Walker andP.L. Boveng (National Marine MammalLaboratory, National Marine FisheriesService, 7600 Sand Point Way NE, Seattle,Wa. 98115, USA), 16 pp. (English,unpublished).

WG-CEMP-94/19Variability in diving behaviour ofAntarctic fur seals: implicationsfor TDR studies. P.L. Boveng,B.G. Walker and J.L. Bengtson (NationalMarine Mammal Laboratory, NationalMarine Fisheries Service, 7600 Sand Point

The use of microprocessor-controlledtime-depth recorders (TDRs) or similarinstruments has become widespread instudies of the diving behaviour and

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foraging energetics of marine mammals(e.g., LeBoeuf et al., 1989; Goebel et al. ,1990; Hindell et al., 1991; Boyd andCroxall 1992; Boness et al., 1994), birds(e.g., Croxall et al., 1991; Kooyman et al. ,1992; Williams et al., 1992; Bengtson etal., 1993), and turtles (e.g., Eckert et al. ,1989; Sakamoto et al., 1990; Sakamoto etal., 1993). To ensure that data obtained byTDRs are accurate, it is important to assesschanges in swimming and diving behaviourand foraging characteristics that may becaused by encumbering study animals withthese instruments. A few studies havefocused on the effects of attaching TDRsand other research devices to diving birds(Wilson et al., 1986; Wanless et al., 1988;Croll et al., 1991). A specialisedconference addressing this issue wasrecently convened (Fraser and Trivelpiece,1994). However, to our knowledge, nostudies of reptiles and only one pertainingto mammals (Boyd et al., 1991) have beenreported regarding the effects of instrumentattachment. A number of characteristicsmake Antarctic fur seals (Arctocephalusgazella) ideal subjects to use in examiningthe effects of instrument attachment. First,the general size of A. gazella females fallsin between that of smaller seabirds (e.g.,Adélie (Pygoscelis adeliae), chinstrap(Pygoscelis antarctica), gentoo (Pygoscelispapua), king (Aptenodytes patagonica) andemperor (Aptenodytes forsteri) penguins)and the larger pinniped species (e.g., grey(Halichoerus grypus), Weddell(Leptonychotes weddellii) and elephant(Mirounga sp.) seals), for which a largenumber of instrument studies have beenconducted. Second, the repeatedforaging-nursing strategy of otariid sealsduring the lactation period (Oftedal et al. ,1987; Costa, 1991) provides a short unit ofcomparison (i.e., one or a group of feedingtrips as compared to, say, the long feedingtrips that elephant seals or gray seals takebetween parturition and molt). Finally, thesite fidelity of females during nursingprovides a high probability of instrumentreturn and retrieval. In this study, weevaluate differences in the duration offoraging trips at sea and nursing visitsashore between lactating Antarctic fur sealscarrying either a TDR and radio transmitter(TDR + TX) or a radio transmitter only(TX-only).

WG-CEMP-94/23Delayed laying and prolongedfasting in Adélie penguins(Pygoscelis adeliae) . J. Ulbricht andD. Zippel. Polar Biol., 14: 215-217, 1994(English).

Observations of nesting Adélie penguins(Pygoscelis adeliae) were made at ArdleyIsland during spring 1990 when snowcover was unusually thick at somesubcolony sites. Adélie penguins at thesesites had to delay egg laying until the snowmelted. Maximum length of fastingperiods, comprising pre-breeding andincubation, was 50 days. Long fastingseemed to have no detrimental effect onbreeding. Furthermore, there was norelationship between penguin arrival massand duration of fast. Even birds with smallmass had sufficient reserves to undergolong fasting periods. In spring 1990, whenwe started with a monitoring study forCEMP (CCAMLR, 1990) at Ardley Island,there were still high quantities of snow atthe subcolony sites. Adélie penguins atArdley Island inhabit both small rockyoutcrops and flat, stony hillocks (stormbars). The latter had a distinctly thickersnow cover at this time so that the pebblesnecessary for nest building wereunattainable. Consequently, we observedthe behaviour of the penguins in thissituation and recorded the laying dates andlengths of fasting periods.

WG-CEMP-94/24A generalised discriminant forsexing fulmarine petrels fromexternal measurements. J.A. vanFraneker and C.J.F. ter Braak. The Auk. ,110 (3): 492-502, 1993 (English).

Discriminant analysis can usemorphometric differences between knownmale and female birds to predict the sex ofunknown individuals in field studies.Geographic variation in birds morphometricmeasurements often limits the predictivevalue of a discriminant function to thepopulation from which it was derived.Specific discriminant functions forpopulations of five species of fulmarinepetrels (Northern fulmar, Fulmarusglacialis; Southern fulmar, F. glacialoides;Antarctic petrel, Thalassoica antarctica;Cape petrel, Daption capense; and snowpetrel, Pagodroma nivea) assigned 81 to

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98% of birds in the samples to the correctsex, but the validity of each discriminantapplied to alternative populations remainedquestionable. Our approach to overcomethis limitation is to combine data from thedifferent species into a single discriminant.Adequate performance of this generaliseddiscriminant in samples of different speciesshows its validity for use in otherpopulations of any of these species. Thegeneralised function calculates thediscriminant scores for individual fulmarinepetrels as: Y = HL + 2.38 BD + 0.41 TL -0.21 CL, where HL is head length, BD is billdepth, TL is tarsus length and CL is billlength (measurements in millimetres). Thecut point to split sexes is different in eachsample and may be calculated directly fromdiscriminant scores, without reference tosexed birds, by using a maximum-likelihood method. Depending on species,the generalised method results in 84 to 97%correct classifications and can be applied toother populations of fulmarine petrelswithout requiring samples of birds ofknown sex.

entirely on sand eels, they themselves atesome fish from other fish families andprobably digested these before theyreturned to the colony. Pellets are easy tocollect and are useful to detect grosschanges in the diet of full-grown, butpossibly non-breeding, shags betweenyears or colonies. Otoliths recovered frompellets cannot be used for age determinationor back-calculations of size of sand eelseaten by shags. Regurgitations can be usedto describe the diet of chicks. There is noeasy way to determine the diet of adultsfeeding chicks.

WG-CEMP-94/27Monitoring Antarctic environmentalvariables using penguins. R. Wilson,B. Culik, R. Bannasch and J. Lage. Mar.Ecol. Prog. Ser., 106: 199-202, 1994(English).

Water temperature and krill abundance inMaxwell Bay, Antarctica, were examinedusing Pygoscelid penguins carryingappropriate sensors linked to position-determining devices. Fifty-three foragingtrips by 49 penguins indicated that duringDecember 1991 and January 1992 thetemperature in the top 100 m of the watercolumn was highest in the western sectionof the bay, which concurred with higherkrill abundance as determined by acatch-per-unit-effort index. This workdemonstrates that abiotic and biotic featuresof the environment can be studied usinganimals to transport probes to the studysite, provided information is given on theposition of the animals when measurementsare made.

WG-CEMP-94/25Sexing chinstrap penguins(Pygoscelis antarctica) bymorphological measurements.J. Amat, J. Viñuela and M. Ferrer.Colonial Waterbirds, 16 (2): 213-215,1993 (English).

We applied discriminant analysis tomorphometric data from chinstrap penguins(Pygoscelis antarctica) to obtain a functionthat can be used to predict sex. Thefunction correctly classified 95% of55 individuals. Bill depth was the mostimportant discriminating variable, withmales having deeper bills.

WG-CEMP-94/28Synthesis of CEMP activities carriedout at Cape Shirreff. D. Torres (JefeDepartamento Planes, Instituto AntárticoChileno, Luis Thayer Ojeda 814, Correo 9,Santiago, Chile), 4 pp. (English,unpublished).

WG-CEMP-94/26The diet of shags (Phalacrocoraxaristotelis) during the chick-rearingperiod assessed by three methods.M. Harris and S. Wanless. Bird Study,40: 135-139, 1993 (English).

During the 1993/94 Antarctic season acensus of Antarctic fur seals was carried outover the whole area of SSSI No. 32 and theCape Shirreff CEMP site: 15 139 animalswere recorded, i.e. an increase of 14.3% on1992/93 numbers. Only two sets of data onpup growth, using Standard Method C2,were obtained, for both (n = 48) male andfemales, on 15 December 1993 and

This paper describes a study of the dietof shags using regurgitations by chicks,stomach contents and pellets collectedconcurrently. Sand eels predominated in allcollections. Non- and failed breeders tooka wider food spectrum than did chicks.Although adults fed their chicks almost

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22 January 1994. Average weights formales were 7.2 kg and 10.62 kg, and forfemales 6.70 and 9.73 on those respectivedates. Foraging trips made by femaleswere observed, and environmental datarecorded. Additional censuses ofpost-breeding elephant seals (1 375) andWeddell seals (75) were carried out.Nearly all marine debris (280 kg) along theshoreline of Cape Shirreff (13 986.5 m)was removed. Three fur seals (peripheralmales) were sighted with neck collars. Adraft bathymetric chart (SHOA No. 14.301,scale 1:15 000) of the waters around theCEMP site was produced to providebackground information for this research.

may have been overestimated in previousstudies.

WG-CEMP-94/30Progress report on AMLR project ‘Amodelling study of the populationbiology of krill, seabirds andmarine mammals in the SouthernOcean’. M. Mangel, A. Stansfield andS. Rumsey (Section of Evolution andEcology, University of California, DavisCa. 95616), 9 pp. (English, unpublished).

WG-CEMP-94/31Analysis of the stomach content inthe blue-eyed shag (Phalacrocoraxatriceps bransfieldensis) at NelsonIsland, South Shetland Islands.N. Coria, R. Casaux, M. Favero andP. Silva (Dirección Nacional del Antártico,Cerrito 1248, 1010 Buenos Aires,Argentina), 16 pp. (English, unpublished).

WG-CEMP-94/29Preliminary results of a feeding trialon the blue-eyed shag(Phalacrocorax atriceps) . R. Casaux,M. Favero, E. Barrera-Oro and P. Silva(Dirección Nacional del Antártico, Cerrito1248, 1010 Buenos Aires, Argentina),14 pp. (English, unpublished).

The stomach contents of 40 blue-eyedshags (Phalacrocorax atricepsbransfieldensis) were sampled at NelsonIsland, South Shetland Islands, in January1994. The analysis of the diet showed thatfish were by far the main component,followed by octopods, polychaetes andgammarids. Notothenia coriicepspredominated by frequency (58%) andweight (65%), whereas Nototheniopsnudifrons was the most important bynumber (47%). A comparison withpublished data on pellet analysis of shagsfrom the same colony gave similar results.However, although the methodology usedin the present study requires more time inthe field, it reduces errors caused by factorsconfounding the examination ofregurgitated casts, such as erosion bydigestion or otolith loss through thegastrointestinal tract. The analysis ofstomach contents is complemented withinformation obtained from film footages ofshags’ foraging trips.

Local fish species were fed to a captiveblue-eyed shag Phalacrocorax atricepsbransfieldensis during 45 days of theaustral summer at Jubany Station, KingGeorge Island, South Shetland Islands.The otoliths of fish identified in pellets wereaffected by the digestive process and,consequently for this reason the fish specieswere differentially under-represented innumber and size (length/mass). Except forGobionotothen gibberifrons, Nototheniopsnudifrons, and, to some extent, forG. gibberifrons the numbers of all specieswere underestimated. N. rossii, Pagotheniabernachii, N. nudifrons, Trematomusnewnesi and Notothenia coriiceps werelargely underestimated. Preliminarycorrection factors were obtained to improvethe accuracy of weight estimations of fishingested, calculated by means of equationsbased on otolith lengths. The shagproduced a total of 16 pellets, with afrequency of one every 2.5 days. Itwillingly ingested a mean ration equivalentto 31% of its mass, which is a higherenergy requirement than that observed inexperiments on other non-Antarctic shagspecies. Algae and polychaetes were foundin casts and fish stomachs. Therefore, theirimportance in the diet of the blue-eyed shag

WG-CEMP-94/32Fish as diet of the blue-eyedshag (Phalacrocorax atricepsbransfieldensis) at Half-moonIsland, South Shetland Islands.E. Barrera-Oro and R. Casaux (DirecciónNacional del Antártico, Cerrito 1248, 1010Buenos Aires, Argentina), 15 pp. (English,unpublished).

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Thirty eight regurgitated casts collectedin a colony at Half-moon Island, SouthShetland Islands, during January andFebruary 1993, were analysed to determinethe importance of fish in the diet of theblue-eyed shag, Phalacrocorax atricepsbransfieldensis. Fish species wereidentified by means of otoliths found in thecasts. The size and weight of the fish wereestimated from the otolith lengths, usingequations derived from data on localpopulations. Fish remains were present inall casts and comprised 91% of prey items.In the 937 otoliths found, 562 individualfish were present and 524 of these wereassigned to five demersal benthic species:Nototheniops nudifrons, Harpagiferantarcticus, Trematomus newnesi,Notothenia coriiceps and Gobionotothengibberifrons. N. nudifrons was the mostfrequent (68.4%) and important by number(37.9%), whereas N. coriiceps prevailedaccording to mass (35.8%). With theexception of G. gibberifrons, the fishspecies (and their size and age ranges) wereidentical to those found in a similar study atDuthoit Point, Nelson Island. However,the relative importance of the various fishspecies in the diet differed among shagsfrom the two areas.

values for healthy penguins, which may beof use in diagnosis, are presented also.Just as environmental factors are beingexamined for their possible effect on thevariables being monitored, we suggest thatthe health of monitored species should alsobe considered in CEMP.

WG-CEMP-94/35Diseases and parasites of penguins.J. Clarke and K. Kerry. Korean Journal ofPolar Research, 4 (2): 79-96, 1993(English).

The study of diseases in wild penguinsis important for the identification ofendemic diseases and the detection of exoticdiseases should these occur. It is alsoimportant in the understanding of the degreeto which disease may be expected toinfluence the results of biological studies.Results may be confounded andinterpretation made difficult by both thetransient and longterm presence of disease,particularly if it is at the sub-clinical level.We present here a compilation of diseasesand parasites recorded for all species ofpenguins both in the wild and in captivity.Normal values for blood biochemistry andhaematology are given as an aid to theidentification of illness in penguins.

WG-CEMP-94/33 WG-CEMP-94/36Adélie penguins as consumers offish and zooplankton communities.K. Kerry, J. Clarke, S. Brown,R. Lawless and K. Young (AustralianAntarctic Division, Channel Highway,Kingston, Tasmania 7050, Australia),10 pp. (English, unpublished).

Diving behaviour of chinstrappenguins at King George Island.H.-C. Shin and S. Kim (Polar ResearchCenter, Korea Ocean Research andDevelopment Institute, Ansan PO Box 29,Seoul, Republic of Korea), 12 pp.(English, unpublished).

The diving behaviour of threechick-rearing adult chinstrap penguins(Pygoscelis antarctica) was studied at KingGeorge Island, Antarctica in January 1994.Foraging dives by chinstrap penguins weremade most frequently at depths of 5 to10 m and were usually less than 40 mdeep. Dive duration distribution wasbetween 20 and 120 seconds and only asmall number of foraging dives were longerthan 120 seconds. Diving effort wasconcentrated around midnight, with a slightpeak observed around noon and infrequentdives occurring in the morning. Averagedive depth was approximately 20 to 30 maround midnight and 40 to 50 m aroundnoon. Diurnal changes in the diving pattern

WG-CEMP-94/34Infectious diseases and parasites ofAntarctic and sub-Antarcticpenguins and the implications forCEMP. J. Clarke and K. Kerry (AustralianAntarctic Division, Channel Highway,Kingston 7050, Tasmania, Australia),14 pp. (English, unpublished).

This paper draws attention to thepossible implications for the CCAMLREcosystem Monitoring Program (CEMP) ofinfectious and parasitic disease amongpenguins being monitored. A summary ofall such diseases of penguin species foundin the Antarctic and sub-Antarctic ispresented. Haematological and biochemical

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of chinstrap penguins may be related to thediurnal migration of their prey, Antarctickrill.

Due to between-measurer variation, it isrecommended that morphometricmeasurements obtained by others on sexedbirds are compared with ours beforeproceeding with the use of the discriminantfunction on unsexed individuals.

WG-CEMP-94/37AMLR 1993/94 field season report:Objectives, accomplishments andtentative conclusions. AdministrativeReport LJ-94-13, Southwest FisheriesScience Center, Ja Jolla, Ca., USA, 1994,117 pp. (English).

Joint Meeting of WG-Krilland WG-CEMP

WG-CEMP-94/38TDR-derived foraging performanceindices. W.Z. Trivelpiece andS.G. Trivelpiece (Department of Biology,Montana State University, Bozeman, Mt.59717, USA), 1 pp. (English,unpublished).

WG-Joint-94/4Further development of a krillfishery simulation model.D.J. Agnew (CCAMLR Data Manager,25 Old Wharf, Hobart, Tasmania 7000,Australia), 4 pp. (English, unpublished).

The krill fishery model presented in1993 (WG-Krill-93/14) is refined and appliedto both Japanese and Chilean krill-fishingfleets in Subarea 48.1. A stochasticelement is introduced to account forvariability in catch rates. The mostsuccessful management regime is found tobe one which limits fishing within 75 km ofbreeding penguins during January andFebruary. For this regime, the modelpredicts a 90% reduction in overlap withforaging predators and a 15 to 20%reduction in catch. Closure of LivingstonIsland for the breeding period resulted in a60% reduction in overlap with predatorsand a 0 to 15% reduction in catches.

WG-CEMP-94/39Seabird research at Svarthamaren,Dronning Maud Land. N. Røv(Norwegian Institute for Nature Research,Tungasletta 2, N-7005 Trondheim,Norway), 6 pp. (English, unpublished).

WG-CEMP-94/40Recommendations from theworkshop on researcher-seabirdinteractions for consideration forinclusion in the WG-CEMP StandardMethods. W.Z. Trivelpiece (Departmentof Biology, Montana State University,Bozeman, Mt. 59717, USA), 4 pp.(English, unpublished).

WG-Joint-94/5WG-CEMP-94/41 Modelling functional relationships

between predators and prey.J.P. Croxall, I.L. Boyd and P.A. Prince(British Antarctic Survey, High Cross,Madingley Road, Cambridge CB3 0ET,United Kingdom), 9 pp. (English,unpublished).

Sex determination of Antarcticpetrels (Thalassoica antarctica) bydiscriminant analysis ofmorphometric characters.S.-H. Lorentsen and N. Røv. Polar Biol. ,14: 143-145, 1994 (English).

We present data on sexual dimorphismin some morphological measurements(wing length, head length, bill depth andbill length) in the Antarctic petrel,Thalassoica antarctica. Males were onaverage larger than females for allmeasurements. Sexual dimorphism was onaverage largest for bill depths, whereaswing lengths discriminated least betweenthe sexes. A discriminant functionincluding bill depth, head length and winglength correctly sexed 92% of the sample.

Preliminary analyses of this topicidentified some problems with the dataoriginally submitted. To clarify theseproblems and to provide additional data tomake the overall model more accurate andrelevant, this paper provides quantitativeinformation on potential biases associatedwith the estimation of survival rate,observed rates of population increase (bothmaxima and by study colonies from whichthe data derived) and diet for black-browedalbatross, gentoo penguin and Antarctic fur

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seal at Bird Island, South Georgia. Inaddition, the paper presents year-specificdata for (i) black-browed albatross breedingpopulation size and success and adultsurvival (1976 to 1992); (ii) gentoo penguinbreeding population size and success (1977to 1993); and (iii) Antarctic fur seal adultfemale survival (1984 to 1993, includingallowance for tag loss), pregnancy rate, pupproduction, pup growth rates and mortalityrates and foraging trip duration (1984 to1993).

Secretariat, 25 Old Wharf, Hobart,Tasmania 7000, Australia). CCAMLRScience, (in press): 8 pp. (English).

CCAMLR has been using the total catchof krill taken within 100 km of penguincolonies during their breeding season(December to March) as an indicator of theoverlap between the foraging areas ofpenguins and the distribution of the krillfishery in Subarea 48.1 (South ShetlandIslands). As this indicator of the overlap ofpredators and the fishery is unsuitable for anumber of reasons, an alternative method ofcalculating an indicator of fishery-predatorinteraction has been developed. The newindicator reflects the functional interactionbetween these two utilisers of the krillresource and is based on a detailed model ofthe foraging patterns of the penguinscombined with catch positions. Thisanalysis shows that the overlap between thefishery and chinstraps is much greater thanfor other penguins, and that this overlap hasbeen decreasing since 1988.

WG-Joint-94/6Modelling functional relationshipsbetween predators and prey.W.Z. Trivelpiece and S.G. Trivelpiece(Department of Biology, Montana StateUniversity, Bozeman, Mt. 59717, USA),6 pp. (English, unpublished).

WG-Joint-94/7Diagnostic model of functioning ofAntarctic krill population in theSodruzhestva Sea. V. Belyaev,M. Khudoshina, V.N. Yakovlev,V.A. Bibik and E.A. Pakhomov (ScientificCentre of Problems in EcologicalModelling, Ukrainian Academy of Science,Crimea, Ukraine), 2 pp. (English,unpublished).

WG-Joint-94/9Distribution and abundance ofAntarctic krill in the vicinity ofElephant Island during the 1994austral summer. R.P. Hewitt andD.A. Demer (Southwest Fisheries ScienceCenter, La Jolla, Ca. 92038, USA), 15 pp.(English, unpublished).

This paper describes several approachesto the mathematical modelling of Antarctickrill populations in the Sodruzhestva Sea.The area was chosen because YugNIRO hasbeen conducting longterm observationsthere on krill biology and biomass and othercomponents of the local pelagic ecosystem,and also because of the availability of catchdata from 1978 to 1984 and 1988. Theobjective of the study was to reveal bymeans of mathematical modelling the causesof sharp fluctuations in krill abundance inthe Sodruzhestva Sea. The main task wasto assess variations in parameters of theecosystem and its stability against theimpact of such variations. The potential fordeveloping a prognostic model describingthe functioning of Antarctic krill populationis discussed.

The distribution and abundance ofAntarctic krill (Euphausia superba) wereestimated from four acoustic surveysconducted in the vicinity of Elephant Island,Antarctica, from mid-January to mid-March1994. The first and fourth surveys coveredapproximately 15 000 n miles2 aroundElephant Island and the eastern end of KingGeorge Island; the second and third surveyscovered approximately 2 100 n miles2

immediately north of Elephant Island.During the first survey, the highestdensities of krill were mapped north ofKing George Island and over a broad bandnorthwest of Elephant Island. For a portionof the survey area around Elephant Island(approximately 12 000 n miles2), biomasswas estimated to be 401 x 106 tonnes. Fiveweeks later highest densities of krill weremapped north of Elephant Island andbiomass in the same survey portion wasestimated to be 359 x 106 tonnes. Duringthe second and third surveys, high densities

WG-Joint-94/8Development of a fine-scale modelof land-based predator foragingdemands in the Antarctic.D.J. Agnew and G. Phegan (CCAMLR

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of krill were mapped in the shoal waters tothe north of Elephant Island; biomasseswere estimated to be 87 x 106 tonnes and97 x 106 tonnes respectively. Average krilldensities were the lowest observed duringthe last five years of AMLR surveys in theElephant Island study area and one-fifth ofthe average density for the period 1990 to1992. In spite of the low krill densities, thereproductive success of land-breedingpredators did not appear to be adverselyaffected.

E. chrystallorophias appears to peak fromthe end of November to early December andmay extend to the beginning of January.Most larvae were in the stage ofmetanauplius/calyptopis I at the beginningof January, and calyptopis III/furcilia Iduring February. The year-1 cohort wasidentified in January-February with a meanlength in the range of 10.8 to 16.8 mm. Insitu feeding rates were estimated in theLazarev Sea using the gut fluorescencemethod. Ingestion rates during australsummer 1990/91 ranged from 52 to 471 ng(pigm) ind/-1h-1 in adults and from 2.5 to25.2 ng (pigm) ind/-1h-1 in calyptopis IIIlarvae. Total population impact on thephytoplankton biomass varied between 160to 2 860 and 215 to 652 µ g (C) m-2d-1 foradults and larvae respectively. This isequivalent to 0.06 to 1.12% and 0.02 to0.07% of total daily primary production. Inareas with dense E. chrystallorophiasswarms, however, daily consumption ratesmay attain levels as high as 13.6 to 96.5%of daily primary production. The longtermmonitoring of different populations ofE. chrystallorophias allowed theidentification of covariance patternsbetween abundance and spawning successof this species and the formation of coastalpolynyas, especially in the Prydz Bayregion.

WG-Joint-94/10Antarctic neritic krill Euphausiachrystallorophias: spatio-temporaldistribution, growth and grazingrates. E.A. Pakhomov andR. Perissinotto (Southern ScientificResearch Institute of Marine Fisheries andOceanography (YugNIRO), 2 SverdlovStreet, Kerch 334500, Crimea Ukraine),11 pp. (English, unpublished).

Dynamics of distribution, growth,life-span and feeding were studied in theendemic Antarctic euphausiid Euphausiachrystallorophias in the central part of theIndian sector of the Southern Ocean duringthe austral summer (1977 to 1990), and inthe Lazarev Sea during the summer of1990/91. Both larvae and adultE. chrystallorophias were found inabundance in shelf waters 100 to 500 mdeep. Maximum abundances of larvae (upto 7 688 ind/m-2) and adults (up to1 267 ind/m-2) were found in the PrydzBay region. Size frequency analysisindicated that the generation time was ≈three years in the Indian sector of theSouthern Ocean. Total life span ofE. chrystallorophias may exceed five yearsin the Prydz Bay region and four years inthe Kosmonavtov Sea. Analysis of sizedistribution by sex showed that maleE. chrystallorophias had a shorterlife-span than females, although theirgrowth rates were similar. Assuminggrowth for only 180 days per year, meangrowth rates ranged from 0.070 to 0.075 to0.019 to 0.022 mm per day during the firstand the fourth year respectively. VonBertalanffy growth curves calculatedfor different areas were similar to thoseobtained by Siegel (1987) for theAntarctic Peninsula region. In Prydz Bayand the Kosmonavtov Sea, spawning of

WG-Joint-94/11Gentoo penguin (Pygoscelis papua)diet as an indicator of planktonicavailability in the KerguelenIslands. C.A. Bost, P. Koubbi,F. Genevois, L. Ruchon and V. RidouxPolar Biol., 14: 147-153, 1994 (English).

Since penguins rely on the mainplanktonic resources of the SouthernOcean, knowledge of penguin diet may beused for monitoring these resources.During the winter and spring of 1987 and1989, we investigated the composition ofthe diet of gentoo penguins, Pygoscelispapua, in relation to changes in theavailability of two prey species, Euphausiavallentini and Themisto gaudichaudii,sampled during plankton surveys in theKerguelen Islands. The results of planktonsurveys and diet analysis were comparedfor samples taken 2 to 4 km from thestudied colonies. Data on the abundance ofzooplankton derived from penguins’ diet

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matched closely those obtained from nethauls during a year of high planktonavailability (1987). On the other hand, aweaker correspondence was found during ayear of restricted availability (1989). Themean sizes of amphipods taken by penguinsand caught in net hauls were very similar,but the size distribution showedcomparatively fewer small and largeindividuals in net-hauls than in penguinstomachs. Detailed studies on the feedingrange and foraging effort of penguins aretherefore needed in the near future tovalidate the potential of penguin diet as ameasure of plankton abundance.

patchiness must be incorporated intoanalyses of krill availability to predatorpopulations if we are to predict predatorresponses to a changing food environment.

WG-Joint-94/13Birds as indicators of change inmarine prey stocks.W.A. Montevecchi. Birds as Monitors ofEnvironmental Change. Chapman andHall, London: 217-266, 1993 (English).

WG-Joint-94/14Draft report of the study ground onseabird/fish interactions.Copenhagen, 6-10 September 1993, 22 pp.(English).WG-Joint-94/12

Acoustic visualisation of thethree-dimensional prey field offoraging chinstrap penguins.J.E. Zamon, C.H. Greene, E. Meir,D.A. Demer, R.P. Hewitt and S. Sexton(Department of Ecology and EvolutionaryBiology, University of California - Irvine,Irvine Ca. 92717, USA), 25 pp. (English,unpublished).

WG-Joint-94/15Estimated food consumption bypenguins at the Prince EdwardIslands. N.J. Adams, C. Moloney andR. Navarro. Antarctic Science, 5 (3):245-252, 1993 (English).

The consumption of food by the fourspecies of penguins breeding at the PrinceEdward Islands is assessed on annual andseasonal bases. Total annual foodconsumption was estimated at 880 000tonnes, of which king penguins accountedfor 74%, macaroni penguins 21%,rockhopper penguins 5% and gentoopenguins <1%. Pelagic fish, almostentirely myctophids, were the mostimportant prey (70% of total prey biomass),followed by pelagic crustaceans (18%) andcephalopods (11%). Demersal fish andbenthic crustaceans accounted for <1% oftotal consumption, being consumed only bygentoo penguins. Peak demands ofbetween 2 and 3.3 x 106 kg day-1 occurredfrom October to December when three ofthe four species, including the twodemi-populations of king penguins, werebreeding. Food demand decreased to1.2 x 106 kg day-1 during winter, whenonly king and gentoo penguins werepresent. Much of the prey are presumablycaptured within 300 km of the islands.Assuming an even distribution of foragingeffort within their respective foragingranges, rates of food transferred topenguins in November from 4.1 x 10-3

gm-2day-1 for macaroni penguins to 1.24 x10-2 gm-2day-1 for king penguins. Inmid-July, transfer rates to king and gentoo

Predator-prey interactions play animportant role in determining the dynamicsof pelagic ecosystems. Human interventionin such interactions may have effects thatcascade throughout these ecosystems.Recently, concerns have arisen due to thecommercial harvesting of Euphausiasuperba, the Antarctic krill, a keystone preyspecies in the Southern Ocean food web. Ithas been difficult to evaluate these concernsbecause of problems associated withdetermining the availability of krill to itsnatural predators. In this paper we report anovel method for assessing prey availabilityto an important krill predator, Pygoscelisantarctica, the chinstrap penguin. Acoustictechniques were used to analyse thethree-dimensional distribution of krillwithin a 1 852 x 1 852 x 100 m volume ofocean. Our study revealed the presence ofat least six distinct krill aggregations andsubstantial vertical and horizontalpatchiness at scales of tens to hundreds ofmetres. Monte Carlo simulations revealedsignificant spatial concordance between thesurface distribution of penguins and krilldistributed in the 30 to 40 m depth layer; nospatial concordance was detected inshallower layers. We conclude thatfine-scale, depth-dependent patterns of krill

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penguins were 3.9 x 10-3 gm-2 day-1 and6.7 x 10-3 gm-2 day-1 respectively. Theimportance of pelagic myctophid fish topenguin populations at the Prince EdwardIslands is clear.

103 tonnes/half-month period), the presentcatch rate (≤13 x 103 tonnes/half-monthperiod) is smaller by one or more orders ofmagnitude within the localised areas. Thus,the present fishery is very unlikely to behaving an adverse impact on the local krillbiomass and hence on penguins, whencatch levels are also taken into account.

WG-Joint-94/16An environmental information andmodelling system (EIMS) forsustainable development: from thearid subtropical to Antarctica.V. Marín (Depto. Cs. Ecológicas, Facultadde Ciencias, Universidad de Chile, Casilla653, Santiago, Chile), 2 pp. (English,unpublished).

Working Group onFish Stock Assessment

WG-FSA-94/4WG-Joint-94/17 Dynamics of Notothenia rossii

rossii size-age structure on theKerguelen Islands shelf.P.B. Tankevich (Southern ScientificResearch Institute of Marine Fisheries andOceanography (YugNIRO), Laboratory ofSouthern Ocean Fish Resources,2 Sverdlov Street, Kerch 334500 Crimea,Ukraine), 12 pp. (English, unpublished).

A revised assessment of the impactof the krill fishery on penguins inthe South Shetlands. T. Ichii,M. Naganobu and T. Ogishima (NationalResearch Institute of Far Seas Fisheries5-7-1, Orido, Shimizu 424, Japan), 20 pp.(English, unpublished).

This paper presents a revision of theassessment of the competition between theJapanese krill (Euphausia superba) fisheryand penguins (WG-Krill-93/7). The mainfishing areas were confined to the slope andshelf to the north of either Livingston orElephant Islands. In contrast, the mainforaging areas of penguins are consideredto be found in areas to the north of KingGeorge, Nelson and Robert Islands, andaround Low, Clarence and DeceptionIslands. This small overlap between themain fishing and foraging areas occursbecause large colonies of the dominantpenguin species (chinstrap penguins,Pygoscelis antarctica) are closely associatedwith areas where sea-ice disappears earlierin spring, and not necessarily with areas ofhigh krill abundance. The overlap betweentrawling depth and foraging dive depth ofpenguins was also insignificant.Furthermore, less similarity was observedbetween krill caught by trawlers and thosecaptured by penguins. Theabovementioned results imply a low level ofcompetition between the fishery andpenguins. Krill biomass was estimated tobe as large as 200 to 1 500 x 103 tonneswithin the preferred fishing areas during thebreeding season. Compared with thelevel of biomass (≥200 x 103 tonnes)and its variability (the order of 100 x

Size-age structure dynamics of themarbled rockcod (Notothenia rossii rossii)population are shown (based on results ofresearch expeditions and fishing cruises tothe Kerguelen Island shelf in the period1970 to 1991). Age data from 1970 to1989 (Tankevich, 1990) and data collectedduring the joint Soviet-French expedition ofthe RTMA Orlinoye in May and June 1991were used to characterise age composition.It was determined that in the initial years ofexploitation of the stock, most catches(more than 80%) were comprised of repeatspawners. As the fishery developed, theproportion of fish spawning for the firsttime increased considerably in catches, andin some years (1981 to 1985) fisheries werebased practically on recruitment. After theclosure of the fishery in 1985, and after themarbled rockcod by-catch in other fisherieswas limited to 500 tonnes, a stable trendtowards an increase in catches of the meanage and length was noted. In May and June1991, the mean length was 59.2 cm andmean age was 7.4 years; some 70% of thecatch consisted of repeat spawners. Theauthor considers the demographicpopulation structure in 1991 to be close tothat observed in the initial years ofexploitation and that further closure of themarbled rockcod fishery may lead to an

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increase in natural mortality of thepopulation as the whole. Removal of olderage groups is recommended to start in thenear future. This will make it possible tocontrol size-age structure changes in thespawning part of the population.

WG-FSA-94/8Preliminary results of agedetermination by otolith mass inmackerel icefish (Champsocephalusgunnari Lönnberg 1905) in theHeard Island area (Australia).I.B. Russelo (Southern Scientific ResearchInstitute of Marine Fisheries andOceanography (YugNIRO), 2 SverdlovStreet, Kerch 334500 Crimea, Ukraine),10 pp. (Russian, unpublished).

WG-FSA-94/5Analyses performed at the 1993Meeting of the Working Group onFish Stock Assessment. CCAMLRSecretariat (25 Old Wharf, Hobart,Tasmania 7000, Australia), 25 pp.(English, unpublished).

Otolith mass was used to determine theage of mackerel icefish Champsocephalusgunnari. The material was collected in Julyand August 1987 during the joint Soviet-Australian expedition of the RV ProfessorMesyatsev to the Heard Island shelf area.The otoliths were weighed with an electricbalance to within 0.0001 g. The data thusobtained underwent statistical processingusing the cluster analysis method. Five agegroups were defined. The Bertalanffylinear growth equation was calculated:

WG-FSA-94/6Preliminary results of mackerelicefish (Champsocephalus gunnari)age determination by weightmethod. I.B. Russelo (SouthernScientific Research Institute of MarineFisheries and Oceanography (YugNIRO),2 Sverdlov Street, Kerch 334500, Crimea,Ukraine), 1 pp. (English, unpublished). Lt = 41.73 (1-e -0.5149(1+0.05225))

On this basis the age/length key for thisseason has been estimated.WG-FSA-94/7

Course of fisheries in the LenaBank area (Division 58.4.4) in theseason of 1990/91. A.K. Zaitsev(Southern Scientific Research Institute ofMarine Fisheries and Oceanography(YugNIRO), 2 Sverdlov Street, Kerch334500, Crimea, Ukraine), 8 pp. (English,unpublished).

WG-FSA-94/9 Rev. 1New data on spawning, hatchingand growth of the Kerguelen IslandsChampsocephalus gunnari shelfstock. G. Duhamel (Museum nationald’histoire naturelle, Laboratoired’ichtyologie générale et appliquée, 43 rueCuvier, 75231 Paris Cedex 05, France).CCAMLR Science, (in press): 8 pp.(English).

In the season of 1990/91, fishingoperations in Division 58.4.4 (Lena Bank)were carried out by only one vessel, RTMAZvezda Kryma, from April to June 1991.The total catch in that period comprised971 tonnes of grey rockcod (Nototheniasquamifrons) and 29 tonnes of Patagoniantoothfish (Dissostichus eleginoides). Thereal catch exceeds the data in the StatisticalBulletin by nearly two-fold. Therefore it isnecessary to update the relevant documents.The size-age composition of catches did notundergo significant changes. The mean ageof fish was 7.0 years. Interannualfluctuations in size-age composition ofpopulations are more a result of the qualityand period of sampling than a reflection ofobjective changes in population structure ofthe species.

Combined studies of the inner and outershelves of the Kerguelen Islands (1989/90to 1992/93) have provided new informationabout the Champsocephalus gunnari stock.An inner-shelf quarterly program allows theyearly identification, both from the resultsof ichthyoplanktonic surveys and bottomhauls, of an annual cohort. Largedifferences in the abundance of larvae areobserved yearly. One cohort seemeddominant in the samples taken during thestudy. This would explain the previouslyobserved three-years cycle. Spawners havebeen observed in large numbers only onceduring the studied period, and are fishes ofthe 1988 cohort that first spawned duringthe winter of 1991/92.

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WG-FSA-94/10 Mean length-at-age data presented here fallin the range of available results fromprevious surveys in the South Georgiaregion.

Fish distribution and biomass in theHeard Island zone (Division58 .5 .2 ) .WG-FSA-94/30Addendum to documentWG-FSA-94/10. R. Williams andW. de la Mare (Australian AntarcticDivision, Channel Highway, Kingston7050, Tasmania, Australia). CCAMLRScience, (in press): 32 pp. (English).

WG-FSA-94/12Validation of age determination inNotothenia coriiceps by means of atag-recapture experiment at PotterCove, South Shetland Islands.E. Barrera-Oro and R. Casaux (DirecciónNacional del Antártico, Cerrito 1248, 1010Buenos Aires, Argentina), 21 pp. (English,unpublished).

Division 58.5.2 encompasses thesouthern part of the Kerguelen Plateau, andcontains Heard Island and the McDonaldIslands, an Australian territory aroundwhich a 200-mile EEZ has been declared.In order to assess the potential of this areafor commercial fishing, and to obtain somepreliminary data for its management, threebiomass surveys were conducted on theKerguelen Plateau in this division toinvestigate the distribution, abundance andbiology of the most important species,covering a number of years and seasons.Results of these surveys are discussed.

Of 409 Notothenia coriiceps specimenstagged and released at Potter Cover, SouthShetland Islands, in successive years from1989 to 1992, nine were recaptured at thesame site after periods of 11 to 21 months.A comparison was carried out between theannuli found in scales removed at themoment of tagging and after recapture. Inscales of those specimens recovered after11 to 13 months, one extra annulus waslaid down. The same analysis in oneindividual recovered after 21 monthsresulted in two extra closely spaced scleritezones, which corresponds with two winterseasons having elapsed. The comparativeanalysis between scales taken at recaptureand otolith cross sections of the sameindividual allowed the simultaneouscounting of annuli, which showed goodagreement. These results validate theprinciple of annual deposition of theannulus in scales and otoliths ofN. coriiceps. A preliminary analysis ofscales regenerated after release indicates thatthese observations are of value in validationstudies.

WG-FSA-94/11Age-length key forChampsocephalus gunnari fromSubarea 48.3, RV Dr EduardoHolmberg survey, February/March1994. E. Barrera-Oro, E. Marschoff andR. Casaux (Dirección Nacional delAntártico, Cerrito 1248, 1010 BuenosAires, Argentina), 10 pp. (English,unpublished).

An age/length key was prepared forChampsocephalus gunnari in Subarea 48.3,based on the readings of otoliths randomlycollected during the RV Dr EduardoHolmberg survey in February/March 1994.Small and medium-sized fish (total length -12 to 33 cm) constituted the bulk of thesamples (93%), while larger specimens(>33 cm) were scarce. At South Georgia,fish of age groups 1 to 4 were trulyrepresented; at Shag Rocks, a largeconcentration of fish belonging to agegroups 2 (90%) and 3 (10%) was found.The length-weighted distribution of all thefish sampled in Subarea 48.3 showed goodcorrespondence between modes and themean lengths of age groups 1 and 2. Suchcorrespondence was also obtained forage group 3 when the data fromSouth Georgia were analysed separately.

WG-FSA-94/13Areas of seabed within the 500 misobath around Elephant Island(CCAMLR Statistical Subarea 48.1).K.-H. Kock and U. Harm (Institut fürSeefischerei, Bundesforschungsanstalt fürFischerei, Palmaille 9 D-22767 Hamburg,Germany). CCAMLR Science, (in press):8 pp. (English).

Areas of seabed within 50 m depthcontours down to 100 m and within 100 mdepth contours from 100 to 500 m havebeen estimated from soundings obtainedduring plankton and bottom trawl surveysaround Elephant Island (the northernmost

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island of the South Shetland Islands) from1977/78 to 1992/93. The results arepresented on a fine-scale grid of 15’ latitudex 30’ longitude.

(British Antarctic Survey, High Cross,Madingley Road, Cambridge CB3 0ET,United Kingdom), 11 pp. (English,unpublished).

In 1991 the 0 age-class of C. gunnariwas sampled at Shag Rocks on 18 January,off Possession Bay, South Georgia during19 and 20 January and off much of thenorth-east coast of South Georgia between19 January and 19 February. The sizefrequency of fish at Shag Rocks containedtwo modes of 31 to 46 mm and 55 to87 mm SL. However, off Possession Bayonly one mode of 25 to 57 mm SL wasapparent. Fish in combined samples off thecoast of South Georgia were 24 to 63 mmSL. The mean and median sizes of fish atthese locations were all significantly(p < 0.001) different. The size differencebetween the large size mode at Shag Rocksand those at South Georgia must be theresult of different spawning seasons and/oregg development periods and/or growthrates. This suggests that there are twoseparate stocks of C. gunnari in a singleCCAMLR statistical subarea. There is anapparent growth of around 0.76% SL d-1

(0.27 mm SL d-1) for larvae on the SouthGeorgia shelf, which is comparable withprevious reports of early growth inC. gunnari.

WG-FSA-94/14The early life history of thePatagonian toothfish (Dissostichuseleginoides Smitt, 1898).S.A. Evseenko, K.-H. Kock andM.M. Nevinsky (Laboratory of OceanicIchthyofauna, P.P. Shirshov Institute ofOceanology, Russian Academy ofSciences, Krasikova 23, Moscow 117218,Russia), 17 pp. (English, unpublished).

Patagonian toothfish, Dissostichuseleginoides, spawn over the continentalslope from July to September. Eggs havebeen observed primarily in the upper part ofthe water column over 2 200 to 4 400 mbottom depth. Embryos in stages III andIV of their embryonic development aredescribed. Hatching is likely to occur inOctober/November. Scales do not start toform before the fish are 64 to 74 mm long.

WG-FSA-94/15The diet composition and feedingintensity of mackerel icefish(Champsocephalus gunnari) atSouth Georgia in January/February1994. K.-H. Kock, I. Everson,L. Allcock, G. Parkes, U. Harm,C. Goss, H. Daly, Z. Cielniaszek andJ. Szlakowski (Institut für Seefischerei,Bundesforschungsanstalt für Fischerei,Palmaille 9 D-22767 Hamburg, Germany),24 pp. (English, unpublished).

WG-FSA-94/17Large variations in mackerel icefish(Champsocephalus gunnari)standing stock at South Georgia: areAntarctic fur seals (Arctocephalusgazella) the cause? I. Everson,G. Parkes, I.L. Boyd and K.-H. Kock(British Antarctic Survey, High Cross,Madingley Road, Cambridge CB3 0ET,United Kingdom), 9 pp. (English,unpublished).

The diet composition and feedingintensity of mackerel icefish(Champsocephalus gunnari) around ShagRocks and the mainland of South Georgiawere analysed from 3 691 stomachscollected in January/February 1994. Mainprey items were the amphipod hyperiidThemisto gaudichaudii, mysids (primarilyAntarctomysis maxima), and krill(Euphausia superba) in the vicinity of SouthGeorgia, and T. gaudichaudii andThysanoessa sp. around Shag Rocks.

The mackerel icefish (Champsocephalusgunnari) stock at South Georgia has beensubject to heavy fishing in the past 20 yearswhich has caused significant impact onstock size. There has been no reportedcommercial catch since March 1990.Variations in standing stock in recent yearshowever, have been far greater than can beexplained by the effects of fishing alone. Amajor component in the diet of icefish iskrill (Euphausia superba). Seasons inwhich icefish show the greatest reduction inits stock size coincide with periods of krill

WG-FSA-94/16Evidence of two stocks ofChampsocephalus gunnari in theSouth Georgia region, CCAMLRfishing Subarea 48.3. A.W. North

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scarcity. Food shortage appears to havesome effect on fish condition, but this is notsufficient to explain recent large-scale stockdeclines. Emigration and dispersal into thewater column in years of scarcity can leadto a negative bias in stock size estimates.Both of these factors are consideredunlikely to have such a dramatic effect, butneither are considered likely to haveproduced the dramatic changes in observedstock size. Fur seals feed preferentially onkrill, but when krill are scarce they switchto feeding on fish. Even if icefishrepresented a very small proportion of thediet of fur seals, this could explain the greatreduction in icefish standing stock. Thisconclusion has significant implications formanaging icefish and for fisheries marinemammal interactions in general.

krill yield model. A.J. Constable andW. de la Mare (School of Aquatic Scienceand Natural Resources Management,Deakin University, PO Box 426,Warrnambool, Victoria 3280, Australia),12 pp. (English, unpublished).

Traditional methods for estimatingyield-per-recruit as a function of fishingmortality can result in inappropriate highestimates of yield that may lead to depletionof stocks because of widely varyingrecruitment patterns, overestimation of theabundance of the stock and age of the mostrecent survey. These problems areaddressed in this paper by using stockprojections to assess the probabilities of thestock of Electrona carlsbergi becomingdepleted over a 20-year period. Theseprojections have been undertaken using ageneralised version of the CCAMLR KrillYield Model. This is appropriate becausethis species shares a number of attributeswith krill, including population dynamics,behaviour and its importance as prey in theAntarctic ecosystem. The decision rules fordetermining yield adopted by the WorkingGroup on Krill were used for this analysis(where yield = γ , median pre-exploitationbiomass): (i) choose γ 1, so that theprobability of the spawning biomassdropping below 20% of its pre-exploitationmedian level over a 20-year harvestingperiod is 10%; (ii) choose γ 2, so that themedian escapement over a 20-year period is75%; (iii) select the lower of γ 1 and γ 2 asthe level of γ for calculation of yield. Theestimate of γ for a fishery targeting juvenilefish was 0.091.

WG-FSA-94/18Fish stock assessment survey inSubarea 48.3. I. Everson, G. Parkes,K.-H. Kock, C. Goss, Z. Cielniaszek,J. Szlakowski, H. Daly, L. Allcock andG. Pilling (British Antarctic Survey, HighCross, Madingley Road, Cambridge CB30ET, United Kingdom), 34 pp. (English,unpublished).

WG-FSA-94/19Software for WG-FSA-94 . CCAMLRSecretariat (25 Old Wharf, Hobart,Tasmania 7000, Australia), 4 pp. (English,unpublished).

WG-FSA-94/20Summary of the Dissostichuseleginoides fishery in Subarea 48.3in the 1993/94 season. D.J. Agnew(CCAMLR Secretariat, 25 Old Wharf,Hobart, Tasmania 7000, Australia), 7 pp.(English, unpublished).

WG-FSA-94/22Determination of local density ofDissostichus eleginoides in Subarea48.3: CCAMLR protocol localdepletion experiment Ihn Sung 66 -January 1994. C. Jones and G. Parkes(Marine Resources Assessment Group,8 Prince’s Gardens, South Kensington,London SW7 1NA, United Kingdom),46 pp. (English, unpublished).

The progress of the fishery forDissostichus eleginoides in Subarea 48.3 inthe 1993/94 season is described. Fishingtook place around Shag Rocks and SouthGeorgia, being concentrated in four of thefive experimental areas. CPUE for 1994appears similar to that from previous years,except for Chilean vessels.

A longlining stock depletion trial wasundertaken by the Korean longliner IhnSung 66 in January 1994 in accordancewith CCAMLR Conservation Measure 69/XIIand the Experimental Protocol circulated bythe Secretariat in COMM CIRC 93/50. Theresults of this experiment are presented.

WG-FSA-94/21Revised estimates of yield forElectrona carlsbergi based on ageneralised version of the CCAMLR

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Leslie and DeLury methods are tested usingsimulations to determine which of these isthe most appropriate method. The Lesliemethod is applied using a specialised Catchand Effort Data Analysis computer package(CEDA) to calculate local abundance.Alternative error models are investigated toestimate confidence intervals for the localstock estimate. The initial population sizewas estimated to be 2 914 fish. Assuminga fishable area of 50 n miles2, thisrepresented a density of 0.5kg/n miles2.Suggestions are made for the design offuture depletion experiments.

1NA, United Kingdom), 12 pp. (English,unpublished).

WG-FSA-94/25Preliminary results on by-catch offish during krill fishery in March toMay 1993 on the Polish trawlerMT Lepus. Z. Cielniaszek andR. Pactwa (Department of Biology andConservation of Fish Resources, SeaFisheries Institute, Kollataja 1, 81-332Gdynia, Poland), 15 pp. (English,unpublished).

From the end of March to the beginningof May 1993 investigations were carriedout to determine biological/fisheriescharacteristics of exploited fish stocksduring krill fishing operations conducted bythe MT Lepus on the fishing grounds offSouth Orkney Islands and South Georgia.One goal was to determine the proportion ofjuvenile fish forms present in krillconcentrations. This study gives the resultsof these observations. It appears from theinvestigations that the by-catch of juvenilefish in the krill fishery was small, while offthe South Orkney Islands there was no suchby-catch at all in the samples collected. Inboth areas a small by-catch of species fromthe family Myctophidae was observed.

WG-FSA-94/23Performance and geometry of theFP-120 trawl used during the UK1993/94 fish stock assessmentsurvey around South Georgia,Subarea 48.3. G. Pilling and G. Parkes(Marine Resources Assessment Group,8 Prince’s Gardens, South Kensington,London SW7 1NA, United Kingdom).CCAMLR Science, (in press): 18 pp.(English).

Methods for the calculation of thehorizontal opening (swept area) of a bottomtrawl are discussed. Details are provided ofthe Scanmar trawl monitoring equipmentused for making in situ measurements ofhorizontal opening and heading height ofthe FP-120 trawl during the 1993/94 UK fishstock assessment survey around SouthGeorgia on the MV Cordella are provided.Empirical equations are derived for thecalculation of horizontal opening fromother, more easily obtained, measurements,such as tow speed and trawl depth. A newmultiple regression equation is compared tothat used previously for the estimation ofbiomass parameters of the major fishspecies around South Georgia. Theresulting difference in biomass estimates isof the order of a 1% to 5% increase,depending upon species.

WG-FSA-94/26Preliminary aspects of a simulationmodel to be used for evaluating theexperimental crab fishery. G. Watters(Southwest Fisheries Science Center,PO Box 271 San Diego, Ca. 92038,USA), 23 pp. (English, unpublished).

At the 1993 meeting of the WorkingGroup on Fish Stock Assessment,members requested that work be undertakento evaluate certain aspects of theexperimental management strategy for theAntarctic crab fishery. A simulation modelis proposed for conducting this work.Length-frequency and catch-rate data fromthe 1991/92 crab fishery are used tomotivate the construction of an ontogeneticmigration model for describing crabdistribution, movement and recruitmentduring the simulation. The fisherysimulation is spatially explicit, and thedynamics of crab abundance are describedon a daily basis. The simulation includesadvective and diffusive movement rates, a

WG-FSA-94/24Comments on the use of stockdepletion models for the assessmentof local abundance of toothfish inSubarea 48.3 and adjacent waters.G. Parkes and G. Pilling (MarineResources Assessment Group, 8 Prince’sGardens, South Kensington, London SW7

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lagged Beverton-Holt stock recruitmentrelationship, and a model for catch thatcontains a random normal deviate. Finally,an algorithm is developed for describing thespatial and temporal distribution of fishingeffort during the simulation. This algorithmis based on the idea that each fishing vesselconstructs a map of expected catch ratesacross the fishing grounds. Each vesselupdates this expectation map on a dailybasis and uses it to determine thedistribution of targeted fishing effort andsearching effort.

WG-FSA-94/28Preliminary study on reproductionin Champsocephalus gunnari fromSubarea 48.3, RV Dr EduardoHolmberg survey, February/March1994. G. Macchi and E. Barrera-Oro(Instituto Nacional de Investigación yDesarrollo Pesquero, Mar del Plata,Argentina), 6 pp. (English, unpublished).

A preliminary histological analysis of theovarian development in Champsocephalusgunnari was carried out. Six stages ofoocytary development were identified andare similar to those described for otherspecies. A gonad maturation scale waselaborated and adapted to the macroscopicscale commonly used. Oocytary resorptionprocesses were observed during ovarianmaturation. In some cases the ovariespresented few atretic oocytes; in others ageneralised regression was found. In thesouthwest portion of the South Georgiashelf, 50% of the ovaries exhibited apre-reproductive regression stage similar tothat reported for the same species in the1991 summer season.

WG-FSA-94/27Diet composition ofChampsocephalus gunnari inSubarea 48.3, RV Dr EduardoHolmberg survey, February/March1994. E. Barrera-Oro, R. Casaux andA. Roux (Dirección Nacional del Antártico,Cerrito 1248, 1010 Buenos Aires,Argentina), 17 pp. (English, unpublished).

The diet composition of the icefishChampsocephalus gunnari caught inSubarea 48.3 in February/March 1994 wasanalysed using the frequency of occurrence(%) method. Krill (Euphausia superba),followed by the amphipod hyperiidThemisto gaudichaudii, were the main preyitems at South Georgia and Shag Rocks;fish were found in the stomachs morefrequently than in past seasons aroundSouth Georgia, which contrasts with thevirtual absence of mysids and Thysanoessaspp. Krill abundance was at levels similarto those of previous years (e.g., 1985,1992). However, high proportions ofempty stomachs were found in fish at SouthGeorgia and Shag Rocks, close to thevalues reported for the 1991 year of krill‘shortage’. Moreover a tentative analysis ofpart of the samples using the coefficient Q(%) showed T. gaudichaudii to be moreimportant than krill. It is possible that theinconsistencies found between the resultsobtained by both methods are due to aparticular spatial distribution of krill in thearea during the period of study, however noprevious data are available for comparison.No krill aggregations were found in theregion by acoustic methods in the 1994summer season; this may be related to asignificant change in surface temperatureobserved during the cruise.

WG-FSA-94/29Preliminary results of theRV Dr Eduardo Holmberg 1994cruise to Subareas 48.2 and 48 .3 .E. Marschoff, B. Prenski, B. Gonzalez,C. Remaggi and C. Balestrini (InstitutoAntártico Argentino, Cerrito 1248, 1010Buenos Aires, Argentina), 28 pp. (English,unpublished).

A total of 63 hauls and10 oceanographical transects were carriedout. Of these, 44 hauls made inSubarea 48.3 according to a randomstratified design are used to estimate the sizeof standing stocks of the main commercialfish species using different methods, aswell as to estimate their length frequencydistributions. A change in surface watertemperature of about -0.5° to -1.0° over aperiod of approximately 20 days wasdetected around the South Georgia islands.In the Scotia Sea the boundary of theWeddell-Scotia confluence was withinhistorical limits, while surface water (downto 50/70 m) was warmer than expected. Itwas also found that the spatial structure offish populations significantly affects theresults of biomass estimates.

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WG-FSA-94/31 WG-IMALF-94/6Depletion experiment ofDissostichus eleginoides stock inthe south of South Georgia Island(Antarctica). P.S. Rubilar, C. Morenoand J.R. Ashford (Instituto de Ecología yEvolución, Universidad Austral de Chile,Casilla 567, Valdivia, Chile), 13 pp.(Spanish, unpublished).

Albatross mortality and associatedbait loss in the Japanese longlinefishery in the Southern Ocean.N. Brothers. Biol. Conservation,55: 255-268, 1991 (English).

A conservative calculation of the numberof albatrosses killed annually on Japaneselonglines in southern oceans is 44 000.The actual figure could be double this, andis sufficiently high to substantiate claimsthat serious declines in albatrosspopulations are due to this fishing activity.Albatrosses have an economic impact onlongline fisheries, with annual losses to thesouthern bluefin tuna fishery aloneexceeding A$7 million. If all fish speciesand the total longlining effort wereconsidered, this figure would be manymillions of dollars greater. Apart from aconcern for albatrosses, Japan’s longlinefishermen would also benefit by using thesolutions offered. It is suggested that a70% reduction in the problem is possibleand that an overall reduction in excess of90% could be achieved. Furthermonitoring is essential.

A depletion experiment was carried outfrom 11 to 21 April 1994 to assess an initialbiomass of Dissostichus eleginoides, southof South Georgia. Ten longlines were setwith at least part of each longline fallingwithin a circle of diameter 10 n milescentred at 55°03’S 36°53’W. The Lesliemethod was applied to the data. Initialbiomass was projected to 3 244.8 n miles2,giving an estimated biomass of 937.8tonnes. Due to the statistical limitations ofthese data, another data-based analysis(kg/n miles2) of the fished area was alsoperformed. The positions of the vesselwere verified by information obtained froman ARGOS automatic position system.

WG-FSA-94/32Bottom trawling survey on the Oband Lena Banks. Ukraine, 5 pp.(English, unpublished).

WG-IMALF-94/7Population dynamics of thewandering albatross (Diomedeaexulans) on Macquarie Island andthe effects of mortality fromlongline fishing. W. de la Mare andK. Kerry (Antarctic Division, ChannelHighway, Kingston, Tasmania 7050,Australia) 50 pp. (English, unpublished).

Ad Hoc Working Group onIncidental Mortality Arisingfrom Longline Fishing

The estimated breeding population ofwandering albatrosses on Macquarie Islandincreased from 17 in 1956 to a maximum of97 in 1966, and then declined at an averagerate of 8.1% per year. Mark-recaptureanalysis shows that the population is notclosed (i.e., it is subject to immigration andemigration). The decline is correlated withthe onset of large-scale fishing for tuna inthe Southern Hemisphere using longlines.The effect of longline mortality on thepopulation dynamics of the wanderingalbatross is estimated. An annual numberof longline hooks in the SouthernHemisphere tuna fishery of 41.6 million iscalculated as the ceiling below which thepopulation would begin to recover.

WG-IMALF-94/4Seabird mortality on longlinefishing for tuna in southern Brazil.T. Vaske Junior. Ciencia e Cultura, 43(5):388-390, 1991 (English).

The mortality of seabirds(Procellariiformes) accidentally hookedduring longline fishing for tuna in southernBrazil is estimated. Results obtainedthrough onboard observation during fishingcruises showed that this fishing technique isa significant cause of bird mortalityassociated with tuna fishing.

WG-IMALF-94/5Seabird mortality in longlinefisheries around South Georgia.J. Dalziell and M. de Poorter. PolarRecord, 29 (169): 143-145, (English)._________________________________________________________________________________________

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WG-IMALF-94/8 setting of gear might cause considerable baitloss and occasional hooking of birds mighteventually give high mortalities consideringthe large numbers of hooks used. Bothfrom a fishery and bird conservation pointof view there is a strong incentive to solvethis problem. This paper describes trialsusing a seabird scarer in the Norwegianlongline fishery. The scarer, a line withstreamers trailing behind the vessel duringsetting of the gear, proved to be an effectivedevice for scaring the birds away, and gavesignificantly reduced bait loss and no birdmortality.

Use of a population model to assessthe impact of longline fishing onwandering albatross (Diomedeaexulans) populations. C. Moloney,J. Cooper, P. G. Ryan and W. RoySiegfried. Biological Conservation, 70:195-203, 1994 (English).

An age-structured model of a wanderingalbatross Diomedea exulans population isdeveloped to simulate population trendsover time, using demographic parametersfrom the population at Possession Island,Crozet Island, during the period 1968 to1986. The simulation results portray apopulation decreasing at a rate of 2.29% peryear, which concurs with global populationtrends. Sensitivity analyses of modelparameters indicate that both adult andjuvenile mortality are contributing to thedecrease. Wandering albatross mortality ispresumed to have increased as a result ofdeaths caused by longline fishing vessels;such deaths are likely to be relatively morefrequent among young, naive birds. Themodel is used to investigate the potentialimpacts of new longline fisheries such asthat for Patagonian toothfish Dissostichuseleginoides in Antarctica. Assuming thatlongline fishing operations affect juvenilesmore than adults, there is a time lag of 5 to10 years before further decreases inpopulation numbers are reflected in thebreeding population. Also, becausewandering albatrosses are long-lived,population growth rates take approximately30 to 50 years to stabilise after aperturbation. Consequently, caution mustbe exercised when interpreting populationtrends; short-term (<20 year) estimates maynot provide good indications of longtermtrends.

WG-IMALF-94/10Report on a tuna longlining fishingvoyage aboard Southern Venture toobserve seabird by-catch problems.M.J. Imber (New Zealand), Department ofConservation, 1994 (Science and ResearchSeries, 0113-3713, No. 65).

Incidental captures of seabirds, and thebehaviour of seabirds around the fishinggear as it was deployed, were observedduring eight days’ fishing by a NewZealand-owned tuna longliner. From11 200 hooks set, six seabirds werehooked and recovered: five wanderingalbatross (Diomedea exulans) of whichthree were released alive, and oneblack-browed mollymawk (D. melanophrysimpavida). Relatively more birds survivedhooking in this study because of the lightergear and quicker recovery of the longline(about six hours between beginning the setand beginning hauling in). Petrels,particularly cape pigeons Daption capense,were mainly responsible for bringing thesinking baits back to the surface wherealbatrosses/mollymawks subsequently atemost of them. About 1.2% of baits weretaken by seabirds, but only 4.5% ofbait-takes resulted in a bird being hooked.The mollymawk was hooked at night nearfull moon, but under thick cloud. Mostbait-takes occurred in daylight, particularlybefore dusk. The vessel’s bird-scaring lineseemed to reduce, but not eliminatebait-taking. The mortality rate of seabirds(0.27/1 000 hooks set) is similar to that inthe only other two reported studies.Seabirds scavenged intensively on thewaste baits (41% of those cast) thrownoverboard during hauling in. More birds

WG-IMALF-94/9Reduced bait loss and by-catch ofseabirds in longlining by using aseabird scarer. S. Løkkeborg andÅ. Bjordal (Fish Capture Division,Institute of Marine Research, PO Box1870, N-5024 Bergen, Norway), 5 pp.(English, unpublished).

Although longlining is regarded as ahighly conservation-oriented method offishing, the by-catch of seabirds onlonglines is a problem in certain seasonsand areas. Birds feeding on bait during the

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32


followed in the wake during hauling thanduring setting.

Niort, France), 30 pp. (English,unpublished).

In recent years, a new longline fisheryfor the fish Dissostichus eleginoides hasdeveloped in the vicinity of South Georgiaand Kerguelen Islands, two internationallyimportant breeding areas for procellariiformbirds. The attractiveness of this fishery forseabirds, together with the incidentalcapture of birds and a method to reducemortality were investigated during 13 daysof fishing activity in Kerguelen watersduring February 1994. Between 100 and600 seabirds were observed to be followingthe vessel at all times. The main speciesobserved to be following the ship were thewhite-chinned petrel (67% of the counts),the giant petrel (8%) and three species ofalbatrosses, the wandering (11%),black-browed (6%) and grey-headed (2%)albatrosses. All these species are attractedby baited hooks which sink during linesetting(s). More attempts to feed on baitsare made by skilled divers such as thewhite-chinned petrel (87% of the totalnumber of tries), the black-browed (7%)and the grey-headed (6%) albatrosses, thanby species never observed submerged suchas the wandering albatross (<1%).Consequently, the seabird by-catchincluded only species which are capable ofdiving, i.e., the white-chinned petrel(n = 36) and the grey-headed albatross(n = 2). Marked differences in themortality rate were observed between dayand night (1.00 versus 0.38 birds per 1 000hooks), and, at night, when the deck lightswere on or off (0.59 versus 0.15 birds per1 000 hooks). Importantly, dumping ofhomogenised offal during line settinggreatly reduced incidental capture ofseabirds (only one white-chinned petrelkilled on 41 longlines), mainly becausebirds were more attracted by offal than byhooked baits. On average, the mass ofoffal (crushed head, gut and tail ofD. eleginoides) thrown overboard duringline setting was 10-times greater than that ofbait. Moreover, offal sank slower thanhooked baits, being thus available to theseabirds in larger amounts and over alonger time. We therefore propose thatregulation governing the longline fisheryfor D. eleginoides include the use of offaldumping during line setting in order tominimise seabird mortality.

WG-IMALF-94/11Changes in population size of largeprocellariiformes breeding in theFrench sub-Antarctic islands:potential influence of southernfisheries and particularlylonglining. H. Weimerskirch andP. Jouventin (Centre d’Etudes Biologiquesde Chizé, Centre National de la RechercheScientifique, Villiers-en-Bois, 79360Beauvoir-sur-Niort, France), 21 pp.(English, unpublished).

Studies carried out over the past threedecades in the French austral territoriesindicate that most albatross and giant petrelpopulations have markedly declined.Demographic studies indicate that thesedeclines are mainly the result of increasedadult mortality. This high rate of mortalityhas been suspected to be the result ofmortality incurred in longline fisheries.Satellite tracking studies of breeding birdsand band recoveries of non-breeding birdsindicate that during and outside the breedingseason these populations are in contact withlongline fisheries, mainly the pelagicJapanese tuna fishery but also, to a lesser,extent the neritic toothfish, Dissostichuseleginoides, fishery operating in theKerguelen EEZ. The decrease in the fishingeffort of the Japanese fishery during recentyears has probably resulted in the slowrecovery of the wandering albatrosspopulation. Longline fisheries are likely torepresent a major threat to long-livedseabirds in the Southern Ocean. IndianOcean populations are particularly at riskfrom the tuna fishery. Potential threatsfrom the Kerguelen toothfish fishery exist,but can be kept to a minimum if measures toreduce mortality continue to be enforced inthe EEZ.

WG-IMALF-94/12Interactions between longlinevessels and seabirds in Kerguelenwaters and a method to reduceseabird mortality. Y. Cherel,H. Weimerskirch and G. Duhamel (Centred’Etudes Biologiques de Chizé, CentreNational de la Recherche Scientifique,Villiers-en-Bois, 79360 Beauvoir-sur-

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33

WG-IMALF___________________________________________________________________________

WG-IMALF-94/13 J.P. Croxall, P.S. Rubilar and C. Moreno(British Antarctic Survey, NaturalEnvironment Research Council, HighCross, Madingley Road, Cambridge, CB30ET, United Kingdom). CCAMLR Science,(in press): 22 pp. (English).

Entanglements and incidentalmortality of birds and seals -summary of reports to CCAMLR1985 to 1993. CCAMLR Secretariat(25 Old Wharf, Hobart, Tasmania 7000,Australia), 21 pp. (English, unpublished). Longlining operations for Dissostichus

eleginoides off South Georgia wereassessed for incidental mortality andinteractions with seabirds. Twenty-sevenlines were observed and 98 mortalitiesrecorded over 20 sets of the line; nomortalities occurred during hauls. The16 sets made at night contributed 15% ofthe overall mortality, all of white-chinnedpetrels; the four day-time sets contributed85% of overall mortality, with giant petrels,grey-headed albatrosses and black-browedalbatrosses predominating. Our datasuggest that grey-headed albatrosses,whose populations at South Georgia are inserious decline, were disproportionatelyaffected in relation to their numbers in thevicinity of the fishing vessel; giant petrelsalso may be disproportionately affected, atleast in relation to the size of theirbreeding population at South Georgiawhen compared to the albatrosses.Average mortality rate for the20 sets was 0.48birds/1 000 hooks andmaximum mortality 3.12 birds/1 000hooks. Mortality and interactions of birdswith operations varied with site and time ofday, and due to behavioural interactionsbetween birds. Setting only at night woulddramatically reduce albatross deaths, butwould substantially increase white-chinnedpetrel mortalities. A streamer line made toCCAMLR specifications may also reducemortalities but may be less effective duringcalm weather, intense feeding activity byseabirds, or when incorrectly constructed.

This paper summarises the incidence ofentanglements and incidental mortality ofbirds and seals reported by CCAMLRMembers for the CCAMLR Convention Areaand adjacent waters from 1985 onwards. Abibliography on entanglement, incidentalmortality and effects of marine debris onseabirds and marine mammals is attached.The bibliography includes papers cited indocuments submitted to CCAMLR.

WG-IMALF-94/14Report on incidental bird mortalityand effectiveness of mitigationmeasures during demersallonglining by Ihn Sung 66 inSubarea 48.3: December 1993 toFebruary 1994. C. Jones and G. Parkes(Marine Resources Assessment Group,8, Princes Gardens, South Kensington,London SW7 1NA, United Kingdom),17 pp. (English, unpublished).

A method of surveying incidentalmortality of seabirds during longliningoperations and the effectiveness ofmitigation measures is described. Analternative streamer line design for use withthe ‘Spanish’ method of longlining(separate hauling and fishing lines) isdescribed. The results of observations ofincidental mortality of seabirds made duringthe fishing operations of the Koreanlongliner Ihn Sung 66 are presented.Preliminary findings suggest that the phaseof daylight during which the longline is setis more important than the use of a streamerline in the mitigation of incidental mortality.The use of a streamer line during setting oflonglines during the day reduced theobserved rate of bird deaths from snaggingand drowning by 79%. More data arerequired to develop the investigationfurther.

WG-IMALF-94/16Interactions between cetaceans andlonglining operations for Patagoniantoothfish Dissostichus eleginoidesaround South Georgia. J.R. Ashfordand P. S. Rubilar (British Antarctic Survey,Natural Environment Research Council,High Cross, Madingley Road, Cambridge,CB3 0ET, United Kingdom), 18 pp.(English, unpublished).

WG-IMALF-94/15Seabird interactions with longliningoperations for Dissostichuseleginoides around South Georgia,April and May 1994. J.R. Ashford,

Longlining operations for Dissostichuseleginoides around South Georgia wereassessed for interactions with sea

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34


mammals. Twenty seven lines wereobserved and interactions recorded during25 of these. During setting of lines neithermortalities nor interactions were recorded.All interactions occurred during haulingoperations, both during the day and atnight. Killer whales (Orcinus orca) werepresent during one haul, from which only11 intact fish were taken aboard, comparedto a mean of 510 fish/haul for all 27 lines.Sperm whales (Physeter macrocephalus)were also associated with haulingoperations and may have been removingfish captured on the lines. Numbers ofsperm whales varied with location; somewhales with identifying marks wereobserved over successive lines to thesouthwest of South Georgia, but were notseen on subsequent operations to thenorthwest of the island. On two occasions,sperm whales were snagged on the line butwere freed. Interviews with fishermenindicated that interactions of killer whalesand sperm whales with longliningoperations may be common in the SouthAtlantic and off southern Chile. Fishermenrecognised that these interactions werecostly in terms of fish and fishing time lost;the development of measures to reduceinteractions may help prevent fishermentaking action potentially harmful tocetaceans.

have been found at Gough Island and nobirds have been found dead ashore on eitherisland as a result of fishing gear.Recoveries of banded birds at sea suggestthat wandering albatrosses are more at riskof being hooked than giant petrelsMacronectes sp.

WG-IMALF-94/19Principles of birdline constructionand use to reduce bait loss and birddeaths during longline setting.N. Brothers (Department of Parks,Wildlife and Heritage, GPO Box 44A,Hobart, Tasmania 7001, Australia), 5 pp.(English, unpublished).

WG-IMALF-94/20Catching fish not birds: a guide toimproving your longline fishingefficiency (English version).N. Brothers (Department of Parks,Wildlife and Heritage, GPO Box 44A,Hobart, Tasmania 7001, Australia), 40 pp.(English, unpublished).

Part 1 of this guide provides generalinformation on species composition andnumbers of birds caught, and Part 2explains why and how the birds take baitsand how many they take. Part 3 discussesthe factors which affect the rate of bait loss,while Part 4 gives details of methods whichcan be used to reduce bait loss and birddeaths. Finally, Part 5 briefly describeswhat makes seabirds so vulnerable to beingcaught on longlines.

WG-IMALF-94/17Mortality of albatrosses and otherseabirds produced by tuna longlinefisheries in Uruguay. L. Barea,I. Loinaz, Y. Marin, C. Ríos,A. Saralegui, A. Stagi, R. Vaz-Ferreiraand N. Wilson (Instituto Nacional de Pesca(INAPE), Consitiuyente 1497, MontevideoC.P. 11200, Uruguay), 12 pp. (English,unpublished).

WG-IMALF-94/21Population trends and vulnerabilityto tuna longlining by-catch ofalbatrosses, mollymawks andProcellaria petrels of New Zealandseas. M.J. Imber (Science and ResearchDivision, Department of Conservation,PO Box 10-420, Wellington, NewZealand), 6 pp. (English, unpublished).

WG-IMALF-94/18Seabird mortality from longlinefisheries: evidence from Marion andGough Islands. J. Cooper (PercyFitzpatrick Institute of African Ornithology,University of Cape Town, Rondebosch7700, South Africa), 8 pp. (English,unpublished).

This paper presents up-to-date data oncounts and estimates of those groups ofseabirds most often caught on longlines fortuna. The by-catch problem has promptedincreased effort towards counts of severalspecies poorly surveyed before. Thesources of data on censuses were asfollows: southern wandering albatross,southern royal albatross, black-browedmollymawk, yellow-nosed mollymawk

Two tuna longline-fishing hooks havebeen recovered from beside wanderingalbatross (Diomedea exulans) nests atMarion Island in the 1990s. No hooks

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35

WG-IMALF___________________________________________________________________________

(Gales, 1993); Gibson’s wanderingalbatross (Robertson, 1975; Walker et al. ,1991; Walker, 1993); antipodes wanderingalbatross (Warham and Bell, 1979;C.J.R. Robertson, pers. comm.; Clark etal., in press); northern royal albatross,northern Buller’s mollymawk (Robertson,1991); New Zealand black-browed andgrey-headed albatrosses (Moore andMoffat, 1990; Gales, 1993); New Zealandwhite-capped mollymawk (Robertson,1975; B. Rebergen, pers. comm.); Salvin’smollymawk (Robertson and van Tets,1982); Chatham mollymawk (Robertson,1991); southern Buller’s mollymawk(Sagar et al., 1994); grey petrel, Westlandpetrel (Marchant and Higgins, 1990); blackpetrel (pers. obs.); white-chinned petrel(Walker, 1993; Marchant and Higgins,1990).

WG-IMALF-94/22Aspects of seabird by-catch and itsmitigation in the New Zealandlongline fishery for tuna. M.J. Imber(Science and Research Division,Department of Conservation PO Box10420, Wellington, New Zealand), 5 pp.(English, unpublished).

WG-IMALF-94/23Cooperative analysis of NewZealand seabird by-catch data -interim report. New Zealand FishingIndustry Board (Fishing Industry House,74 Cambridge Terrace, Private Bag 24-901,Wellington, New Zealand), 4 pp. (English,unpublished).

WG-IMALF-94/24Influence of bait quality on seabirdmortality and economic losses inlongline fishing: an experimentalapproach. N. Brothers, A. Foster andG. Robertson (Department of Parks,Wildlife and Heritage, GPO Box 44A,Hobart, Tasmania 7001, Australia), 7 pp.(English, unpublished).

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36


Adams, N.J. Bone, D.G.WG-JOINT-94/15 23 WG-KRILL-94/32 10

Agnew, D.J. Bost, C.A.WG-FSA-94/20 28 WG-JOINT-94/11 22WG-JOINT-94/4 20 Boveng, P.L.WG-JOINT-94/8 21 WG-CEMP-94/17 15WG-KRILL-94/4 3 WG-CEMP-94/18 15WG-KRILL-94/5 3 WG-CEMP-94/19 15WS-FLUX-94/4 2 WG-CEMP-94/22 15

Allcock, L. Boyd, I.L.WG-FSA-94/15 27 WG-CEMP-94/11 12WG-FSA-94/18 28 WG-CEMP-94/12 12

Amat, J. WG-CEMP-94/13 13WG-CEMP-94/25 17 WG-FSA-94/17 27

Arnould, J.P.Y. WG-JOINT-94/5 20SC-CAMLR-XIII/BG/3 1 Brothers, N.WG-CEMP-94/11 12 WG-IMALF-94/19 35WG-CEMP-94/12 12 WG-IMALF-94/20 35

Ashford, J.R. WG-IMALF-94/24 36WG-FSA-94/31 31 WG-IMALF-94/6 31WG-IMALF-94/15 34 Brown, S.WG-IMALF-94/16 34 WG-CEMP-94/33 19

Balestrini, C. Butler, P.J.WG-FSA-94/29 30 WG-CEMP-94/13 13

Bannasch, R. Butterworth, D.S.WG-CEMP-94/27 17 WG-KRILL-94/23 8

Barea, L. WG-KRILL-94/24 8WG-IMALF-94/17 35 Casaux, R.

Barrera-Oro, E. WG-CEMP-94/29 18WG-CEMP-94/29 18 WG-CEMP-94/31 18WG-CEMP-94/32 18 WG-CEMP-94/32 18WG-FSA-94/11 26 WG-FSA-94/11 26WG-FSA-94/12 26 WG-FSA-94/12 26WG-FSA-94/27 30 WG-FSA-94/27 30WG-FSA-94/28 30 Cherel, Y.

Barton, T. WG-IMALF-94/12 33WG-CEMP-94/12 12 Cielniaszek, Z.

Basson, M. WG-FSA-94/15 27WG-KRILL-94/11 4 WG-FSA-94/18 28

Belyaev, V. WG-FSA-94/25 29WG-JOINT-94/7 21 WG-KRILL-94/9 4

Bengtson, J.L. Clarke, J.WG-CEMP-94/17 15 WG-CEMP-94/33 19WG-CEMP-94/19 15 WG-CEMP-94/34 19WG-CEMP-94/21 15 WG-CEMP-94/35 19

Bevan, R.M. WG-CEMP-94/8 11WG-CEMP-94/13 13 Constable, A.J.

Bibik, V.A. WG-FSA-94/21 28WG-JOINT-94/7 21 Cooper, J.WG-KRILL-94/10 Rev. 1 4 WG-IMALF-94/18 35WG-KRILL-94/33 10 WG-IMALF-94/8 32WG-KRILL-94/7 Rev. 1 4 Coria, N.

Bjordal, Å. WG-CEMP-94/31 18WG-IMALF-94/9 32 Croxall, J.P.

SC-CAMLR-XIII/BG/3 1

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37

Author Index___________________________________________________________________________

SC-CAMLR-XIII/BG/4 1 Goss, C.WG-CEMP-94/12 12 WG-FSA-94/15 27WG-CEMP-94/14 14 WG-FSA-94/18 28WG-CEMP-94/4 11 WS-FLUX-94/10 3WG-CEMP-94/6 11 Greene, C.H.WG-IMALF-94/15 34 WG-JOINT-94/12 23WG-JOINT-94/5 20 Hall, A.J.

Culik, B. WG-CEMP-94/14 14WG-CEMP-94/27 17 Harm, U.

Daly, H. WG-FSA-94/13 26WG-FSA-94/15 27 WG-FSA-94/15 27WG-FSA-94/18 28 Harris, M.

Dalziell, J. WG-CEMP-94/26 17WG-IMALF-94/5 31 Hewitt, R.P.

de la Mare, W. WG-JOINT-94/12 23WG-FSA-94/10 26 WG-JOINT-94/9 21WG-FSA-94/21 28 WG-KRILL-94/12 4WG-FSA-94/30 26 WG-KRILL-94/14 5WG-IMALF-94/7 31 Higginbottom, I.WG-KRILL-94/17 6 WG-KRILL-94/21 7WG-KRILL-94/18 7 Hill, H.J.WS-FLUX-94/7 3 WG-CEMP-94/14 14

de Poorter, M. Hiramatsu, K.WG-IMALF-94/5 31 WG-KRILL-94/15 6

Demer, D.A. Huin, N.WG-JOINT-94/12 23 SC-CAMLR-XIII/BG/4 1WG-JOINT-94/9 21 Ichii, T.WG-KRILL-94/12 4 WG-JOINT-94/17 24WG-KRILL-94/13 5 WG-KRILL-94/27 9WG-KRILL-94/14 5 WG-KRILL-94/28 9

Duhamel, G. Imber, M.J.WG-FSA-94/9 Rev. 1 25 WG-IMALF-94/10 32WG-IMALF-94/12 33 WG-IMALF-94/21 35

Else, G. WG-IMALF-94/22 36WG-CEMP-94/8 11 Iwami, T.

Everson, I. WG-KRILL-94/25 8WG-FSA-94/15 27 Jones, C.WG-FSA-94/17 27 WG-FSA-94/22 28WG-FSA-94/18 28 WG-IMALF-94/14 34WS-FLUX-94/10 3 Jouventin, P.

Evseenko, S.A. WG-IMALF-94/11 33WG-FSA-94/14 27 Kawaguchi, S.

Favero, M. WG-KRILL-94/27 9WG-CEMP-94/29 18 WG-KRILL-94/28 9WG-CEMP-94/31 18 WG-KRILL-94/30 9

Ferrer, M. Kerry, K.WG-CEMP-94/25 17 WG-CEMP-94/33 19

Foster, A. WG-CEMP-94/34 19WG-IMALF-94/24 36 WG-CEMP-94/35 19

Furusawa, M. WG-CEMP-94/8 11WG-KRILL-94/35 11 WG-IMALF-94/7 31

Genevois, F. Khudoshina, M.WG-JOINT-94/11 22 WG-JOINT-94/7 21

Gonzalez, B. Kim, S.WG-FSA-94/29 30 WG-CEMP-94/36 19

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38


Kishi, M.J. Murphy, E.J.WG-KRILL-94/26 9 WG-CEMP-94/10 11

Kock, K.-H. WS-FLUX-94/10 3WG-FSA-94/13 26 WS-FLUX-94/5 2WG-FSA-94/14 27 WS-FLUX-94/9 3WG-FSA-94/15 27 Murray, A.W.A.WG-FSA-94/17 27 WG-KRILL-94/31 10WG-FSA-94/18 28 WG-KRILL-94/32 10

Kokoz, L.M. Naganobu, M.WG-KRILL-94/7 Rev. 1 4 WG-JOINT-94/17 24

Koubbi, P. WG-KRILL-94/26 9WG-JOINT-94/11 22 WG-KRILL-94/27 9

Lage, J. WG-KRILL-94/28 9WG-CEMP-94/27 17 WG-KRILL-94/29 9

Lawless, R. WG-KRILL-94/30 9WG-CEMP-94/33 19 WS-FLUX-94/8 3

Liddle, G.M. Navarro, R.WG-CEMP-94/15 14 WG-JOINT-94/15 23

Loeb, V. Nevinsky, M.M.WG-KRILL-94/22 7 WG-FSA-94/14 27

Loinaz, I. Nicol, S.WG-IMALF-94/17 35 WG-KRILL-94/17 6

Løkkeborg, S. North, A.W.WG-IMALF-94/9 32 WG-CEMP-94/14 14

Lorentsen, S.-H. WG-FSA-94/16 27WG-CEMP-94/41 20 Ogishima, T.

Macchi, G. WG-JOINT-94/17 24WG-FSA-94/28 30 WG-KRILL-94/27 9

Mangel, M. Pactwa, R.WG-CEMP-94/30 18 WG-FSA-94/25 29

Marín, V. Pakhomov, E.A.WG-JOINT-94/16 24 WG-JOINT-94/10 22WG-KRILL-94/14 5 WG-JOINT-94/7 21

Marin, Y. WG-KRILL-94/16 6WG-IMALF-94/17 35 WG-KRILL-94/34 10

Marschoff, E. Parkes, G.WG-FSA-94/11 26 WG-FSA-94/15 27WG-FSA-94/29 30 WG-FSA-94/17 27

Martin, L.V. WG-FSA-94/18 28WG-KRILL-94/13 5 WG-FSA-94/22 28

Meir, E. WG-FSA-94/23 29WG-JOINT-94/12 23 WG-FSA-94/24 29

Miller, D.G.M. WG-IMALF-94/14 34WG-KRILL-94/19 7 Pauly, T.WG-KRILL-94/20 7 WG-KRILL-94/21 7WG-KRILL-94/31 10 Perissinotto, R.

Moloney, C. WG-JOINT-94/10 22WG-IMALF-94/8 32 Phegan, G.WG-JOINT-94/15 23 WG-JOINT-94/8 21

Montevecchi, W.A. Pilling, G.WG-JOINT-94/13 23 WG-FSA-94/18 28

Moreno, C. WG-FSA-94/23 29WG-FSA-94/31 31 WG-FSA-94/24 29WG-IMALF-94/15 34 Prenski, B.

WG-FSA-94/29 30

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39

Author Index___________________________________________________________________________

Prince, P.A. Stansfield, A.WG-JOINT-94/5 20 WG-CEMP-94/30 18

Reid, K. Sun, S.SC-CAMLR-XIII/BG/3 1 WG-KRILL-94/17 6

Remaggi, C. Symon, C.WG-FSA-94/29 30 WS-FLUX-94/6 2

Ridoux, V. Szlakowski, J.WG-JOINT-94/11 22 WG-FSA-94/15 27

Ríos, C. WG-FSA-94/18 28WG-IMALF-94/17 35 Takao, Y.

Robertson, G. WG-KRILL-94/27 9WG-IMALF-94/24 36 Tankevich, P.B.

Rodhouse, P.G. WG-FSA-94/4 24SC-CAMLR-XIII/BG/15 2 ter Braak, C.J.F.WG-CEMP-94/14 14 WG-CEMP-94/24 16

Roux, A. Thomson, R.B.WG-FSA-94/27 30 WG-KRILL-94/23 8

Røv, N. WG-KRILL-94/24 8WG-CEMP-94/39 20 Torres, D.WG-CEMP-94/41 20 WG-CEMP-94/28 17

Rubilar, P.S. Trathan, P.N.WG-FSA-94/31 31 WS-FLUX-94/6 2WG-IMALF-94/15 34 Trivelpiece, S.G.WG-IMALF-94/16 34 WG-CEMP-94/38 20

Ruchon, L. WG-JOINT-94/6 21WG-JOINT-94/11 22 Trivelpiece, W.Z.

Rumsey, S. WG-CEMP-94/38 20WG-CEMP-94/30 18 WG-CEMP-94/40 20

Russelo, I.B. WG-CEMP-94/7 11WG-FSA-94/6 25 WG-JOINT-94/6 21WG-FSA-94/8 25 Ulbricht, J.

Ryan, P.G. WG-CEMP-94/23 16WG-IMALF-94/8 32 van Franeker, J.A.

Saralegui, A. WG-CEMP-94/24 16WG-IMALF-94/17 35 Vaske Junior, T.

Sawada, K. WG-IMALF-94/4 31WG-KRILL-94/35 11 Vaz-Ferreira, R.

Schwartz, M.K. WG-IMALF-94/17 35WG-CEMP-94/21 15 Viñuela, J.

Sexton, S. WG-CEMP-94/25 17WG-JOINT-94/12 23 Walker, A.

Shin, H.-C. SC-CAMLR-XIII/BG/3 1WG-CEMP-94/36 19 Walker, B.G.

Siegel, V. WG-CEMP-94/19 15WG-KRILL-94/22 7 WG-CEMP-94/22 15

Siegfried, W. Roy Wanless, S.WG-IMALF-94/8 32 WG-CEMP-94/26 17

Silva, P. Watkins, J.L.WG-CEMP-94/29 18 WG-KRILL-94/32 10WG-CEMP-94/31 18 Watters, G.

Sosinski, J. WG-FSA-94/26 29WG-KRILL-94/9 4 Weimerskirch, H.

Stagi, A. WG-IMALF-94/11 33WG-IMALF-94/17 35 WG-IMALF-94/12 33

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Williams, R.WG-FSA-94/10 26WG-FSA-94/30 26

Williamson, N.J.WG-KRILL-94/35 11

Wilson, N.WG-IMALF-94/17 35

Wilson, R.WG-CEMP-94/27 17

Woakes, A.J.WG-CEMP-94/13 13

Yakovlev, V.N.WG-JOINT-94/7 21WG-KRILL-94/10 Rev. 1 4WG-KRILL-94/33 10WG-KRILL-94/7 Rev. 1 4

Young, K.WG-CEMP-94/33 19

Zaitsev, A.K.WG-FSA-94/7 25

Zamon, J.E.WG-JOINT-94/12 23

Zippel, D.WG-CEMP-94/23 16

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Documents

CCAMLR SCIENTIFIC ABSTRACTS 1994 · Surveys of Antarctic fur seals entangled in man-made marine debris were carried out for the fourth consecutive winter and sixth consecutive summer