Bundesforschungsanstalt für Fischerei, Institut für Ostseefischerei,

Report on the Acoustic Survey in leES Sub-divisions 22, 23 and 24 in October 1995

C.M. 1996/J:ll

. Baltic Fish Cttee

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.An der Jägerbäk 2, D-18069 Rostock

.. Bundesforschungsanstalt für Fischerei, Institut für Fangtechnik,

Palmaille 9, D-22767 Hamburg

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by

Tomas Gröhslerl and Eberhard Götze2

Results of 44 fishery stations are given. Length. distributions, age compositions and estimates

of biomass and number of herring. and sprat are presented for each Stratum/Sub-division. The

herring stock and the sprat stock were estimated to be 7.6 x 109 individuals or 244.5 x 103

tonnes and 13.1 x 109 individuals or 140.0 x 103 tonnes r~spectively in the area of 11,000 mh2

surveyed.

An enclosed 'figure shows the course track and positions of tra~l hauls...

Abstract

This paper describes the results of an acoustic survey carried out with RV 'Solea' in

cooperation between the Federal Republic of Germany and Denmark in Sub-divisions 22, 23

and 24 from 5th to October 20th, 1995.

International Council for

the Exploration of the Sea

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1 Introduction ~

The first attempts to estimate. stock sizes of herring and sprat by echo-iritegration were made in '., , - '

the years 1975 to 1977 (Falk et 3.1. 1976, Lindquist et al. 1977, Lindquist & Gullmann 1975).. '. '.' . '.' . \

Internationally coordinated hydro'acoustic surveys for herring and sprat stocks have been·. . . _. .

conducted in the Baltic Sea in Gctober since 1978 (Hakansson ei al. 1979, Falk et al. 1980,I, . • •

Hagsträm et al. 1981, 1982a+b, 1983, 1985, 1986, 1987, 1988, 1989, 1990). ~. . '

Besides 'these international coordinated' activities some national acoustic surveys were made. .

separately since 1979(Aro et al. 1981, Aro ~ Sjäblom 1982, 1983,'Bleil & Kästner 1987~. ..,

Kästner & Haman 1982).. A joirit hydroacoustic survey petween the German Democratic. , . \

Republic and USSR for sprat was carrie~ outthe first time in 1979 (Falk et al. 1981) and was. . ..... . ,

, repeated in 1984 and 1986 (Kästner et al. 1984, Shvetsov et al. 1986)..

The starting point 'for acoustic surveys' i~ .Division' lIla (Kattegat and' Skagerrak) was iri '.

1976/1978 (Linquist et al. 1979) which was continued in the years 1980, 1984 and 1985.' .., . . .

(Anon.1981, Degnbol ei al. 1985, 1986). Since 1986 internationally coordinated acoustic

sUrVeys were conducted during summer time in the North Sea and in Divisi~n lIra (Skagerrak

and Kattegat) (Kirkegaard et al. 1987, 1989, 1990: Simmonds et at: 1994, 1995).. '. \ . . .. .

The first joint hydroacoustic survey between the Federal Republic of Germany and DenmarkJ " •

was carried out with ?JV '~c:lea' in Sub-Divisions 22-24 in O~tober 1987 (Neudecker and

Staehr 1988). Since 1989 the survey was repeated every year as a part of an international

hydnicoust~c SUrvey in ~he Baltic coordinated, by ,ti1e ICES (Staehr &' Neurlecker 1990;

Neudecker et al. i991, Götze et al. 1992, 1993a+b, 1994).• . I. •

The 379th cruise ofR/V 'Solea' in 1995 represents the 8th subsequent survey and took piace• • • '. I

fr~m 5th to' 20th Gctober in 1995. Due to limited time and bad weather conditions the SUrvey. 1 .••••• '. '.

, only covered Sub-Divisions 22 , 23 and 24. Based on echo-integration and trawling, estimates'. . '. . I.. ' . .., . . . .' .'

of the biomassand abundance of herring and sprat are' given in this report. These estimates . ., . , ". . ,.

"were used by the 'Herring Assessment Working Group for the Area South of 62°N' for herring

(Anon. 1996a) and by the 'Baltic Fisheries Assessment Woi-king Group' f~r sprat. (Anon.

1996b) as fishery independent source to esdmate terminal fishing m'ortality and to tu~e the

VPA.

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2 Methods'

2.1 Acoustic rneasurernents .

The acoustic measurements were perforrned with the echosounder 'EK500 ~nthe working

frequency of 38 .kHz. The echo~ounder w~s connect'ed to the Berg~n-I~tegrator BI500 f~r" ."

storing and analysing the echosignals. A 'single beam trarisducer 38-26M was inst~Iled on a',

t6wed body running 100'm behind the shlp to avoid fish re~ctions to vessel noise. The 'lateral

distance of 30 ~ 40 m from the ship kept the transducer free froin' bubbled keel water. o~

'daytime thefish,was ~ainl~ distrlbuied clo'se to the bottom. Therefore the investigilÜons were" J • " "

conducted in the da~k from 6 p.rn.. to 6 a.m. Duri,ng this period the fish indications are

scattered over the whole watercolumn. The Sv values ~ere i~tegrated over 1 nm intervals •

from ,3 m below the transducer to the bottom. Contributions from air bubbles, bo~tom part's. . . .

and scattering layers were removed frorn the e~hograrn. The acoustic system was calibrated

according to recommendaÜons in the siMRAD operator manual (Anon.. 1991) b~fore the

cruise in Rostock harbour and during th~ survey ~n October 13th in 'the harbour of Abenrade,~ '.. . .

Denmark. During this time the Sv gain ofthe echosounder changed from 20.0 dB to 20.1 dB,, "

reflecting a stable 'operatioll'ofthe hydroacoustic measuring system.

2.2 Trawling

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Trawling was done with the pelagic gear "Octopus" in the mi~water as weIl as in the near, .

bottom. This gear is a modification of the former used trawl "Blacksprutte". It is characterised, .. . .. . I

by a slightly sinaIler net opening of 8-9 rn ("Blacksprutte'~ 11 m). The modification was aimed

io a hetter trl:lwl handling ,i~ the sha1low water areas'of the Western Baliic. The ~~shsize in the

codend was 10 mm. The intention was to carry out at least 'two' hauls by ICES statistical'., ~ - "'. . .

rectangles!strata. The trawling depth and the net opening were checked by a netsonde.

NormaIly a net opening of 11 m was achieved.' The trawl depth \.va~ chosen to catch the

.'characteristic in?ications' showing in, the ',echogram. ,.The trawling time' la~ted usuall'y 30 ,

minutes bui in dense concentrations the duration was reduced.

The position of trawl himls is shown in F.igure 1.: The survey covered the whole Sub-divisions, .

22, 23 and 24., Duc to bad weather conditions the plaimed coveragc of thc southern Kattegat

(Division IIIa) wa~ fnigmenta~·and therefore the results were not presented in this report.'The, , .' . . . . ~

total survey area was 10,200 nm2 (1994 including Sub-division 21: 12,900 nm2) and thc cruise

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track 990 nm (1,162 nn: in 1994). The total number of trawl hauls made was 44. The catch

composition (kg/O.5 h) by fishery station/Sub~division is given in Table 1-3.

The catch composition was dominated in Sub-division 24 by' sprat and in Sub-division 22 and

23 by,herring. Normally further'North distributed, mullets and an'chovy were caught in Sub-\

. division 22 and Sub-divisons 22/24respectively. "

2.3 ,Stratification and abundance estimation

In Sub-division 22 the stratification is based on four geographical units which ~ere used since

1989 (Staehr & Neudecker 1990). For Sub-divisions 23 and 24 the normal statistical rectangles

were used as strat~. The target'pelagic'~peciesherring and sprat are dist~bu~ed in mixed layers '

so that it is impossible to allocate the integrator readings to fish species. Therefore the species

composition is based on the trawl catch results. For each stratum the species composition and. . .~, ", . ' ..... '. '

length distribution were determined as the unweighted mean of all trawl results in this stratum.

From these distributions we got the mean scattering cross section cr according the following

TS-Iength relationships:

Clupeoids

Gadoids

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, TS = 20 log L (ern) - 71.2

TS = 20 log L (cm) - 67.5

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(Anon. 1983)

(Foote et al. 1986)

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The total number of fish in the stratum was estimated as the product of the mean Sa and the, . . . ,',

stratum area divided by the corresponding mean seattering cross section. The total' number, ' ,

.were splitted into the main species herring and sprat age classes corresponding to the rnean

catch composition and the age readings. In some cases, no hauls could be'made in astratum, '. ' .

and therefore the results ofthe closest neighbouring stratum ~ere used for splitting biomass.

The survey statistic concerning {he su~ey ~rea, the mean Sa, the mean scattering cross section

cr, the estimated total number of fish, the percentages of herring .and sprat per Sub~

division/Stratum are shown in Table 4.

4

3 Rcsults'

3.1 Herring

The herring stock w~s estimated to be 7.6 x 109 fish or about 244,500 tonnes' in Sub-divisions

, 22, 23 and 24.

The length distribution of herring by Sub-division is presented in Figure 2. The estimated

; number of herring by age group'and Sub-divi~ion/Stratum includi~g the adult stock' (3+ group). " ,

is given in Table 5. The mean weightby age group and Sub-division/Stratum is shown in Table:' ,

6. The corresponding estimates of he~ng biomass by Sub-division/Stratum are summarised in

, Table 7.,

The highest number ofherring was found in Sub-division 22 (about 49 % ofthe total estimate).. . . ..' . .

Compared to the results in Sub-division 23 and 24 this area contained the lowest amount off' . .' ' ..

adults. The total -~umber of herring 'in Sub-division 24, was' somewhat' lower th~m 'in Sub-

divisi~n 22. In contrast to the estimates in Sub-division 22, Sub-division 24 was dominated by~. . .

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adult herring. The lowest contribution to the overall stock size was found in Sub:"division 23,'. - ~ I .'

which was characterised hy a relatively high fracti~n ofadult fish. '

3.2 Sprat

The estimated sprat stock was 13.1 x 109 fish cr 140,000 tonnes in Sub-divisions 22, 23 and, ' . ..

24,

The length distribution of sprat by Su~-division is presented in ~igure 3. The estimated number

ofsprat byage group and Sub-division/StratUm includi~g the adult stock (3+ group) is given in. , . .

Table 8. The mean weight by age group and Sub-diVision/Stratum is shown in Table 9. The, . \.," . . .

corresponding estimates of sprat biomass by Sub-division/Stratum are listed in Table 10.

Most of all the sprat including the' amount' of juveniles' and adults (3+ group) were

concentrated in Sub-division 24. In Sub-division 22 and 24 the contribution of adults to the

total stock size per Sub-division was' comparable (17 % and 15 % in number as weIl as 29 %

and -25 % in biomass). In Sub-division 23 the overall small sto~k si'zc co~tained to a high

degree adults (44 % in'number and 54 % in biomass).

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4 Discussion

4.1 Herririg'

. . .The overall estimates in Sub-divisions 22-24 ranged in the period from, 1989 to 1995 from

about' 3.6 x 109 fish in 1993 'to' 27..6 x i09 fish in 1990 (Götze et al. 1992, 1993, 1994," . ~ .

• ' Neudecker ct al. 1991, Staehr & Neudecker 1990). Compared to these estimates the present

result of a~out 7.6 x 109 .individuals is as last years result stillbelow'the mean number ofthis

period. The cstimate in i995 reachcd ~bout 82 % of the total numbcr and about 95 % of thc

total biomass calculated for 1994. The· decrease in numbe~s was mainly caused by low~r .., . . .

. estimates of the youngest yearcl~sses in Sub-Division 22 and 24. The contribution of, the 0-

•. group to the total number decreased in the last two years in Sub-Division'22 from 93 % to 81

% and in Sub-division' 24 from' 59 % to 47 %. The overall smaller diff~renc~s in biomass'. . \

compar~d to thc results in .1994 were mainly caused by th~ higher riumber of adults in 1995 in, .

Sub-division 22. Even so thc total number in Sub-division 22 was in 1995 about 10 % lower, "

than in 1994, the higher number of adults resulted in 8 % higher biomass in .1995 for this area.

A~ in prcvious years most of the fish in Sub-division 22 were juveriiles (0-2-group in 1995 and·. . \'.. .

1994: 97 % and 99 % of the total number and 86 %. and -95 %, of the total biomass

respectively)... .

The num~er ofjuveniles (0-2-group) in Sub-division 24 varied since 1989 from about 42 % to. .

99 % and now reached about 75 % (1994: 79 %). Comparcd to Sub-division 22 thc stock size- . .

in Sub-division 24 is in general characte~sed by a highe~ proportion of adults. In 1995 and

1994 they made 25 % and 21 % ofthe total number and 60 .%and 57 % of the total biom~ss..

The stock number in Sub..divis~on 23' reached in 1995 just about the same level as in 1994 (0.3

x 109). In 1995 as w~it as in 1994 most ofthe herring in this area were adult~ (about 57 %and .

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71 % ofthe total number rind about 86 % arid 88 % ofthe biomass respectively) ... .'

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Comparing the O-group number estimated ~or the total are~ of Sub-~ivision22-24 since 1989

the esiimated size i~ 1995 (4.8 x'109 fish) just reached about the half of the mean value for 'this

period (9.1 X 109 fish). Since the 0- and l~group is tho~ght to be mainly distributed within t'he

coastal areas and these areas 'are not regarded to be adequa~ely c~vered by this s~rvey the.. I • •

estiinated strength of O-group do not nec~ssarily indicate' a weak cr a strong upcoming

yearc1ass.

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4.2 Sprat

The overall estimates in Sub~~ivisions' 22-24 in the, period 'from 1989 to 1994, ranged from" '

about 3.2 x 109 fish in 1993 to 29.4 x109 fish in 1991 (Götze et a1. 1992, ~993, 19?4,

Nc~decker ct al. 19~'1, Staehr & Neudecker 1990). Compared to'last years estimate t~e result

ofabout 13:1 x 109 individuals in 1995 shows an increase of about 102 %. The estimate in' :, \. . .1995 represents the· second highest vahie in, time series si~ce the' record ievel in 1991. '.

Compared to 1994, the higher estimate iri 1995 was caused by an increase of juveniles in Sub-' ,. . ~ , .

DiVision 24 (0-2-group) ofabout 180 % in number and 135 % in biomass.

The stock size in Sub~division' 22 remained just about at the 'same level ase iast year. The. '. .', abund~1I1Ce in 1995 was about 6 % ilOd the biomass about 4 % lower than in 1994.

In 1995 as in i 994 th~ co~tribution of sprat in Sub-division' 23 to the overall estimate in Sub-. ' . .

, divisions 22-24 was less than 1 % in numbers as weIl as in biorriass.\

The time series of O-group estimate from the acoustic s,urvey in Sub-divi,sions 22-24 since 1989

shows that this, yearclass of about 4.6 x 109 fish is the third strongest since th~ record yearsin

1991 (dominated by ahigh yearclass in Sub-division 22) and 1992 with 19.0 x'109 and 5.4 x

109 i~dividuals respectively.:

Thc time serles of O-gr~up estimate' from the acoustic survey in' Sub-divisions 24 since 1978

shows that ihis year ciass ofabout 3.4 x 109 fish is on the highest ~ver recorded level. '

Since the ac<?ustic survey see~s at least to be able to indicate streng and weak yearclasses the

'prcsent estimate indicates even ~ore than last year thata' big yearclass is recruiting to the. . . : " .

Baltic sprat stocks.

References, ' ,

Anon. 1981. Final report on the joint Danish-Swedish acoustic survey in Skagerrak- the" Kattegat 25 August - 12 September 1980. ICES C.M. 1981fH:30. ,

Anon. 1983. Report ofthc Planning Group on ICES-coordinatecl herring and sprat acoustic,, surveys. ICES C.M. 1983fH:12. "

Anon: ,1991. Operator Manual EK 500; P2170E, Simrad Subsea NS, Horten.

'Anon. 1996a. Hcrring Asessment Working Group for the Area South of 62° N.ICES C.M. 1996/Assess:l0.. '

, Anon, 1996b. Report ofthe Baltic Fisheries Assessment Working Group.. ICES C.M.1996/Assess:13. '

7 .

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· Aro, E.; Sjöblom, V.; Suuronen, P. & Parmane, R. 1981. The abundance ofB~ltic herring imd"\ sprat in the seas around Finland in 1979 arid 1980 according to echo countings.

ICES C.Iv1. 1981/1:21.. "

, Aro, E. & Sjöblom, V. 1982. The abundance ofBaltic herring and s"prat according to echocounting in the sens around Finland in 1981. ICES C.M. 1982/1:20..

, . , '

· Aro, E. & Sjöblom, V. 1983. The abundance ofBaltic herring and sprat to'echo counting inthe seas around Finland in 1982. ICES C.M.'1983/J:22.

, ,

Bleil, W. and Kästner, D. 1987. Hydroacoustic investigations on day- and night-." ". concentrations and the variability oftrawls in the western Baltic.

ICES C.M. 1987/1:23.

Degnbol; P.; Hagström, O. & Palmen L.-E: 1985. Acoustical survey in Skagerrak - Kattegatand western Baltic in Augu~t-September ~984. ICE~ C.M.. 1985.1H:47."

. .. '\. . ,

Degnbol, P.; Hagström; 0.; Palmen, L.-E: & Staehr, K-J. 1986. Acoustical survey inSkagerrak:' Kattegat and western Baltic in August - September 1985.ICES C.M. 19861H:66. "

Falk, U; Götze, E.; Rechlin; O. 1976. Anwendung der hydroakustischen Methode zurquantitatiyen Bestimmung 'des Sprottbestandes in der Gotlandsee im Mai 1975.Fischerei-Forschung 14(1): 35-38:

Falk, U; Kästner, D:; Hagström, 0.; Hakansson, N.";' Lindqui~t, A. 1980. Hydroacotistic ."observations in Baltic proper in October 1979. Preliminary tesults.

ICES C.M. i980/1:16. . .

· Falk, U.; Götze, E.; Tesler, W.D.; Shvetsov, F. 1981 Bestimmung'der Sprottbiomasse in dei­Ostsee im Mail1uni" 1979 mittels akustischer Methoden und einer,

•. Trawlaufnahme.Fischerei:-Forschung, Wissenschaftliche Schriftenreihe 19(1981)2.

"Fetter, M.E. and Ojaveer, E.A.1988.Assessment ofthe Eastern Baltic Herrlng Stocks by. ' .Hydroacoustic Method. ICES C.M. 1988/J:l1. .

.Foote: KG., Aglen', A.& Nakken, O. '1986. Measurement offish' Targ~t Strength with a. split-beam echosounder. J.Acoust.Soc...Am. 80(2):612-621. .

Götze, p.; Neudeccker, Th. and Staehr, K-J. 1992.Report on the Hydroacoustic 'Su~ey in'ICES sub.div. 22, 23 and 25 in October 1991. ICES C.M. 1992/1:32.

Götze, E.; Oeberst, R.,Rechlin, O. and Staehr, K-J.·1993a. Report on the Acoustic Survey inICES sub.div. 22 and 24 in OctoberlNovember.I992. ICES C.M. 1993/J:28.

, . I ...

· Götze, E.; Bethke, E.; Oeberst, R. '1993b. Hydroacoustic srriall scale investigations ofpelagicfish stocks. ICES C.M. 19931B:34. . . I

Götze, E.; Oeberst, R.and Staehr, K.-i. 1994. Report on the Acustic Survey in leES sub.div.21,22,23 and 24 in September/Oetober 1993. ICES C.M. 1994/J:13. '

8

H~gström, 0.; Hakanssso~,N.; Lindqui~t, A.; Kästner, D.; Rechlin, O. 1981. Aco~stic, , estimates of the' herring and the sprai stocks in the Baltic proper October 1980.

Preliminary results: ICES C.M. 1981/J:14. ' '

Hagströin, 0.; Hakansson, N.;Kästner. D. ami Schutz, N. 1982a. Acoustic'~'stimates oftheherring and the sprat stocks in the Baltic proper and the Bothnian Sea 1981.

, Preliminary results. ICES C.M. 1982/J:6.

Hagström, 0.; Hakansson, N.;Lindqui_si,'A; Falk, u.; Kästner, D. 19~2b. Acoustic estimates,ofherrii1.g and sprat ofthe Baltic proper in October 1979.Meddelande frim Havsfiskelaboratoriet, Lysekil, No. 273: 14 pp.

Hagström, 0.; Palmen, L.-E., Degnbol, Pi; Rechlin, 0.1983. Acoustic'estimates ofthe herringand sprai stocks in the Baltic proper, the Bothnian Sea and the 'Gulf ofBothnia

, 1982. Pn~liiniriarY results:ICES C.M. 1983/~:9. ' .. ', , '. '

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Hagström, 0.; Palmen,'L.-F.;'Kästrier, D.; Rechlin, O. 1985. Acousiic estirriates ofthe herringimd the sprat stocks in the Baltic proper 1983 and 1984. ICES C.M. 1985/J:4.

\ '

Hagström, 0.; Palrrieh, L.-E.; Rechlin, 0.'; Schultz, N; Orlowski; A.; Kalinoviski, i.; ,\Vyszynski, M. 1986. Acoustic estimates ofthe herring and the sprat stocks inthe Baltic prop.er 1985. ICES C.M. 1986/J:3.

Hagström,O.; Palmen, L.-E.;' Kästner, D.; Bremer-Rothbart, H.; Orlowski, A.; Kalinowski, J.;, \Vyszynski, M. 1987. Acoustic estimates ofthe herring and the sprat stocks in

the Baltic p'rop,er, October.l?86. ICES C.M. 1987/J:18.

. Hagström, 0.; Palmen, L.-E.; Kästner, D.; Bremer-Rothbart, H.; Orlowski, A.; Wyszynski, M.. ' 1988.'Acoustic esti~iltes ofthe he~ng and the sprat stocks ofthe Baltic proper

October 1987. Preliminary,results. ICES C.M. 1988/J:30.

Hagström, 0.; Palmen, L~-E., Hakansson, N.~ Kästner, D.; Bremer-Rothbart, H.; GrygieI, \V.;'. Wyszynski, M. 1989. Acoustic estimates ofthe nerring and the sprat

stocks in the Baltic proper October'1988. ICES C.M. 1989/J:26.

H~gström, 0.; Palmen, L.~E.: Hakansso~, N.; Kästner, D.; Rothbart, R; Grygiel, W.; : ''Wyszynski, M. 1990. Acoustic estimates 'ofthe herring and sprat stocks in the

. Baltic proper October 1989: ICES C.M. 1990/J:35. '

Hakansso~, N.; Kollberg; S.; Falk, u.; Götze, E.~ Rechlin, O. 1979. A hydroacoustic and. trawl survey ofherring and sprat stocks ofthe Baltic proper in October'1978.

, Fischerei-Forschung, Wissenschaftliche Schriftenreihe 17(1979)2:7-23.' ,

Kästner, D. and Haman, K. 1982. On the reciuitment ofthe Baltic spring-spawning herring of, Rügen lsland acco,rding to a hydroacoust~c ,survey. ICES C.M. 1982/J:13.'

. . . . .",.' I "'_ '," " . . " " ,

Kästner, D.; Oeberst, R.; Haman, K; Shvetsov, F.; Baturin, V.; Litvinov, 1. 1984. Preliminaryresults ofajoint hydroacoustic sprat surveyby the USSR arid GDR in the Balticin May 1984. lCES C.M. 1984/J:7. ', ,

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I'

Kirk~gaard, E.; Lewy, P.; Staehi-, K.-J. 1987. TheDanish acoustical survey in Div. lila andeastem North Sea August 1986. ICES C.M. 19871H:42: ,

. . '. .'... .

.. Kirkegaard, E.; Aglen, A; Baily, R.S.; Forbes.. S.T. and Hagström: O. 1989. Report ori theheiring acoustic surveys in the North Sea, Skagerrak and Kattegat during'summer 1988. ICES C.M. 1989/H:37. '

Kirkegaai-d, K.; Aglen~ A; Degnbol, P.; Hagström, 0.; Palmen, L.-E. and Simnionds, E.J.1990. Report on the herring acousiic surveys in the North Sea, Skagerrak and ,Kattegat during summer 1989. ICES C.M 19901H:24. '

Lindquist, A & Gullmann~ J. 1975. Ekointegreringar med "Argos"·rid Öland och Skagerrak. . Medd.fr.Havsfiske1~b.;Lysekil, no 187,25 pp. "

. ' ,

Lindquist; A; Hagströn:t, 0.; Hakansson, N. and Kollberg, S. 1977. Preliminary results fromecho~integrations in the Baltic:1976 and 1977. ICES ~.M. 19771P:13

" "

Lindquist, A 1979. Sprat(Sprattus sprattus) in the Baltic and the Skagerrak/Kattegat: Stock.sizes calculated from VPA, egg surveys and echointegrations. 'ICES C.M. 1979/J:9. ,

Neudecker, Th. and S'taehr~ K-J. 19'88. Repoi-t ~n the A~oustic Survey in ICES Sub~Div.22and 24 in Oct6ber 1987. ICES C.M. 1988/J:31.

, . ,

Neudecker, Th.; Staehr, K-J. and Götze, E. 1991. Report on the Acoustic Survey in ICES~ . s~b.div. 22 and 24 in November 1990. ICES C.M. 1991/J:12

Shvetsov, F.; Bat~rin, V.; Götze, E.; Geberst, R.; Kästncr, D. 1986. Pre1imiri~ry' results of ajoint hydroacoustic sprat survey by the USSR and GDR in the Baltic in May ,1986. ICES C.M. 1986/J:15:

Shvetsov, F.G.; Gnidalev, E.B.; Volkow, N.D. 1987. Results ofhydroacoustic assessment ofsprat stocks in the Eastem Baltic. ICES C.M. 1987/J:12 ". . ' '

Simmonds, EJ.; Reid, D.G.; Aglen, A.;'Skagen, D. and Corten, j.... 1992. Report ofthe 1991ICES coordinated Acoustic Survey ofHerring Stocks in ICES Divisions VIa,IVa and IVb. ICES C.M. 19921H:35.

Simmonds, EJ.;Dommasnes, A; Aglen; A; torten: A and'Reid, D.G. 1993. 1992 ICEScoordinatedAcOllstic Survey ofICES Divisions IVa, IVb and VIa.ICES C.M. 1993/H:11.

Simmonds, EJ.; Dommasnes, A; Corten, A; Pedersen, J. and Reid, D.G. 1994. 1993 ICES. coordinated Acoustic Survey ofICES Divisions IVa, IVb, and VIa.

ICES C.M. 19941H:22. '

Simmonds, E.J.; Toresen, R.; Corten, A; Pedersen, 1. Reid, D.G. and Fernandes, P.G. 1995.. 1994 ICES coordinated Acoustic Survey ofICES Divisions IVa;IVb, VIa and

VIIb. ICES C.M. i9951H:15. .

Staehr, K.-J. and Neudeck~r, Th. 1990. Report on the Acousiic S~rvey in ICES sub.div. 22,, . 23 and 24 in November 1989: ICES C.M.'1990/J:13.

10

Table 1 Catch composition (kg/O.S h) per fishery station in Sub-division 22

fishiStation 21 . 22 23 24 2S 26 27 2~ 29 30 31 32 33 34 3S 36 37 38 21-38AGONUS CATAPHRACfUS . - + +BEWNE BELONE 0.57 ·0.57CLUPEA HARENGUS 10.98 25.67 12.45 .. 48.37

.12.11 14.53 9.06 3.54.32.44·12.37 20.10 5.59 39.60 218.84 0.51 28.54 3.08 497.78

SPRATTUS SPRATTUS " 24.18 36.61 27.37 11.00 0.46 1.19 12.32' 26.38 . 3.02: 20.02 3.27 2.15 6.75 9.58 0.03 0.09 0.39 184.81CRYSTALLOGOBIUS LINEARIS . . + . +ENGRAULIS ENCRASICOLUS .

.. . 0.04 0.05, 0.02 0.55 0.04 0.01 0.02 0.73GADUS MORHUA" 2.40 1.99 4.34 1.03 0.60 4.36 6.53 + 0.04 , 21.29

1;

GASTEROSTEUS ACULEATUS 0.02 0.02 0.01 + 0.03 '0.38 0.01 0.01 21.06 1.80 0.55 0.05 0.03 0.13 0.04 . 24.14GOBIUS NIGER " + +LIMANDA LIMA.'lDA 0.19 0.08 0.29 0.56LOLIGO - + 0.01 • 0.01 •MERLANGIUS MERU"iGUS 0.96 0.50 0.16 0.27 0.05 0.02 0.67 0.20 0.29. 3.06 0.81' 0.90 0.05 0.02 0.07 8.03MUGILCHELO - 17.00 3.34 20.34OSMERUS EPERLANUS + + I +POMATOSCHISTUS ML"iUTUS 0.03 0.01 .+ + 0.04SALMOTRUTTA 0.81 0.81SYNGNATHUSROSTELLATUS

' . .+ +TRACHINUS DRACO " 0.01 0.01TRACHURUS TRACHURUS 0.02 0.03 0.01. ' + 0.03 0.13 1.44 0.05 +' 0.54 2.24 0.08 0.04 0.01' 0.06 4.68TRISOPTERUS ESMARKI ' + +Total 38,54 65.62 61.32 60.71 12.63 15.93 22.08 33.62 37.57 35.50 24.89 28.82 49.59 236.12 0.70 35.98 0.18 4.00 763.80 iMedusae' 30· 40 40 11 7 108 20 ·66 442 18 48· 6 4450 .. 661' 14 4 3 4 5972

/

Table 2 Catch composition (kg/O.S h) per fishery station in Sub-division 23

FishiStation 43 44 4S 46 47 4~ , 0-48" ANGUILLA ANGUILLA . 2.63 0.09 4,45 7.17

CLUPEA HARENGUS 71.17100.00 743.62 932.06 521.64 231.15 2599.64SPRATTUS SPRATTUS 3.94 6.29 2.90 1.10 2.36 2.09 18.68GADUS MORHUA 3.86 105.85 111.18 160.01 38.34 419.24 ;GASTEROSTEUS ACULEATUS 0.01 0.01LIMANDA LIMANDA 0.24 0.24

,

MERLANGIUS MERLANGUS 3,42 5.08 47.63 11.86 5.79 0.53 74.31POMATOSCHISTUS ML"iUTUS + +TRACIlURUS TRACHURUS ,0.11 .' . 0.02 0.13Total 78.65 115.47 900.00 1058.83 689.89 276.58 3119.42Medusae 8 5 0 0 3 14 30

Table 3 Catch composition (kg/O.S h) per fishery station in Sub-division 24

+ =O<welght<O.01 kg

l'ishiStation 1 2 3 4 5 6 7 ~ 9 10 ,11 12 13, 14 15 16 17 1~ 19 20 1-20ANGUILLA A....GUILLA 0,41 . 1.04 1.20. 0.38 0.26 - 3.29CLUPEA IIARENGUS 24.52 23.94 94.92. 25.64· 0.83 10.85 18.58 0.38 118.56 74.46 0.38 7.98 1.50 1.68 10.44 24.23 20.55 32.88 30.74 23.38 546.44SPRATTUSSPRATTUS 63.82 40.69 1.38 44.98 4.79 3.07 62.60 32.19 44.61 ' 1.91 4.89 24.30 3.62 39.18 174.33 0.76 7.09. 9.77 9.51 17.04 590.53CYCLOPTERUS LUMPUS 0,43 0.10 0.53ENGRAULIS ENCRASICOLUS

,0.01 0.01".

GADUS MORIIUA 7.19 11.75 0.77 6.49 1.56 26.85 20.78 1.15 21.57 3,45 1.72 0.28 1.17 1.14 3.35 0,44' 2.90 6.34 2.75 ; 121.65GASTEROSTEUS ACULEATUS 0.02 0.02 . 0.01 + . 0.01 0.01 0.01 0.08 'MERLANGIUS MERLANGUS 0.41 0.82 0.07 0.86 1.26 ~ 3.82 1.45", 0.67 0.19 1.57 1.13 12.25OSMERUS EPERLANUS - 0.02 0.02PLATICIlTIlYS FLESUS 0.36 . 0.36POMATOSCHISTUS MINUTUS + 0.02 0.02 0.03 . 0.05 0.02 , 0.01 0.15TRACHURUS TRACIIURUS 0.02 0.01 0.07 - 0.06 0.02 0.01 0.19Total \l5.9ll 77.23 \17.57 78.06 1:l.S1 40.81 102.37 33.72 .lll\l.60 ll2.53 5.65 34.\13 5.83 42.03 185.91 28.36 2ll.08 45.8) 48.18 44.30 1275.50Medusae 70 104 11 159 11 10 102 27 6 7 26 II 24 66 24 \I 122 52 20 lJ 874

• .e '.

- Tablc 4

.eSurvey statistics RN"Solea" in October)995 .

Sub- Stratum Area Sa N Ts TotalN Herring Sprat NHerring NSpratdivision (nm*2) (m*2/nm*2) (nm) (<1) (mil) (%) (%) (miI) (mil)

22 22a 1297 58 114 1.065 707 36.9 3.9 260 2822 22b 1694 120 92 1.065 . 1909 36.9 3.9 704 7522 22c 1086 329 176 1.467 2435 56.6 37.1 .. 1378 90322' 22d 1102 443 . 98 1.688 2892 48.1 50.9 1392 1471

I' ~ '" .23 4057 195' 948 90 7.730 239 , , 92.5 ' 4.5 1 221

"

11.'23 4157 56 " 650 29 3.085 ' "118 ' 81.7 13.7 96 ' 16

..24 3757 1 205 541 15 1.658 669 17.9 81.6 120 I· 546 .24 3857 853

..503 67 . ' 1.837 2335 . 52.6 46.8 1229 1093

24 3858 . 882 . 1195 101 1.864 5654 13.9 82.0 787 I' 463424 3859 ., 1036 208 30 1.673 1288 ' 9.8 . 88,0 127 113424 3957 438 407 45 2.093 , 852 57.3 ' 41.2 488 - 35124 3958 780 505 72 3.088 1276 53.2 41.7 679 532..24 3959 529 710 56 1.529 2456 5.7 94.1 141 2312

Table 5 ,Herring num~er (million) per age group and Stratum/Sub-divis~onin October 1995

1._ Sub- Stratum Age groupsdivision O. 1 2 3 4 5 6 7 8+ Sum

22. 22a 259 1 0 0 0 0 0 0 0 260 ', 22 22b 571 120 8 1 2 1 1 0 0 704I' ,

22 22c 1133 173 23 14 ". 21 8 6 0 0 1378. 22 22d

.36 15 ,25 14 131050 239 - ·0 0 1392 •.

22 Total " 3013 533 67 30 48 23 20 0,

0 3734 "-,Sum 3+ group: 121 I .. '

23 4057 ·23 11 21 42 47 23 21 19 14 221,23 4157 43 20, 17 13 3 0 0 0 .. 0 96

23 Total- 66 31 38 55 50 ,23 21 19 14 317. ,

Sum 3+ group: 182 -"

24 3757 65 38 5 5 3 3 1 0 0 12024 3857 834 203 39 ,',49 54 29 I 15 2 4 122924 3858- 310 147 73 75 79 67 28 , ' 6 2 . 78724 3859 36 38 14 12 11 11 4 1 '0 127 -24 3957 350 66 15 17 18 . 14 7 1 0 48824 3958 67 200 84 98 100 86 32 8 4 67924 3959' 25

.57 18 12 11, 13 5 0 0 141

24 Total 1687 749 248 . 268 276 223 92 18 10 3571'. , .. Sum 3+ ,,-oup: 88722-24 Total' 4766 1313 .353 353 374 . 269 133 ' , 37 24 7622

Sum 3+ ,,-oup: 1190

Table 6 Herrillg estimated mean ,veight (g) per age gr~up and Stratum/Sub-division in O~tober1995

/.

Sub- Stratum .' ·Age groupsdivision .' 0 1 2 3 4 5 6. , 7 8+ .'22 22a 11.7 '27.4 ..

22' 22b '13.3 32.1 39.7 79.1 86.0 71.6 60.722 22c 10.7 33.6 ,49.9 . 85.0 77.3 . 72.3 69.2 1

22. 22d 10.5 34.5 47.0 82.9 73.7 67.6 . 62.4"

(

23 . 4057 11.3 64.1 108.4 128.4 177.2, 206.7 222.0' 236.1 259.6

4157' 12.5 . 50.7.

70.1 85.8 91.623

I· I··-

24 3757 10.0 32.2. 52.5 48.2 55.5 ·48.8 58.7 --24 3857 . 9.1 32.6· 63.4 89.7 117.3 111.2 89.7 150.0 150.024 3858···. 8.1 . 33.6 64.5 80.4 104.4 98.4 . 85.8 198.7 150.0.

32.8 '.68.0 74.7 72.3.,

215.3 162.224 3859 -. 12.9 63.2. 81.424 3957 11.6 33.1 66.3 78.7 112.5 102.8 99.8 150.0 150.0 '24 3958 14.1 33.8 62.2 81.5 : 105.3 93.9 88.7 166.7 150.0

.. - ..24 3959 I: 11.5 . '.31.9 62.0 . 64.6 . 74.0 65.3 68.3 150.0 150.0 .

Table 7 Herring total biomass (t) per age group and Stratum/Sub-division in October 1995. . .'

Sub- Stratum Age groups .'division 0 1 2 3

.'

4 5 6 7 8+ . Sum

22 22a 3030.3 27.4 0.0 ·0.0 0.0 0.0 0.0 . 0.0 0.0 3057.722 22b 7594.3 3852.0 317.6 , 79.1 .' 172.0 71.6 . 60.7 0.0 0.0 12147.3

. 22 22c I' 12123.1 5812.8 1147.7 1190.0 1623.3 578.4 415.2 0.0 . 0.0 22890.51

.,

I' 22d-. 22 11025.0 8245.5 1692.0 1243.5 . '1842.5 946.4 811.2 0.0 0.0 25806.1

22 Total 33772.7 17937.7 3157.3 "' 2512.6 3637.8 1596.4 . 1287.1 0.0 . 0.0 ~ 63901.6Sum 3+ group: 9033.9

23 4057 259.9 705.1 - 2276.4 5392.8 . 8328.4 4754.1 4662.0 . 4485.9 . 3635.0 34499.623 4157 537.5 .. 1014.0 1191.7 1115.4 274.8 0.0 0.0 0.0 0.0 4133.4

c. 23 Total . 797.4 . 1719.1 3468.1 6508.2 8603.2 . 4754.1 4662.0 . 4485.9 3635.0 . .38633.0Sum 3+ group: 32648.4 . '

24 . 3757 .. 650.0 1223.6 262.5 241.0 166.5 . 146.4 58.7 0.0 ·0.0 2748.7 1"

, 24 3857 7589.4 . 6617.8 2472.6 4395.3 . 6334.2 3224.8" 1345.5 300.0 600.0 32879.624 3858 2511.0 . - . '4939.2 4708.5 ' 6030.0 ·8247.6 . 6592.8 2402.4 1192.2 300.0 .. 36923.724 3859 464.4 1246.4 884.8 - 816.0 . 895.4 821.7 289.2 215.3 0.0 5633.224 3957 4060.0 .. 2184.6 994.5 1337.9 2025.0 1439.2 698.6 150.0 0.0 12889.824 . 3958 944.7 6760;0 5224.8 7987.0 10530.0 8075.4 " 2838.4 1333.6 600.0 44293.924 ' 3959 287.5 1818.3 ' 1116.0 .775.2 814.0 848.9 341.5

J

0.0 0.0 ' 6001.424 Total 16507.0 24789.9 15663.7 21582.4 . 29012.7 21149.2 7974.3 3191.1, 1500.0 141370.3

, :Sum 3+ group: 84409.7 .

22-24 Total 51077.1 44446.7 22289.1 30603.2 41253.7 27499.7 . 13923.4 . 7677.0 5135.0 243904.9. Sum 3+ group: 126092.0 .

. ,

·Table 8 Sprat number (million) per age group and Stratum/Sub-division in October 1995 .

·eSub- Stratum Age groups

division 0 1 2 3 4 5 6 7 8+ Sum

22 22a 26 2 0 0 0 0 0 0 0 2822 22b 21 43 7 1 0 1 2 0 0 7522 22c 540 228 62 9 16 15 28 2 3 90322 22d 530 459 150 51 100 84 71 ' 10 16 . 147122 Total 1117 732 219 61 116 100 101 12 19 2477

Sum 3+ group: 40923 4057 2 2 2 2 2 1 0 0 0 11

23 4157 1 4 4 3 3 . 1 0 0 0 1623 Total 3 6 6 5 5 2 0 0 0 27

Sum 3+ group: 1224 3757 129 163 82 25 83 29 27 4 4 54624 3857 381 426 178 28 46 18 11 4 I 109324 3858· 2122 1348 779 88 162 79 37 14 5 463424 3859 350 405 227 34 65 29 16 6 2 113424 3957 83 122 75 15 30 14 8 3 1 35124 3958 22 155 118 43 106 47 28 II 2 53224 3959 . 370 975 539 92 185 79 49 18 5 231224 Total 3457 3594 1998 325 677 295 176 60 20 10602

Sum 3+ group: 155322-24 Total 4577 4332 2223 391 798 397 277 72 39 13106

Sum 3+ group: 1974

Table 9' Sprat mean weight (g) 'per age group and ~t'raturitlSub~divisionin October 1995 '

..

Sub- Stratum Age groups~

division 0 1 2 3 4 ' 5 6 7 8+22 22a 5.3 9,222 22b. 6A 12.7 14.1

,18.5 18.6 14.2

22 22c 4.8' , 14.0 15.0 19.5 '20.8 20.2 14.7 20.5 ' .' 24.122 22d' 4.9 14.7, 15.5 20.0' 21.9 21.0 16.1 21.0 24.7

.. . .23 4057 . 4.9 13.0, 14A 16.5 19.0 20A23 4157 4.6 13.5 14.0 15.9 17.6 19.2I,

24 3757 4.9 11.6 ,13.9, 16.8 - 20A 20.0 21.9 18.0 23.524 3857 ,- 5.2. 10.7 13A 16.6 18.6 - 18.6 19.6 17.8 . 20.524 3858 4.2 11.7 12.3 17.1 18.7 18.6 18.8 18A 17.824 3859 4.2 .. 12.1 12.8 17.1 19.1 18.8 ' 19.7 18.3 20.124 3957 4.6, 12A 13.3 16.9 .. 18.9 19.0 19.5 - 18A 20.724 3958 4.3 12.9 13.1 17A 19A 18.9 19.7 " 18.5 18.724 3959 4.5,

,12.2 12.9 17.0 19.0 18.7 19.7 18.3

.19.9

Table 10 Sprat total biomass (t) per age group and Stratum/Sub-division in October 1995

Sub- Stratum Agegroups ,

division 0 L 2 3 4 5 6 7 8+ Sum22

/22a 137.8 18.4 - 0.0 0.0 0.0 0.0 0.0 0.0 0.0 .'- , 156.2

22 22b 134A 546.1 98.7 18.5 0.0 18.6 28A 0.0 0.0 844.722 22c 2592.0 3192.0 930.0 175.5 332.8 : 303.0 411.6 41.0 : 72.3 8050.2 ,22 '22d 2597.0' 6747.3 ,2325.0 1020.0 2190.0 1764.0, 1143.1 210.0 395.2 18391.622 Total 5461.2 10503.8 " 3353.7 1214.0 2522.8 2085.6 1583.1 251.0 467.5 27442.7 .'

Sum 3+ group: 8124.023 4057

,9.8 26.0 28.8 33.0 38.0 20A 0.0 0.0 0.0 156.0 i-·

, -23 '4157 4.6 54.0 56.0, ' 47.7 52.8 19.2 0.0' 0.0 0.0 234.323 Total 14A 80.0 84.8 80.7 90.8 39.6 0.0 0.0 0.0 390.3

, suin 3+ group: 211.124 3757' 632.1 1890.8 1139.8 ' 420.0 1693.2 . 580.0 591.3 72.0 94.0 ' 7113.224 I· 3857 1981.2 4558.2 2385.2 ' 464.8 855.6 334.8 215.6 71.2 20.5 10887.124 3858 8912A 15771.6 9581.7 1504.8 - 3029A 1469A 695.6 257.6 89.0 41311.524 3859 1470.0 4900.5 ' 2905.6 581.4 1241.5 545.2 315.2 109.8 40.2 12109A24 3957 -' 381.8 1512.8 997.5 253.5 567.0 266.0 156.0 55.2 . 20.7 ,4210.524 3958 94.6 1999.5 1545.8 748.2 2056.4 888.3 551.6 203.5 37A 8125.324 3959 1665.0 11895.0 6953.1 1564.0 3515.0 1477.3 965.3 329A 99.5 28463.624 Total 15137.1 42528A , 25508.7 5536.7 12958.1 5561.0 3490.6 1098.7 -401.3 112220.6

.. Sum3+~oup: 29046A - -22-24 Total 20612.7 53112.2 28947.2 6831.4 15571.7 ,7686.2 5073.7 1349.7 868.8 140053.6

Sum3+ ~oup: 37381.5

.e

1 5

1 5

3859

1415

1 4

14

·11 12

1 3

1 3·12

·12

1 1

1 1

1 09

55

56· 1l§--------+---+--+---+~~---__::;T"'''+_----.:....A~~+___:---~--./_-_..:..,,,L....:.::.L....L-_l3ll5 6

37575 4 . ffi---------:---1f-------'--r:;;:t--==..:::;--~r_--__+-------t__~----=~_rl""'i"'<::_--~~7___s"i 5 4

Fig'-!re 1 Cruise track and trawl positions RV 'Solea' 1995

%.N %N %N

--. ............... ...a."" ...a. ............... ~1'.J O""~o)(X)O~Ao;o;~Oi')~OlCXlOi')~OlCXlO Oi')~OlCXlOi')~OlCXlO

6.75 6.75 6.75

~ 7.75 7.75 7.75riQ'

. 8.75c: . 8.75 8.75~ .~

9.75 9.75 9.75N

10.75 10.75 10.75

~ 11.75 11.75 11.75~

= 12.75 12.75 12.75ao-::r 13.75 13.75 13.75Q,r;;' 14.75 14.75 14.75-~.... 15.75 15.75 15.75C'"c:- 16.75 16.75 16.75Ö·

= 17.75 17.75 17.750....,

18.75 18.75 Cf)18.75 r

Icn

::r r- Cf) r- C j 19.75C

~~ 19.75 ~ 19.75 N N

~ C~ lQ lQ W N

S' - N~ 20.75 -:T 20.75 ~ ~ 20.751;ao n n /

S' a 21.75 a 21.75 a 21.75

rJ:l 22.75 22.75 22.75c:C'"I 23.75 23.75 23.75

Q,

§: 24.75 z 24.75 z 24.75 zVl 11 11 11Ö· 25.75 - 25.75 - 25.75 (.ol

= ~(.ol 00 (.ol

Vl 26.75 Ol 26.75 (.ol 26.75 0

Ni') <J1 CXl

N'27.75

Z27.75

Z27.75 Z.. :3 :3 :3N (l) (l) (l)

~ 28.75 ll.l 28.75 ll.l 28.75 ll.l(Jl (Jl (Jl

~ c c c

= 29.75 iil 29.75 iil 29.75 iilQ,

Q. Q. Q.11 11 11

N 30.75(.ol

30.75 i') 30.75 CXl~ ~ (0 ".:1

.E'3 0

31.75 31.75 .:j 31.75~

32.75 32.75 32.75

33.75 33.75 33.75

• e

SO 22

45403530

z 25';!!. 20

151050

5.25 6.25 7.25

IN= 18179 (N-measured = 2690)

8.25 9.25 10.25 11.25 12.25 13.25 14.25 15.25 ' 16.25 17.25

Length (ern)

SO 23

45

40

35 IN = 1048 (N-measured = 385)

30

2 25~ 200

15

105

05.25 6.25 7.25 8.25 9.25 10.25 11.25 12.25 13.25 ' 14.25 15.25 16.25 17.25

Length (ern)

SO 24

45

e 40

35IN = 57674 (N-measured = 3815)

30

z 25';!!. 20

151050

5.25 6.25 7.25 8.25 9.25 10.25 11.25 12.25 13.25 14.25 . 15.25 16.25 17.25

Length (ern)

Figure 3 Length distribution of sprat in Sub-divisions 22, 23 and 24