COMMISSION STAFF WORKING PAPER - Europa · 2011. 3. 30. · 1 INTRODUCTION 1.1 TERMS OF REFERENCE 1 To evaluate and comment thelatest ICES advice in the light of possible new information

COMMISSION OF THE EUROPEAN COMMUNITIES

Brussels, SEC(2005) ****

COMMISSION STAFF WORKING PAPER

REPORT OF THE SCIENTIFIC, TECHNICAL AND ECONOMIC

COMMITTEE FOR FISHERIES

Evaluation of the report of the

STECF-SGRST Working Group on Anchovy in the bay of Biscay

Brussels 11-14 July, 2005

CONTENTS

Executive Summary...................................................................................................................................................... 1 1 introduction .......................................................................................................................................................... 3

1.1 Terms of Reference ....................................................................................................................................... 3 1.2 Participants...................................................................................................................................................... 3 1.3 Rationale for the meeting ............................................................................................................................. 3 1.4 Confidentiality ................................................................................................................................................ 4

2 Fisheries independent information ................................................................................................................... 5 2.1 Spanish Acoustic Survey (JUVENA).......................................................................................................... 5

2.1.1 REFERENCES: .................................................................................................................................. 9 2.2 Spanish commercial purse seine vessel fishing surveys in 2005........................................................... 10 2.3 DEPM surveys ............................................................................................................................................. 12 2.4 Direct assessment of anchovy by the PELGAS05 acoustic survey..................................................... 17

2.4.1 Eggs...................................................................................................................................................... 18 2.5 On a recruitment index for anchovy from the autumn EVHOE bottom trawl surveys ................. 27

3 Fisheries Information........................................................................................................................................ 29 3.1 Spanish Purse Seine Fishery....................................................................................................................... 29

3.1.1 Spanish Spring fishery in 2005-comparisons to previous years ................................................. 29 3.2 Spanish tuna live bait fishery...................................................................................................................... 30 3.3 French landings ............................................................................................................................................ 31

4 New Information............................................................................................................................................... 33 4.1 Assessment update....................................................................................................................................... 33 4.2 Short term projections and recruitment scenarios.................................................................................. 37

4.2.1 Inputs:.................................................................................................................................................. 37 4.2.2 Results.................................................................................................................................................. 37

4.3 Economic evaluation of the French fleets for anchovy in the Bay of Biscay. ................................... 38 5 Evaluation of management measures other than closure ........................................................................... 40

5.1 Introduction.................................................................................................................................................. 40 5.2 The model ..................................................................................................................................................... 40 5.3 Evaluation of alternative management measures.................................................................................... 41 5.4 Long-term population growth rate ........................................................................................................... 42 5.5 Short-term effects of management measures.......................................................................................... 42 5.6 References ..................................................................................................................................................... 42

6 Response to ICES Recommendations ........................................................................................................... 43 7 Evaluation of current survey activity and timing and potential for additional surveys .......................... 44

7.1 September/October .................................................................................................................................... 44 7.2 February......................................................................................................................................................... 45 7.3 Recommendation......................................................................................................................................... 45

7.3.1 Possible additional Spanish survey in 2005. .................................................................................. 45 8 Conclusions ........................................................................................................................................................ 47

EXECUTIVE SUMMARY

In May 2005 ICES ACFM recommended for the Biscay anchovy stock that:

“…strong management measures are urgently required, in order to protect the remaining stock, i.e. that the fishery be closed immediately, and remain closed until there is reliable fishery independent evidence of a strong year class recruiting to the stock. “

The present STECF subgroup was established to evaluate this recommendation and the information used to underpin it. In addition the subgroup was asked to consider alternative management measures short of closure and to evaluate the timings of surveys in support of the management of this fishery. The subgroup reviewed the currently available survey information, most importantly the following: • Spanish Acoustic Survey (JUVENA) -September/October 2003 & 2004 • Spanish commercial purse seine survey – May 2005 • Spanish Daily Egg Production Survey(BIOMAN) – May 2005 and annually • French Acoustic Survey (PELGAS)– May 2005 The surveys all confirmed the historically low level of the SSB and the very low level of recruitment by the 2004 year class. Summaries of the results of these surveys are presented in Chapter 2.

The subgroup also reviewed the currently available information on the fisheries in late 2004 and the first half of 2005. In particular, the Spanish live bait fishery in the autumn of 2004 and the Spanish and French fisheries in the first half of 2005. The Spanish fishery, substantially a purse seine fishery, showed a historically very low catch. The catch in the French (principally trawl) fishery was also low, but not as marked as the Spanish. This difference was believed to be due to the different accessibility of the stock to the different metier under the present stock level. Summaries of these results are presented in Chapter 3.

An analytical assessment (ICA) was carried out following the same approach used by the assessment WG and updated with the latest survey information and landings data for 2004. This assessment provided an SSB value for 2005 of around 8,500t and recruitment in 2004 of 703 million fish. Both the SSB and the recruitment are the lowest in the time series by a significant degree. The assessment confirmed the current perceptions based on the surveys and the fishery in 2005. Short term deterministic projections based on the assessment results were also carried out. These examined a range of recruitment scenarios and evaluated these in terms of recovery to Blim and to Bpa under a closed fishery. It was predicted that relatively modest recruitment of at least 5,300 million would bring 2006 SSB above Blim and that recruitment of at least 9,100 million would bring SSB above Bpa. Long term average recruitment is approximately 14,500 million (excluding 2004) and since 2002 it has varied between approximately 4,000 and 7000 million. These results are presented in chapter 4. This chapter also contains an examination of the economic impact of a variety of closure scenarios on the French fishing industry. The analysis describes the possible effects and the potential for targeting other fisheries, but emphases that in the current stock scenario the fleet would have to expect reduced revenue due to the severely depleted stock. Similar impacts on the Spanish fishing fleet would be expected.

The subgroup evaluation was that the ICES advice presented in May was correct in terms of its presentation of the current state of the knowledge about this fishery. The detailed examination of the survey and fishery data, combined with the analytical assessment confirm that the stock is at a dangerously low level (well below Blim) and that recruitment in 2004 was also extremely low. It was agreed that the ICES advice to close the fishery immediately was correct. The subgroup also agreed that it should remain closed until fishery independent data was available to provide a reliable estimate of the 2006 SSB and 2005 year class. The subgroup emphasised that such information could only come from the established acoustic

STECF-SGRST Working Group on Anchovy in the Bay of Biscay

and DEPM survey series carried out in May 2006. Additional information from other surveys would be valuable but should not be taken as a reliable indicator of SSB or the strength of the 2005 year class. The ICES advice stipulated that the fishery should remain closed until there was evidence of a “strong” year class entering the fishery. The projections given in chapter 4 suggest that recruitment levels between the lower quartile and the median of the time series would lead to a stock over Blim and possibly approaching Bpa. These findings are presented in chapter 5.

The subgroup was also asked to evaluate measures short of the complete closure proposed by ICES. Given the short notice for this meeting it was not possible to carry out a detailed examination of any proposed alternate measures using simulations or other established evaluation tools. Two previous suggestions for management measures have been made for this stock, although not in the context of the current stock scenario. These were for a closed area off the Gironde to protect juveniles, or for a closure during the spawning season. The effects of these two proposals compared to no closure and complete closure were studied using a simple but preliminary matrix model structure, although this has not yet been validated. The model uses fishing mortality surrogates for the actual management measures, and is not spatially explicit. The tentative findings were that both alternate measures provided some protection for the stock but neither separately or together were as effective in protecting the stock as a full closure, particularly for the older adults. The model showed that incoming recruitment is by far the most important factor in any stock prognosis. The model also highlighted the sensitivity of the results to the assumed values of natural mortality. The subgroup concluded that neither were suitable in the current situation, although both the proposals and the model evaluation should be considered in the future, with a healthier stock. In this context it should be noted that the current SSB level is much lower than any previously seen and recruitment from that stock must be uncertain. This material is presented in chapter 6.

Finally the subgroup considered what surveys and/or survey timing would provide the best improvements in management advice. The spring acoustic and DEPM surveys provide the main tuning indices to the current assessment and should be maintained. The key to improving the management of this stock would be to have a reliable estimator of year class strength prior to these entering the fishery, i.e. in the same year as their spawning. This would best be achieved using targeted acoustic and fishing surveys carried out in the September/October period. Spain has carried out such surveys in 2003 and 2004. This survey was able to give an early warning of possible recruitment failure of the 2004 year class. The subgroup felt that the best option was to continue and to enhance these surveys in the future. The key problems for the surveys were that they did not completely cover the likely area of juvenile distribution, and currently were dependent on purse seine for fish capture. The addition of other research vessels and the development of an integrated survey using trawls as well as purse seine and covering the full potential distribution area would be very important. Other possibilities were considered e.g. a similar survey in February, but the timing in September/October was felt to be the most appropriate and the existing short survey series made this the best choice. The findings are presented in chapter 7.

1 INTRODUCTION

1.1 TERMS OF REFERENCE 1 To evaluate and comment the latest ICES advice in the light of possible new information from

scientific surveys or monitoring of commercial fisheries targeting anchovy; 2 To evaluate possible management measures alternative to the complete closure of the fishery until a

strong recruitment is identified, as recommended by ICES. 3 In particular, scientists are expected to provide quantitative information from the recent French

survey as well as detailed information on what has happened in the Spanish and French fisheries in 2005.

4 To evaluate whether the current survey(s) timing is adequate for management of this resource and what other survey(s) might help

1.2 PARTICIPANTS D. Reid (FRS, chairman) A Bisseau (IFREMER) J Masse (IFREMER) V Trenkel (IFREMER) O Guyader (IFREMER) J Casey (CEFAS) B Roel (CEFAS) P Abaunza (IEO) C Porteiro (IEO) B Villamor (IEO) L Ibaibarriaga (AZTI) A Uriarte (AZTI) I Shepherd (JRC) F Biagi (DGFISH)

1.3 RATIONALE FOR THE MEETING The meeting was called at short notice in response to the “ad hoc advice on anchovy subarea VIII management” provided by ICES ACFM to the European Commission (Annex ??). In brief, ACFM had become aware that indications from the anchovy fishery and from surveys in the first half of 2005 suggested a strong reduction of recruitment into this stock by the 2004 year class. Combined with a low stock level at the last assessment in 2004 and the recent low recruitment levels, ICES felt that immediate management action was required.

“Although based on preliminary information, ICES considers that strong management measures are urgently required, in order to protect the remaining stock, i.e. that the fishery be closed immediately, and remain closed until there is reliable fishery independent evidence of a strong year class recruiting to the stock. “

The present meeting was convened to evaluate this recommendation, the data supporting it, any alternatives to this approach, and options for future surveys to be developed to provide better management of the fishery.

The ACFM advice was based on preliminary and largely non-quantitative information provided by fisheries research institutes. The first task of the subgroup was to examine the detailed results from both surveys and fisheries used in the advice, and determine whether these supported the statements about these made in the ICES advice. This work was supplemented by an updated analytical assessment and a range of short term deterministic projections. This addressed the principle part of ToRs 1 and 3. The


second task was to advise on the ICES recommendations on management action and the evaluation of any alternative management to the closure recommended by ICES. Detailed evaluations of alternative management and/or recruitment scenarios were not possible in the time scale of this meeting. However, a preliminary model was used to explore the implications of simplified area or seasonal closures. This work addressed ToR 2. Finally, the subgroup examined what survey options were available to provide a reliable early estimate of incoming year class strength prior to its exploitation in the fishery. This examination addressed ToR 4.

1.4 CONFIDENTIALITY The Commission asked the Working Group to respect confidentiality on the basis of Article 10 of Commission Decision 93/619/EC.

2 FISHERIES INDEPENDENT INFORMATION

2.1 SPANISH ACOUSTIC SURVEY (JUVENA) The JUVENA acoustic surveys aims at estimating the abundance of the anchovy juvenile population and their growth condition at the end of the summer in the Bay of Biscay in order to be able to assess the strength of the recruitment entering the fishery the next year, so that assistance to the formulation of the scientific advise for management can be provided.

Currently, two surveys have been conducted (Boyra et al 2004 and 2005). They took place from mid September to the beginning of October covering the area from the coast to 5º W and 46º N onboard the commercial purse-seines Divino Jesús de Praga in 2003 and Nuevo Erreñezubi in 2004.

Acoustic data were recorded with a 38 and 120 KHz Simrad EY60 split-beam, scientific echo sounder system (Kongsberg Simrad AS, Kongsberg, Norway), calibrated using standard procedures (Foote et al. 1987). The water column was sampled with acoustics up to depths of 100 m. A threshold of -70 dB was applied for data collection. Acoustic back-scattered energy by surface unit (SA, MacLennan et al. 2002) was recorded for each geo-referenced nautical mile (1852 m).

Fish identity and population size structure was obtained from fishing hauls and echo-trace characteristics. The hauls were grouped by strata of homogeneous species and size composition. Inside each of these homogeneous strata, the echo-integrated acoustic energy was separated by the contribution of each species according to the composition of the hauls. The composition by size and species of each homogeneous stratum is obtained by averaging the composition of the individual hauls contained in the stratum, being the contribution of each haul weighted to the acoustic energy found in its vicinity (2 nm). Afterwards, the energy corresponding to each specie-size was transformed into biomass using their corresponding conversion factor. The scattering cross section of anchovies according to their size was estimated using the parameters for anchovy detailed in Dinner & Marchand (1995).

In addition, continuous sea surface temperature and salinity measurements and CTD casts every 10 nm were conducted.

In 2003, anchovy was mostly located at the Cantabrian Sea (Figure 2.1-1). In this area, anchovy shoals (over 99% of them composed by juveniles) were spread over a narrow strip parallel to the shelf edge, about five miles off shore from it. Inside this strip, the shoals were quite dense and of good size (typically, about 40 to 50 m of diameter). The western limit of the juvenile distribution along the Cantabrian Sea was 5º W. In the northern coastal area the anchovy was less abundant and anchovy detections were made close to shore at the plume of the Garonne river. Here, half of the collected individuals were juveniles of about 10 cm in length and the rest 1 year old adults.


Figure 2.1-1: Spatial distribution of acoustic energy (echo-integrated between 5 and 65 m depth) and

species composition in JUVENA 2003.

In 2004, very little anchovy was found in the surveyed area, more than 95% of it being located in the Northern part of the French Coast (Figure 2.1-2). Of this, the population found in the Garonne plume consisted mainly in 1 year old adults and the population found in the southern part of the Garonne, were 11 cm long juveniles. In the Cantabrian Sea, the small amount of anchovy found, were juveniles of about 6 cm in length.

STECF-SGRST Working Group on Anchovy in the Bay of Biscay Page 7

Figure 2.1-2 Spatial distribution of acoustic energy (echo-integrated between 5 and 65 m depth) and species

composition in JUVENA 2004.

The anchovy juvenile abundance estimates for 2003 and 2004 are shown in Table 2.1-1. These biomass estimates are still pending of an exhaustive checking of the method and a sensibility analysis to the parameters used in the data processing. In addition, given the experimental nature of this survey, the biomass estimates should not be taken as absolute biomass values but as relative ones. However, results indicate a large reduction in total anchovy abundance in 2004 (to 1/5 of the previous years). The larger differences were observed in the Southern area of the bay of Biscay (Cantabrian and Landes areas) which were almost empty of juvenile detections. Table 2.1-1 Estimates of anchovy juveniles abundance (in tones) by different strata.

2003 2004 Cantabrian 46,299.16 198.19 Landes 101,286.14 1,000.39 North-West 1.57 0.00 Garonne 44,587.13 37,012.24 Total 192,174.00 38,210.83

JUVENA surveys are still in a preliminary stage: Only two surveys have been conducted in the series. By the time being, the results were encouraging since the huge drop in juveniles abundance estimates recorded by JUVENA surveys in 2004 matches well with the drop in recruitment to the adult population of age 1 occurring in 2005, as recorded by the spring surveys (Acoustic and DEPM May 2005). The strength of this survey is that it is implemented during September and early October when juveniles are usually found in the upper layers of water as pure schools, being therefore well detectable with acoustics and well fishable with purse seine, with little risk of species misidentification. The experimental surveys carried out by AZTI and IFREMER within JUVESU project (FAIR CT97-3374, Uriarte editor 2002) in 1998 and 1999, provide additional contrasting background on the abundances and spatial distribution of juveniles. In those years juveniles were well detected in the Cantabrian regions and in front of the Garonne area (Figure 2.1-3), giving support to the impression of a big failure of recruitment in 2004


according to the absence of detections in most of these areas during JUVENA2004. JUVESU project served to establish the current JUVENA survey design. Furthermore, it is expected that a quantitative index can be obtained from the 1999 survey. This would enlarge the series of juvenile’s acoustic estimates to three years (1999, 2003 and 2004).

The drawbacks of JUVENA surveys are that the surveyed area, south of 46ºN, cover the area where the bulk of recruitment is presumed to occur (Uriarte et al. 2001) but does not cover the whole distribution of the juveniles. Detections of juveniles have been made further north by JUVEGA survey (Petitgas et al. 2004) in 2003. The limits of the area surveyed in JUVENA 2005 will be expanded further north.

Comparisons between JUVENA and JUVEGA surveys in 2003 (op. cit.) suggested that bad weather conditions can make the juveniles to sink or disperse, thus making them less visible to the equipment. However in JUVESU survey in 1998 after a strong storm such phenomena did not occur and juveniles were still detectable in subsequent days. In order to overcome some noisy results due to that behaviour of juveniles, the inclusion (as a contrasting information) of juvenile detections reported by live bait tuna fishing boats can be studied; this can ultimately point out if a failure in the detections of juveniles have occurred during the survey.

During autumn (second half of October) anchovy juveniles at some stage disappear from the surface layers of waters, recruiting either to more coastal area and/or to deeper waters and mixing then with other species. If a part of the population by the time of the survey is being carried out has already sank to bottom then purse seine fishing will not allow identification of those juveniles and therefore the survey results will in those cases be biased. For that the inclusion of pelagic trawling would be convenient.


Figure 2.1-3 Spatial distribution of the different species captured in JUVESU 1998 and 1999.

2.1.1 REFERENCES: G. Boyra, A. Uriarte, P. Alvarez and U. Cotano, 2004: Preliminary results of an Acoustic survey on

juvenile anchovy in September 2003. Working Document to the ICES Working Group on the assessment of Mackerel, Horse Mackerel, Sardine and Anchovy. Copenhagen, 7-16 September 2004.

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Engraulis encrasicholus Sardinia pilchardus Scomber sp. Trachurus sp. Cnidaria/salps Euphysiceae

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G. Boyra, P. Alvarez, U. Cotano and A. Uriarte, 2005: Campaña acústica de juveniles de anchoa “JUVENA 2004” Informe de PROYECTO RP2003JUVENA04 para el Departamento de Agricultura y Pesca del Gobierno Vasco- Eusko Jaurlaritza. 28 de febrero de 2005.

Foote, K.G., Knudsen, H.P., Vestenes, D.N., MacLennan, D.N. and Simmonds, E.J. (1987) Calibration of acoustic instruments for fish density estimation: a practical guide. ICES Cooperative Research Report, No. 144, 1-69.

MacLennan, D.N., Fernandes, P.G. and Dalen, J. (2002) A consistent approach to definitions and symbols in fisheries acoustics. ICES Journal of Marine Science, 59, 365-368.

Diner, N. and Marchand, P. (1995) Acoustique et Peche Maritime. Editions Ifremer. Petitgas, P., Beillois, P., Massé, J. and Grellier, P. 2004. On the importance of adults in maintaining

population habitat occupation of recruits as deduced from observed schooling behaviour of age-0 anchovy in the Bay of Biscay. ICES CM 2004/J:13.

Uriarte, A., Y. Sagarminaga, C. Scalabrin, V. Valencia, P. Cermeño, E. de Miguel, J.A. Gomez Sanchez and M. Jimenez, 2001: Ecology of anchovy juveniles in the Bay of Biscay 4 months after peak spawning: Do they form part of the plankton?. ICES CM 2001/W:20.

Uriarte, A. (editor), 2002: Experimental surveys for the assessment of juveniles . Final Report to the European Commission of FAIR Project CT97-3374 (JUVESU).

2.2 SPANISH COMMERCIAL PURSE SEINE VESSEL FISHING SURVEYS IN 2005 This year, given the difficulties of the Cantabrian fleet to catch anchovy in April and May, two surveys (PROA05-I and PROA05-II) were carried out with the participation of the commercial fleet, the support of the Basque Government and under the technical coordination of AZTI-Tecnalia. The main objective of the surveys was the localization of anchovy concentrations of commercial interest for the purse-seine fleet.

The first survey took place between 12-16 May and aimed at covering the northern area of the French shelf (at North of 45º15'N ) and the oceanic area (to the West of the 2ºW) where the commercial fleet didn’t track before. Seven purse seines, with an observer on board each of them, covered in parallel and situated between 5 and 10 nm apart, the 100 m depth isoline up to 47ºN, and then went back following the 200 m depth isoline (Figure 2.2-1). In the northern areas the vessels did not detect any anchovy patches. Most of the detections and fishing hauls corresponded to sardine and horse mackerel Figure 2.2-2). On the other hand the oceanic area from the 45ºN to the Cantabrian shelf, among 2º30'W up to the 3º30W, were empty of any detections. The conclusion was that no commercial fishing concentrations of anchovy were available in the surveyed areras to the North or West from the areas were they had been fishing up to then (Figure 2.2-2).

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Figure 2.2-1: Spatio-temporal summary of the areas prospected during PROA05-I.


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Figure 2.2-2: Species composition of the hauls during PROA05-I.

Given that the commercial fishing activities of the Cantabrian fleet stopped on 12th May, the second survey, conducted between 20 May and 3 June, aimed at determining the presence of concentrations of anchovy in the areas where the fleet usually works at those dates, namely, in the Southern area of the French shelf (south of 45ºN) and around the shelf edge at West of 2ºW. Four purse seines, with a observer on board each of them, started prospecting northward through the French shelf until reaching the 45º10'N. Then, a westward trip was done reaching 3º30'W (Figure 2.2-3). In the areas at South of 45º10'N main detections corresponded to horse mackerel and mackerel, but only very small quantities of fishable anchovy were detected by the purse seines. On the other hand the Cantabrian area no anchovy concentration was found (Figure 2.2-4).

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Figure 2.2-3: Spatio-temporal summary of the areas prospected during PROA05-II.


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15 608 1202

Figure 2.2-4 Species composition of the hauls during PROA05-II.

Besides the fact that the sampling strategy could be improved for future surveys by covering different areas at different times, so as to assure that they all are covered by day and night, the main conclusion from these surveys was that no profitable anchovy concentration were available for the purse seine fleet in the surveyed areas, either outside or inside the traditional fishing grounds. This all reveals above all a weak abundance of the resource, but in addition some catchability problems may have also occurred, never observed before, perhaps related to a too disperse distribution of anchovies, given that the Frech pelagic trawling boats could still obtain some catches at the beginning of June (although smaller than in previous years).

2.3 DEPM SURVEYS Egg surveys to estimate the spawning stock biomass (SSB) of the bay of Biscay anchovy through the Daily Egg Production Method (DEPM) have been implemented from 1987 to 2005, with a gap in 1993. In addition, whenever possible, the age composition of the population has been estimated. At present 18 years of SSB estimates and 15 years of population at age estimates are available.

In the last WGMHSA (2004) the spawning frequency estimate was not available for the full implementation of the DEPM in 2004. Given that sea surface temperature (SST) in 2004 was the lowest of the past series (13.7ºC), and that a significant amount of beta atresia was found, a preliminary SSB estimate was based on the average spawning frequency of the 6 years showing temperatures below 16ºC during the survey implementation. The definitive SSB and age composition estimates in 2004 as reported by Santos et al. (pers. comm.), including now the definitive spawning frequency estimates, are shown in tTable 2.3-1 Table 2.3-1 Estimates of total daily egg production, adult parameters, SSB and population numbers at age in 2004 after the full implementation of the DEPM.

Parameter Estimate Error est. CV

DEP 8.4E+11 9.7E+10 0.1150 R' 0.5388 0.0045 0.0084 S 0.2147 0.0135 0.0631 F 9589.8 1145.4 0.1194 Wf 25.42 1.9867 0.0782 BIOMASS 19,498 2863.99 0.1469 Wt 20.17 1.91 0.0947


POPULATION 979.9 197.5 0.2016 Pa 1 0.8496 0.0349 0.0411 Pa 2 0.1213 0.0306 0.2521 Pa 3 0.0291 0.0075 0.2588

Nage 1 837.0 193.0 0.2306 Nage 2 114.9 22.2 0.1935 Nage 3 28.0 7.3 0.2623

This definitive estimate of SSB in 2004 by the DEPM is just 7% higher than the provisional one reported in past September 2004.

In 2005 a new DEPM survey took place between 8 and 28 of May on board the Spanish R/V Vizconde de Eza (Santos et al. pers. comm.). Sampling strategy was similar to previous years. The total area sampled was 61,619 km2. Figure 2.3-1 shows the egg abundance distribution (number of eggs per 0.1 m2) and the limits of the spawning area that covered 25,936 km2.

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BIOMAN 2005B/O VIZCONDE DE EZA8-28 May

sampled stationsTotal area = 61,619 Km^2Positive area = 27,863 Km^2

anchovy eggs/0.1m^2

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Figure 2.3-1 Anchovy eggs distribution (egg/0.1m2) and abundance found during BIOMAN 2005. Solid line

encloses the positive spawning area.

The eggs staged in the laboratory were transformed into daily cohort abundances using the Bayesian ageing method. Daily egg production (P0) and mortality (Z) rates were estimated by fitting an exponential mortality model as a weighted non-linear regression model with weights given by the number of standard area units represented by each station:

ageZePPE 0 ][−=

where P denotes the egg abundance by cohort in each station and age is the corresponding mean age. The estimated parameters with the correspondent coefficient of variation are shown in Table 2.3-2 Table 2.3-2 P0 and Z estimates from the weighted non linear regression model with the corresponding variance and CV.

Bayesian + N linear reg Value Variance CV

P0 1.5822 6.1649 0.16 Z 0.1969 1.35E-05 0.45


The total egg production, computed as the product of the daily egg production and the positive area estimates, was of 0.440*E12 eggs per day with a coefficient of variation of 16%. This is the lowest egg production of the historical series.

Adult samples for estimating both the daily fecundity and the age composition of the population were obtained from 3 different sources: samples taken directly during the egg survey on board R/V Vizconde de Eza, opportunistic samples from the commercial fleet and samples from the French acoustic survey conducted by IFREMER on board R/V THALASSA.

Until the laboratory adult processing is completed a preliminary daily fecundity (DF) estimate was obtained from a linear regression model between DF and SST on the past time series:

SSTDFE ⋅+−= 74.656.40][

Based on this model the preliminary DF estimate for 2005 was 59.86 eggs/g. The SSB estimate for 2005 was 7422 tones and was computed as the quotient between the total egg production and the daily fecundity estimates. By applying the delta method to the quotient of total egg production by Daily Fecundity (DF) a CV of 23% of deduced for the above SSB estimate. The lowest and the highest DF estimates from the time series were 43.6 in 2004 and 90.1 in 1990 respectively. Assuming that DF in 2005 would be within the range of values of the past time series, the final point SSB estimate in 2005 provided by the DEPM will be between 4,883 and 10,102 tones. If instead of using the above regression model for estimating the DF the average value of the series would have been taken, the final point estimate of SSB would be equal to about 6,500 t.

Preliminary estimates of anchovy mean weights and proportions at age in the adult population were computed as a weighted average of the mean weight and age composition per samples where the weights were proportional to the number of individuals per kilogram. Weighting factors were allocated according to the amount of samples in two regions (Garonne and Souther regions) respective to the relative egg abundance in those areas. Table 2.3-3 shows the estimates of the numbers at age of the population Table 2.3-3 Preliminary population at age estimates in 2005 with the corresponding standard error and coefficient of variation.

Summary DEPM 2005 Parameter Estimate S.e. CV BIOMASS 7,422 1678.9 0.2262 Wt (g) 25.69 1.78 0.07 POPULATION 288.9 68.4 0.2366 Pa 1 0.3871 0.0622 0.1608 Pa 2 0.5827 0.0542 0.0931 Pa 3+ 0.0302 0.0120 0.3974 Nage 1 111.8 32.0 0.2861 Nage 2 168.4 42.8 0.2542 Nage 3+ 8.7 4.0 0.4625 Wage 1 20.57 Wage 2 26.96 Wage 3+ 41.26

From a historical point of view, the current biomass estimate is the lowest in the time series, well below Blim (set by ICES at 21,000 tones). Furthermore, the upper biomass limit that would follow from the lowest DF of the past time series is still the lowest one in the time series (Table 2.3-4 and Figure 2.3-2). Age composition of the population is shown in Figure 2.3-3. The age class abundances in 2005 were very low, only comparable to the levels found in 1989. However, in 2005 the 2 year old class was more abundant than the 1 year old, indicating a failure of recruitment. This age structure was only found in another year, 2002, in the whole time series. Distribution maps of the egg abundance over the past 8 years are shown in Table 2.3-4. The egg distributions in the last 4 years occupy a smaller area, being concentrated in the southeast corner of the bay of Biscay and decreasing mainly in the northern area. In 2005 there was an overall decrease of egg abundance (the maximum number of eggs per station was 1/3 the last year’s). In particular, the egg abundance decrease over the Gironde area, which is one of the most relevant spawning areas of 1 year old anchovies, indicating again a recruitment failure this year.


Table 2.3-4 Summary of the DEPM parameter estimates time serie

Year Actual dates SSB cv Ptot cv P0 cv SA DF SSTª Z cv

1987 2 - 7 June 29,365 0.48 2.199 0.39 4.61 0.32 23,850 81.3 16.4 0.26 0.78

1988 21 - 28 May 63,500 0.31 5.010 0.24 5.52 0.21 45,384 81.4 16.5 0.18 0.68

1989 10 - 21 May 11,861 0.41 0.730 0.40 2.08 0.27 17,546 62.3 16.6 0.18 0.99

1989 14-24 June 10,058 0.55 0.826 - 1.50 0.30 27,917 54.8 20.8 0.94 0.41

1990 4 - 15 May 97,237 0.17 4.518 0.15 3.78 0.20 59,757 52.2 16.9 0.34 0.39

1990 29 May- 15 June 77,254 0.19 7.239 - 5.21 0.13 69,471 90.1 17.7 0.62 0.31

1991 16May-07Jun 19,276 0.14 1.238 0.06 2.55 0.22 24,264 67.5 15.6 0.22 0.65

1992 16May-13Jun 90,720 0.20 5.789 0.14 4.27 0.14 67,796 71.6 17.7 0.22 0.65

1994 17 May-3June. 60,062 0.17 3.829 0.14 3.93 0.19 48,735 62.9 15.8 0.11

1995 11 - 25 May 54,701 0.09 3.094 0.07 4.96 0.12 31,189 56.7 14.5 0.19 0.34

1996 18 - 30 May 2.771 0.16 4.87 0.19 28,448 15.2 0.31 0.41

1997 9 - 21 May 51,176 0.10 2.697 0.07 2.69 0.14 50,133 53.2 15.3 0.19 0.47

1998 18 May - 8 June 101,976 0.09 5.595 0.05 3.83 0.12 73,131 56.5 15.9 0.28 0.25

1999 22 May - 5 June 3.593 0.09 3.52 0.08 51,019 16.8 0.12 0.40

2000 2- 20 May 2.612 0.19 3.45 0.28 37,883 16.7 0.18 1.02

2001 14-May - 8 June 120,403 0.11 8.480 0.09 5.89 0.11 72,022 70.8 17.1 0.45 0.20

2002 6 - 21 May 30,697 0.13 2.342 0.13 3.28 0.13 35,980 76.4 14.7 0.13 0.51

2003 22 may-9Jun 23,962 0.28 2.150 0.28 2.53 0.28 42,535 89.91 17.3 0.33 0.66

2004 2 may- 17 May 19,498 0.15 0.842 0.11 1.82 0.11 23,124 43.6 13.7 0.10 -

2005 8 may- 28 may 0.441 0.16 0.79 0.16 27,863 14.9 0.20 0.45

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

110,000

120,000

130,000

140,000

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Figure 2.3-2: Series of Biomass estimates (tonnes) obtained from the Egg surveys since 1987. Most of them

are full DEPM estimates, except in 1996, 1999 and 2000, which were deduced indirectly from the relationship of biomass with the spawning area and P0.


0

1000

2000

3000

4000

5000

6000

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Age 1Age 2Age 3+

Figure 2.3-3 Series of numbers at age estimates (in million of individuals) obtained from the Egg surveys since 1987 (except in 1993, 1996, 1999 and 2000).


-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

-7 -6 -5 -4 -3 -2 -1 043

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46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

-7 -6 -5 -4 -3 -2 -1 043

44

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46

47

0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

2005

2003 2002

-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

2004

-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

2001

-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

2000

-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

1999

-7 -6 -5 -4 -3 -2 -1 043

44

45

46

47 0 to 1 1 to 5 5 to 10 10 to 50 50 to 100 100 to 250 250 to 500

1998

Figure 2.3-4 Egg distribution maps from 1998 to 2005.

2.4 DIRECT ASSESSMENT OF ANCHOVY BY THE PELGAS05 ACOUSTIC SURVEY An acoustic survey was carried out in the bay of Biscay from May 3rd to June 1st on board the French research vessel Thalassa. The objective of PELGAS05 survey was to study the abundance and distribution of pelagic fish in the Bay of Biscay. The target species were mainly anchovy and sardine and were considered in a multi-specific context.

To assess an optimum horizontal and vertical description of the pelagic ecosystem in the area, two types of actions were combined : i) Continuous acquisition by storing acoustic data from four different frequencies and pumping sea-water under the surface, in order to evaluate the distribution of fish eggs using CUFES system, and ii) discrete sampling at stations (by trawls, plankton nets, CTD). Concurrently,


a visual counting and identification of cetaceans and of birds (from board) was carried out in order to characterise the higher level predators of the pelagic ecosystem.

A total of 2300 nautical miles were prospected during the survey and 41 pelagic hauls were carried out for identification of echo-traces (Figure 2.4-1). At the time of the meeting, only the southern part of the transects have been scrutinised. This area match with the anchovy distribution as no anchovy was present in the northern transects. Therefore, it is possible to have the acoustic assessment for this species. As the previous years, the global area has been splitted into strata where coherent communities were observed (species associations) in order to minimise the variability due to the variable mixing of species (ICES 2005). Three areas were identified (Figure 2.4-2) :

- "Gironde" : closed to the coast in front of the Gironde where mainly sprat, sardine and

anchovy (in minor importance) was seen, - "Offshore" : off the Gironde area until the shelf break characterised by more surface

echotraces where horse mackerel, mackerel and sardine were predominant, - "Adour" : the southern area from the French coast to the shelf break with anchovy, horse

mackerel and sardine (in minor importance). According to otoliths and length distributions in each haul and the resulting age/length key, a biomass estimate in number has been processed for each area at age group (Figure 2.4-11) and the global estimate was 16 500 t. The results are presented in Table 2.4-1.

Table 2.4-1 biomass estimates

numbers (x106) area (nm²) G 1 G 2 G 3+ Total North coastal 2 226 55.3 107.4 17.9 180.6 North offshore 4 176 2.5 4.8 0.8 8.2 South of Arcachon 2 456 49.8 256.0 77.7 383.4 total 8 858 107.6 368.2 96.3 572.2 % 18.8 64.4 16.8 100 in tons area (nm²) G 1 G 2 G 3+ Total North coastal 2 226 909 2 098 384 3 391 North offshore 4 176 44 91 16 151 South of Arcachon 2 456 1 142 7 302 2 671 11 115 total 8 858 2 095 9 492 3 070 14 657 % 14.3 64.8 20.9 100

During this survey, more than acoustic transects and pelagic trawl hauls, 955 CUFES samples were collected and counted, 53 vertical plankton hauls and 79 vertical profiles with CTD were carried out.

2.4.1 Eggs. The eggs provided by CUFES were sorted and counted during the survey and two spawning areas were therefore localised (Figure 2.4-3). On the one hand, the spawning area localised in the south of the Bay of Biscay (Adour) seems to be well linked with the adults distribution. On the other hand, the eggs presence in front of Gironde is broader than the few adults that were seen by acoustics. CUFES data are used for distribution purposes and can't be considered for a quantitative estimate;

According to this, the survey was interrupted before the end of the whole coverage and the last week was therefore devoted exclusively to anchovy in the southern area with two objectives : i) to check the adults distribution in the southern area and have more samples in the Gironde coastal area and ii) to study the vertical distribution of eggs, validate a vertical model and therefore study the hypothetical validity of CUFES samples in a quantitative point of view.

The mix of anchovy and horse mackerel observed during the first week of May was still present in the same echotraces structure that previous one. A new pelagic haul was carried out and showed the same proportions of species and length distributions.


A dense acoustic and CUFES covering of the Gironde area was then carried out. It showed the same presence of eggs and fish echoes. Hauls revealed the presence of some small anchovies when they occurred close to the coast, confirming the fact that the adults of anchovy producing the eggs were probably very close to the coast and may be difficult to be observed by acoustics with a vessel like Thalassa. Many plankton net hauls combined to dense CUFES samples (1 nm instead of 3 nm) were carried out in this area. A gradual distribution of eggs was observed according to the stage of eggs proving that the broad distribution was due to the drift of eggs from the coast to offshore and that these eggs were mainly produced very close to the coast. This area (depth < 25 m) is of course badly surveyed by acoustics for security reasons and spawners in this area might be under-estimated..

Hydrological observations showed surface temperatures rather similar to previous years but well visible up-wellings along the Landes coast. The river plumes are narrow and rather cold at the surface, showing a recent flow of fresh water and well corelated to the dry winter which preceded. Nevertheless, temperatures at 40 m depth were very cold (< 11°), even 2° below the colder one registered since 2000.

The number of 1 year old anchovy was estimated at a level of 108.106 millions fish. Nevertheless, the combination of the two observations 1) of eggs (CUFES) and 2) acoustics and pelagic trawl hauls, shows that the Gironde spawners were certainly very close to the coast and might be under-estimated. Therefore, the abundance of anchovy seemed to be very low and the predominance of big fish indicated a very low level of recruitment.

These spring acoustic surveys are yearly carried out in the Bay of Biscay since 2000 applying the same surveying and sampling strategy. Looking at the series, 2 kinds of results may be considered. On the one hand, the eggs distribution in 2005 (Figure 2.4-3) doesn't reveal a dramatic situation, but it must be highlight that this indicator is not representative of the global spawning but only of a fraction of it. Looking at Figure 2.4-4 it is visible that number of eggs look similar to the one observed the previous years (except 2001 where eggs numbers were extremely high) and only positive areas seem to change from one year to the other. On the other hand, the adult distributions (Figure 2.4-5 to Figure 2.4-10) compared for the same series show a drastic decrease in both the distribution area and in abundance in 2005. The age compositions in numbers along the series shows the same decrease and particularly the lack of age 1 in 2005.

Figure 2.4-1 Prospected transects by acoustics and

species compositions of catches obtained from identification hauls into during PELGAS05

Figure 2.4-2 Areas taken into consideration for the

biomass estimate of anchovy at the date of the STECF meeting. No anchovy was observed in the

northern area


Figure 2.4-3 distribution of anchovy eggs observed with CUFES during PELGAS05

0

10000

20000

30000

40000

2000 2001 2002 2003 2004 2005

Année

0

50

100

150

200

250

300

350

400

Figure 2.4-4 Number of eggs and positive areas observed during PELGAS surveys from 2000 to 2005


Figure 2.4-5 Distribution and abundance of anchovy from acoustic survey in 2000 (survey PEL2000). (data

used for this figure are densities per nm² at each ESDU)


Figure 2.4-6– Distribution and abundance of anchovy from acoustic survey in 2001 (survey PEL2001)


Figure 2.4-7 Distribution and abundance of anchovy from acoustic survey in 2002 (survey PELGAS02)


Figure 2.4-8 Distribution and abundance of anchovy from acoustic survey in 2003 (survey PELGAS03)


Figure 2.4-9 – Distribution and abundance of anchovy from acoustic survey in 2004 (survey PELGAS04)


Figure 2.4-10– Distribution and abundance of anchovy from acoustic survey in 2005 (survey PELGAS05)


G 1 G 2 G 3 G 4

GirondeOffshoreAdour

0

5000000

10000000

15000000

Figure 2.4-11– Abundance of anchovy per age group in each area taken into consideration for the biomass

estimate by acoustics from PELGAS05 data.

0

100000

200000

300000

400000

500000

600000

PEL0

0

PEL0

1

PEL0

2

PEL0

3

PEL0

4

PEL0

5

1 an2 ans3 ans +

Figure 2.4-12 – Age proportions of anchovy as observed during PELGAS surveys since 2000 (numbers used

in this figure are sum of numbers per nm² at each ESDU)

2.5 ON A RECRUITMENT INDEX FOR ANCHOVY FROM THE AUTUMN EVHOE BOTTOM TRAWL SURVEYS

An investigation has been done of the potential useful information coming from the French autumn bottom trawl surveys EVHOE for providing an early recruitment index for anchovy in the Bay of Biscay.

These EVHOE bottom trawl surveys have been carried out by France since 1987 on the continental shelf of the Bay of Biscay from October to December (Poulard et al., 2003). The sampling strategy, gears and processing are standardised since the origin of the series and the sampling design is stratified according to latitude and depth. Catch weights and numbers at length are recorded for all species each year and therefore a recruitment index has been calculated by summing stratum density indices considering only individuals < 11cm as assimilated to anchovy O group in autumn.


This index was compared to existing recruitment indices such as the ICA stock assessment estimates (Figure 2.4-1), the abundance index derived from the acoustic spring survey Pelgas (Figure 2.5-2) and the anchovy recruitment index derived from environmental variables (Figure 2.5-3).

12 14 16 18

11.6

12.0

12.4

12.8

Achovy total biomass

ln(B) EVOHE Oct year t

ln(B

) IC

A s

tock

ass

essm

ent J

an y

ear

t+1

Figure 2.5-1 Comparison between EVHOE recruitment index and the one provided by ICA

0 e+00 2 e+07 4 e+07 6 e+07

5.0

e+06

1.5

e+07

Year class 97, 99-2003

Evohe abundance < 11 cm year t

Pel

gas

abun

danc

e ag

e 1

year

t+1

Figure 2.5-2 Comparison between EVHOE recruitment index and the one provided by acoustic surveys

1000 2000 3000 4000 5000 6000 7000

020

0040

0060

0080

00

Recruitment index

Evo

he a

bund

ance

10^

4 <

11 c

m

Figure 2.5-3 Comparison between EVHOE recruitment index and the one provided by environmental factors

Although the correlation are fairly noisy , it appears that there may be potential to develop a useful recruitment index from the EVHOE bottom trawl catch data which is coherent with other recruitment estimates. It is therefore possible that the age-0 anchovy caught by bottom trawl in October could provide an indicator of that part of the incoming year class that had already recruited to the adult stock. The remaining juveniles which were still at the surface (not already fully recruited to the adult fish) would not be taken into account and another method to estimate their abundance should be considered at this period of the year.

3 FISHERIES INFORMATION

3.1 SPANISH PURSE SEINE FISHERY. The Spanish fleet is composed of purse seines (around 220 boats). Operative mainly in the spring, when more than 80 % of the annual catches of Spain are usually taken. This spring fishery operates at the south-eastern corner of the Bay of Biscay in Divisions VIIIc and b. Until 1995, the Spanish purse-seines were allowed to fish anchovy in Sub-division VIIIb only during the Spring season and under a system of fishing licences (Anon. 1988), while Division VIIIa was closed to them for the whole year. Since 1996 this fleet can fish anchovy throughout the year in Sub-area VIII with the same system of fishing licences.

The major part of this fleet goes for tuna fishing in summer time and by then they use small anchovies as live bait for its fishing. These catches are not landed but the observations collected from logbooks and fisherman interview (up to 1999) indicate that they are supposed to be less than 5 % of the total Spanish catches. Since 1999, a part of the Spanish fleet goes to fish in the VIIIa during summer and autumn and lands significant amounts of fish, but there was no catch in 2003 and 2004.

3.1.1 Spanish Spring fishery in 2005-comparisons to previous years

3.1.1.1 Catch in tonnes: The fishery for the last three years (2002-2004) has suffered consecutive failures of catches: Spanish catches since 2002 have been about half or less than half the average levels of the period 1990-2001. The Spanish Spring fishery in 2005 has suffered a complete failure: By 12 May, (when usually about 40% of annual Spanish catches are already achieved) about 200 t had only be caught (i.e. about 1% of a normal year). This is a complete crash of the commercial fishery. Since then commercial fishery has stopped and claim for financial aids for a ban of the commercial fishery. Figure 3.1-1 shows the serie of Spanish catches in the Spring fishery until half of the May, to compare the fishery of the 2005 with the previous years. This drastic drop observed in 2005 indicated a great decrease in the abundance of the anchovy. The fact that this level of the catches is the lowest of the time series could indicate that, in addition to the low abundance level of anchovy, a problem with the accessibility to the purse seine could be present.

Spring Spanish catches (until half of May)

0

2000

4000

6000

8000

10000

12000

14000

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Years

To

nn

es

Figure 3.1-1 Spring Spanish catches (t) (until half of May) from 1987 to 2005


3.1.1.2 Catch in numbers at age Figure 3.1-2 shows the Spanish catch at age compositions of the first half of the year from 1987 to 2005. The age composition in 2002, 2003 and 2005 is different compared to the rest of the historical series. In these years, age 2 predominated in the catches of the first half of the year, while usually is age 1 the one predominating.

The age composition of the Spring Spanish catches show a failure of catches at age 1 since 2001. This age composition is typical of the occurrence of weak year classes, otherwise age 1 would have largely sustained all catches. Thus a reduction of recruitment is happening in these years.

Spring Spanish Catch at age (number)

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Nu

mb

er ('

000) 1

2

3

4

Spring Spanish Catch at age (percentage)

0102030405060708090

100

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Per

cen

tag

e 1

2

3

4

Figure 3.1-2: Age composition of Anchovy catches (in number and percentage) obtained in Spring Spanish

fishery from 1987 to 2005.

3.2 SPANISH TUNA LIVE BAIT FISHERY Fishermen reported that they could hardly catch any juvenile achovies for live bait tuna fishing in summer-autumn 2004. A similar observation in 2001 was followed by the failure of recruitment in 2002.


3.3 FRENCH LANDINGS

BB ANchovy : French landings

0

1000

2000

3000

4000

5000

6000

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

qu

arte

rly

lan

din

gs

in t

on

nes

0

5 000

10 000

15 000

20 000

25 000

To

tal l

and

ing

s in

to

nn

es

Q1

Q2

Total

Figure 3.3-1 French landings for the two first quarters (and full year) from 1987

Between 1987 and 2005, French landings in the first quarter have fluctuated widely reaching 5000 tons in some years (Figure 3.3-1). In 2003, given that the vessels avoided the south area of the Bay of Biscay because of the Prestige oil spill, the catches were almost nil. In 2004 and 2005, the landings in the first quarter were very low, 300 and 400 tons respectively.

In the second quarter, landings have fluctuated between 1000 and 3000 tons from 1987 to 1997. Since then, they have fluctuated at a lower level between 1000 and 2000 tons.

The 2005 landings (550 tons) is the lowest value of the recorded series, three times less than the 2004 value.

BB Anchovy - French landings

0

1 000

2 000

3 000

4 000

5 000

6 000

7 000

8 000

9 000

10 000

10 11 12 13 14 15 16 17 18 19classes de taille (cm)

nom

bre

d'in

divi

dus

(mill

iers

)

1er semestre 20041er semestre 2005

Figure 3.3-2 Length composition of the 2004 and 2005 French landings (first half of the year)

The length compositions of French landings in 2004 and 2005 are given in Figure 3.3-2 and the age composition for the corresponding years are given in Figure 3.3-3. Figure 3.3-2 clearly shows the lack of small anchovies in the French landings in the first half of the year.


0

10 000

20 000

30 000

40 000

50 000

60 000

70 000

80 000

1 2 3 4classes d'âges (années)

nom

bre

d'in

divi

dus

(mill

iers

)

1er semestre 20041er semestre 2005

Figure 3.3-3 Age composition of the 2004 and 2005 French landings (first half of the year)

The lack of young fish is even clearer when looking at the age composition (Figure 3.3-3). Because of a higher growth rate, the proportion of fish of greater sizes belonging to age 1 was higher in 2004 than in 2005. This explains why with relative similar length distribution over 14 cm, the number of age 2 is bigger in 2005.

0

50 000

100 000

150 000

200 000

250 000

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

123

Figure 3.3-4 Age composition of French landings (first half of the year) from 1987-2005

In the period 1987-2004, the age group 1 contributes to 62% in average to the French landings of the first half of the year (Figure 3.3-4). In some years, age 2 predominates (1991, 1999, 2002). In the first half of 2005, the age groups 1 to 3 contribute to 16, 67 and 16%, respectively.

4 NEW INFORMATION

4.1 ASSESSMENT UPDATE Integrated Catch at Age Analysis (ICA), was run following the same procedure performed by the ICES Mackerel Horse Mackerel Sardine and Anchovy (MHSA) Working Group in September 2004: SSB and numbers at age from DEPM were used as absolute indices and the corresponding estimates from the French acoustic survey were used as relative (standard run). There is no reason for not accepting the levels of biomass provided by acoustics as absolute, but in fact taking DEPM as absolute is all that is needed to scale the assessment. The update assessment (Table 4.1-1) is very consistent with the past series of recruitment, biomass and fishing mortality estimates produced up 2003 by ICES (MHSA ICES WG 2004) (Figure 4.1-1).

The assessment points out low levels of recruitments since 2001, dropping to a level just above 700 million in 2004 (by far being the lowest of the series). Those low recruitment levels have lead the spawning population (SSB) to the lowest value in the series in 2005 (well below Blim), showing an increasing trend in fishing mortality in 2003 and 2004. The SSB level pointed out by ICA, under the assumption of F status quo (F2005=F2004) is about 8500 t, and a projection based on the actual catches occurring during first half of 2005 points out a value about 11,500 t for 2005. These results on SSB follow closely the survey information on the anchovy population which tunes the assessment, providing synthetic estimates of both surveys.

In addition to the standard run, a sensitivity analysis of the catchability assumptions was performed by running the ICA taking all indices as absolute, all as relative, acoustics as absolute and DEPM as relative and considering the estimates from each survey alone. All assessments showed the same tendencies (dropping R and SSB and raising up of fishing mortality, Figure 4.1-2) and therefore the outcome of the analysis was rather insensitive to the catchability models selected for surveys. It was however noticed that when the surveys were treated as relative indices in the assessment, catchability coefficients for age group 2 were about 50% higher than the one for age group 1 and there is no basis to believe that that could be related to the performance of the surveys (MHSA ICES WG 2004, Petitgas et al. WD 2004). The model achieves a better fit to the data by doing so and therefore it is possible that M at age 1 was set too high in the model. Furthermore, there are indications of patterns in the residuals from the model fit both for the separable period and the age structured indices which point to the problem. It is suggested that this is further investigated by the ICES MHSAWG. However, the Study Group concluded that this possible model misspecification could only result in a re-scaling of both the numbers at age 2 throughout the time-series and, consequently of the precautionary reference points; therefore it should not have an effect on the current perception of the stock in relation to precautionary limits. This means that the current perception of the population being well below Blim is not affected by this unsolved fitting problem. Furthermore,the survey estimates indicated that the biomass has fallen well below Blim.

In addition to ICA, an update of the last WGMHSA (2004) assessment based on the biomass model was performed. Figure 4.1-2 shows the time-series of recruitment median estimates from the corresponding posterior distributions. The estimates corresponding to recent years are very close to the ones provided by ICA Figure 4.1-2). Table 4.1-1 Summary output of the ICA assessment on the anchovy population with the most recent information up to 2005.

Year Recruits Total Spawnin Landings ³ Yield Mean F Age 0 Biomass Biomass ³ /SSB Ages thousands tonnes tonnes tonnes ³ ratio 01-Mar

1987 6004800 191826 64994 15308 0.2355 0.9439 1988 4829540 139311 41501 15581 0.3754 0.5308 1989 19241240 297630 26117 10614 0.4064 0.534 1990 7297180 179102 53090 34272 0.6455 1.0652 1991 26990750 471135 30401 19634 0.6458 1.0491


1992 24078980 429022 70931 37885 0.5341 1.021 1993 12515200 309916 82563 40293 0.488 0.7772 1994 10454150 265202 53237 34631 0.6505 0.8513 1995 14162920 258976 43364 30115 0.6945 0.9466 1996 17553920 298895 40004 34373 0.8592 1.3423 1997 28108620 419076 44767 22337 0.499 0.5855 1998 13997740 330812 93280 31617 0.3389 0.4056 1999 23466790 417611 75542 27259 0.3608 0.4082 2000 22034430 427606 90105 36994 0.4106 0.527 2001 4714030 218123 88720 40564 0.4572 0.5141 2002 4003660 141769 49658 17507 0.3525 0.4826 2003 8502240 141755 20003 10595 0.5297 0.692 2004 703270 65658 29209 16361 0.5601 0.8924 2005 8433


Anchovy assessments of Recruitment with Aged and SSB indexes

0

5,000,000

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Last WG Assessment Similar assessment in July 2005

Assessment of Fishing Mortality on Anchovy

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Assessment of SSB for anchovy

010,000

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100,000

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1988

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2005


7 Figure 4.1-1: Comparison of the ICES MHSAWG (ICES 2005) assessment of anchovy in 2004 with the

current updated assessment in July 2005.


Anchovy assessments of Recruitment with Aged

and SSB indexes

05,000,000

10,000,00015,000,00020,000,00025,000,00030,000,00035,000,000

1987

1988

1989

1990

1991

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2004

Bosth Surveys_AbsoluteBoth surveys RelativeStandard assessment 2005 DEPMabsol&3+DEPM Relative & Acoustic Aboslute

Assessment of SSB for anchovy

0

20000

40000

60000

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120000

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Assessment of Fishing Mortality on Anchovy

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1988

1989

1990

1991

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1997

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2004


Figure 4.1-2 Sensitivity analysis for different catchability assumptions in the ICA assessment.


050

000

1000

0015

0000

Run 6

Year

Rec

ruitm

ent (

tone

s)

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

median95 % C.I.

ICA

Figure 4.1-3 Median recruitment (solid line) and 95% credibility intervals (dashed lines) at the beginning of the year from the biomass-based model. ICA estimates of recruitment (thick red line).

4.2 SHORT TERM PROJECTIONS AND RECRUITMENT SCENARIOS The anchovy population in 2006, as in any other past year, largely depends on the incoming recruitment, which will occur in this case during 2005 (as age 0). However no recruitment index is nowadays available for anchovy. And hence the strength of the recruitment occurring in 2005 is totally unknown.

For the purposes of showing potential evolution of the population for different levels of recruitments, deterministic projections of the population were made for several scenarios of recruitments, and in the context of a complete closure of the fishery.

4.2.1 Inputs: An electronic Excel book was built for the projections based on a catch constraint of about 1,250 t for 2005, taken during the first half of this year 2005. Next the evolution of the population during the second half of 2005 and years 2006 and 2007 is made under no fishing activities but subject to a constant natural mortality of 1.2 per year (as used in ICES). Mean weights at age in the stock correspond to the average of past series of estimates since 1990. Starting population at the beginning of year 2005 is the one provided by the ICA assessment output, except of the recruitment, for which different scenarios were tested . (Table 4.2-1, upper panel)

a) The same low level as estimated for the 2004 cohort (which is lowest of the series). b) 25 % percentile of historical recruitment values estimated since 1987 by the ICA assessment c) Median of historical recruitment values estimated since 1987 by the ICA assessment d) 75 % percentile of historical recruitment values estimated since 1987 by the ICA assessment

4.2.2 Results Results show (Table 4.2-1) that the strength of the 2004 is so weak that in case of repetition of those levels of recruitments the stock would still decline in the following years (up to about 5,000 t in 2007) even in the absence of any fishery.

Recruitments at 25% percentile recover the population just above Blim (to about 24,500 t). And median or higher level of recruitment levels would restore the population well above Bpa.


Table 4.2-1 Inputs and outputs for an anchovy population projections under different recruitments levels. Departing from first January 2005 (under the closure of the fishery scenario). Recruitment in thousands of anchovies. INPUTSMean weight at age at the stock (1990-2004) and at catches (1990-2004)Fbar age range: 1-3 F which produces 1,250 t of catches in the first half of 2005

INPUTS

Age N M Mat PF PM SWt Sel CWt0 Recruitment 1.2 0 0.4 0.375 0.0123 0.0034 0.01311 211,120 1.2 1 0.4 0.375 0.0165 0.4394 0.02192 494,750 1.2 1 0.4 0.375 0.0295 1.0819 0.02943 26,511 1.2 1 0.4 0.375 0.0346 1.0632 0.03524 4,150 1.2 1 0.4 0.375 0.0405 0.8547 0.04045 4,472 1.2 1 0.4 0.375 0.0420 0.8547 0.0420

OUTPUT OUTPUT

2005 2005 2005 2005 2005 2006 2006 2007 2007Scenarios of Recruitment Recruitment SSB FMult FBar Landings SSB Landings SSB Landings

at 2004 cohort level 703,270 11,532 0.09 0.0775 1,240 6,614 0 4,968 025% percentile 6,327,895 11,532 0.09 0.0775 1,256 24,453 0 32,423 0

Median value 13,256,470 11,532 0.09 0.0775 1,277 46,429 0 66,243 075% percentile 21,336,132 11,532 0.09 0.0775 1,301 72,055 0 105,682 0

Finally an examination of the recruitment levels required for the recovering the population above the biological reference points established by ICES (2004) was made for the purposes of providing reference values for any next coming recruitment estimates. Table 4.2-2 provides those values of reference for minimum recruitment levels. Table 4.2-2 Minimum recruitment levels to restore the anchovy population above the reference precautionary limits of Blim (=21,000 t) and Bpa (33,000 t) (Recruitment in thousands of anchovies)

a) Minimum Recrutiment to rebuild the stock in 2006 above Blim (without fishery in second half 2005 and all 2006)2005 2005 2005 2006 2006

SSB Landings SSB LandingsRecruitment 1st January 5,300,000 11,532 1,253 21,193 0

Recruitment End September 2005 2,154,169Recruitment at Spawning time 2006 (age 1) 1,017,557

b) Minimum Recrutiment to rebuild the stock in 2006 above Bpa (without fishery in second half 2005 and all 2006)2005 2005 2005 2006 2006

Recruitment SSB Landings SSB LandingsRecruitment 1st January 9,100,000 11,532 1,265 33,246 0

Recruitment End September 2005 3,698,667Recruitment at Spawning time 2006 (age 1) 1,747,127

This exercise show that a recruitment a bit below the 25% percentile is capable of rebuilding the population just above Blim, but in order to rebuild it above Bpa a value close to the geometric mean of the series would be required (the geometric mean being 10,385 millions).

4.3 ECONOMIC EVALUATION OF THE FRENCH FLEETS FOR ANCHOVY IN THE BAY OF BISCAY.

The WG reviewed a working document (Guyader, pers comm.), which described the evolution of the French fleets that exploit anchovy and evaluated the likely economic impact of a complete closure on the French fishery for anchovy in the Bay of Biscay. The evaluations examined what the effects of a closure have been for each of the years 2000-2003. The results were expressed as the change in gross revenue for each year individually. The evaluation also considered the impact of potential mitigation measures that the fleets may be able to adopt such as directing some of their effort onto species other than anchovy. Three scenarios were examined:

1. Closure of the fishery for three months (July-September) 2. Closure of the fishery for six months (July to December)


3. Closure of the fishery for nine months (January-March and July – December) For each of the above scenarios, three further options were examined:

1. No fishing activity 2. No landings of anchovy but all other species would be landed 3. Diversification of their activities to maximise their potential revenue by targeting species other

than anchovy. The overall results for a closure in 2003 are given in Figure 4.3-1 which indicates that cessation of all fishing activity would lead to losses in gross revenue ranging from 40% - 80% depending on the length of closure.

-

100 000

200 000

300 000

400 000

500 000

600 000

700 000

800 000

Reference (2) Jul-Sept (3) Jul-Dec (4) Jan-Mar, Jul-Dec

In E

uros

reference

No fishing activity

No anchovy landings

Sw itch to the "best"

Figure 4.3-1 Pelagic trawlers (>50tons): potential impact of fisheries ban on average gross revenue (2003)

Continuing to fish for species other than anchovy but maintaining their base-line activity would result in losses ranging from 30% -55%. Maximising their potential revenue by targeting species other than anchovy would result in losses in the region of 15%-20%. The latter option should be considered optimistic since crewing effects, licensing quota restrictions for other species, price effects etc have be taken into account in the predictions.

The WG notes that there may be some scope for reducing the economic impact of a closure for the French fleets fishing for anchovy provided that they are able to diversify their activity and target other species. The analysis suggests that in the most optimistic scenario, losses in gross revenue of the order of 40%-80% could be reduced to 15%-20%. However this is dependent on the period of closure the availability of other fishing opportunities and their ability to exploit them. In principle more informative economic indicators would include inter alia gross surplus, net profit and wages.

While the potential losses in gross revenue through closures can be evaluated using this approach, the WG notes that the results must be considered in the context of the current stock situation. The stock is at an historically low level and has experienced recruitment failure in 2004. As a result, even without a closure the fleets exploiting anchovy would have experienced reduced catches of anchovy in 2005 with a consequential reduction in gross revenue. The introduction of the emergency closure in 2005 will therefore have less of an impact on the fleets than would have been the case, had there been a higher stock of anchovy to exploit.

5 EVALUATION OF MANAGEMENT MEASURES OTHER THAN CLOSURE

5.1 INTRODUCTION Two different management measures have been proposed for this fishery (STECF SEC(2004) 180). One was for a closed fishing area around the Gironde estuary, the other for a closure during the spawning season.

The proposal for an area closure refers to the box shown in Figure 5.1-1. The position of the box corresponds to the area in which the mean length of anchovy in spring is less than 13.5 cm (grade of 60), based on the series of acoustic surveys (1985-2002) (Petitgas and al, 2002). So the closure would be designed to protect a part of the incoming year class. The closure during the spawning period is intended to protect the stock during this critical period and would entail no catches of anchovy being allowed from May to mid August.

The long-term and short-term effects of these alternative management measures for anchovy stock dynamics was explored (Petitgas pers. Comm.) using a preliminary and simple Leslie matrix model . The results of this exercise are presented for illustration purposes only and should not be used as a basis for any management decisions.

30'-2°30'-3°30'-4°30'-5°30'-6°

30'30'

4444°

30'30'

4545°

30'30'

4646°

30'30'

4747°

30'30'

4848°

Figure 5.1-1 closure box

5.2 THE MODEL The standard Leslie model is

)1()( −= txAtx where A is the time invariant transition matrix, x(t)=[x1(t), x2(2), x3(t)] are numbers at age. The long term equilibrium is determined by the transition matrix

xA λ= where λ is the population growth rate and x is the stable population age structure. λ is determined by the first eigenvalue of A. For anchovy

=

020001

321

SS

FeFeFeA ,


where S=exp(-(M+F)) is the survival at age

M and F are the annual natural and fishing mortality. Fe=Fb*sd*sf*We*Se*Su*S0=fec*Su*S0; is the fertility at ag

Fb is the batch fecundity (number of eggs spawned per batch per gramme of female)

Sd is the spawning duration (days) Sf is the spawning fraction (percent of females spawning per day)

We: is the weight at age Se is the ex ratio S0 is the survival from egg to age 1

Su=exp(-(M+F)*(sb+sd/2)/12) is the survival to next year at spawning time;

Table 5.2-1 Parameter values used for anchovy status quo Leslie matrix model

Parameter Value Source M 1.2 all ages ICES working group WGMHSA 2004 F 0.4 all ages WGMHSA 2004 Fb 600 Motos 1996 Sd 3.5 Sf 0.25 per day Motos 1996 We 16, 28, 36 ages 1, 2 & 3 Average 2000-2005 Pelgas Se 0.5 Sb 4.75 S0 1.33 10-5 Motos 1996

5.3 EVALUATION OF ALTERNATIVE MANAGEMENT MEASURES Five alternative measures were explored:

1 omplete closure of fishery, 2 closing fishing during the spawning season, 3 halving of annual catches, 4 no fishing during spawning season, 5 spatial fishery closure covering part of the observed juvenile distribution (see below) and a

combination of the previous two measures. In the model, all measures were parameterised by a reduction in the value of fishing mortality, which assumed to be the same for all ages. The assumed effects of each of these measures on F and survival at age 0 are shown in Table 5.3-1. Table 5.3-1 Multipliers s for juvenile survivale rates used for short term one-year ahead predictions for 2006 under different recruitment scenarios. S0* = s S0; S0 as in Table 5.2-1. Management scenarios as in Table 5.5-1.

Management scenario

Recruitment scenario

Status quo

No fishing

Closed during spawning

50% catch

Closed box for juveniles

Closed box and closed during spawning

low 0.02 0.021 0.02 0.02 0.021 0.021

mean 1 1.05 1 1 1.03 1.03

high 1.98 2.08 1.98 1.98 2.04 2.04

Fishing mortality

0.4 0 0.28 0.17 F1=0.18, F2&F3=0.4

F1=0.13,

F2&F3=0.28


5.4 LONG-TERM POPULATION GROWTH RATE The population growth rate was calculated by analysis of the properties of the time invariant transition matrix of the model. The population growth rate corresponds to the first eigenvalue of the transition matrix.

As a baseline for comparison, the population growth rate for the status quo fishing mortality was calculated. Input parameters are given in Table 5.2-1. Population growth rate at status quo was estimated as 1.01, showing that in the long term the modelled anchovy population was just viable, as its growth rate was just above 1. The long-term stable age structure is found to be 81% age 1, 16% age 2 and 3% age 3.

Long-term effects on population growth rate were similar for most management measures, but most important for complete closure of fishery (population growth rate 1.37). The combination measure (reducing fishing mortality on ages 0 and 1 by a spatial fishing closure, i.e. a closed box, and no fishing at all during the spawning period) was second best (1.30). The stable age structures were very similar to the age structure under the status quo situation.

5.5 SHORT-TERM EFFECTS OF MANAGEMENT MEASURES To evaluate short-term effects of the alternative management measures, estimated p

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COMMISSION STAFF WORKING PAPER - Europa · 2011. 3. 30. · 1 INTRODUCTION 1.1 TERMS OF REFERENCE 1 To evaluate and comment thelatest ICES advice in the light of possible new information