Fisheries and Resources Monitoring System

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Cod - Baltic Sea (western part)
Marine Resource  Fact Sheet
ICES Advice 2009
Cod - Baltic Sea (western part)
Fact Sheet Citation  
Cod in Sub-divisions 22-24 (including Sub-division 23)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Atlantic cod, fr - Morue de l'Atlantique, es - Bacalao del Atlántico, zh - 大西洋鳕, ru - Треска атлантическая
Geographic extent of Cod - Baltic Sea (western part)
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2008
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateUndefinedUncertain/Not assessed
Abundance levelIncreased riskLow abundance


Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long term yield Fishing mortality in relation to agreed target reference points Comment
Increased risk Undefined Over-exploited Above target EU Management plan implemented in 2008 with target fishing mortality of 0.6

Based on the most recent estimates of SSB (in 2009) ICES classifies the stock as being at risk of reduced reproductive capacity (SSB<Bpa).

Fishing mortality in 2008 was estimated to be 0.83 and has been stable during the last three years. The fishing mortality in 2008 is estimated to be above the target F at 0.6. The year classes 2004-2007 were among the weakest in time-series for this stock. Surveys indicate that the 2008 year class may be the highest since the 2003 year class.
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Demersal/Benthic.  

Geographical Distribution
Jurisdictional distribution: National

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Factors affecting the fisheries and the stock

Regulations and their effects

The EC Council Regulation for the Baltic TAC and quota 2009 involves reductions in the effort (10% in terms of number of fishing days per year, which results in 201 days maximum in 2009) and reduction in TACs for Western Baltic cod (15%) following the agreed management plan (EC REG 1098/2007).

The cod fisheries in the Western Baltic are also regulated by a seasonal closure, from 1st to 30th of April in 2009. The TAC was taken in 2008.

A ‘Bacoma’ codend with a 120-mm mesh was introduced by IBSFC in 2001 in parallel to an increase in diamond mesh size to 130 mm in traditional codends. The expected effect of introducing the Bacoma 120-mm exit window was nullified by compensatory measures in the industry. This was to some extent explained by the mismatch between the selectivity of the 120-mm Bacoma trawl and the minimum landing size. In October 2003, the regulation was changed to a 110-mm Bacoma window. This was expected to enhance the compliance and to be in better accordance with the minimum landing size.

In Denmark, annual quota shares for individual vessels were introduced on 1 January 2007 according to which fishers are allocated a yearly share of the Danish quota. Fishers can subsequently fish, trade, exchange, or pool their share with other fishers. This could potentially affect the efficiency of the vessels, but a change in efficiency has not been observed.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

The assessment includes catch data, supplemented with one commercial CPUE index and three survey indices. The assessment is based on the recently developed stochastic state-space model (SAM) that provides statistically sound estimates of uncertainty in the model results. The model was adopted at the Benchmark workshop in 2009.

Discard data have been available since 1996 and are used in the assessment as yearly proportions discarded per age-group. For years prior to 1996, an average proportion discarded per age-group estimated for 1996–2003 is applied. The season and area coverage of discard sampling requires improvement. A relationship between year class strength and discard rates cannot be estimated from the available data. Due to recent changes in technical regulations, e.g. the increase of minimum landing size, introduction of BACOMA 110 and varying closures, discard rates may have varied additionally.

Uncertainties in assessment and forecast

The assessment has shown a retrospective pattern with a consistent overestimation of F and underestimation of SSB. Although the SAM model shows the same retrospective pattern as XSA the magnitude of the overestimation of F is less in the SAM model, and stays within the confidence intervals.

The increase in SSB in 2010 and 2011 is very dependent on one relative strong year class (2008), and the current estimate of abundance of this year class (65.2 million fish at age 1) has a high degree of uncertainty (95% confidence limits: 20.0 to 213 million fish at age 1).

There are indications of high and variable removals of cod in recreational fisheries especially in the western Baltic, as indicated by an EU pilot study finalized in 2007. These catches are currently not consistently and completely sampled, and therefore have not been included in the assessment. The EU has initiated a procedure to harmonize sampling methods, and this could lead to an inclusion of catches from recreational fisheries in future assessments.

Comparison with previous assessment and advice:

The SSB estimates have been revised upwards by 15% compared to last year’s assessment, and the fishing mortality and recruitment estimates were revised downwards by 25% for 2007. This reflects the uncertainty of the assessment. The new model shows a less pronounced retrospective bias than the older method.

The basis for the advice is different from last year, when it was based on the precautionary approach. As the management plan has been evaluated and considered in accordance with the precautionary approach, the basis for the advice is now to apply the EU management plan for the year 2010.
Overall Assessment Results


Figure 8.4.1.1. Stock Cod in Area SD2224. landings discard and catches in tonnes.
Figure 8.4.1.2. Cod in Area Subdivisions 22-24. Summary of stock assessment with point-wise (95%) confidence limits. The solid line is the estimated 50% quantile.
Figure 8.4.1.4. Cod in Subdivisions 22-24. Historic performance of the assessment. Left-hand panel: SSB in ‘000 t, mid-panel: F, and right-hand panel: Recruitment (age 1).
Table 8.4.1.2. Cod in Subdivisions 22-24. Landings (‘000 tonnes) by country and area.
Table 8.4.1.3. Cod in Subdivisions 22-24. Summary of stock assessment (weights in ‘000 tonnes). Recruits (age 1), Low= lower confidence limit, High = higher confidence limit. F36=Fbar 3-6 years.
Reference Point
 


  Type Value Technical basis
Precautionary approach Blim Not defined  
  Bpa 23 000 t MBAL
  Flim Not defined  
  Fpa Not defined  
Targets Fmgt 0.6 EU management plan 2007
(unchanged since: 2008)



Yield per recruitment analysis from the most recent assessment.
Yield and spawning biomass per Recruit F-reference points (2008):
  Fish Mort Yield/R SSB/R
  Ages 3–6    
Average last 3 years 0.821 0.684 0.661
Fmax 0.271 0.885 3.429
F0.1 0.163 0.829 5.398
Fmed 1.375 0.633 0.399


Projection

Outlook for 2010

Basis: Fsq (2006–08 unscaled)=0.82; SSB (2010) = 17.4kt; HC landings (2009) = 16.0kt; Discards (2009) = 1.9kt;
Rationale Human Consumption (2010) Basis F Total(2010) F HC (2010) F Disc (2010) Catch Total(2010) Discards (2010) SSB (2011) %SSB change1) %TAC change2)
Zero catch 0 F = 0 0 0 0 0 0 32.3 85% -100%
High long-term yield 8.6 Fsq*0.375 0.31 0.29 0.02 9.8 1.2 26.4 51% -47%
  15.0 Fsq *0.725 0.59 0.56 0.03 17.2 2.2 22.0 26% -8%
Management plan 17.7 Fsq *0.9 0.74 0.70 0.04 20.3 2.6 20.1 16% +9%
Precautionary approach 13.3 B2011>Bpa 0.51 0.49 0.03 15.2 1.9 23.1 33% -19%
Status quo 7.0 Fsq*0.3 0.25 0.23 0.01 8.0 1.0 27.4 58% -57%
  12.8 Fsq *0.6 0.49 0.47 0.03 14.7 1.9 23.4 35% -21%
  16.2 Fsq *0.8 0.66 0.62 0.03 18.6 2.4 21.2 22% 0%
  17.7 Fsq *0.9 0.74 0.70 0.04 20.3 2.6 20.1 16% +9%
  19.2 Fsq *1.0 0.82 0.78 0.04 22.1 2.9 19.2 10% 17%
  20.6 Fsq *1.1 0.90 0.86 0.05 23.6 3.1 18.2 5% 26%
  24.2 Fsq *1.4 1.15 1.09 0.06 28.0 3.7 15.8 -9% 48%
  27.3 Fsq *1.7 1.39 1.32 0.07 31.6 4.3 13.8 -21% 67%
Units: ‘000 tonnes.Scenarios in italics are not considered consistent with the precautionary approach.1) SSB 2011 relative to SSB 2010.2) Human Consumption landings 2010 relative to TAC 2009.


Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of the management plan that TAC should be increased by 8.6 % to 17 700 t in 2010.

Exploitation boundaries in relation to existing management plans

Following the agreed and evaluated EU management plan a reduction of 10% of the 2009 Ftotal = 0.82 results in an Ftotal 2010 of 0.74, which implies landings of 17700 t in 2010. This results in an increase of landings by 8.6% compared to the TAC in 2009. This is expected to lead to a SSB in 2011 at 20100 t.

Exploitation boundaries in relation to high long term yield, low risk of depletion of production potential and considering ecosystem effects

ICES has previously recommended target fishing mortalities in the range of 0.3–0.6 which would result in a low risk to reproduction and high long-term yields. To reach this level within 2010 would imply landings between 8600 t and 15000 t.

Exploitation boundaries in relation to precautionary limits/considerations

Landings below 13300 t in 2010 would be expected to increase SSB to above Bpa in 2011.


Table 8.4.1.1. Cod in Area Subdivision 22-24. Single stock exploitation boundaries (advice), management and catch/landings.
Year ICESAdvice Predicted landingscorresp. To advice AgreedTAC1 ICESLandings(22–24) ICESLandings (22–32)
1987 TAC 9   29 236
1988 TAC 16   29 223
1989 TAC 14 220 19 198
1990 TAC 8 210 18 171
1991 TAC 11 171 17 140
1992 Substantial reduction in F - 100 18 732
1993 F at lowest possible level - 40 21 662
1994 TAC 22 60 31 1242
1995 30% reduction in fishing effort from 1994 level - 120 34 1422
1996 30% reduction in fishing effort from 1994 level - 165 51 173
1997 Fishing effort should not be allowed to increase above the level of recent years - 180 44 132
1998 20% reduction in F from 1996 35 160 34 102
1999 At or below Fsq with 50% probability 38 126 42 115
2000 Reduce F by 20% 44.6 105 38 128
2001 Reduce F by 20% 48.6 105 34 126
2002 Reduce F to below 1.0 36.3 76 24 92
2003 Reduce F to below 1.0 22.6–28.83 75 25 94
2004 Reduce F to below 1.0 < 29.6 29.6 21 *
2005 Reduce F to below 0.92 < 23.4 24.7 22 *
2006 Management plan < 28.4 28.4 23 *
2007 Keep SSB at Bpa < 20.5 26.7 24 *
2008 Rebuild SSB to Bpa < 13.5 19.2 20 *
2009 Rebuild SSB to Bpa < 13.7 16.3    
2010 Management plan <17.7      
Weights in ‘000 t.1 Included in TAC for total Baltic, until and including 2003. 2 The reported landings in 1992–1995 are known to be incorrect due to incomplete reporting. 3 Two options based on implementation of the adopted mesh regulation. * Separate management for western and eastern Baltic cod since 2004.

Management plan (refer to eastern Baltic cod).
Management
Management unit: Yes

Management Objectives

The EC agreed on a management plan for cod in the Baltic Sea in September 2007. For Western Baltic cod the final aim of this plan is to reach and maintain a fishing mortality rate at 0.6. This should be reached through an annual reduction of fishing mortality (F) by 10% in relation to the fishing mortality estimated for the preceding year. ICES interprets the F for the preceding year as the estimate of F for the year in which the assessment is carried out (i.e. the intermediate year). The plan specifies a 10% reduction in total fishing days at sea per year until the target F has been reached. In the evaluation, this is also interpreted as a 10% reduction on F in the intermediate year assuming a constant fleet catchability. The plan sets a maximum change of 15% of the TAC between consecutive years, unless the fishing mortality is estimated to be higher than 1. In this latter case the TAC shall be set in correspondence to the reduction of fishing mortality by 10%. ICES has evaluated the management plan in 2009 and considers it to be in accordance with the precautionary approach. The evaluation is most sensitive to assumptions about implementation error; i.e. TAC and effort overshoot.
Management Advice

Management considerations

The fishery is largely based on recruiting year classes. The positive perception of the stock development in the short-term is dependent upon only one strong year class (the 2008 year class) which is expected to contribute 50% of the total catch in 2010. The appearance of this strong year class allows the TAC to increase while decreasing the F in accordance with the management plan. The level of this year class is currently estimated with high uncertainty and it will take a few years to be confident that fishing mortality has actually declined to the extent predicted by the ICES' evaluation.

Management plan evaluations

ICES evaluated the EC management plan in March 2009 and concluded that the plan is in accordance with the precautionary approach. In its evaluation, ICES assumed that the annual effort reduction is fully achieved and notes that the evaluation of the plan is most sensitive to assumptions about implementation error; i.e. TAC or effort overshoot.In the past, the implementation error has not been insignificant with the exception of 2008. Under the evaluations, F is predicted to decrease rapidly under the annual 10% effort reduction.
Source of information
 
ICES. 2009. Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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