Fishery Resources Monitoring System

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Sole - Bay of Biscay, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Sole - Bay of Biscay, 2008
Fact Sheet Citation  
Sole in Divisions VIIIa,b (Bay of Biscay)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Common sole, fr - Sole commune, es - Lenguado común, zh - 欧洲鳎
Geographic extent of Sole - Bay of Biscay
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes
 
 
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 landings of sole in the Bay of Biscay are subject to a TAC regulation in combination with technical measures. Estimated landings have frequently exceeded TACs, in particular in the years 2002–2006.

Changes in fishing technology and fishing patterns

The French fixed-net fishery for sole, taking place mainly in the spawning season, has increased from less than 5% of total landings prior to 1985 to around 60% in recent years. This shift between the fleets has resulted in a change of the selection towards older fish.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

An age-based analytical assessment (XSA) was conducted based on landings and indices from two surveys (ending in 2002) and two commercial fleets. Discard information is not included in the assessment. No recruitment indices are available for this stock.

Information from the fishing industry



A meeting with representatives of the fishing industry in France was held prior to the Working Group meeting to present the data used to assess the Bay of Biscay sole stock. The participants did not express reservations on these data.

Uncertainties in assessment and forecast

There is a need for fisheries independent data to improve the stock assessment and the estimation of recruitment. This assessment relies on times series of commercial fleets. In addition, the proportion of landings taken by these fleets is decreasing. Commercial data do not provide reliable estimates of incoming year classes. The catch and SSB in the forecast is dominated by year classes for which geometric mean recruitment is assumed.

Presently, different age reading methodology and age interpretation exists between nations involved in the fisheries.

Available discard data are patchy and noisy. The effect of excluding discard data from the assessment is currently unknown.

Environment conditions

Environmental conditions have a large influence on catches of the fixed-net fishery in the first quarter. Environmental conditions were especially favourable in 2002.

Studies in Vilaine Bay showed a significant positive relationship between the fluvial discharges in winter–spring and the size of the local nursery. The extent of the river plume influences both the larval supply and the size and biotic capacity of habitats in estuarine nursery grounds and determines the number of juveniles produced. This localized effect is not apparent on the scale of the whole Division VIIIa,b,d stock and the impact of this relationship was therefore not taken into account in stock projections.

Comparison with previous assessment and advice

In this year’s assessment SSB in 2008 has been revised upward by 8% and F in 2007 has been revised downwards by 17% compared to last year assessment. Last year’s advice was based on Fpa. This year´s advice is based on precautionary considerations that SSB in 2011 should not be allowed to decrease.
Overall Assessment Results


Figure 7.4.11.1 Sole in Divisions VIIIa,b (Bay of Biscay). Summary of stock assessment: landings, fishing mortality, recruitment, and SSB. Shaded recruitments were replaced by geometric mean.


Figure 7.4.11.2 Sole in Divisions VIIIa,b (Bay of Biscay). Stock-recruitment plot, yield per recruit analysis and, PA plot.


Figure 7.4.11.3 Sole in Divisions VIIIa,b (Bay of Biscay). Comparison of current assessment with previous assessments (predicted intermediate years are included).


Table 7.4.11.2 Bay of Biscay sole (Division VIIIa,b). Official landings and ICES landings estimates and catches (in tonnes).
  Official landings Unallocated ICES Discards 2 ICES
Years Belgium France1 Nether. Spain Others Total Landings3 landings   catches
1979 0 2376   62*   2443 176 2619 - -
1980 33* 2549   107*   2689 297 2986 - -
1981 4* 2581* 13* 96*   2694 242 2936 - -
1982 19* 1618* 52* 57*   1746 2067 3813 - -
1983 9* 2590 32* 38*   2669 959 3628 - -
1984   2968 175* 40*   3183 855 4038 99 4137
1985 25* 3424 169* 308*   3925 326 4251 64 4315
1986 52* 4228 213* 75*   4567 238 4805 27 4832
1987 124* 4009 145* 101*   4379 707 5086 198 5284
1988 135* 4308   0   4443 939 5382 254 5636
1989 311* 5471   0   5782 63 5845 356 6201
1990 301* 5231   0   5532 384 5916 303 6219
1991 389* 4315   3   4707 862 5569 198 5767
1992 440* 5928   0   6359 191 6550 123 6673
1993 400* 6096   13   6496 -76 6420 104 6524
1994 466* 6627   2***   7095 134 7229 184 7413
1995 546* 5326   0   5872 333 6205 130 6335
1996 460* 3842   0   4302 1552 5854 142 5996
1997 435* 4526   0   4961 1298 6259 118 6377
1998 469* 3821 44 0   4334 1693 6027 127 6154
1999 504 3280   0   3784 1465 5249 110 5359
2000 451 5293   5***   5749 11 5760 51 5811
2001 361 4350 201 0   4912 -76 4836 39 4875
2002 303 3680   2***   3985 1501 5486 21 5507
2003 296 3805   4***   4105 3 4108 20 4128
2004 324 3739   9***   4072 -70 4002 - -
2005 358 4003   10   4371 168 4539 - -
2006 393 4030   9   4432 361 4793 - -
2007 401 3707   9   4117 246 4363 - -
2008 305 2514**     2* 2821 1479 4300    

1 including reported in VIII or VIIIc,d

2 Discards = Partial estimates for the French offshore trawlers fleet

3 Unallocated landings= WG landing (based on logbook and auction sales data) – Official landings

* Reported in VIII

** Preliminary

*** Reported as Solea spp (Solea lascaris and Solea solea) in VIII



Table 7.4.11.3 Bay of Biscay sole (Division VIIIa,b). Contribution (in %) to the total landings by different fleets.
Year 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993
Shrimp trawlers 7 7 8 11 6 5 4 3 3 2 2 2 1 1 1
Inshore trawlers 29 28 27 25 31 29 30 25 27 25 17 13 13 12 13
Offshore otter trawlers 61 62 60 60 59 60 45 45 47 46 41 41 39 31 28
Offshore beam trawlers 0 1 0 0 0 0 1 1 2 3 5 5 7 7 6
Fixed nets 3 3 5 4 4 6 20 26 20 24 35 39 40 49 52
 
Year 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Shrimp trawlers 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Inshore trawlers 11 13 12 11 10 5 8 9 7 8 9 7 8 9 6
Offshore otter trawlers 29 26 26 30 30 24 21 24 18 24 23 21 19 21 19
Offshore beam trawlers 6 9 8 7 8 10 8 8 6 7 8 8 9 9 7
Fixed nets 52 53 54 52 52 61 63 59 70 60 60 63 64 61 69


Table 7.4.11.4 Bay of Biscay sole (Division VIIIa,b). Contribution (in %) to the total landings by different fleets.
Year

Recruitment

Age 2

thousands

SSB

tonnes

Landings

tonnes

Mean F

Ages 3-6

1984 22885 10648 4038 0.374
1985 27832 11229 4251 0.380
1986 27809 11894 4805 0.502
1987 24733 12556 5086 0.465
1988 26794 13060 5382 0.460
1989 28273 13059 5845 0.561
1990 32248 13276 5916 0.466
1991 35923 14410 5569 0.421
1992 35580 15959 6550 0.598
1993 25137 16572 6420 0.516
1994 26434 16099 7229 0.632
1995 23797 14548 6205 0.559
1996 29612 14147 5854 0.522
1997 23792 13713 6259 0.589
1998 22647 13640 6027 0.524
1999 24494 12625 5249 0.603
2000 25167 12151 5760 0.612
2001 16670 10824 4836 0.566
2002 24615 9902 5486 0.811
2003 24281 9706 4108 0.475
2004 19723 11448 4002 0.364
2005 18937 12189 4539 0.430
2006 22490 12485 4793 0.422
2007 23068 13069 4363 0.377
2008 23191* 13750 4300 0.376
2009 23191* 14465    
Average 25539 12978 5315 0.504
* replaced by GM 1993–2006

Reference Point
 


  Type Value Technical basis
Precautionary approach Blim - Not defined.
  Bpa 13 000t The probability of reduced recruitment increases when SSB is below 13 000 t, based on the historical development of the stock.
  Flim 0.58 Based on the historical response of the stock.
  Fpa 0.42 Flim * 0.72
Targets Bmgt 13 000 t Management plan (EC regulation 388/2006)
(Unchanged since: 2006)




Yield and spawning biomass per Recruit F-reference points (2009):
 

Fish Mort

Ages 3-6

Yield/R SSB/R
Average last 3 years 0.39 0.22 0.64
Fmax 0.24 0.23 0.98
F0.1 0.10 0.20 1.89
F35%SPR 0.12 0.21 1.67
Fmed 0.50 0.22 0.51



Candidates for reference points consistent with taking high long-term yields and achieving a low risk of depleting the productive potential of the stock are in the range of F0.1–Fmax.
Projection



Basis: F(2009) = Fsq = mean F(06–08) =0.39; R09–11 = GM(93–06) = 23.2 million; SSB(2009) = 14.5; SSB(2010) = 14.6; landings (2009) = 4.9.


Outlook for 2010
Rationale Landings (2010) Basis F(2010) SSB(2011) %SSB change1) %TAC change2)
Zero catch 0.00 F=0 0.00 20.35 39% -100%
Status quo 4.90 Fsq 0.39 14.70 1% 12%
High long-term yield (candidate) 3.27 Fmax 0.24 16.58 13% -26%
  0.58 Fsq *0.1 0.04 19.68 35% -87%
  1.40 Fsq *0.25 0.10 18.74 28% -68%
  2.68 Fsq *0.5 0.20 17.25 18% -39%
Status quo 3.83 Fsq *0.75 0.29 15.93 9% -13%
  4.49 Fsq *0.9 0.35 15.17 4% 2%
  4.90 Fsq *1 0.39 14.70 1% 12%
  5.30 Fsq *1.1 0.43 14.25 -2% 21%
  5.85 Fsq *1.25 0.49 13.62 -7% 33%
  0.62 Fpa *0.1 0.04 19.63 34% -86%
  1.50 Fpa *0.25 0.11 18.62 27% -66%
  2.85 Fpa *0.5 0.21 17.05 17% -35%
  4.08 Fpa *0.75 0.32 15.64 7% -7%
  4.76 Fpa *0.9 0.38 14.86 2% 8%
Precautionary limits 5.19 Fpa 0.42 14.37 -2% 18%
  5.60 Fpa *1.1 0.46 13.90 -5% 28%
  6.19 Fpa *1.25 0.53 13.22 -10% 41%
  7.10 Fpa *1.5 0.63 12.18 -17% 62%
  7.93 Fpa *1.75 0.74 11.24 -23% 81%
  8.88 Fpa *2 0.84 10.15 -31% 102%
  9.99 Fpa *2.25 0.95 8.88 -39% 128%

All weights in thousand tonnes.

Shaded scenarios are not considered consistent with the precautionary approach.

1) SSB 2011 relative to SSB 2010.

2) Catch 2010 relative to TAC 2009.



Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of exploitation boundaries in relation to precautionary considerations that landings for 2010 should not exceed 4 900 t.

Exploitation boundaries in relation existing management plans

The agreed management plan aims to bring SSB above 13 000 t in 2008 as a first step. This target has been reached since 2007. According to the multi-annual plan a target fishing mortality should be established by the EU.

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

Target reference points have not been agreed for this stock. The fishing mortality in 2008, estimated to be 0.38, is well above any candidates for reference points in the range of F0.1– Fmax.

Exploitation boundaries in relation to precautionary limits

F should be kept below Fpa. Applying Fpa in 2010 results in landings of 5 190 t in 2010, and generates an SSB in 2011 of 14 370 t, corresponding to a 2% decline compared with 2010.


Table 7.4.11.1 Sole in Divisions VIIIa,b (Bay of Biscay). Single stock exploitation boundaries (advice), management, catch, and landings
Year

ICES

Advice/ Single-stock exploitation boundaries from 2004

Catch corresp. to advice Predicted catch corresponding to single-stock boundaries

Agreed

TAC

Official

Landings

ICES

Landings

Disc.

slip.

ICES

Catch

1987 Not assessed -   4.4 4.4 5.1 0.23 5.3
1988 Precautionary TAC 3.7   4.0 4.4 5.4 0.33 5.6
1989 No increase in effort; TAC 4.5   4.8 5.81 5.8 0.43 6.2
1990 No increase in F; TAC 5.1   5.2 5.51 5.9 0.33 6.2
1991 Precautionary TAC 4.7   5.3 4.71 5.6 0.23 5.8
1992 F = F(90) 5.0   5.3 6.41 6.6 0.13 6.7
1993 No long-term gain in increasing F -   5.7 6.5 6.4 0.13 6.5
1994 No long-term gain in increasing F -   6.6 7.1 7.2 0.23 7.4
1995 No long-term gain in increasing F 5.42   6.6 5.9 6.2 0.13 6.3
1996 No increase in F 5.0   6.6 4.3 5.9 0.13 6.0
1997 40% reduction in F 3.1   5.4 5.0 6.3 0.1 6.4
1998 No increase in F 7.6   6.0 4.44 6.0 0.1 6.1
1999 Reduce F below Fpa < 5.0   5.4 3.84 5.2 0.2 5.4
2000 F at Fpa < 5.8   5.8 5.94 5.7 0.1 5.8
2001 TAC 2001, at most TAC 2000 < 5.8   6.3 5.24 4.8 0.0 4.9
2002 Establish rebuilding plan or no fishing -   4.0 4.0 5.5 0.0 5.5
2003 Establish rebuilding plan or no fishing -   3.8 3.7 4.1 0.0 4.0
2004 5) 65% reduction in F or recovery plan   <2.0 3.6 4.1 4.0 - -
2005 F at Fpa   <4.1 4.14 4.4 4.5 - -
2006 F at Fpa   <4.2 or management plan 4.1 4.4 4.8 - -
2007 Management plan: 10% reduction in F   4.54 4.54 4.2 4.4 - -
2008 Reach Bpa in 2009   3.85 4.58   4.3 - -
2009 F at Fpa   <4.43 4.39        
2010 F at Fstatus quo   <4.9          

Weights in ‘000 t.

1Not reported for all countries.

2Landings assuming current discarding practise.

3 Discards revised in 1998.

4 Preliminary. TAC in 2001 increased from 5.8 to 6.3 in November.

5 Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries



Management
Management unit: Yes

Management Objectives

The EU regulation 388/2006 of 23 February 2006 established a management plan aimed at bringing the spawning-stock biomass above 13 000 tonnes in 2008 (see Appendix 7.4.11 in the source of information). The main elements in the plan are a 10 % annual reduction in F and a 15 % constraint on TAC change between years.

This plan has not yet been evaluated by ICES.
Management Advice

Management considerations

Since the stock is estimated to be above the target SSB of 13 000 t, according to article 3 of the multi-annual plan it is necessary for EU to decide on a long-term target fishing mortality. Fishing at Fpa in 2010 will keep SSB at current level.

Impacts of fisheries on the ecosystems

Considerable discards at age one occurs occasionally in inshore trawl fleets.
Biological State and Trend
Exploitation rate: Harvested sustainably
Abundance level: Full reproductive capacity


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

Comment

Full reproductive capacity Harvested sustainably Overfished NA SSB above Biomass target of the management plan since 2007



Based on the most recent estimates of SSB (in 2009) ICES classifies the stock as having the full reproductive capacity. Based on the most recent estimates of fishing mortality (in 2008), ICES classifies the stock as being harvest sustainably. The most recent estimates of SSB are above Bpa. The most recent estimates of fishing mortality are below Fpa. Recruitment has been stable since 1993.


Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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