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Lepidorhombus whiffiagonis - Bay of Biscay and Iberian Basin, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Lepidorhombus whiffiagonis - Bay of Biscay and Iberian Basin, 2008
Fact Sheet Citation  
Lepidorhombus whiffiagonis in Divisions VIIIc and IXa
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Megrim, fr - Cardine franche, es - Gallo del Norte
Geographic extent of Lepidorhombus whiffiagonis - Bay of Biscay and Iberian Basin
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

Megrims are caught in a mixed fisheries context. Regulations intended to protect others species, mainly hake and Nephrops, could have an effect on megrim stocks. The minimum mesh size for towed gears catching megrims ranges between 40 and 90 mm. The minimum landing size of megrims is 20 cm.

Changes in fishing technology and fishing patterns

Both species are caught in the mixed bottom trawl fisheries by Portuguese and Spanish fleets. Both species are also taken in small quantities by the Portuguese artisanal fleet. During the last decade, the Spanish trawl fleet has changed the main target species focusing more often on species such as horse mackerel, blue whiting, or mackerel, and do not usually take megrim in the catch.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

Age-based (XSA) assessments were conducted for each species separately. They are based on landings data, two commercial lpue series, and one cpue survey series.

Portuguese and Spanish landings of megrim were split into the two species using their relative abundances in the sampled landings. Discards data are not used in this assessment because of the lack of data in some years.

Uncertainties in assessment and forecast

The assessments are uncertain. There is a consistent retrospective pattern with an overestimation of SSB. This has led to a new perception of the stock development especially for L. whiffiagonis.

The lpue series from the La Coruña trawl fleet has been used only up to 1999 for L. boscii. For the most recent years, only a Spanish survey series is used for tuning in the L. boscii assessment. There are no tuning indices for a large proportion of Division IXa.

Since the proportion of catch discarded is in the range of 0.15 – 0.65 (in numbers) the effect of excluding discards from the assessments could compromise their quality.

Comparison with previous assessment and advice

The current assessments are consistent with last assessments. For L. whiffiagonis, SSB in 2007 was revised 18 % downwards and F in 2006 was revised 24 % upwards. For L. boscii, SSB in 2007 was revised 1 % downwards and F in 2006 was revised 7 % upwards. The advice this year is based on high long-term yield. Last year the advice was based on precautionary considerations.
Overall Assessment Results


Figure 7.4.2.1 Megrim (L. whiffiagonis) in Divisions VIIIc and IXa. Summary of stock assessment: landings, fishing mortality, recruitment, and SSB


Figure 7.4.2.2 Megrim (L. whiffiagonis) in Divisions VIIIc and IXa. Stock-recruitment plot, yield per recruit analysis, and PA plot.


Figure 7.4.2.3 Megrim (L. boscii) in Divisions VIIIc and IXa. Summary of stock assessment: landings, fishing mortality, recruitment, and SSB.


Figure 7.4.2.4 Megrim (L. boscii) in Divisions VIIIc and IXa. Stock-recruitment plot, yield per recruit analysis and PA plot.


Figure 7.4.2.6 Megrim (L. boscii) in Divisions VIIIc and IXa. Comparison of current assessment with previous assessments (predicted intermediate years are included). 2007 SSB value from 2007 assessment was corrected.


Table 7.4.2.2 Megrim (L.whiffiagonis) in Divisions VIIIc and IXa. Nominal landings by country and area.
Spain Portugal Total
Year VIIIc IXa Total IXa VIIIc IXa
1986 508 98 606 53 659
1987 404 46 450 47 497
1988 657 59 716 101 817
1989 533 45 578 136 714
1990 841 25 866 111 977
1991 494 16 510 104 614
1992 474 5 479 37 516
1993 338 7 345 38 383
1994 440 8 448 31 479
1995 173 20 193 25 218
1996 283 21 305 24 329
1997 298 12 310 46 356
1998 372 8 380 66 446
1999 332 4 336 7 343
2000 238 5 243 10 253
2001 167 2 169 5 175
2002 112 3 115 3 117
2003 113 3 116 17 134
2004 142 1 144 5 149
2005 120 1 121 26 147
2006 173 2 175 35 210
2007 139 2 141 14 155
2008 159 2 161 17 178


Table 7.4.2.3 Megrim (L. boscii) in Divisions VIIIc and IXa. Nominal landings by country and area.
Spain Portugal Total
Year VIIIc IXa Total IXa VIIIc IXa
1986 799 197 996 128 1124
1987 995 586 1581 107 1688
1988 917 1099 2016 207 2223
1989 805 1548 2353 276 2629
1990 927 798 1725 220 1945
1991 841 634 1475 207 1682
1992 654 938 1592 324 1916
1993 744 419 1163 221 1384
1994 665 561 1227 176 1403
1995 685 826 1512 141 1652
1996 480 448 928 170 1098
1997 505 289 794 101 896
1998 725 284 1010 113 1123
1999 713 298 1011 114 1125
2000 674 225 899 142 1041
2001 629 177 807 124 931
2002 343 247 590 130 720
2003 393 314 707 169 876
2004 534 295 829 177 1006
2005 473 321 794 189 983
2006 542 348 891 201 1092
2007 591 295 886 218 1104
2008 500 262 761 172 933


Table 7.4.2.4 Megrim (L. whiffiagonis) in Divisions VIIIc and IXa. Summary of stock assessment

Year

Recruitment

Age 1

thousands

SSB

tonnes

Landings

tonnes

Mean F

Ages 2-4

1986 9304 2260 659 0.336
1987 12271 1895 497 0.299
1988 11012 2276 817 0.438
1989 9577 2614 714 0.368
1990 12259 2690 977 0.397
1991 4845 1715 614 0.414
1992 10307 1681 516 0.378
1993 4265 1468 383 0.285
1994 1326 1168 479 0.422
1995 8688 990 218 0.190
1996 8117 1305 329 0.189
1997 6594 1412 356 0.219
1998 4137 1369 446 0.359
1999 2137 1195 343 0.270
2000 3282 1341 253 0.236
2001 3134 1030 175 0.208
2002 2635 1025 117 0.131
2003 2899 1157 134 0.154
2004 3111 892 149 0.168
2005 2920 934 147 0.199
2006 2801 974 210 0.294
2007 3628 905 155 0.209
2008 1666 902 178 0.200
2009 2964 906    
Average 5578 1421 385 0.277


Table 7.4.2.5 Megrim (L. boscii) in Divisions VIIIc and IXa. Summary of stock assessment.

Year

Recruitment

Age 0

thousands

SSB

tonnes

Landings

tonnes

Mean F

Ages 2-4

1986 54114 5772 1124 0.257
1987 34707 7071 1688 0.326
1988 38734 7898 2223 0.372
1989 34304 7548 2629 0.501
1990 21137 6707 1945 0.323
1991 43639 6067 1682 0.263
1992 40323 5455 1916 0.485
1993 12533 5589 1384 0.380
1994 30461 5331 1403 0.370
1995 36420 4723 1652 0.471
1996 24332 4456 1098 0.339
1997 21304 4311 896 0.223
1998 10421 4680 1123 0.282
1999 21701 4401 1125 0.287
2000 25647 4176 1041 0.275
2001 26755 3798 931 0.288
2002 26964 4395 720 0.253
2003 34848 4528 876 0.261
2004 27648 4438 1006 0.329
2005 34384 4602 983 0.262
2006 21796 5130 1092 0.310
2007 19130 5033 1104 0.235
2008 18914 5228 933 0.230
2009 25491 5001    
Average 28571 5264 1329 0.318

Reference Point
 

Four-spotted megrim (L. boscii) in Divisions VIIIc and IXa


Yield and spawning biomass per Recruit F-reference points (2009):
  Fish Mort Yield/R SSB/R
  Ages 2–4    
Average last 3 years 0.26 0.04 0.21
F0.1 0.18 0.04 0.25
Fmed 0.31 0.04 0.18



Candidate target reference points which are consistent with taking high long-term yields and achieving a low risk of depleting the productive potential of the stock may be identified around F0.1.

Megrim (L. whiffiagonis) in Divisions VIIIc and IXa


Yield and spawning biomass per Recruit F-reference points (2009):
  Fish Mort Yield/R SSB/R
  Ages 2–4    
Average last 3 years 0.23 0.07 0.37
F0.1 0.17 0.07 0.45
Fmed 0.26 0.07 0.34



Candidate target reference points which are consistent with taking high long-term yields and achieving a low risk of depleting the productive potential of the stock may be identified around F0.1.
Projection



L. whiff.: Basis: Fsq = mean F(06–08) unscaled = 0.23; R09–10 = GM 1998–2006 = 3 million; landings (2009) = 0.18; SSB(2010) = 0.94.
L. boscii: Basis: Fsq = mean F(06–08) unscaled = 0.26; R09–10 = GM 1990–2006 = 25 million; landings (2009) = 1.12; SSB(2010) = 4.83.

Outlook for 2010
Scientific Advice

Single-stock exploitation boundaries

Considering the options below, ICES advises on the basis of exploitation boundaries in relation to high-long term yield and low risk of depletion of the production potential that combined catches of L. whiffiagonis and L. boscii should not exceed 900 t.

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

2008 fishing mortality for L. whiffiagonis estimated at 0.20, is above F0.1 = 0.17.

2008 fishing mortality for L. boscii estimated at 0.23, is above F0.1 = 0.18.

Fishing at F0.1 in 2010 is predicted to generate SSBs in 2011 that are 6-10% higher than in 2010 for the two megrim stocks


Table 7.4.2.1 Megrim (Lepidorhombus boscii and L. whiffiagonis) in Divisions VIIIc and IXa. Single stock exploitation boundaries (advice), management and landings
Year ICESAdvice/ Single-stock exploitation boundaries from 2005

Predicted catch

corresp.

to advice1

Predicted catch corresp to single-stock exploitation boundaries

Agreed

TAC1

ICES

landings1

Landings

L. boscii

Landings

L. whiff.

1987 Not dealt with -   13.0 2.19 1.69 0.50
1988 Not dealt with -   13.0 3.04 2.22 0.82
1989 Not dealt with -   13.0 3.34 2.63 0.71
1990 Not dealt with -   13.0 2.93 1.95 0.98
1991 No advice -   14.3 2.29 1.68 0.61
1992 No advice -   14.3 2.44 1.92 0.52
1993 L. boscii no gain in increasing F, L. whiff. safe biological limits -   8.0 1.76 1.38 0.38
1994 No l gains in increasing F -   6.0 1.88 1.40 0.48
1995 Concern about low SSB -   6.0 1.87 1.65 0.22
1996 Mixed fishing aspects -   6.0 1.43 1.10 0.33
1997 Reduce F by at least 50% -   6.0 1.25 0.90 0.36
1998 Reduce F by at least 50% 0.9   6.0 1.57 1.12 0.45
1999 Reduce F by at least 50% 1.0   6.0 1.46 1.12 0.35
2000 Reduce F by at least 20% < 1.5   5.0 1.29 1.04 0.25
2001 No increase in F 1.61   5.0 1.11 0.93 0.18
2002 No increase in F 1.55   4.0 0.84 0.72 0.12
2003 No increase in F 1.55   2.4 1.01 0.88 0.13
2004 No increase in F 1.38   1.336 1.14 0.99 0.15
2005 No increase in F 1.092 1.05 1.336 1.13 0.98 0.15
2006 No increase in F   1.2 1.269 1.30 1.09 0.21
2007 No increase in F   1.4 1.440 1.26 1.10 0.16
2008 No increase in F   1.4 1.430 1.11 0.93 0.18
2009 Same advice as last year   1.4 1.430      
2010 Reduce F to F0.1   0.9        

Weights in ‘000 t.

1 L. whiffiagonis+ L. boscii.

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



Management
Management unit: Yes

Management Objectives

There are no explicit management objectives for these stocks.
Management Advice

Management considerations

Both species are caught in mixed fisheries targeting demersal fish including southern hake, anglerfish and Nephrops. Management measures aimed at reducing fishing mortality on these stocks should also ensure lowest possible catches of megrim.

The two species are managed under a common TAC. They are caught and recorded together in the landings statistics. It is impossible to manage each species separately under a common TAC. This problem is highlighted by the different status of the two stocks. L. whiffiagonis (the stock in poor status) constitutes around 20% of the total megrim landings.

The spatial distribution of the two stocks shows some differences that could be utilized for separate management of the two stocks. Megrim (L. whiffiagonis) is distributed in both Divisions (VIIIc and IXa), with its highest abundance in Division VIIIc. Four-spotted megrim (L. boscii) is distributed in both Divisions (VIIIc and IXa). There is a certain bathymetric segregation between the two species. L. boscii has a preferential depth range of 100 to 450 m and L. whiffiagonis of 50 to 300 m.

The perception of the L. whiffiagonis stock has changed compared to the last assessment in 2007. For L. whiffiagonis SSB in recent years is now estimated to be lower than it was in 2007, and recruitment continues to be very low. Therefore strong measures should be taken to improve the stock status.

Discards of megrim are substantial. For L. whiffiagonis between 15 % and 45 % of the total catches in numbers are discarded. In the last two years discards of this stock are very low, providing a further indication of low recruitment. For L. boscii between 40 % and 62 % of the total catches in numbers are discarded.

Landings in 2007 and 2008 have been below the TAC.

TACs for combined megrim stocks have not been restrictive, and the fishing mortality of both stock are above candidates for FMSY. Following the EU Commission consultation paper on TACs for 2010 (COM(2009) 224, 12 May 2009), this corresponds to a TAC reduction of 36%. ICES has not evaluated the proposed option in relation to the precautionary approach.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Undefined


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 targets

Comment

Undefined Undefined

Overfished (L. boscii),

Overfished (L. whiffiagonis)

NA  



In the absence of defined precautionary reference points, the state of the two stocks cannot be evaluated with regard to these. SSB of both species has decreased since the late 1980s. However, SSB for L. boscii shows a slightly upwards trend after reaching a minimum in 2001. For both species fishing mortality has decreased since the late 1990s. Recent recruitment for L. boscii has been below average. For L. whiffiagonis recruitment has been low in the last decade.
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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