6.4.24 advice october 2012 ecoregion north sea stock rays … · 2012-11-19 · ices advice 2012,...

ICES Advice 2012, Book 6 1

6.4.24 Advice October 2012 ECOREGION North Sea STOCK Rays and skates in Divisions and Subarea IIIa, IV, and VIId, e (Kattegat,

Skagerrak, North Sea, and English Channel) Introduction There are 13 species of ray and skate (Rajidae) and 7–8 demersal shark species in the North Sea ecoregion. This advice section addresses the main commercial skates and rays. Section Stock 6.4.24.1 Blonde ray (Raja brachyuran) in Divisions IVc and VIId, e (Southern North Sea and English Channel) 6.4.24.2 Thornback ray (Raja clavata) in Subarea IV, and Divisions IIIa and VIId,e (North Sea, Skagerrak, Kattegat,

and English Channel) 6.4.24.3 Small-eyed ray (Raja microocellata) in Divisions VIId, e (English Channel) 6.4.24.4 Spotted ray (Raja montagui) in Subarea IV, and Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat,

and Eastern English Channel) 6.4.24.5 Undulate ray (Raja undulata) in Divisions VIId, e (English Channel) 6.4.24.6 Cuckoo ray (Leucoraja naevus) in Subarea IV, and Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat,

and Eastern English Channel) 6.4.24.7 Common skate (Dipturus batis) complex (Dipturus cf. flossada and Dipturus cf. intermedia) in Subarea IV,

and Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat, and Eastern English Channel) 6.4.24.8 Starry ray (Amblyraja radiata) in Subarea IV, and Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat,

and Eastern English Channel) 6.4.24.9 Other ray and skate species in Subarea IV, and Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat, and

Eastern English Channel) Skates and rays fisheries are currently managed under a common TAC, although this complex comprises species that may have different vulnerabilities to exploitation. TAC advice is based on the status of the main commercial species, with species-specific advice also provided on an individual basis. Demersal elasmobranchs in this region are caught in mixed target and non-target fisheries. TACs alone may not adequately protect these stocks as restrictive TACs may lead to high discarding. At present ray and skate fisheries are managed by means of a generic, multi-species TAC, along with prohibitions for severely depleted species. Management measures such as closed areas/seasons or effort restrictions may better protect demersal elasmobranchs. In particular, measures to protect spawning/nursery grounds would be beneficial. ICES could provide advice on such measures. Advice for 2013 and 2014 ICES provides advice on the overall exploitation (landings and discards) of the ray and skates species assemblage, and also on individual species. ICES does not advise that individual TACs be established for each species, at present. This is because the catch statistics for individual species are not reliable. ICES considers the generic TAC, at best, as an ineffective measure, regulating overall outtake from the assemblage. ICES advises that a suite of species- and fishery-specific measures be developed to manage the fisheries on commercial species and achieve recovery of the depleted species. Such measures should be developed by managers involving all stakeholders; ICES is willing to assist in the process. Given that the TAC does not regulate overall outtake, but only landings, ICES does not advise a decrease in the current TAC. Such a decrease would add to the problem of regulatory discards. Management measures should be framed in a mixed-fisheries context, considering the overall behaviour of demersal fleets, and the drivers for such behaviour. Because these species are mainly caught in mixed fisheries, when the TAC is exhausted, catches continue to take place, but are discarded. In order to achieve optimal harvesting of the commercial species, and to assist recovery of the depleted species, a suite of measures should be put in place. Closure to fishing of spawning and/or nursery grounds, and measures to protect the spawning component of the population (e.g. maximum landing size) are powerful tools to protect rays and skates. In some cases, single-species TACs may be appropriate, especially for easily identified species, and/or discrete stocks in limited distribution areas.

2 ICES Advice 2012, Book 6

Given that the European Community intends to introduce a ban on discards, minimum or maximum landing sizes should be carefully considered before they are introduced, because they could lead to increased discards. Size limits may best be applied if discard (escapee) survival can be shown to be high. Stock status Three commercial skate species (thornback ray, spotted ray, and cuckoo ray) show increasing trends in relative abundance in fishery-independent trawl surveys. There is evidence of a long-term decline to depleted levels in the distribution and relative abundance of one commercial species (Dipturus batis complex). Trends in the relative abundance of two other commercial species (blonde ray, undulate ray) are unclear. Starry ray is an abundant non-commercial species and is almost exclusively discarded, and stock trends are decreasing. Discard survivorship is not known. The advice is based on the stock status of the main commercial species in the ecoregion, with species-specific advice provided below. Landings of skates and rays in the North Sea have generally declined, and this is associated with changes in species composition and relative abundance.


Table 6.4.24.1 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. ICES advice, management, and landings.

Year

Advised percentage change in catch (landings + discards)

Thor

nbac

k ra

y (I

V, V

IId,

IIIa

)

Spot

ted

ray

(IV

, VII

d, II

Ia)

Cuc

koo

ray

(IV

, VII

d, II

Ia)

Blo

nde

ray

(VII

d, e

)

Smal

l-eye

d ra

y (I

V,

VII

d,

IIa)

Und

ulat

e ra

y (V

IId,

e)

Com

mon

skat

e co

mpl

ex

(IV

, VII

d, II

Ia)

Star

ry ra

y IV

, VII

d, II

Ia)

Oth

er sp

ecie

s

Tota

l adv

ice

General advice Agreed TAC 1

ICES landings

2002 Reduce exploitation 4.8 3.9 2003 No advice 4.1 3.8 2004 No advice 3.5 3.2 2005 No advice 3.2 3.0 2006 0 0 Zero catch 2.7 2.8 2007 0 0 Zero catch 2.2 3.1 2008 0 0 Zero catch 1.6 3.0 2009 0 < 3.12 Av. land. 2002–2006 2.8 3.23 2010 0 < 3.12 No new advice, same advice as for 2009 2.3 3.0 2011 0 < 2.7 Av. land. 2006–2008 2.3 2.7 2012 0 < 2.7 No new advice, same advice as for 2011 2.3 2013 +20% +20% +20% −20% −20% No targeted fishery 0 -36% −20% - No TAC + species-specific measures 4 2.7 2014 No new advice, same advice as for 2013 No new advice, same advice as for 2013 2.7 Weights in thousand tonnes. 1 EU only. 2 Subject to the individual recording of landed species, no targeted fisheries and minimal bycatch of common skate and undulate ray, and no landings of angel shark. 3 TAC split in three components 1) Division IIa and Subarea IV, 2) Division IIIa, and 3) Division VIId. 4 Additional species-specific measures (see main text).


Assessment methodology The assessment is based on ICES framework for data-limited stocks, where change in survey catch rates is the main indicator. In each case the survey index used was (average of last two years)/(average of previous five years). An average of the previous five years was chosen over the default average of the previous three years. This is to allow time for changes in abundance to become visible, as generation times are longer in these species than in those of many bony fishes. A recommended change in catch is applied according to change in survey indices, with a ±20% uncertainty cap applied in each case (Category 3.2). Where no suitable survey index was available, a precautionary decrease of 20% was applied (Category 5.2). ICES does not advise a precautionary decrease in TAC, because it is considered that this would lead to increased regulatory discarding and further reduce the quality of the catch data. ICES does not view the TAC as the main means to manage the fishery, but rather as an upper boundary on the outtake. Therefore, further reductions to the TAC are not considered to be the best approach to allow recovery of depleted species at present. Biology Many elasmobranchs are slow growing, have a late age-at-maturity, low reproductive capacity, they are large in size and have an aggregating behaviour. Because of this they are considered to be highly vulnerable to over-exploitation. Skates (Rajidae) are oviparous, and often produce more young than live-bearing species. Some species of demersal elasmobranchs may be locally common and found in discrete areas. Resource competition and species interactions between the various skate species is poorly understood. Historically, common skate have been known to predate on individuals of smaller skate species, and the longer-term decline in the larger skates may have benefited populations of smaller skate species. The fisheries Demersal elasmobranchs are caught as a bycatch in the mixed demersal fisheries for roundfish and flatfish. A few inshore vessels target skates and rays with tanglenets and longlines. Landings have declined since their peak in 1982. Most fisheries now take place to the south of the region, in Divisions IVc and VIIe. TACs were introduced in 1999, but only became restrictive in 2004. Raja clavata composes 42% of the total ray catch and 62% of the species-specific landings. Effects of the fisheries on the ecosystem Some demersal sharks, including lesser-spotted dogfish, may benefit from scavenging on trawl-damaged organisms and discards. Quality considerations Species-specific catch data for all the species covered in this advice sheet are of limited extent and there are data quality issues. Age data are not routinely collected. Data limitations and the biological characteristics of elasmobranchs restrict the use of length-based assessment methods. In the absence of formal stock assessments and defined reference points for skate stocks and demersal sharks in this ecoregion, the general status of the major species is evaluated from surveys. Stock trends from fishery-independent trawl surveys are available for many stocks, but it is not possible to quantify whether overfishing takes place. Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of species-specific data are reported. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. Management considerations TACs only regulate the landings, and a low TAC on a low-value bycatch species could induce more discards. Because the elasmobranch species are usually caught as a bycatch in demersal fisheries, they would benefit from a reduction in the overall demersal fishing effort.


In the Dutch commercial fishery the quota for skates and rays was reached halfway through July 2011. Therefore, fishermen were forced to discard any skate and ray catches during the second half of 2011. Additional considerations Rays and skates offer a unique opportunity to institute spatial, seasonal, and technical measures that can be used to improve stock status and regulate fishing mortality. This is because they have defined spatially discrete life history stages, and because stock–recruitment relationships are believed to be very strong. Comparison with previous assessment and advice The previous advice was given for 2011 and 2012. The basis of this advice was ICES precautionary approach. This year, individual advice is given for each of the main stocks, on the basis of ICES approach to data-limited stocks. An overall TAC advice is also provided using ICES approach to data-limited stocks. Scientific basis Assessment type Survey-based trends. Input data IBTS Q1 Survey, including French, UK (Scotland), Norwegian, Swedish, Danish, German,

and Dutch surveys. IBTS Q3 Survey, including UK (England), UK (Scotland), Swedish, Danish, and German surveys.

UK Beam trawl survey. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF

http://ices.dk/workinggroups/ViewWorkingGroup.aspx?ID=123


0

2

4

6

8

10

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

2003

2006

2009

Land

ings

in '0

00 to

nnes

Year

Ray landings in the North Sea ecoregion

VIId

IV

IIIa

Figure 6.4.24.1 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. Landings (in thousand

tonnes) of skates and rays per ICES (sub)area.

Table 6.4.24.2 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. Total landings of skates (Rajidae) in ICES Division IIIa. “.” indicates zero landings, “+” indicates landings < 0.5, and “n.a.” indicates not available.

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Belgium . . . . . . . . . . . . .

Denmark 11 41 56 22 36 129 65 26 8 5 12 12 44

Germany . . . . . . . 1 . . . . +

Iceland . . . . . . . . . . . . .

Netherlands . . . . . . . . + . . . .

Norway 208 123 154 159 163 85 94 51 13 23 33 24 25

Sweden 2 2 12 13 9 20 10 18 11 6 2 10 +

UK (E, W_& NI) . . . . . . . . . . . . .

UK (Scotland) . . . . . . . . . . . . .

Total of submitted data 221 166 222 194 208 234 169 95 32 34 47 45 69


Table 6.4.24.3 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. Total landings of skates (Rajidae) in ICES Subarea IV. Note that “.” indicates zero landings, “+” indicates landings < 0.5, and “n.a.” indicates not available.

Table 6.4.24.4 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. Total landings of skates (Rajidae) in ICES Division VIId. “.” indicates zero landings, “+” indicates landings < 0.5, and “n.a.” indicates not available.

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Belgium 93 69 79 113 153 96 94 109 164 174 125 111 103

France 558 693 729 725 796 695 602 687 792 710 1270 1043 954

Germany . + . . . . . . . . . . .

Ireland . . . . . . . . . . . . .

Netherlands . . . . . . . 13 21 13 10 11 12

Spain . . . . . . . . . . . . 0

UK (E, W_& NI) 437 355 169 140 186 157 147 139 188 199 152 133 141

UK (Scotland) . . . . . . . 2 . 6 8 5 6


1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Belgium 336 332 370 436 323 276 327 350 272 371 299 294 231

Denmark 45 93 65 34 33 25 23 26 27 23 29 30 38

Faroe Islands . . . . . . . . . . . n.a. n.a.

France 41 31 61 62 36 37 34 15 56 69 74 89 57

Germany 16 23 11 22 21 17 29 16 17 30 21 32 19

Iceland . . . . . . . . . . . . n.a.

Ireland . . . . . . . . 119 . . . .

Netherlands 515 693 834 805 686 561 680 603 721 564 379 390 212

Norway 152 161 173 83 113 77 87 96 71 97 119 105 56

Poland . . . . . . . . . . . . n.a.

Sweden + + + + + + + + + + + + 2

UK (E, W_& NI) 618 516 476 500 537 550 434 348 329 392 348 372 413

UK (Scotland) 965 860 822 853 741 512 404 374 331 343 311 289 358



Table 6.4.24.5 Rays and skates in the North Sea, Skagerrak, Kattegat, and eastern Channel. Total landings of skates (Rajidae) North Sea, Skagerrak, Kattegat, and eastern Channel. “.” indicates zero landings, “+” indicates landings < 0.5, and “n.a.” indicates not available.

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Belgium 429 401 449 548 476 372 422 459 436 545 424 405 334

Denmark 56 134 121 56 69 154 88 52 35 28 41 42 81

Faroe Islands . . . . . . . . . . . n.a. n.a.

France 599 724 790 725 796 732 636 701 848 779 1344 1132 1011

Germany 16 23 11 22 21 17 29 17 17 30 21 32 19

Iceland . . . . . . . . . . . . .

Ireland . . . . . . . . 119 . . . .

Netherlands 515 693 834 805 686 561 680 615 742 577 389 401 224

Norway 360 284 327 242 276 162 181 120 84 120 152 129 81

Poland . . . . . . . . . . . . n.a.

Spain . . . . . . . . . . . . n.a.

Sweden 2 2 12 13 9 20 10 18 11 6 2 10 3

UK (E&W and NI) 1055 871 645 640 723 707 580 487 517 591 500 504 555

UK (Scotland) 965 860 822 853 741 512 404 375 331 349 320 295 365



6.4.24.1 Advice October 2012 ECOREGION North Sea STOCK Blonde ray (Raja brachyuran) in Divisions IVc and VIId, e (Southern

North Sea and English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches should be decreased by at least 20%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. Additional measures should be identified that can regulate exploitation of this species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Stock status

F (Fishing Mortality) 2009–2011

Qualitative evaluation Unknown

SSB (Spawning-Stock Biomass) 2009–2011

Qualitative evaluation Unknown The state of the stock is unknown and there is insufficient information to present trends in species-specific landings for this stock. Blonde ray has a patchy occurrence in the North Sea. It is at the edge of its distributional range in this area. It is captured in coastal waters of this survey area, but generally in low numbers. Catch rates fluctuate as a result of this. Numbers in other surveys are too low to evaluate trends. Management plans No specific management objectives are known to ICES. Biology This is one of the larger-bodied, moderately long-lived skate species. The fisheries This species is usually caught as a bycatch in demersal fisheries. Effects of the fisheries on the ecosystem Some demersal sharks, including lesser-spotted dogfish, may benefit from scavenging on trawl-damaged organisms and discards. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data are reported to this level. This information covers too short a time period to influence advice at the present time, and in some instances there are data quality issues (e.g. the proportion of blonde ray and spotted ray). The advice is based on a precautionary reduction of catches because of missing or non-representative data. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. Scientific basis Assessment type No assessment. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators UK Q3 Beam trawl survey. Other information Life history. Working group report WGEF



6.4.24.1 Supporting information October 2012 ECOREGION North Sea STOCK Blonde ray (Raja brachyuran) in Divisions IVc and VIId, e (Southern

North Sea and English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No reliable assessment can be presented for this species. It has a patchy occurrence in the North Sea and is at the edge of its distributional range in this area. Survey trends may not be reliable due to the low numbers captured in certain areas. ICES approach to data-limited stocks For data-limited stocks without information on abundance or exploitation ICES considers that a precautionary reduction of catches should be implemented, unless there is ancillary information clearly indicating that the current exploitation rate is appropriate for the stock. Following this approach, ICES advises that catches should decrease by 20% in relation to the last three years’ average landings. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. Additional measures should be identified that can regulate exploitation of this stock. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Additional considerations This species is captured in coastal waters of this survey area, but generally in low numbers. The stock is believed to extend into the Celtic Sea. Management considerations TACs only regulate the landings, and a low TAC on a low-value bycatch species could induce more discards. Because this species are usually caught as a bycatch in demersal fisheries, it would benefit from a reduction in the overall demersal fishing effort. Management measures should aim to regulate fishing mortality and maintain SSB above any candidate reference point. In developing such measures, the linkages between the Channel and the Celtic Sea should be considered. Uncertainties in the assessment There are known identification problems between blonde ray and spotted ray (R. montagui) in landings and potentially in surveys. While blonde ray are caught in the UK Q3 Beam-trawl survey, this survey is not considered sufficiently reliable to be used as an abundance index for this stock. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. Comparison with previous assessment and advice No species-specific advice has previously been provided for blonde ray in Divisions VIId, e. The advice is based on category 5 of ICES approach to advice provision in data-limited situations.


Sources Ellis, J. R. 2010. An overview of the demersal elasmobranchs in the eastern English Channel (ICES Division VIId).

Working Document for WGEF 2010. WD2010-16. ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19.

-3 -2 -1 0 1 2 349.0

49.5

50.0

50.5

51.0

51.5

52.0

52.5

53.0

53.5

Figure 6.4.24.1.1 Blonde ray (Raja brachyura) in Divisions IVc and VIId, e. Distribution and relative abundance of

blonde ray in the survey area (from Ellis, 2010). Table 6.4.24.1.1 Blonde ray (Raja brachyura) in Divisions IVc and VIId, e. ICES advice, management, and landings. Year ICES advice Predicted catch

corresp. to advice

ICES Species-specific landings:–minimum estimate based on reported landings

2011 No specific advice 168 2012 No specific advice 2013 No TAC, species-specific measures needed, catch

to decrease by at least 20%. -

2014 No new advice, same as 2013 - Weights in tonnes.


6.4.24.2 Advice October 2012 ECOREGION North Sea STOCK Thornback ray (Raja clavata) in Subarea IV and in Divisions IIIa and

VIId, e (North Sea, Skagerrak, Kattegat, and English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches could be increased by a maximum of 20%. However, ICES does not advise that an individual TAC be set for this species, at present. Additional measures should be identified that can regulate exploitation of this species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by managers through stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Stock status




Qualitative evaluation Increasing Abundance index Quarter 3

0.00

2.00

4.00

6.00

8.00

10.00

12.00

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

Mea

n ca

tch

per u

nit e

ffort

(ind

/h)

Figure 6.4.24.2.1 Thornback ray in Divisions and Subarea IIIa, IV, and VIId, e. Abundance estimates in Division

IVc–VIId (mean survey catch rates, UK Beam-trawl survey Q3). Dashed lines show the mean ±1 std. dev. annual cpue for 2005–2009, the red line shows the mean annual cpue for 2010–2011.

There is insufficient information to present trends in species-specific landings for this stock. Thornback ray in this area are now concentrated in the southwestern part of the ecoregion, where it is the main commercial skate species. The stock has increased, considering the abundance estimate (survey catch rates) in the last two years is 95% above the previous five year average. Management plans No specific management objectives are known to ICES.


Biology Many elasmobranchs are slow growing, having a late age-at-maturity and a low reproductive capacity. Thornback ray are oviparous, and often produce more young than live-bearing species. The large size and aggregating behaviour of elasmobranchs make them susceptible to over-exploitation.

Environmental influence on the stock Resource competition and species interactions between the various skate species is poorly understood. Historically, common skate have been known to predate on smaller skate individuals, and the longer-term decline in the larger skates may have benefited populations of smaller skate species. The fisheries Thornback ray is the most commercially important ray species in this ecoregion. It is mainly caught close to shore. Considerable catches are taken in artisanal coastal fisheries in southeast England. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. The UK Q3 beam trawl survey is considered to sample the main stock in Divisions IVc and VIId, e more effectively than the IBTS, given that there are more stations in the main stock area, and that the gear is more effective at sampling smaller skates. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or overfished. Assessment type Survey-based trends. Input data IBTS Q3 Survey, UK Beam trawl survey. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.2 Supporting information October 2012 ECOREGION North Sea STOCK Thornback ray (Raja clavata) in Subarea IV and in Divisions IIIa and

VIId, e (North Sea, Skagerrak, Kattegat, and English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. ICES approach to data-limited stocks For data-limited stocks for which an abundance index is available, ICES uses as harvest control rule an index-adjusted status quo catch. The advice is based on a comparison of the two most recent index values with the five preceding values, combined with recent catch or landings data. Knowledge about the exploitation status also influences the advised catch. For this stock the abundance is estimated to have increased by 95% between 2005 and 2009 (average of the five years) and 2010–2011 (average of the two years). This implies an increase of catches of 20% in relation to the last three years’ average. Additional measures should be identified that can regulate exploitation of this species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. A precautionary buffer has not been applied as the abundance increase is significantly large. This is the first year ICES is providing quantitative advice for data-limited stocks. Additional considerations In historical times, this species was distributed across the North Sea. However, it is now mainly confined to the southwestern North Sea. Within this restricted range, it appears to be increasing in abundance. Given its discrete distribution in the southwestern North Sea, and its being targeted in artisanal and static gear fisheries, this species could be a good candidate for specific spatial, seasonal, and technical measures. Comparison with previous assessment and advice The advice is different to that provided in previous years. In 2011 and 2012, status quo catch was advised, based on the precautionary approach. The current advice is based on category 3 of ICES approach to advice provision in data-limited stocks. Sources Ellis, J. R. 2010. An overview of the demersal elasmobranchs in the eastern English Channel (ICES Division VIId).


CM 2012/ACOM:19.


-3 -2 -1 0 1 2 349.0

49.5

50.0

50.5

51.0

51.5

52.0

52.5

53.0

53.5

Figure 6.4.24.2.2 Thornback ray (Raja clavata) in Divisions and Subarea IIIa, IV, and VIId, e. Distribution and

relative abundance of Raja clavata in the survey area (from Ellis, 2010). Table 6.4.24.2.1 Thornback ray (Raja clavata) in Divisions and Subarea IIIa, IV, and VIId, e. ICES advice,

management, and landings. Year ICES advice Predicted catch

corresp. to advice


2006 Zero catch 0 2007 Zero catch 0 2008 No new advice, same as 2007 2009 Status quo catch 2010 No new advice, same as 2009 2011 Status quo catch 1335 2012 No new advice, same as 2011 2013 No TAC, species-specific measures needed, catch

could increase by max. 20%. -



6.4.24.3 Advice October 2012 ECOREGION North Sea STOCK Small-eyed ray (Raja microocellata) in Divisions VIId, e (English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches should be decreased by at least 20%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. Additional measures should be identified that can regulate exploitation of this species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed through stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Stock status




Qualitative evaluation Unknown The state of the stock is unknown and there is insufficient information to present trends in species-specific landings for this stock. Management plans No specific management objectives are known to ICES. Biology This is a medium-bodied skate species of intermediate productivity. Small-eyed ray only occurs in the southern part of this ecoregion (eastern English Channel), as an extension of the western Channel stock.

The fisheries Only marginal bycatches occur for this species. Quality considerations Numbers caught are low and there may be issues of misidentification. Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time. The advice is based on a precautionary reduction of catches because of missing or non-representative data. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. Scientific basis Assessment type No assessment. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.3 Supporting information October 2012 ECOREGION North Sea STOCK Small-eyed ray (Raja microocellata) in Divisions VIId, e (English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No reliable assessment can be presented for this stock. The main cause of this is the limited time-series of species-specific landings data at the present time. ICES approach to data-limited stocks For data-limited stocks without information on abundance or exploitation ICES considers that a precautionary reduction of catches should be implemented, unless there is ancillary information clearly indicating that the current exploitation rate is appropriate. For this species, ICES advises that catches should decrease by 20%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch at the present time. ICES does not advise that an individual TAC be set for this species, at present. Additional measures should be identified that can regulate exploitation of this species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Additional considerations Management considerations TACs only regulate the landings, and a low TAC on a low-value bycatch species could induce more discards. Because this species is usually caught as a bycatch in demersal fisheries, it would benefit from a reduction in the overall demersal fishing effort. Management for this species should be applied across the Channel and the eastern Celtic Sea, as it is likely that this constitutes one stock in these areas. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. Comparison with previous assessment and advice ICES has not previously provided species-specific advice for this stock. Advice is based on category 5 of ICES approach to data-limited stocks. Source ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19.


Table 6.4.24.3.1 Small-eyed ray in the North Sea and English Channel. ICES advice, management, and landings. Year ICES advice Predicted catch

corresp. to advice






6.4.24.4 Advice October 2012 ECOREGION North Sea STOCK Spotted ray (Raja montagui) in Subarea IV and in Divisions IIIa and VIId

(North Sea, Skagerrak, Kattegat, and eastern English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches could be increased by a maximum of 20%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this species, at present. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Stock status




Qualitative evaluation Increasing

Abundance estimate Abundance estimate Southern North Sea and Channel North Sea Figure 6.4.24.4.1 Spotted ray (Raja montagui) in Divisions and Subarea IIIa, IV, and VIId. Left: Abundance estimate (mean

cpue) in Division IVc, UK Beam-trawl survey Q3 IVc,VIId. Right: Abundance estimate in Subarea IV, IBTS trawl survey in quarter 1 (top) and quarter 3 (below). Dashed lines show the mean ±1 std. dev. annual cpue for 2005–2009, the red line shows the mean annual cpue for 2010–2011.

There is insufficient information to present trends in species-specific landings for this species. Abundance is estimated to have increased between the average of the last two years compared to the previous five years by between 43% (southern North Sea) and 109% (in quarter 3 in the North Sea). The quarter 3 survey mainly catches juveniles, and may indicate an increase in recruitment in the past three years.

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Management plans No specific management objectives are known to ICES. Biology The stock of spotted ray is concentrated in Divisions IVb, c. However, recent survey data show that this species is wide ranging in the ecoregions and can also be found in Division IVa. The fisheries This species is usually caught as a bycatch in demersal fisheries. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time, and in some instances there are data quality issues (e.g. there are identification issues between spotted ray and blonde ray (Raja brachyura). Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or overfished. Scientific basis Assessment type Survey-based trends. Input data UK Beam trawl survey, IBTS Q1 survey, and IBTS Q3 survey. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.4 Supporting information October 2012 ECOREGION North Sea STOCK Spotted ray (Raja montagui) in Subarea IV and in Divisions IIIa and VIId

(North Sea, Skagerrak, Kattegat, and eastern English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. ICES approach to data-limited stocks For data-limited stocks for which an abundance index is available, ICES uses as harvest control rule an index-adjusted status quo catch. The advice is based on a comparison of the two most recent index values with the five preceding values, combined with recent catch or landings data. Knowledge about the exploitation status also influences the advised catch. For this stock the abundance is estimated to have increased by more than 20% between 2005 and 2009 (average of the five years) and 2010–2011 (average of the two years). These surveys are considered indicative of overall stock abundance. This implies an increase of catches of at most 20% in relation to the last three years’ average. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. A precautionary buffer has not been applied as the abundance increase is significantly large. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Additional considerations Management considerations TACs only regulate the landings, and a low TAC on a low-value bycatch species could induce more discards. Because this species is usually caught as a bycatch in demersal fisheries, it would benefit from a reduction in the overall demersal fishing effort. Comparison with previous assessment and advice ICES has not previously provided species-specific advice for this stock. Advice is based on category 3 of ICES approach to data-limited stocks. Sources Ellis, J. R. 2010. An overview of the demersal elasmobranchs in the eastern English Channel (ICES Division VIId).


CM 2012/ACOM:19.


-3 -2 -1 0 1 2 349.0

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Figure 6.4.24.4.2 Distribution and relative abundance of spotted ray in the survey area (from Ellis, 2010 and IBTS). Table 6.4.24.4.1 Spotted ray in the North Sea, Skagerrak, Kattegat, and eastern English Channel. ICES advice and

landings. Year ICES advice Predicted catch

corresp. to advice


2009 Status quo catch - 2010 No new advice, same as 2010 - 2011 Status quo catch - 262 2012 No new advice, same as 2011 - 2013 No TAC, species-specific measures needed, catch




6.4.24.5 Advice October 2012 ECOREGION North Sea STOCK Undulate ray (Raja undulata) in Divisions VIId, e (English Channel) Advice for 2013 and 2014 Based on the precautionary approach ICES continues to advise that there be no targeted fishery for undulate ray unless information is provided to show that these are sustainable. Measures should be taken to minimize bycatch. Stock status




Qualitative evaluation Unknown There is no new information to alter the perception of the stock, which is uncertain. The species is locally common in discrete areas. Abundance estimates are low and highly variable, but the survey does not cover the main stock area sufficiently. Management plans Undulate ray has been on the EU prohibited species list since 2009. Biology Raya undulata is considered to be patchily distributed within this ecoregion, mostly in inshore waters of the English Channel. Catches here are comprised mainly of juveniles, in the eastern Channel. This stock extends into the western English Channel, and Division VIIe comprises the main part of the stock. Undulate ray appears to form a discrete population in the English Channel that is isolated from other stocks of undulate ray. This is one of the larger-bodied rays, and is likely to have a life history that is more conservative than smaller species like spotted ray. In view of its isolated nature, this population is particularly vulnerable.

The fisheries Undulate ray are one of the main bycaught species in the English Channel. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. Scientific basis Assessment type No assessment. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators UK Beam trawl survey (Q3). Other information Life history. Working group report WGEF



6.4.24.5 Supporting information October 2012 ECOREGION North Sea STOCK Undulate ray (Raja undulata) in Divisions VIId, e (English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. Precautionary approach Based on the precautionary approach, ICES advises that there be no targeted fishery for undulate ray unless information is provided to show that these are sustainable. Measures should be taken to minimize bycatch. Available evidence shows that there may be discrete stocks in the English Channel. In view of the patchy distribution, and following the precautionary approach, ICES recommends that no target fisheries (defined in terms of percentage of total catch) should be permitted unless information is provided to show that these are sustainable. Such information should include information on distribution, stock identity, and abundance trends. Additional considerations Uncertainty in the assessment Survey catch rates (abundance estimates) are low and highly variable (Figure 6.4.24.5.1). Juveniles tend to be caught in coastal areas. Although adults are known to occur in the area (Ellis et al., 2012), the low density of stations to the west of the survey grid means that the main stock area is sampled poorly. Although absent in 2006–2007, the species has been present each year since. Comparison with previous assessment and advice The advice and the basis for advice are unchanged. Sources Ellis, J. R. 2010. An overview of the demersal elasmobranchs in the eastern English Channel (ICES Division VIId).

Working Document for WGEF 2010. WD2010-16. Ellis, J. R., McCully, S. R., and Brown, M. J. 2012. An overview of the biology and status of undulate ray Raja

undulata. Journal of Fish Biology, 80: 1057–1074. ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19.


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North Sea Figure 6.4.24.5.1 Undulate ray (Raja undulata) in Divisions VIId and VIIe. Mean cpue of Divisions IVc–VIId

undulate ray, UK Beam-trawl survey Q3. Dashed lines show the mean ±1 std. dev. annual cpue for 2005–2009, the red line shows the mean annual cpue for 2010–2011.

-6 -5 -4 -3 -2 -148.0

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-3 -2 -1 0 1 2 349.0

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Figure 6.4.24.5.2 Left: Undulate ray in the western English Channel UK beam trawl survey (presence/absence only)

2006–2010 (Ellis, 2010). Right: Undulate ray in the eastern English Channel. Relative abundance. UK beam trawl survey 2003–2011.

Table 6.4.24.5.1 Undulate ray in the English Channel. ICES advice and landings. Year ICES advice Predicted catch

corresp. to advice


2009 No targeted fishery - 2010 No new advice, same as 2009 2011 No targeted fishery - 3 2012 No new advice, same as 2011 2013 No targeted fishery, minimize bycatch - 2014 No new advice, same as 2013 - Weights in tonnes.


6.4.24.6 Advice October 2012 ECOREGION North Sea STOCK Cuckoo ray (Leucoraja naevus) in Subarea IV and in Divisions IIIa and

VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches could be increased by a maximum of 20%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed through stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Stock status




Qualitative evaluation Increasing

Abundance estimate, 1st quarter Abundance estimate, 3rd quarter Southern North Sea and Channel Southern North Sea and Channel

00.10.20.30.40.50.60.70.80.9

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Figure 6.4.24.6.1 Cuckoo ray (Leucoraja naevus) in Divisions and Subarea IIIa, IV, and VIId. Mean abundance

(catch per unit effort) in Division IV, IBTS trawl survey Q1 (top left) and IBTS Trawl survey Q3 (top right). Dashed lines show the mean ±1 std. dev. annual cpue for 2005–2009, the red line shows the mean annual cpue for 2010–2011.

There is insufficient information to present trends in species-specific landings. Abundance estimates have increased by 61% (Q1) and 47% (Q3), comparing the last two years with the previous five year survey averages. Management plans No specific management objectives are known to ICES.


Biology This is a largely offshore species caught in mixed fisheries in the central and northern North Sea. Cuckoo ray in this ecoregion is primarily found in Divisions IVa and IVb. The stock may extend into Subarea VI.

Environmental influence on the stock Resource competition and species interactions between the various skate species is poorly understood. Historically, common skate were known to predate on smaller skate individuals, and the longer-term decline in the larger skates may have benefited populations of smaller skate species. The fisheries Cuckoo ray is a commercial species. They are a more offshore species than the (inshore) Rajidae and so are normally caught by the beam and otter trawl fleets rather than by gill or tangle nets. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or overfished. Assessment type Survey-based trends. Input data IBTS Q1 survey, IBTS Q3 survey. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.6 Supporting information October 2012 ECOREGION North Sea STOCK Cuckoo ray (Leucoraja naevus) in Subarea IV and in Divisions IIIa and

VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. ICES approach to data-limited stocks For data-limited stocks for which an abundance index is available, ICES uses as harvest control rule an index-adjusted status quo catch. The advice is based on a comparison of the two most recent index values with the five preceding values, combined with recent catch or landings data. Knowledge about the exploitation status also influences the advised catch. For this stock the abundance is estimated to have increased by more than 20% between 2005 and 2009 (average of the five years) and 2010–2011 (average of the two years). This implies an increase of catches of at most 20% in relation to the last three years’ average. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for this stock, at present. A precautionary buffer has not been applied as the abundance increase is significantly large. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. This is the first year ICES is providing quantitative advice for data-limited stocks. Additional considerations Comparison with previous assessment and advice ICES has not previously provided species-specific advice for this stock (Table 6.4.24.6.1). Advice is based on category 3 of ICES approach to data-limited stocks. Source ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19.


Figure 6.4.24.6.2 Distribution of Leucoraja naevus within the surveys. Closed circles show presence for 2010–2011,

open circles show presence for 2005–2009. Table 6.4.24.6.1 Cuckoo ray in the North Sea. ICES advice and landings. Year ICES advice Predicted catch

corresp. to advice


2009 Status quo catch - 2010 No new advice, same as 2009 - 2011 Status quo catch - 165 2012 No new advice, same as 2011 - 2013 No TAC, species-specific measures needed, catch

could increase by max. 20%. -



6.4.24.7 Advice October 2012 ECOREGION North Sea STOCK Common skate (Dipturus batis) complex (Dipturus cf. flossada and

Dipturus cf. intermedia) in Subarea IV and in Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel)

Advice for 2013 and 2014 Based on the precautionary approach, ICES advises that there should be no targeted fishery for either Dipturus cf. flossada or Dipturus cf. intermedia, and measures should be taken to minimize bycatch. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Stock status




Qualitative evaluation Depleted The common skate (Dipturus batis) complex is now considered to be depleted in the North Sea. Limited information suggests that only D. cf. intermedia is found in the ecoregion, and only to the north where it likely merges with the neighbouring population in Subareas VI and II. Management plans The Dipturus batis complex is currently on the EU prohibited species list. Biology Common skate has a late age-at-maturity and a low reproductive capacity. They are considered to be particularly vulnerable due to their large size. These are very large, slow-growing species, and as such are highly vulnerable to overfishing. It is now only found in the northern part of the ecoregion. Environmental influence on the stock Resource competition and species interactions between the various skate species is poorly understood. Historically, common skate have been known to predate on smaller skate individuals, and the longer-term decline in the larger skates may have benefited populations of smaller skate species. The fisheries Commercial fisheries existed for the common skate complex in the past, but declining numbers now means that recent catches have been pure bycatch. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data have been reported to this level. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for these species. Scientific basis Assessment type No assessment. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators Survey indices, not sufficiently representative for the stock. Other information Life history Working group report WGEF



6.4.24.7 Supporting information October 2012 ECOREGION North Sea STOCK Common skate (Dipturus batis) complex (Dipturus cf. flossada and

Dipturus cf. intermedia) in Subarea IV and in Divisions IIIa and VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel)

Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. Precautionary approach ICES advises on the basis of the precautionary approach that there should be no targeted fishery for either Dipturus cf. flossada or Dipturus cf. intermedia. Measures should be taken to minimize bycatch. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Additional considerations Comparison with previous assessment and advice The advice and the basis of advice are the same as for 2011 and 2012. Source ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19. Table 6.4.24.7.1 Common skate (Dipturus batis) complex (Dipturus cf. flossada and Dipturus cf. intermedia) in

Divisions and Subarea IIIa, IV, and VIId. ICES advice and landings. Year ICES advice Predicted catch

corresp. to advice


2006 No targeted fishery 2007 No targeted fishery 2008 No new advice, same as 2007 2009 No targeted fishery 0 2010 No new advice, same as 2009 0 2011 No targeted fishery 0 15 2012 No new advice, same as 2011 0 2013 No targeted fisheries, minimize bycatch. 0 2014 No new advice, same as 2013 0 Weights in tonnes.


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6.4.24.8 Advice October 2012 ECOREGION North Sea STOCK Starry ray (Amblyraja radiata) in Subarea IV and in Divisions IIIa and

VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel) Advice for 2013 and 2014 Based on ICES approach to data-limited stocks, ICES advises that catches should be reduced by 36%. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise on an individual TAC for this species, which is discarded in most fisheries. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Stock status




Qualitative evaluation Declining

Abundance estimate, North Sea Spatial distribution • = 2010-2011, o = 2005-2009

Figure 6.4.24.8.1 Starry ray (Amblyraja radiata) in Divisions and Subarea IIIa, IV, and VIId. Left: Abundance

estimate (survey catch per unit effort, cpue). Dashed lines show the mean annual cpue ±std. dev. for 2005–2009, the red line shows the mean annual cpue for 2010–2011. Right: Distribution of Amblyraja radiata. Closed circles show presence for 2010–2011, open circles show presence for 2005–2009.

There is insufficient information to present trends in species-specific landings for this species. Starry ray is widespread throughout the region, with no evidence of change of distribution, Abundance estimates have been declining over the last decade, with a 47% decrease between the average of the last two years compared to the previous five years. Management plans No specific management objectives are known to ICES.


Biology This is a small-bodied, quite productive ray. Its abundance increased in the 1990s before declining again. Environmental influence on the stock This is a cold-water ray that extended its range into the North Sea from boreal waters. Cooler temperatures would be associated with increasing range and abundance of this stock. The fisheries Starry ray is a small-bodied ray, of little commercial importance and mainly discarded. Because it is usually caught as a bycatch in demersal fisheries, this species would benefit from a reduction in the overall demersal fishing effort. Quality considerations Little information is available on discarding of this species, but it is known to be comparatively high. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or overfished. Scientific basis Assessment type Survey-based trends. Input data IBTS Q1 survey. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.8 Supporting information October 2012 ECOREGION North Sea STOCK Starry ray (Amblyraja radiata) in Subarea IV and in Divisions IIIa and

VIId (North Sea, Skagerrak, Kattegat, and eastern English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. ICES approach to data-limited stocks For data-limited stocks for which an abundance index is available, ICES uses as harvest control rule an index-adjusted status quo catch. The advice is based on a comparison of the two most recent index values with the five preceding values, combined with recent catch or landings data. Knowledge about the exploitation status also influences the advised catch. For this stock the abundance is estimated to have decreased by more than 20% in the main survey, between 2005 and 2009 (average of the five years) and 2010–2011 (average of the two years). This implies a decrease in catches of at most 20% in relation to the last three years’ average. Additionally, the precautionary buffer is applied because of lack of information on exploitation rate, resulting in overall advice for a 36% decrease in catch. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise on an individual TAC for this species that is discarded in most fisheries. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Additional considerations Comparison with previous assessment and advice ICES has not previously provided species-specific advice for this stock. Advice is based on category 3 of ICES approach to data-limited stocks. Source ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19.

Table 6.4.24.8.1 Starry ray in the North Sea, Skagerrak, Kattegat, and eastern Channel. ICES advice and landings. Year ICES advice Predicted catch

corresp. to advice


2011 No specific advice < 1 2012 No specific advice 2013 No TAC, species-specific measures needed, catch




6.4.24.9 Advice October 2012 ECOREGION North Sea STOCK Other ray and skate species in Subarea IV and in Divisions IIIa and VIId

(North Sea, Skagerrak, Kattegat, and eastern English Channel) Advice for 2013 and 2014 Other species of skates and ray are also found in this ecoregion. These include: Dipturus linteus, Dipturus nidarosiensis, Dipturus oxyrhinchus, Leucoraja circularis, and Leucoraja fullonica. Based on ICES approach to data-limited stocks, ICES advises that catches should be decreased by at least 20%. However, ICES does not advise that individual TACs be set for these stocks, at present. Additional measures should be identified that can regulate exploitation of these species. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Stock status




Qualitative evaluation Unknown There is insufficient survey or abundance data available to assess these species individually. There is insufficient information to present trends in species-specific landings. Management plans No specific management objectives are known to ICES. Biology There are a variety of species declared in this category. Members of the Dipturus family are large-bodied skates. The fisheries These species are bycaught in small quantities in different fisheries. Quality considerations Since legal obligations to declare most demersal elasmobranchs to species level were introduced, a greater proportion of data are reported to this level. This information covers too short a time period to influence advice at the present time. Fishery-independent trawl surveys provide the longest time-series of species-specific information, although these surveys do not sample all the size classes and habitats for the various species. The advice is based on a precautionary reduction of catches because of missing or non-representative data. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. Scientific basis Assessment type No assessment. Discards and bycatch Data not examined. Improved knowledge of discard rates and discard survival is required. Indicators None. Other information Life history. Working group report WGEF



6.4.24.9 Supporting information October 2012 ECOREGION North Sea STOCK Other ray and skate species in Subarea IV and in Divisions IIIa and VIId

(North Sea, Skagerrak, Kattegat, and eastern English Channel) Reference points No reference points have been defined for this stock. Outlook for 2013 and 2014 No analytic assessment can be presented for this stock. Therefore, fishing possibilities cannot be projected. ICES approach to data-limited stocks For data-limited stocks without information on abundance or exploitation ICES considers that a precautionary reduction of catches should be implemented, unless there is ancillary information clearly indicating that the current level of exploitation is appropriate for the stock. For these species, ICES advises that catches should decrease by 20% in relation to the last three years’ average. However, as species-specific landings data are not complete, it is not possible to quantify the current catch. ICES does not advise that an individual TAC be set for these stocks, at present. Additional measures should be identified that can regulate exploitation. Such measures may include seasonal and/or area closures, technical measures, and tailored measures for target fisheries. Such measures should be developed by stakeholder consultations, considering the overall mixed fisheries context. Additional considerations Comparison with previous assessment and advice ICES has not previously provided species-specific advice for these species/stocks. Advice is based on category 5 of ICES approach to data-limited stocks. Source ICES. 2012. Report of the Working Group on Elasmobranch Fishes (WGEF), 19–26 June 2012, Lisbon, Portugal. ICES

CM 2012/ACOM:19. Table 6.4.24.9.1 Other ray and skate species in Divisions and Subarea IIIa, IV, and VIId. ICES advice and landings. Year ICES advice Predicted catch

corresp. to advice





6.4.24 advice october 2012 ecoregion north sea stock rays … · 2012-11-19 · ices advice 2012,...

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