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Elasmobranchs - Bay of Biscay and Iberian waters, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Elasmobranchs - Bay of Biscay and Iberian waters, 2008
Fact Sheet Citation  
Demersal elasmobranchs in the Bay of Biscay and Iberian waters
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
RAJIFORMES
SQUALIFORMES
Geographic extent of Elasmobranchs - Bay of Biscay and Iberian waters
Main Descriptors
Considered a single stock: No        Spatial Scale: Sub-Regional
Management unit: No
 
 
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: No
Exploitation
 

Factors affecting the fisheries and the stock

The effects of regulations

There are no TACs for demersal elasmobranchs.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

Survey data and commercial data are the basis for the qualitative assessments of the overall status of skates and demersal sharks in the Bay of Biscay and the Iberian region.

Uncertainties in assessment and forecast

In general data on these species are limited. The lack of species-specific information in the landings is a particular problem. Only lesser-spotted dogfish is currently reported to species level.

Comparison with previous assessment and advice

ICES has not previously produced advice for these species and stocks.
Overall Assessment Results


Table 7.4.12.1 Demersal elasmobranchs in the Bay of Biscay and Iberian waters. Nominal landings (tonnes) of smooth hounds by Subarea and country (Source: ICES).
Smooth hounds unident. (Mustelus spp.) - ICES Area VIII
  1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007*
Belgium . . . . . . . . + 0,1 0,1 .
France 96,6 115 158 47,8 142 149 188 321 407 394 437 354
Portugal . . . . + . . . 1 . .  
Spain (Basque Country) 53 56 57 46 61 58 85 58 56 54 62 45
Total 150 170 214 94 202 207 273 379 464 448 500 399
* provisional data


Smooth hound (Mustelus mustelus) - ICES Area IX
  1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007*
Portugal 5 2 4 4 2 2 2 1 1 10 25 45
Total 5 2 4 4 2 2 2 1 1 10 25 45
* provisional data


Smooth hounds unident. (Mustelus spp.) - ICES Area IX
  1999 2000 2001 2002 2003 2004 2005 2006 2007*
Portugal 72 39 41 43 50 35 24 11 11
Total 72 39 41 43 50 34 24 11 11
* provisional data


Table 7.4.12.2 Landings (t), effective effort (fishing days = trips*(days/trip)), and lpue (landings in kg/day) of lesser-spotted dogfish, Rajidae and spurdog of the Bakk trawler fleet, recorded at Basque Country (Spain) ports in the period 1994–2007.
  BAKA trawl-ON-VIIIa,b,d
  Lesser-spotted dogfish Rajidae spurdog
Year Landings (t) Effort (days) lpue (kg/days) Landings (t) Effort (days) lpue (kg/days) Landings (t) Effort (days) lpue (kg/days)
1994 112 5619 20 179 5619 32 32 5619 6
1995 202 4474 45 505 4474 113 23 4474 5
1996 206 4378 47 471 4378 108 45 4378 10
1997 242 4286 56 549 4286 128 34 4286 8
1998 303 3002 101 598 3002 199 25 3002 8
1999 231 2337 99 362 2337 155 12 2337 5
2000 228 2227 102 272 2227 122 38 2227 17
2001 217 2118 103 292 2118 138 9 2118 4
2002 331 2107 157 265 2107 126 12 2107 5
2003 303 2296 132 219 2296 95 3 2296 1
2004 235 2159 109 177 2159 82 1 2159 0.5
2005 320 2263 141 233 2263 103 3 2263 2
2006 311 2398 130 185 2398 77 3 2398 1
2007 256 2805 91 194 2805 69 0.7 2805 0.3


Figure 7.4.12.1 Demersal elasmobranchs in the Bay of Biscay and Iberian Waters. Historical trends in landings of skates (Rajidae) in Divisions VIIIab, VIIId, VIIIc, and IXa. From ICES (2008). 2007 data are unavailable for Spain and preliminary for other nations.


Figure 7.4.12.2 Demersal elasmobranchs in the Bay of Biscay and Iberian Waters. Historical trends in landings of lesser-spotted dogfish in Divisions VIIIab, VIIId, VIIIc, and IXa (From ICES, 2008). 2007 data are unavailable for Spain and preliminary for other nations.


Figure 7.4.12.3 Demersal elasmobranchs in the Bay of Biscay and Iberian Waters. Changes in Rajidae spp. (Raja clavata) biomass indices in ICES Divisions IXa and VIIIc, from the Northern Spanish Coast Survey time-series (1983–2007). Boxes mark parametric standard errors of the stratified abundance index. Lines mark bootstrap confidence intervals ( = 0.80, bootstrap iterations = 1000).


Figure 7.4.12.4 Demersal elasmobranchs in the Bay of Biscay and Iberian Waters. Changes in lesser spotted dogfish (Scyliorhinus canicula) biomass indices in ICES Divisions IXa and VIIIc, from the Northern Spanish Coast Survey time-series (1983–2007). Boxes mark parametric standard errors of the stratified abundance index. Lines mark bootstrap confidence intervals ( = 0.80, bootstrap iterations = 1000).

Reference Point
 

No reference points have been defined.
Scientific Advice

Single-stock exploitation boundaries

ICES advises that landings of demersal elasmobranchs in 2009 should not exceed recent average landings (2002–2006), treating skates and rays, and lesser-spotted dogfish separately. Species-specific landings data should be collected for the major skate species (including cuckoo ray, blonde ray, thornback ray, spotted ray, undulate ray, and smalleyed ray).


Skates and rays

Year

ICES

Advice

Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresponding to single-stock exploitation boundaries

Agreed

TAC (1)

ICES

Landings

Disc.

slip.

ICES

Catch


Year
1996 No advice       no TAC 4.2      
1997 No advice       no TAC 4.8      
1998 No advice       no TAC 4.4      
1999 No advice       no TAC 3.1      
2000 No advice       no TAC 3.7      
2001 No advice       no TAC 4.4      
2002 No advice       no TAC 3.5      
2003 No advice       no TAC 4.2      
2004 No advice       no TAC 4.2      
2005 No advice       no TAC 3.8      
2006 No advice       no TAC 3.6      
2007 No advice       no TAC 2.4 (2)      
2008 No advice       no TAC        
2009 landings not to exceed recent average (2002–2006) (3)   3.9            

Weights in ‘000 t.

(1)EU only.

(2)Preliminary data.

(3)Given that landings of major species are recorded by species.



Lesser-spotted dogfish

Year

ICES

Advice

Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresponding to single-stock exploitation boundaries

Agreed

TAC (1)

ICES

Landings

Disc.

slip.

ICES

Catch


Year
1996 No advice       no TAC 1.9      
1997 No advice       no TAC 2.1      
1998 No advice       no TAC 2.4      
1999 No advice       no TAC 2.0      
2000 No advice       no TAC 1.7      
2001 No advice       no TAC 1.7      
2002 No advice       no TAC 1.6      
2003 No advice       no TAC 1.7      
2004 No advice       no TAC 1.9      
2005 No advice       no TAC 1.9      
2006 No advice       no TAC 1.7      
2007 No advice       no TAC 1.3 (2)      
2008 No advice       no TAC        
2009 landings not to exceed recent average (2002–2006) (3)   1.8            

Weights in ‘000 t.

(1)EU only.

(2)Preliminary data.

(3)Given that landings of major species are recorded by species.



Management
Management unit: No

Management Objectives

None have been adopted.

An EC Action Plan on elasmobranchs is being considered in 2008.
Management Advice

Management considerations

Demersal elasmobranchs are landed as a bycatch in the demersal fisheries for teleosts. In the Bay of Biscay and Iberian waters they are not generally identified to species in the landings data. For example, several skate species are landed as “skates and rays”. In addition to species identification, market sampling is needed to support the scientific advice.

Since demersal elasmobranchs are a bycatch in mixed fisheries, a restrictive TAC may result in additional discards without necessarily reducing fishing mortality. The survival rate of discards is a relevant management consideration. For some species it is believed that survival rate is high (e.g. lesser-spotted dogfish), but for other species it is unknown.

Elasmobranchs are typically slow growing, having a high age-at-maturity and a low reproductive capacity. These aspects of the biology as well as the limited information on the stock status, indicate that a cautious approach to management should be considered, which could imply reducing landings compared to recent averages.

Generally it should be noted that since elasmobranch species are caught as a bycatch in demersal fisheries, they would benefit from a reduction in the overall demersal fishing effort.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Undefined

The stock boundaries for demersal elasmobranch species in Subareas VIII and IX are unknown.

Skates (Rajidae)

Reported landings of skates (the groups as a whole) in the area seem stable or slightly declining in recent years (Figure 7.4.12.1).

Analyses of lpue from the Basque trawl fleet since 1996 indicate that there has been a decrease in skate abundance (mainly cuckoo ray Leucoraja naevus and thornback ray Raja clavata) in Divisions VIIIa,b,d since the 1998 peak. Landings have also decreased since 1996, but have been more stable in recent years (Table 7.4.12.1).

In Division VIIIc, results obtained from groundfish surveys indicate an increase in thornback ray biomass since 1996. Survey data for the cuckoo ray seems to indicate an increasing trend in biomass although there is considerable year-to-year variability.

Surveys in Subarea IX were judged to be inadequate for estimating abundance trends. In this subarea, skate landings have been stable since 1996, averaging 1800 t year−1.

The status of the less common skate species is unknown due to the lack of species information in landings and their low frequencies in surveys.

Lesser-spotted dogfish (Scyliorhinus canicula)

Reported landings of lesser-spotted dogfish in the area seem stable or slightly decreasing in recent years (Figure 7.4.12.2).

Analyses of lpue from the Basque trawler fleet indicate that the lpue of lesser-spotted dogfish in Divisions VIIIa,b,d has increased from 1994 to 2006. In 2007 a slight decrease in lpue was observed (Table 9.4.12.2). Estimates from groundfish surveys indicate an increase in the biomass of this species in Division VIIIc since 2002. Overall the population of lesser-spotted dogfish in Subarea VIII appears to be stable or slightly increasing (Figure 7.4.12.3).

Landings from Subarea IX decreased since 2004 by more than a factor of two. However, in this area lesser-spotted dogfish is essentially a bycatch from other fisheries, so the decrease in landings during the last few years may be related to changes in the effort distribution targeting different species, and/or better species identification at Portuguese landing ports.

Other demersal elasmobranch species

The state of other elasmobranch species (e.g. smooth hounds Mustelus spp.) is unknown due to a lack of species differentiation in landings and the short and discontinuous nature of relative abundance indices.

The available landing data of smoothhounds showed that landings in Subarea VIII have increased sharply since 1996, from 151 t to a peak of 500 t in 2006. In Subarea IX Mustelus spp. landings have declined since 1999.


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

Unknown Unknown Unknown N/a  


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