Skate, Common

Dipturus batis

Method of production — Caught at sea
Capture method — All applicable methods
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea and Skagerrak; Celtic Sea and West of Scotland
Stock detail — 6 & 7
Picture of Skate, Common

Sustainability rating five info

Sustainability overview

Red-Rated Species. Common skate form two species: Flapper and Blue skate. Flapper skate is generally found in the northern North Sea and north-western Scotland, or in the Celtic Sea. Whereas, Blue skate is predominantly found in the Celtic Sea to Iceland. Common skate are an EU Prohibited Species. It is illegal to fish for, retain or land this species as it is prohibited in EU waters. Common skate is assessed as Critically Endangered by IUCN and is listed by OSPAR as a threatened and declining species. Because of this, they are automatically a red-rated species.

Biology

Common skates belong to the Rajidae family which includes skates and rays. The common skate is the largest European batoid fish (flat elasmobranch fish with the pectoral fins fused to the sides of the head). Females can reach lengths of about 280cm and males about 200cm. Males mature at a length of about 125cm and females at about 180cm (both at over 10 years old). The species can live from 20 up to 100 years.

Stock information

Criterion score: 1 info

Stock Area

North Sea and Skagerrak; Celtic Sea and West of Scotland

Stock information

The stock status of Blue and Flapper skate is unknown. There are no reference points to determine an overfished or overfishing status. However, they are a prohibited species as their populations have declined over the latter half of the 20th century. Due to the lack of robust data collected for the species, there are no robust indicators to determine the population trends. However, the Spanish Porcupine Bank survey has observed increasing catch rates of common skate and the UK southwestern beam trawl survey has observed an increasing trend of blue skate in Division 7.e. However, these are preliminary results and may not be representative of the whole area.

Management

Criterion score: 1 info

Blue and flapper skates are prohibited species under EU law. This means that it is prohibited to fish, retain, tranship, or land either species. This rule applies to ICES Division 2.a and subareas 3-4 and 6-10.

Monitoring
Neither blue skate or flapper skate have received formal quantitative stock assessments. There are a lack of data to conduct full stock assessments.

This is the highest protection possible under the EUs Common Fisheries Policy (CFP) and is a long-term conservation strategy aimed at very depleted and vulnerable species. ICES has evaluated the inclusion of Common Skate as a prohibited species and has concluded that the stock should be removed from the Prohibited Species List. Common Skate is also the subject of a Biodiversity Action Plan. The Plan aims to stabilise populations by minimising fishing mortality and legally protect it in at least 5 key areas.

Landings for both flapper and blue skate are reported, however, they are often misidentified and recorded as Norwegian skate or long-nosed skate. Therefore, landings data do not inform the true catch. There are no discard data available and therefore, true fishing mortality of the species is unknown. Some fishery-independent studies have been conducted but certain attributes about the species and survey methods reduce their applicability in stock assessments. For example, blue skate can be locally abundant and this can make it difficult to survey the species and understand their true population size.

Capture Information

Criterion score: 1 info

Common skates are a prohibited species. They are caught as bycatch in trawl and tangle net fisheries. Under current EU legislation it is prohibited to fish for, retain on board, tranship or land common skate. Because it is an EU Prohibited Species any animal captured should be returned immediately and unharmed, where possible, to the sea.

Blue skate and flapper skate were traditionally a commercially important species in northern European waters, originally caught in trawl and line fisheries Since they are now a prohibited species, they are no longer targeted, however, they may be caught as bycatch, with over 99% of those caught, taken in trawl fisheries.

When captured with tangle nets, skate condition was significantly better during shorter (17-28 hours) soak times, compared with (42-48 h soak time)(Ellis et al. 2018).

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Dab
Halibut, Atlantic (Farmed)
Halibut, Pacific
Megrim
Plaice
Sole, Dover sole, Common sole
Sole, Lemon
Turbot (Caught at sea)
Turbot (Farmed)

References

ICES. 2018. Common skate complex (Blue skate (Dipturus batis) and flapper skate (Dipturus intermedius)) in Subarea 6 and divisions 7.a-c and 7.e-k (Celtic Seas and western English Channel). Available at: http://ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/rjb.27.67a-ce-k.pdf. Published 5 October 2018.



Ellis, J. R., Burt, G.J., Grilli, G., McCully Phillips, S.R., Catchpole, T.L., Maxwell, D.L. 2018. At-vessel mortality of skates (Rajidae) taken in coastal fisheries and evidence of longer-term survival. Journal of Fish Biology. 92, 1702-1719. doi:10.1111/jfb.13597

Mangi, S., Kupschus, S., Mackinson, S., Rodmell, D., Lee, A., Bourke, E., Rossiter, T., Masters, J., Hetherington, S., Catchpole, T. and Righton, D. 2018. Progress in designing and delivering effective fishing industry science data collection in the UK. Fish 00:1-21. https://doi.org/10.1111/faf.12279

Shark Trust ID Guide Factsheet www.sharktrust.org

Sguotti, C., Lynam, C. P., Garcia-Carreras, B., Ellis, J. R. and Engelhard, G. H. 2016. Distribution of skates and sharks in the North Sea: 112 years of change. Glob Change Biol, 22: 2729-2743. doi:10.1111/gcb.13316