Small-eyed ray in Western Channel, Irish and Celtic Seas and West of Scotland, Demersal otter trawl
Content last updated
21st Feb 2017
Small-eyed ray ICES Divisions VIIa-k, and Sub-area VI (Irish, Celtic Seas, western Channel and west of Scotland)
Small-eyed ray (Raja microocellata) is found on the inner continental shelf in the east Atlantic from the south-western coasts of the British Isles to northern Morocco (Stehmann and Bürkel, 1984). It is locally abundant in the Bristol Channel and parts of the English Channel (Ellis et al., 2005). It is an inshore demersal species, inhabiting the inner continental shelf waters down to a depth of about 100 m (Ellis et al., 2005). It is usually found on sandy substrates, favouring sandy bays and sand banks (), with shallow, sandy bays in the northern Bristol Channel acting as important nursery grounds (Kaiser et al., 2004; Ellis et al., 2005).
Small-eyed ray is a medium-sized skate, attaining a maximum length of 91 cm. The estimated maximum age is about 12 years. Total length at maturity is between 69 and 78 cm and they breed during the summer. They predate on shrimps and other small crustaceans when small, with the adults also feeding on sandeels and other demersal fish.
It is a locally important component of targeted skate fisheries using otter trawl or set-nets, as well as a commercial bycatch in mixed demersal trawl and set-net fisheries (ICES, 2015). Smaller individuals are usually discarded (Silva, et al., 2012).
The degree of resource competition and species interactions between skate species is poorly understood. Historically, the larger common skate (Dipturus batis) complex, was known to predate on smaller skate individuals, and earlier, longer-term declines in larger skates may have benefited populations of smaller skate species, due to a reduction in predation or competition.
ICES provides advice for two stocks, one in the Bristol Channel and another in the English Channel (ICES, 2014a,b). Insufficient information is available to present longer-term trends in species-specific landings for these stocks, although the species-specific reporting of skates is improving. The degree of connectivity between small-eyed ray in the Bristol Channel and English Channel is unknown, and they are currently treated as separate stocks. Catch rates in scientific trawl surveys in the Bristol Channel imply suggest a recent decrease in catch rates, although the longer-term trend has shown a general increase. The status of the English Channel stock is unknown.
Ellis, J. R., Cruz-Martinez, A., Rackham, B. D., Rogers, S. I., (2005). The distribution of chondrichthyan fishes around the British Isles and implications for conservation. Journal of Northwest Atlantic Fishery Science, 35: 195-213.
ICES (2014a). Small-eyed ray (Raja microocellata) in Divisions VIIf, g (Bristol Channel). In: Report of the ICES Advisory Committee, 2014. ICES Advice 2014, Book 5, Section 22.214.171.124; 5pp.
ICES (2014b). Small-eyed ray (Raja microocellata) in the English Channel (Divisions VIId, e). In: Report of the ICES Advisory Committee, 2014. ICES Advice 2014, Book 5, Section 126.96.36.199; 4pp
ICES (2015). Report of the Working Group on Elasmobranch Fishes (WGEF), 17–23 June 2015, Lisbon, Portugal. ICES CM 2015/ACOM:19. 711 pp.
Kaiser, M. J., Bergmann, M., Hinz, M., Galanidi, M., Shucksmith, R., Rees, E. I. S., Darbyshire, T., Ramsay, K. 2004. Demersal fish and epifauna associated with sandbank habitats. Estuarine, Coastal and Shelf Science, 60: 445–456.
Silva, J. F., Ellis, J. R. and Catchpole, T.L. (2012). Species composition of skates (Rajidae) in commercial fisheries around the British Isles, and their discarding patterns. Journal of Fish Biology, 80: 1678–1703.
Stehmann, M., and Bürkel, D. L. (1984). Rajidae. In Fishes of the north-eastern Atlantic and Mediterranean. P. J. P. Whitehead, M-L. Bauchot, J-C. Hureau, J. Nielsen, and E. Tortonese (eds.). UNESCO, Paris. Vol. 1, 163–196.
The status of small eyed ray stock in ICES Divisions 7f and 7g (Bristol Channel, Celtic Sea north) has been scored as very high risk
The status of small eyed ray stock in ICES Divisions 7f and 7g (Bristol Channel, Celtic Sea north) has been scored as very high risk. Reference points for long-term sustainability have not been defined for this stock, and therefore cannot be used to derive a risk score. The risk score was calculated using a data-limited approach where the vulnerability score for cuckoo ray (62/100; FishBase, 2015) was weighted with the stock size indicator which is below average in recent years (ICES 2016).
The management of small eyed ray stock in ICES Divisions 7f and 7g (Bristol Channel, Celtic Sea north) has been scored as a moderate risk
The management of small eyed ray stock in ICES Divisions 7f and 7g (Bristol Channel, Celtic Sea north) has been scored as a moderate risk. This is because data-derived management controls are in place, albeit under the framework of a generic TAC for all skates (Rajidae) over a broader management area, and that compliance can be patchy (e.g. misidentifications in skate species can occur). Data-limited assessments and scientific advice for these stocks are provided on a biennial basis and a comprehensive regulatory framework is in place.
The bycatch risk of this fishery is scored as high risk. This is because otter trawls have the potential to take relatively high quantities of bycatch of non-target and vulnerable species (> 30% of catch weight), including demersal elasmobranchs and protected, endangered and threatened (e.g. sharks and rays) species in certain circumstances. However, the incoming EU landings obligation is intended to reduce discarding.
The habitat risk of this fishery is scored as a moderate risk. This is because, although otter trawls are considered to have a potential to cause significant habitat damage, damage to vulnerable and sensitive marine habitats is likely to be minimised given that the footprint of the fishery is within core areas, typically historically fished ground.
Spatial management to reduce potential interactions with vulnerable habitats are being developed, but there remains uncertainties about the location of some sensitive seabed habitats and therefore some risk of further impact.
|Current risk status||Outlook||Reason|
|Stock||Very high||Unknown||There is evidence for stock decline or at best for a stable stock in the Bristol Channel. The most recent ICES advice is for a 36% decrease in the landings of this stock. The status of the English Channel stock is unknown. The most recent ICES advice was for a 20% decrease in the landings of this stock. Whilst species-specific landings data are improving, estimates of dead discards are not available, and some landings data are generic. Hence, recent trends in the catches of small-eyed ray cannot be fully quantified. Ongoing collection of species-specific landings data should improve understanding of stock dynamics.|
|Management||Moderate||Improving||Management decisions for this data-limited No individual TAC is set for this stock at present and only a data-limited assessment has been produced to provide fisheries advice. No reference points for long-term sustainability have been defined, and no management plans are currently in place. Increasing the quantity and quality of species-specific data will help to improve targeted management techniques.|
|Bycatch||High||Improving||Bycatch of non-target species in this fishery is relatively high with poor selectivity. However, with technical and spatial management measures continuously under development and the incoming EU landings obligation intended to reduce discarding of target species, the bycatch risk is likely to reduce in the future.|
|Habitat||Moderate||Improving||Otter trawls disturb seabed habitats, but a range of Marine Protected Areas have been established and are under development to help minimise damage to vulnerable marine habitats.|
|Type||Current Risk Status||Outlook||Reason|
Whilst ICES describes the small eyed ray stock in the Bristol Channel as below the historic average, recent trends suggests that the stock is increasing.
Management decisions for this data-limited No individual TAC is set for this stock at present and only a data-limited assessment has been produced to provide fisheries advice.
No reference points for long-term sustainability have been defined, and no management plans are currently in place.
Increasing the quantity and quality of species-specific data will help to improve targeted management techniques.