Elasmobranch fisheries

  Thomback ray (Raja clavata) © Tom Blasdale/JNCC

 

In general, elasmobranchs are more often taken as bycatch in fisheries for other species rather than as target species in their own right and most fisheries around the UK take some elasmobranch bycatch. Trawlers and seiners working in mixed demersal fisheries on the continental shelf take a bycatch of skates and rays, spurdog, spotted dogfish and occasionally porbeagle shark and tope. Gill netters and longliners targeting flatfish, cod and other species take dogfish and rays and in some cases these may actually become the target species. A limited longline fishery targeting porbeagle sharks has operated in the south-west of England in recent years. Mixed species deepwater fisheries take a number of species of sharks including the Portuguese dogfish and the leafscale gulper shark and a very large bycatch of rabbitfish while offshore fisheries for tuna take a large bycatch of blue and thresher sharks.

 

Elasmobranchs are particularly vulnerable to over-fishing because of a number of unusual characteristics of their biology. Most species are slow growing, mature at a late age and produce very small numbers of young, sometimes as few as one or two every two years. In this respect they are perhaps more similar to marine mammals than to other species of fish. As a result of pressure from fisheries, many species are now severely depleted both in UK waters and beyond. Species such as the common skate, long-nosed skate and angel shark, which once supported profitable fisheries, have now been exterminated from large parts of their former range and may be close to extinction in our waters. Others, such as the spurdog and porbeagle shark have also suffered severe population declines and are in urgent need of effective fisheries management.

 

 

Because they are usually caught as bycatch in fisheries targeting other species, very few of the existing fisheries management measures have been aimed specifically at protecting stocks of elasmobranchs. The FAO International Plan of Action for the Conservation and Management of Sharks calls upon its signatories to address this lack of management through the development and implementation of National Plans of Action. The JNCC is currently working with other European scientists to produce European and UK plans. A number of species have been identified as being in need of immediate protection and to address this, the angel shark and four species of skates (common, long-nosed, Norwegian and white) have been proposed for complete protection in UK waters under the Wildlife and Countryside Act (1981). The basking shark has had this level of protection since 1998.