Bycatch

Bull Shark Caught in Net © Fiona Ayerst.

Bycatch usually refers to fish caught unintentionally in a fishery that is targeting other fish or an unwanted portion of a mixed fishery. Bycatch may comprise different species, undersized individuals of the target species, or juveniles of the target species. Discards are the portion of a catch of fish which are not retained on board during commercial fishing operations and are returned, often dead or dying, to the sea.

Discarding has long been a concern for fisheries managers, conservationists and fishers alike, and in 2011 The Big Fish Fight campaign brought the matter of ‘discarding’ straight into UK homes. Focussing on the level of discard mortality, and thus the shocking waste of often perfectly edible fish, the call for a total ban on discards was enthusiastically supported by the public. This certainly makes sense for bony fish but many shark conservationists are concerned about the impacts a total discards ban could have on shark, skate and ray populations.

In comparison to bony fish, sharks have a robust physiology. Their cartilaginous skeleton gives them greater flexibility, the absence of a swim bladder leaves them less affected by changes in pressure, and dermal denticles provide a tough outer skin – all features which improve their chance of discard survival.

Historically sharks, perhaps with the exception of Spiny Dogfish and some skate, were discarded. With a conservative life history strategy (slow growth, late maturity and few young) this ensured that as many sharks as possible had the opportunity to contribute to population growth. However with the decline in other traditional target stocks, fisheries diversified and in the early 90’s there was an increase in the retention rate of previously discarded sharks. This saw the populations of some species decline dramatically.

Sharks are caught as bycatch and in mixed fisheries. Under current fisheries management regimes the need for precautionary management of Endangered or Critically Endangered species such as Porbeagle or Spiny Dogfish has resulted in a scenario of a zero Total Allowable Catch (TAC) and a prohibition on the retention of bycatch. The stringent nature of this level of management reflects the concern over populations which have exhibited population declines of more than 80%.

However a zero TAC does not equate to zero catch (just zero landings), and these species may be inadvertently caught in quite substantial numbers, leading to a scenario of discarding often dead animals which infuriates fishers and concerns conservationists alike.

In the context of unwanted bycatch or species under precautionary management, the Shark Trust remains adamant that any shark which might survive should be given opportunity to do so, and returned to the water with due haste and care. Under current management regimes, to ensure this occurs the Trust has no choice but to support the ban on retention of bycatch for zero TAC species. However, the matter of dead discarding associated with bycatch prohibitions and other fisheries is of great concern, as the current requirement to discard all animals (dead or alive) does nothing to reduce mortality and therefore improve the conservation status of the species.

Unfortunately the inevitable truth is that sharks will continue to be caught, and so we must work closely with the fishing industry to develop practical measures to ensure the highest chance of avoidance or survival if caught, whilst recognising the nonsensical nature of dead discarding. The European Commission proposes to eliminate the practice of throwing unwanted fish overboard by 2016 and recent votes in the European Parliament on Common Fisheries Policy (CFP) reform have confirmed MEP commitment to this end, recognising that such discards are an unacceptable waste of resources. However, the Commission does state that species with a high expected survival rate should not be covered by the landing obligation and should be released. This is a position the Shark Trust wholly supports.

Related Links:

European Parliament Votes to Rebuild Europe’s Dwindling Fish Stocks - Ocean 2012