The cost of bycatch to the ocean ecosystems is immense. And fisheries with substantial levels of bycatch are clearly neither acceptable nor sustainable.
Around the UK, the most significant example of bycatch is that of small cetaceans (dolphins and porpoises) in fishing nets. Harbour porpoises are particularly at risk from static 'bottom-set' trawling, whereas dolphins are most at risk from huge trawled nets because they feed on the same small fish as the target species.
Evidence of the growing scale of this problem is washed up on beaches around the south west of England and northern France every year in the form of hundreds of dolphin corpses.