Could we restock the oceans by releasing fish bred in captivity?

Sticking to the question ‘could we’, the answer has to be ‘probably not’. Demand is for the apex predators such as salmon and tuna, high up in the food chains. But they require a lot of food in the form of meals made from other marine fish of lesser market value, which means further depletion of wild fish stocks.

Marine fish farms encounter the problems of any intensive monoculture where individuals of a species are crammed together: disease and pollution. There is some evidence that farmed fish spread diseases to wild populations, that they have a damaging effect on the genetics of wild fish stocks through interbreeding, and that they are less able to survive in the wild. There’s also environmental damage, and it looks as if marine fish farming may be more of a threat to wild fish stocks than a means of replenishing them.

Oliver Crimmen, Senior Fish Curator, NHM London