Aquaculture problems: Farming wild-caught fish

The failure of attempts to breed some species, such as tuna and eel, in captivity has led to the relatively new phenomenon of farming wild-caught fish. However, this industry is having a devastating affect on wild populations.

Tuna farming, for example, involves capturing wild tuna and then fattening them in cages, mainly for exportation to Japan for sushi.

Prior to 1995, very little bluefin tuna was farmed this way in the Mediterranean. But according to one report, 22,500 tonnes were farmed in 2004. This has dramatically increased the amount of bluefin tuna caught each year from an already overexploited stock. Some of the tuna caught for farming are juveniles - which will not be able to reproduce in the wild and renew the wild stocks.

To make matters worse, tuna farming is officially considered as a "post-harvesting" practice rather than one based on direct capture, and thus avoids every regional and international rule set up to manage fisheries in the Mediterranean. At the same time, the farms benefit from EU subsidies for aquaculture.

This kind of fish farming has had a similarly devastating affect on wild bluefin tuna populations in southern Australia, as well as on European eel populations.

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