Bluefin tuna--they're so delicious, they're on the brink of extinction. The human appetite for this majestic fish has spurred overfishing that has endangered the wild population, so researchers and aquaculture companies are trying to breed the fish in captivity. But so far bluefin tuna have proved very difficult to farm, since it's impossible to replicate their natural reproductive cycle--researchers think the fish travel hundreds of miles to their traditional spawning grounds. The best results so far have come from an Australian company that is using hormone injections to get the big fish to breed. Now researchers associated with a European project called Selfdott (an odd acronym for "self-sustained aquaculture and domestication of thunnus thynnus") say they can successfully raise fish in captivity without using hormones. The New York Timesreports that the first batch of fish, raised in floating cages, died after a matter of weeks or months, but researchers still think that with better food and parents more adjusted to captivity, the next group of fish will survive.
“If the results of this research can ultimately be commercialized, it can improve food supplies and contribute to economic growth and employment while also helping to ensure a sustainable management of bluefin tuna,” Máire Geoghegan-Quinn, the European Union’s commissioner for research, said this week. [New York Times]
Because the predator fish are high on the food chain, requiring lots of food (in the form of smaller fish) and many years to grow, environmentalists still aren't too keen on the aquaculture fix.
Tuna is one of the most environmentally punishing fish to farm, in part because the fish takes a decade or more to mature. During this time, the captive fish are fed massive amounts of smaller wild fish--an estimated 20 tons of food fish goes into each ton of tuna produced--so those prey species may become depleted in turn. The farms also produce high concentrations of fish waste, polluting the area around the farm, and can be breeding grounds for piscine diseases and parasites like sea lice. [Popular Science]
It would be better, some say, to eat fish lower on the food chain that require less resources. Saskia Richartz, an oceans and fisheries expert with the European unit of Greenpeace told The New York Times:
"[T]his is tantamount to breeding elephants in captivity for their ivory.” [The New York Times]
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Image: Wikimedia / OpenCage