Prized sashimi tuna bred in captivity for first time
Photo by Brian Skerry
“And on that farm he had a…” – tuna? Aquatic Old MacDonalds have moved a stride closer to fully farming bluefin tuna now that all three species of the fish – one of the most endangered of those commercially fished – have produced eggs and larvae in captivity.
Umami Sustainable Seafood of San Diego, California, announced that it has definitive proof from DNA maternity tests that eggs and larvae collected from its research and production facility in Croatia came from around 1000 captive northern bluefin tuna grown to maturity over the past five years.
This is the first time that the endangered species – highly prized for sashimi dishes – has spawned in captivity.
The next step for the company is to demonstrate that the larvae can be grown into fully mature fish, completing the entire growth cycle in captivity. Proof that the fish produce eggs and larvae in captivity is a significant advance, however. “The biggest milestone for us was the massive spawning we had this year, with billions of eggs released,” says Oli Steindorsson, the chief executive of Umami.
Umami already farms northern bluefin, but at present the company replaces harvested fish with young caught fish. It aims to end this practice once replacements can be grown “on the farm”. “Reducing the need for wild capture of juvenile fish and instead being able to breed bluefin tuna in captivity addresses one of the issues needed to move towards more sustainable aquaculture,” says Sebastian Troeng, vice-president of the global marine division at the US environmental group Conservation International.
To boost bluefin numbers in the wild as part of its hatchery project, Umami will deposit most of the eggs in the sea, but will be retaining some eggs and larvae for further experiments.
The breakthrough means that all three species of bluefin have now been bred in captivity. Kinki University in Kushimoto-cho, Japan, successfully bred Pacific bluefin in 2007. And in 2009, Clean Seas, a company based in Port Lincoln, South Australia, managed to breed southern bluefin tuna, the most endangered of the three bluefin species.
Troeng says it is still up for debate whether such fish farming is truly sustainable, though. The fish receive feed containing sardines, herring, anchovies or mackerel. “A major and remaining challenge is to improve the feed conversion ratio, as bluefin tuna in captivity require around 20 times more fish for feed than what is produced,” he says.
But recently, Conservation International broadly backed seafood farming in a report on its global effects and sustainability. It noted that farming is now expanding rapidly: in 2009, for the first time, more seafood was farmed than caught in the wild.
Europe’s fisheries chief called on Wednesday for close monitoring of the trade in bluefin tuna caught in Libyan waters, fearing illegal catches could push the endangered fish closer to extinction amid the chaos of war. Atlantic bluefin fetch more than $100,000 each in markets such as Japan, but stocks have plunged by more than 80 percent since the 1970s due to overfishing, many scientists say.
Tuna really is in dire straits. Help anyway you can.
For millennia, mankind has fished for the Bluefin. Some of the traditional fishing techniques are still being used today. But commercial fishing techniques were launched in the Fifties. Ever since, Bluefin tuna stocks have been reduced by 97%.
A new website wants you to know how grim the situation has become for Atlantic bluefin.
Chances are that the last wild Bluefin tuna will die in 2012. If the Bluefin becomes extinct, it could have a major impact on the fragile ecosystems of our oceans.
If you live in an EU nation, it’s worth your contacting your country’s responsible ministry to ask what they are doing to help avoid the extinction of one of the oceans noblest creatures. Also, its critically important to reject bluefin at the market level, particularly in sushi restaurants, to help reduce demand.
Watch the video to learn about the Bluefin’s biggest problems, including economies of extinction (when an exploited species becomes ever more valuable, the rarer it gets), tragedy of the commons , bycatch, subsidies and the wasteful nature of feeding cultured predatory fishes.
Further readings: the Bluefin tuna on Wikipedia, “The Bluefin Bonanza” by Wietse van der Werf, website of ICCAT, website of the Convention on International Trade in Endangered Species (CITES)
This is incredibly important.