Can Endangered Bluefin Tuna Be Saved by Fish Farming?

By Joseph Calamia | August 30, 2010 5:43 pm

bluefinBluefin 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 Times reports 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]

Related content:
80beats: In “Operation Blue Rage,” Sea Shepherd Activists Will Target Tuna Poachers
80beats: Bluefin Tuna Is Still on the Menu: Trade Ban Fails at International Summit
80beats: DNA Scanner Proves That NYC Sushi Contains Endangered Bluefin Tuna
80beats: Scientists Say Ban Atlantic Bluefin Tuna Trade–and Sushi Chefs Shudder
80beats: Are Fish Farms the Answer to World Hunger or a Blight on the Oceans?

Image: Wikimedia / OpenCage

  • deweaver

    As usual, the environmental activists made false claims and exaggerations. For example, statements about where on a normal marine food chain a species is located is irrelevant to aquaculture. At the present time, aquatic diets use fish meal as a protein source, not because it is required but because it is cheaper. You can grow top carnivorous fish like white seabass on the west coast of the US on a diet made from barley protein and spirulina algae with no fish or meat meals of any kind. The fish actually grew faster with less feed (only a little over 1 lb of feed to grow a lb of fish) on the vegan diet. Soy protein concentrate and corn gluten meal also work well for a lot of “top carnivorous” species of fish.

    Tuna don’t take a decade or more to mature and they grow extremely fast (a factor of 100,000,000 weight increase in the first year of life). If we can solve the larval rearing problem with tuna, they would be sold at only about 1 to 2 years old ( 50+ lb fish). One mature tuna will spawn several tens of millions eggs, so the number of broodstock needed is only a few fish to support a huge aquaculture industry putting all the tuna fishermen out of business. It is the real threat of fishermen going out of business that is driving all this anti-aquaculture PR.

  • Chris the Canadian

    My take on this is, if we can raise these fish in captive cages, why can’t we re-stock the fish into the wild the same way Great Lakes programs have stocked the lakes with Chinook, Koho, Steelhead, Lake Trout, and are now trying to re-introduce Atlantic Salmon? Many of these stocked fish now reproduce in the wild and many rivers have self-sustaining populations of these fish for sport fishermen. These same hatcheries use brood stock fish to fertilize and after the Tuna reach a certian size they can be released to the oceans for them to grow naturally.

  • Brian Too

    Whatever happened to that Japanese fellow trying to raise tuna? Apparently he had invested several years and quite a bit of money in the endeavor. He was using fixed pens close to shore, not the open ocean floating pens that have recently been talked about.

  • Jennifer Angela

    If I had known that tuna is on the verge of extinction, I wouldn´t have eaten those in the past. I feel guilty now. I really do. I think it´s a good idea to rescue tuna. We (human beings) owe that to those fish, as we had been consuming many of their relatives. I can imagine, that you can put any animal on a vegan diet, even predators, as I have made the experience that pets (cats and dogs) are huge fans of vegan food they consider tasty(e.g. rice, potatoes, almost anything with sauce, cheese, spaghetti, eggs, chips, in fact anything bread-alike that – just like bread – contains carbohydrates and gluten, therefore I can easily visualize fish eating a corn gluten meal… bread and chips contain gluten too, after all… No need to be concerned. I feed pets with meat and whatever you will find in pet food, the kind of feeding described above only happens occiasonally…maybe twice a year… and is additional. I have never attempted to turn a cat or a dog into a vegetarian. They have a right to be what they are – carnivores). But can predators survive on a meat-less diet in the long run? On my search for an answer to that question, I tried to evaluate whether lions, being predators, can survive on meat or not. On, I´ve read that felines can´t survive on a vegan diet, as they require taurine in order to live and thrive. Taurine deficiency can result in blindness and even death. Felines also require pre-formed vitamin A and arachidonic acid. Certainly, all of these things can be found in meat, so felines definetely need meat. Anyway, this is about fish and not felines, and there is only one way to find out, if tuna can live on a vegan diet: Learning by doing. Let them eat vegan food and see what happens. They are threatened by extinction, so they don´t have much to lose. Are those smaller fish that tuna relish also on the verge of extinction?

  • fatkid

    As long as we treat the ocean like a toilet and deplete her resources, farm raised tuna will be the only kind on the menu. It’s amazing how fast they grow.

  • Jennifer Angela

    I´ve reconsidered this matter and I honestly think, that those remaining tuna ought to be fed small fish – those that are NOT on the verge of extinction – as opposed to tuna, in order to rescue tuna from extinction. So tuna are predators. That doesn´t make their lives less valuable. After all we (human beings) are predators too, as most of us had always consumed meat, which is probably the case because we have short intestines (8.5 metres compared to a lenght of 18 to 24 metres found in pigs and an impressive length of about 40 metres in cows). Currently most of us still do eat meat (99 percent of all Americans eat meat as stated on the following webpage: and Australians are apparently one of the largest meat consumers in the world…according to ). Thus we shouldn´t be pointing the finger at tuna for enjoying meaty meals, as we are doing the same.

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