Tuna farms in the traditional sense of a farm do not exist. Humans have not yet learned how to hatch tuna from eggs and grow them to size. Rather, tuna farming is more akin to the cattle ranching of a bygone era. Unfortunately, tuna farming is not sustainable and certain types of tuna, such as the bluefin, are thought to be critically endangered.
How Are Tuna Caught?
As Richard Ellis describes in his book Tuna: A Love Story, tuna is a billion dollar industry where million dollar ships deploy helicopters to find schools of tuna. Once a school is found, the most popular way to catch tuna is to deploy a purse seine and then transfer the live fish hundreds of miles to a convenient port. Purse seines are nets that can be over 2 kilometers long and 200 meters deep. Ships ring the net around a school of tuna so the net hangs down around the school in a column. The net is then drawn tight at the bottom, like a purse, so that the fish cannot escape. Sometimes the fish are landed right then and there and are taken onto the ship, but more often than not the fish are transferred to cages, filled up to 100 tons with live tuna, and hauled vast distances to a tuna ranch. At the ranch the tuna are fed twice a day on smaller fish for months or years before they are killed, packaged, and shipped off to consumers. Many of these fish are shipped to Japan to feed the insatiable sushi industry.
Where Are These Tuna Farms?
Due to the explosion of the sushi industry and the increased attention to the health benefits of fish there has been increased pressure on tuna populations. In 2001 there were 12 tuna farms in the Mediterranean landing roughly 11,000 tons of tuna annually. In 2005 Australia was bringing in 9000 tons of tuna largely through tuna ranching. Tuna farms also exist off Mexico and some fishermen would like to start one off of California.
What are the Negative Impacts of Tuna Farms?
Unfortunately tuna farming as it currently is done is not sustainable. Despite fishing quotas, too many fish are being farmed. This is largely because governments do not want to raise or enforce quotas that might hurt their profits. Richard Ellis tells how in 1991 Sweden asked the International Commission for the Conservation of Atlantic Tunas (ICCAT) to list the Bluefin Tuna as “endangered”. The United States and Japan, both of which have a strong economic interest in catching tuna, immediately voted down the proposal. Since then stocks have only declined further. The Atlantic Bluefin tuna populations exist at 12% of their 1975 levels. Besides overfishing in general, catching tuna before they have matured means they won’t be able to reproduce. Fishermen are preventing tuna from replenishing the stock which will mean even fewer tuna in the long run. Finally, tuna are an unsustainable food choice because they are meat eaters. Roughly 22-55 pounds of bait fish are needed for every 2 pounds of tuna. That puts pressure on other fishing stocks.
It is important to be an informed consumer and know what type of tuna is being served at a favorite restaurant. Bluefin tuna is considered a “Critically Endangered” species by the International Union for the Conservation of Nature (IUCN) as well as Greenpeace and the WWF. So lay off the sashimi and consider where that tuna steak came from.
