A Tuna in Trouble

With demand high and populations low, the U.S. needs to step in to protect Pacific bluefin tuna under the Endangered Species Act.

The Pacific bluefin tuna is, as one of our team often says, “a wicked cool fish.” Born in the waters of the western Pacific, many migrate to the eastern Pacific where they feed and grow for several years before returning west. These impressive tuna are one of the largest bony fish in the sea, capable of growing to a staggering ten feet in length and over 1,000 pounds! These ocean giants take up to five years to mature, and can live into their mid-20s.

Like wolves, Pacific bluefin tuna are apex predators. Very few animals can eat these fish (besides humans, that is). The tuna, in turn, feed on squid, crabs, and a variety of fish, including other tuna. To catch these prey, and to migrate tens of thousands of miles across the ocean to feed and spawn, Pacific bluefin are built for speed. They can retract their dorsal fins into slots to lower drag, and their scales are reduced to decrease friction with seawater. One of the fastest fish in the ocean, Pacific bluefin tuna can swim in bursts of speed at more than 30 miles per hour.

Unlike most fish, Pacific bluefin tuna are warm-blooded, just like mammals. They can maintain their body temperatures at 55ºF warmer than their surrounding waters. This impressive trait makes it possible for Pacific bluefin to migrate thousands of miles across the ocean, through a wide range of temperatures. And how do they find their way through such a long migration? With a built-in compass. Pacific bluefin tuna have the mineral magnetite in their snouts. Experts believe that it helps the tuna detect the earth’s magnetic field and use it for navigation.

A Fish Too Popular for Its Own Good

Unfortunately, the fact that Pacific bluefin tuna are slow-growing and long-lived makes them particularly vulnerable to overfishing. Hunted on both sides of the Pacific, bluefin tuna are considered a delicacy in the Japanese sushi-sashimi market. Japan catches more than half of the total catch of Pacific bluefin and consumes 80% of the catch. Mexico has the second largest Pacific bluefin fishery, responsible for 30% of the catch. All this fishing pressure, combined with other threats, has caused a staggering 97.4% decline in Pacific bluefin tuna.

As the number of adult Pacific bluefin tuna dwindles, more and more juvenile tuna are caught for consumption. A full 97.6% of all Pacific bluefin tuna caught are younger than two years of age. This means that not only are the number of adults plummeting, but the juvenile tuna are being taken from the ocean before they have a chance to reproduce. If something doesn’t change soon, this double threat could be a recipe for extinction.

Fishing efforts for Pacific bluefin tuna have only increased, but with so few fish remaining – just 2.6% of the fish’s historic population – fewer are left to be caught. Existing legal protections regulating tuna catch by other nations or by international fishery management organizations are weak. So weak, in fact, that a 2016 stock assessment found that if fishing continues at the levels allowed under the current regulations, there is only a 0.1% chance of rebuilding Pacific bluefin tuna to healthy levels by 2024. There is no doubt that the Pacific bluefin tuna is on the road to extinction. The only question is whether we can turn it around in time.

U.S. Isn’t Off the Hook When it Comes to Protecting Pacific Bluefin

Even though Japan and Mexico are the major players in the Pacific bluefin tuna fishery, there’s still a lot that the U.S. can do to help the species. In U.S. waters Pacific bluefin tuna are caught by both recreational and commercial fishers, and almost all of the fish caught are juveniles. Current U.S. regulations provide little protection. Recreational fishers, now the dominant force in the U.S. Pacific bluefin tuna fishery, have no total cap on take, just per-trip limits. So they can only catch so many fish each trip, but can make as many trips as often as they want. In the last ten years, even as Pacific bluefin numbers have plummeted, U.S. catch of the fish has gone up.

This is why Defenders of Wildlife joined more than a dozen leading conservation organizations to petition the National Marine Fisheries Service to list the Pacific bluefin tuna under the Endangered Species Act. Listing the fish as endangered or threatened would make it illegal for Pacific bluefin feeding in U.S. waters to be deliberately caught and killed. It would also make it illegal for the fish to pass through our ports in trade on their way to foreign markets – a good way to affect the trade in other nations as well. Listing the fish as endangered or threatened could also raise consumer awareness on both sides of the Pacific, encouraging consumers to make more environmentally-conscious seafood choices. And an ESA listing would lend more force to the voices advocating for conservation and protection at regional fishery management organizations composed of countries that participate in the Pacific bluefin tuna fishery.

A single large adult female can spawn millions of eggs each year, so regrowing the Pacific bluefin population is possible with strong management and protection. And that would be good not just for those who care about protecting our wildlife, but for fishermen, too. The Pacific bluefin tuna fishery is valued at nearly $1 billion, and this value can only increase if the tuna are allowed to recover. A healthy population of Pacific bluefin tuna in the ocean means more fish can be caught with less effort, while still leaving plenty of fish in the sea.

Listing the Pacific bluefin tuna under the ESA can signal to the world that the U.S. is leading the way to protect this iconic fish, and can do the same for coordinated international efforts to restore it across the Pacific.