Pacific Bluefin Tuna Population at Brink of Collapse

The mighty Pacific bluefin tuna is in a world of trouble, caught up in a trans-Pacific political battle over who's to blame for driving the population to the brink of collapse and who’s responsible for bringing it back. The fish, loved by the Japanese for its deep red fatty meat and sought after by sport fishers from Baja California to New Zealand, has been decimated by decades of overfishing and an absence of responsible management. Today, the Pacific bluefin population had dropped to just four percent of its unfished size, with a steady decline over the last 15 years. And the most recent assessment shows even deeper signs of trouble.

Data collected by scientists with the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) show that more than 90 percent of a fisherman's bluefin tuna catch today is made up of the smallest fish: juveniles that haven't had a chance to reproduce. And that's not the worst of it. A recent scientific analysis found that the few adult bluefin remaining in the ocean are nearing the end of their lives, meaning they won't be reproducing much longer. With few new fish entering the population, and fishermen catching those juveniles almost exclusively, this species is at a tipping point.

Pacific bluefin is fished predominantly by Japan in the west and Mexico in the east. South Korea and Taiwan also fish for bluefin, with U.S. commercial and recreational fishers catching a small amount as well. Commercially caught bluefin regularly sell for tens of thousands of dollars each, sometimes much more. 

Members should set a minimum size limit for all bluefin caught. Photo credit: Richard Herrmann

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Not only do these Pacific players have an economic interest in a fully recovered population, but they also have an obligation to make it happen. Each is a member of the two regional fishery management bodies responsible for Pacific bluefin tuna—one in the east and one in the west—and this month the Inter-American Tropical Tuna Commission meets to decide on management measures in the east. Here’s how members can engineer Pacific bluefin’s comeback.

First, institute a catch limit. The ISC advice calls for the Commission to establish an annual quota of 2,750 metric tons, which includes all forms of catch from commercial to recreational to discards. Next, members should set a minimum size limit for all bluefin caught—important because another recent study shows that if a 20-kilogram size limit were in place, the population would see significant improvement in as little as three years.

Of course, adopting management measures will require monitoring and enforcement, including a catch documentation system, full observer coverage of bluefin transferred to off-shore fish farming ranches and later harvested, and authorized vessel lists.

The fishery commission in the east must also work with its counterpart in the west. Photo credit: Richard Herrmann

Because there is only one population of Pacific bluefin tuna, and it migrates thousands of miles across the ocean, the fishery commission in the east must also work with its counterpart in the west to develop and implement a comprehensive, basin-wide rebuilding plan to prevent a total collapse of the fishery.

The world has witnessed fish stocks crash before. But what makes this story different than the dramatic decline of Atlantic cod or even Atlantic bluefin tuna is the ability to change the trajectory of the Pacific bluefin population in a short period of time. In just a few years this recovery process could be a case study in how political leadership and commitment from industry can transform even the most depleted fishery. It’s time for Japan, Mexico and the U.S. to step up.

Amanda Nickson directs global tuna conservation for The Pew Charitable Trusts.