Smithsonian Insider – Desire for Pacific bluefin puts fish on red list of threatened species

By John Barrat

Pacific bluefin tuna (Flickr photo by Yasuki Ichishima)

Eaten raw and thinly sliced, the dark-red belly meat of the Pacific bluefin tuna is highly prized—and priced—for its rich oily flavor by sashimi and sushi consumers in Japan. A single 400-pound bluefin sold for $37,500 during the New Year’s opening of Tokyo’s Tsukiji fish market. “And that’s a bargain,” says Bruce Collette, an ichthyologist at the Smithsonian’s National Museum of Natural History in Washington, D.C., who points out that last year a 489-pound bluefin sold for $1.8 million in Tokyo.

In November, Collette, also of the National Marine Fisheries Service Systematics Laboratory, helped list Thunnus orientalis, the Pacific bluefin, on the International Union for Conservation of Nature’s Red List of Threatened Species as “Vulnerable” to extinction. Its close relatives the Atlantic bluefin (IUCN status: “Endangered”) and Southern bluefin (IUCN status “Critically Endangered”) are also on the Red List.

Demand for Pacific bluefin in Japan and its growing popularity worldwide is having a devastating impact on their wild populations, Collette says. “From the most recent assessments it is plain that the bluefin’s spawning stock biomass [the numbers of bluefin capable of reproducing] is really bad and headed lower.”

Bluefin tuna on the auction floor at at Tsukiji Fish Market in Tokyo, Japan. (Flickr photo by Nate Gray)

Bluefin tuna on the auction floor at Tsukiji Fish Market in Tokyo, Japan. (Flickr photo by Nate Gray)

“In the last 30 years we have eliminated 80 percent of the spawning stock biomass of the western Atlantic bluefin and similarly great reductions in the population of the Mediterranean bluefin,” Collette says. “The Pacific bluefin and the southern bluefin have been cropped just as badly.”

Many countries harvest Pacific bluefin. Japan catches the majority, followed by Mexico, the United States, Korea, and Chinese Taipei. Most are taken in purse seine nets, giant nets that surround an entire school of tuna, and the remainder with long-lines, gill nets and rod and reel.

According to Collette major threats to the Pacific bluefin include:

Adult Pacific bluefin tuna are being overfished; due to the demand, their overfishing shows no sign of abating. Large adult tuna are getting scarce and harder to find and catch. (“The overall commercial catch of Pacific bluefin needs to be reduced,” Collette says.)

Since the early 1990s, commercial long-line and purse seine fishermen, while targeting the fewer large adult fish, have been catching and keeping greater numbers of juvenile Pacific bluefin, taking out many of the members of upcoming generations before they have a chance to spawn.

In the eastern Pacific, large numbers of juvenile bluefin, caught in purse seine nets, are now being transferred to ranching pens off the coast of Mexico where they are fattened up and later sold for sushi. This practice also removes many juvenile fish from future breeding and spawning populations.

While bluefin travel the Pacific in search of food, they congregate in the northern Pacific between Japan and the Philippines in April, May and June; off the Japanese island of Honshu in July and in the Sea of Japan in August to lay their eggs. There are few restrictions to fishing for tuna in these areas during these months. (“Pacific bluefin spawning areas need to be protected and closed to fishermen during spawning season,” Collette says.)

Illegal fishing and trade in Pacific bluefin is rampant.

Eaten raw and thinly sliced, the dark-red belly meat of “Thunnus orientalis,” the Pacific bluefin tuna, is highly prized for its rich oily flavor by sashimi and sushi consumers in Japan. A single 400-pound Bluefin sold for $37,500 during the 2015 New Year’s opening of Tokyo’s Tsukiji fish market. (Flickr photo by InvernoDreaming)

“As with any high price items like ivory or rhinoceros horn, there is an insatiable demand in the market for rarities,” Collette says. “People spend thousands of dollars on big fancy meals of bluefin tuna. When a single fish is worth $37,000 there are a lot of games going on. Illegal fishing must be controlled.”

For the future, Collette adds, “My hope is that gradually we will realize that these fish are an important renewable resource and we will respect catch and size limits and close areas where they are spawning. If we do all these things, there is hope that we can rebuild the population, not to what they were originally, but to a more sustainable level.”