Can the world act fast enough to save the disappearing tuna?
Scientists say drastic measures need to be taken to restore the bluefin.
(Page 2 of 4)
With the fate of bluefin hanging in the balance, scientists are now calling for a more comprehensive and, presumably, effective "systems" approach, one that takes the entire ecosystem into account when setting fishing quotas.Skip to next paragraph
Subscribe Today to the Monitor
"Nobody's really done it," says Don Perkins, president of the Gulf of Maine Research Institute (GMRI) in Portland. "And the regulatory system is not set up to consider an individual species from a multispecies perspective." But, he says, by necessity, that's where fishery management is headed.
Fisherman face an Atlantic divide
The warm-blooded bluefin, the largest of the tuna species, travels vast distances during its life. Living up to 30 years, adults fatten up in highly productive northern waters, like, historically, those in the Gulf of Maine, and then spawn in the warmer waters of the Gulf of Mexico and the Mediterranean.
Since the early 1980s, managers have treated North Atlantic bluefin as two separate populations: eastern and western. A north-south line that bisects the Atlantic divides the two stocks. Many scientists assumed a mere 4-to-5 percent exchange between eastern and western tuna. But "no fisherman that I know of ever believed for a second that the two-stock theory was viable," says Mayhew. Enabled by new tagging technology, studies conducted during the past decade substantiate Mayhew's hunch.
"Since the late '90s, we've confirmed that the mixing is much greater than assumed," says Dr. Lutcavage – up to 30 percent. The new evidence has US scientists worried about what's happening in the East, particularly in the Mediterranean. Even by European scientists' account, bluefin catches there are currently at unsustainable levels. The Standing Committee on Research and Statistics (SCRS) recommended a quota of 15,000 tons in 2007. But the ICCAT set the allowable catch at 29,500 tons. Worse, studies put the actual catch somewhere around 50,000 tons. And, says Lutcavage, while 73 inches (about 250 pounds) is the minimum harvest size in US waters, it was only 10 kgs (22 lbs.) in European waters until recently. In late November, ICCAT raised the minimum catch size there to 30 kgs (66 lbs.).
"If you're taking 70,000 metric tons [77,000 tons] and it's much smaller fish, the number of fish you're taking is much greater," she says. For each 250-pounder caught here, up to 10 were potentially removed there. Presumably, these fish never came west.
The Gulf of Mexico and the Mediterranean leave distinct chemical signatures on fish that swim their waters. A laboratory at Texas A&M University in College Station, Texas, is currently analyzing bluefin ear bones to better determine their origin, the results of which should be available early next year, says Dr. Porch.
Calls for a moratorium ignored