Recent studies show that larger, older fish produce more eggs and surviving offspring than younger fish, researchers said yesterday, adding that policymakers need to protect broader swaths of the ocean to preserve these efficient spawners.
Steven Berkeley, a research biologist at the University of California at Santa Cruz who described his findings at the annual conference of the American Association for the Advancement of Science in Washington, said sustained overharvesting of Pacific rockfish and other species is undermining these populations' ability to recover.
A redstripe rockfish is among species that have been overharvested and that scientists are trying to protect.
(W. Savary -- U.s. Food And Drug Administration Via AP)
"We're really running up a debt, and it's becoming harder to repay it," said Berkeley, who found that a 31.5-inch Bocaccio rockfish produces 10 times as many larvae as one that spans nearly 20 inches, and the larger fish's offspring were more than three times as likely to flourish. "We really do know what we need to do; we just have to find the conviction to do it," he said.
The recent findings of Berkeley and other marine biologists -- another AAAS panel yesterday described how vast numbers of deep-sea animals get sustenance from decomposing whale bodies and skeletons -- are fueling an effort to get federal and regional officials to reassess the way they manage ocean resources. Scientists are now pushing for an ecosystems-based approach, in which policymakers take into account how human activities affect vulnerable sea populations on a broad level, not just on a species-by-species basis.
Jeremy Jackson, the Ritter professor of oceanography at the Scripps Institution of Oceanography in La Jolla, Calif., said he and other scientists began to scrutinize how the oceans are used in the past 10 years, once they realized key species were disappearing.
"I really did realize a dozen years ago everything I studied no longer existed," Jackson said. "It doesn't take a rocket scientist to realize this is something profoundly new and different."
Some of this research is already reshaping management decisions: Earlier this month, federal authorities voted to bar bottom trawling, a commercial fishing practice that scours the ocean floor clean, in nearly 386,000 square miles of the north Pacific Ocean around Alaska's Aleutian Islands. Environmentalists, who had successfully sued the federal government for failing to protect the area's ocean habitat, used images of the recently discovered Aleutian coral gardens to press their case.
David Allison, who directs the anti-bottom trawling campaign of the advocacy group Oceana, said the North Pacific Fishery Management Council's Feb. 10 decision to protect an area equal to Texas and California combined represents a dramatic turn in ocean policy.
"This is shifting for the first time from fishery protection management to ocean sustainability management," Allison said in an interview yesterday. "It's a major paradigm shift."
In a series of interviews last week, oceans experts said evidence is mounting that authorities need to take action soon to maintain the sea's biodiversity.
"I wasn't a conservationist initially," said Larry Crowder, who directs Duke University's Center for Marine Conservation, adding that he and other colleagues came to the position "after seeing ocean systems tube out."
Craig Smith, a professor at the University of Hawaii's oceanography department, said continued whaling threatens to devastate dozens of rare species on the sea floor that live on remains known as "whale falls" for as long as a century.
Smith and others have studied the succession of animals that feed on dead whales at the bottom of the ocean, including newly discovered "blind zombie worms," carpet worms and several kinds of sharks. Whale falls support more species than hydrothermal vents, Smith said, but continued whaling by the Japanese and others threatens this critical food source.
Whaling has reduced the North Atlantic whale fall habitat by 75 percent, Smith said, which could in turn drive a third of whale fall-dependent species to extinction. Even whaling at a more sustainable level could cause 15 percent of these species to disappear.
"From a policy perspective, that ought to be considered," he said.
But many politicians are reluctant to curb fishing and other commercial and recreational sea activities, scientists said, because organized constituencies lobby hard against such limits.
Andrew Rosenberg, a professor of natural resources at the University of New Hampshire who regulated the New England fishery under the Clinton administration, said the typical response from most lawmakers is "go away and regulate somebody else, not my guys."
But, Rosenberg added, "You need to provide a refuge" if you want fisheries to recover.