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National Geographic : 1993 Jan
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A Plan With Teeth to Curb Shark Overfishing Sharks worldwide have been dec imated by a feeding frenzy of fishermen. But in the U. S . a new management plan will soon set quotas that will halve 1991's stagger ing catch of 3.2 million sharks in the Atlantic and Gulf of Mexico. Laws will protect 39 species, including coastal sharks such as the tiger and lemon and deepwater varieties like the mako. Mutilation by slicing off fins, then releasing the sharks, will also be tightly controlled. With the Arabian Sea and Nigerian and Mexican waters all but fished out, suppliers are turning to the U. S. population just for the fins, which can bring more than $20 a pound for shark-fin soup. "What you don't want is a big tiger shark to survive without fins, lie starving on the bottom, move into shallow water, and attack a human," says Mike Justen of the National Marine Fisheries Service. Gnawing North America: The Beaver Strikes Back Trapped nearly to extinction a century ago, beavers have staged a triumphant come back. So much so that in the United States and Canada farmers and homeowners are gnashing their teeth when beavers mow down trees and their dams flood crops, block waterways, and back up sewers. "There may be six to ten million beavers in Canada," says Milan Novak of Ontario's Ministry of Natural Resources. Although the primary beaver-control agent is still the trapper, few now make the effort, because pelts bring only about $15, a result of a decrease in consumer demand. In the U. S ., beavered by at least two million of the rodents, 34 states seek federal assistance to con trol damage. One attempt to implant a birth-control device in a female suffered from a misconception: The beaver turned out to be not a she but a he. Mystery Shrouds California Die-off STital winter staging area for water birds, the SSalton Sea National Wildlife Refuge in southern California hosted a teeming horde of a million eared grebes last year. But some thing went very wrong. Many birds became lethargic and gulped water-unusual for grebes. Then they hauled themselves out onto the banks of the Salton Sea and died, 150,000 of them, the biggest die-off ever recorded for this species. The 360-square-mile inland sea collects pesticides and fertilizers from agricultural runoff, plus sew age from Mexico -all suspected candidates for contaminating the birds. Laboratory analysis showed elevated levels of the toxic element selenium in worms that the grebes eat, but not high enough levels in the birds to be fatal. Says U. S. Fish and Wildlife Service biologist Bill Radke, "We still don't know what killed them." -JOHN L. ELIOT IIMANU PATLh N WLLIAM JK. ALIn U. 3. 1mANU WIU199. 3 IL NationalGeographic, January 1993
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