(1)Spanning the ocean divide between the U.S. and Russia, it is one of the richest and most commercially productive marine envir

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问题     (1)Spanning the ocean divide between the U.S. and Russia, it is one of the richest and most commercially productive marine environments on earth, teeming with pollack and halibut, fur seals and Steller’s sea lions, puffins and murres. The seals and seabirds depend on catching fish, and so do humans. More than 2,000 boats from the U.S., Russia, Japan, Norway, China, Poland and the Koreas haul in an annual catch worth roughly $1 billion. The portion taken off the shores of Alaska alone amounts to one-half the sea life caught by commercial fishing vessels in U.S. waters.
    (2)But will the bounty last? Since the majority of the world’s fisheries are in a state of collapse, as too many boats chase too few fish, conservationists fear the same fate for the Bering Sea, the last great refuge of marine abundance. Competition among countries for the rights to fish certain sectors of the sea is already fierce and could turn violent, as it has elsewhere in the world. The Russians have severely depleted fish stocks in their zone, and the international area open to all boats, called the Doughnut Hole, has been nearly stripped of commercial fish.
    (3)No species is more important to man and beast than pollack, the No. 1 ingredient of frozen fish sticks and the fish items served by chains like Burger King and Long John Silver. Each year the Bering Sea yields two billion kg of this bottom-dwelling creature, making the pollack business the biggest fish harvest in the world.
    (4)On the surface, that business is healthy: the pollack catch has stayed near record levels. But signs of overfishing and an ailing ecosystem can be seen higher up in the food chain. The fur-seal population has not increased despite a long-standing ban on commercial hunting. The number of Steller’s sea lions, which feed mostly on pollack, has plunged 80% in the past years, and seabirds such as the red-legged kittiwake are also in trouble.
    (5)The pollack harvest may be huge, but that doesn’t mean the fish is still abundant everywhere. If commercial fishermen overfish a spot near nursing sea lions, both mothers and pups can starve. That’s why the Trustees for Alaska, a public interest law firm, has sued the U.S. government for failing to protect areas vital to endangered marine mammals. The group’s litigation director, Peter Van Tuyn, points out that in southeast Alaskan waters, where there is little industrial fishing of pollack, the sea lion population has held up relatively well. And fur seals in the Pribilofs have done better than sea lions, perhaps because they have a more varied diet.
    (6)Less fortunate are other creatures that get in the fishermen’s way. Dorothy Childers, executive director of the Alaska Marine Conservation Council, notes that fishing boats aiming to catch pollack dump halibut and salmon over the side and that the value of wasted fish in the Bering Sea is equivalent to 25% of the revenues from the entire fishery. Many trawlers drag nets and other gear across the sea floor, destroying the habitat of all the animals that live on the bottom. International agreements restrict the size of fishing nets, but environmental groups like the World Wildlife Fund urge stronger action: enforcing a new agreement to stop bottom trawling for pollack, reducing the pressure on certain areas and putting critical habitats off limits.
    (7)Even if fishing is brought under control, the Bering Sea faces threats that originate thousands of miles away. Wind currents from industrial areas far to the south bring in pollutants like insecticides and heavy metals, which collect in the tissues of wild life and the local Inuit people. At the same time the region has been warming up, and part of the reason may be the buildup of greenhouse gases in the atmosphere. Whatever the cause, sea ice has been retreating farther to the north, making life harder for polar bears and other ice-dwelling animals.
The passage mainly tries to remind us to be aware ______.

选项 A、of the various threats to the Bering Sea now
B、of the impact of commercial activities on the Bering Sea
C、that overfishing will endanger the whole ecosystem
D、that it is essential to accord commerce with ecosystem

答案A

解析 原文共有7段,前六段主要讲白令海峡的过度捕捞情况,最后一段提到了白令海峡faces threats that originate thousands of miles away。即海水受到污染和海水温度上涨。总结来看,本文主要讲的是白令海峡面临的各种威胁,而前六段的“过度捕捞/经济捕捞”只是其中一点,因此,最能全面概括原文所有内容的应为A。其他选项都忽略了最后一段的内容。
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