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  3. What do you do when a charismatic marine mammal is wreaking havoc by gorging on a threatened species that humans also find delic

What do you do when a charismatic marine mammal is wreaking havoc by gorging on a threatened species that humans also find delic

admin2015-03-25  27
问题     What do you do when a charismatic marine mammal is wreaking havoc by gorging on a threatened species that humans also find delicious? That’s the awkward problem faced by wildlife managers along the Columbia River in Washington and Oregon states, where sea lions have been congregating for the past decade to feast on salmon waiting to climb the fish ladders at the base of the Bonneville Dam on their spring voyage upriver to spawn.
    To protect the Chinook salmon and steelhead in the river, some of which are listed as threatened populations, in 2008 the states of Washington and Oregon obtained permission from the National Oceanic and Atmospheric Administration in Silver Spring, Maryland, to kill California sea lions(which are normally protected)seen feeding repeatedly at the dam, after attempts to frighten the animals away proved ineffective.
    In response, the Humane Society of the United States, based in Washington DC, and others filed a lawsuit to stop the practice and their legal challenges have continued. A US district court in Portland, Oregon, is expected to hear full arguments for a final ruling in the next few weeks. In the meantime, more than 40 California sea lions have been killed and 11 transferred to aquaria and zoos.
    Survey data collected by the US Army Corps of Engineers during the years of the killing show that numbers of California sea lions are decreasing at the dam, along with the amount of salmon they eat. The corps and others attribute this to the removal program.
    But the killing may have been too successful. Last year, the larger Steller sea lions, which arrived in earnest at the dam in 2005 and have returned in greater numbers each year, outnumbered California sea lions for the first time and ate fully half of the predated salmon.
    The problem with this shift is that Steller sea lions are themselves listed as a threatened species, meaning that ’hazing’—disturbing them with, for example, rubber bullets—is the only option for dealing with them.
    A key issue is exactly how much the sea lions are affecting the salmon, particularly the species that are listed as threatened. This is a difficult question to answer. Yet the Humane Society says that the killing focuses on the wrong problem—sea lions—instead of reducing the allowable fishing catch, improving habitat, and reducing losses from hydropower, which it maintains are greater threats to the fish.
Why cannot Steller lions be removed the same way as the California lions?
选项 A、Because they themselves are endangered animals.
B、Because they are so large that the removal program does not apply to them.
C、Because they pose threats to human.
D、Because they are of large quantity.
答案A
解析 事实细节题。根据题干关键词Steller lions和be removed定位至倒数第二段可知，问题的关键是北海狮本身是濒危物种，不能捕杀它们不是因为它们体型巨大，而是因为它们数量稀少，因此选[A]，同时排除[B]。此题的关键是要理解threatened species的意思，即“濒危物种”，而且根据倒数第三段第一句可知，北海狮是体型巨大，而不是数量巨大，因此排除[C]和[D]。
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