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  3. Across the western United States alone, trout(a kind of fish)fishing generates hundreds of millions of dollars annually. But tro

Across the western United States alone, trout(a kind of fish)fishing generates hundreds of millions of dollars annually. But tro

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问题     Across the western United States alone, trout(a kind of fish)fishing generates hundreds of millions of dollars annually. But trout habitat will likely be cut in half by 2080 due to warming rivers and altered patterns of flooding, according to a large study published online in the Proceedings of the National Academy of Sciences, " It’s fairly shocking to us, as biologists," says co-author Kurt Fausch of Colorado State University, Fort Collins. This is not a case of winners and losers; the four species examined by the team are all likely to decline to varying degrees.
    By running several climate models and plugging in data on habitat characteristics and fish present at 9,890 locations in the Rocky Mountains and Great Basin, the team of scientists created predictions for trout habitat across more than 1 million square kilometers of the western United States. They factored physical aspects of habitat—water temperature, patterns of flooding—as well as competition among species. Here’s what the study concludes about the future of trout:
    Introduced beginning in the 1800s for fishing, rainbow trout live in larger rivers than do the other species. They typically grow up to 110 centimeters long and are relatively easy to catch. Increases in water temperature will restrict their range, but rainbow trout dodge a bullet. Climate change will mean more frequent and intense winter floods, which can scour away eggs laid in the fall, but rainbow trout spawn in the spring. The size of their habitat is predicted to decline by 35%.
    Smaller than rainbow trout, Brown trout are the most temperature tolerant among the four species and like warmer temperatures. They have the ill fortune to spawn in the fall, so the increased flooding will make many streams inhospitable. Their habitat is predicted to decline by 48%.
    As to Cutthroat trout, the range of these native fish has already shrunk by more than 85% due to competition from introduced species. Two subspecies have already gone extinct. Warming temperatures and continued competition primarily from rainbow trout are predicted to reduce suitable habitat by a further 58%.
    Compared with the other species, brook trout are the biggest losers in 2080. Because they spawn in the fall, the increase in winter flooding is expected to reduce their suitable habitat by 77%—a surprising amount given their success at invading new habitat. "I did not expect brook trout to decline so much," says co-author Seth Wenger, a biologist with Trout Unlimited, a conservation organization in Boise.
    Frank Rahel, a fish ecologist at the University of Wyoming in Laramie, who was not involved with the study, says the findings help paint the big picture for trout this century. "They’re very sobering results that will catch people’s attention," he says. Not much can be done to reduce the impact of winter floods, but managers already try to keep streams cooler by planting trees and shrubs.
Compared with Cutthroat trout, rainbow trout
选项 A、can better adapt to warm temperatures.
B、has to retreat further to a restricted habitat.
C、has shown stronger survival ability.
D、lays more eggs when winter floods come.
答案C
解析 推理判断题。根据题干关键词Cutthroat trout和rainbow trout定位到第五段第三句。该句指出来自虹鳟鱼的竞争等因素预计会使它们的栖息地再减少58％，由此可推断，虹鳟比山鳟具有更强的适应能力，因而生存能力比山鳟强。[C]与原文意思相符，故为答案。[B]“退入更为局促的栖息地”与原文意思相反，故排除；[A]“能够更好地适应变暖的环境”及[D]“冬季洪水来到时，产更多的卵”原文均未提到，故排除。
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