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  3. Harp seals from Canada are showing up in the US waters in greater numbers and farther south than usual, and biologists want to k

Harp seals from Canada are showing up in the US waters in greater numbers and farther south than usual, and biologists want to k

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问题     Harp seals from Canada are showing up in the US waters in greater numbers and farther south than usual, and biologists want to know why.
    "Small numbers of juvenile harp seals are typically found each winter stranded along the coast of the northeastern USA. But this year, well over 100 adult harp seals—not juveniles—have been spotted," said Mendy Garron, regional marine mammal stranding coordinator for the National Oceanic and Atmospheric Administration(NOAA)in Gloucester. The sightings are reported by 14 seal stranding and rehabilitation(康复)organizations in New England and the Middle Atlantic states. "In some areas they’re reporting three times the normal number of sightings," Garron said. "This year, we’ve had four sightings of adult harp seals in North Carolina, which we’ve never had before. We typically don’t see them that far south."
    Seals are common in waters off the northeastern New England states, where the most abundant type is the harbor seal, with a population estimated at about 100 000, the last time they were surveyed a decade ago. Gray seals are the second most common seal. But those numbers are piddling(微不足道的)compared to the number of harp seals found in the northwest Atlantic. Canada’s Department of Fisheries and Oceans says 9 million of them can be found off Canada and Greenland.
    A decade ago, harp seal sightings off Maine were rare, said Lynda Doughty, marine mammal stranding coordinator for the state Department of Marine Resources. The numbers have picked up the past few years, and this year there have been 40 documented sightings—more than double the number spotted last year. The harp seals are typically spotted on nearshore ledges and in coves and harbors, but they have also turned up in parking lots and backyards—and one was found on an oceanside golf course in Scarborough. The seals spend most of their time on ice—they are one of several varieties of so-called ice seals—and have made their way onto land across the snow and ice along Maine’s shores.
    For now, there is no clear explanation for why more seals are showing up in the US waters, said Gordon Waring, who heads the seal program at NOAA’s fisheries science center in Woods Hole. They could be making their way south because of climatic conditions or perhaps in search of food, Waring said. "These animals are known to wander a lot," Waring said. "Whether they’re following food down or whatever, we don’t really have a good understanding of it. "
    Garron said she and the seal organizations will look at environmental trends, such as water temperatures, to see if it’s influencing the harp seal range. Regardless of the reason, biologists are taking notice, Doughty said. "We’re all kind of raising our eyes," she said.
According to Gordon Waring, the reason for the appearance of more seals______.
选项 A、is not yet clear
B、is related to climatic conditions
C、lies in that they seek food in the south
D、lies in that they reproduce rapidly
答案A
解析 细节辨认题。由定位句可知，到目前为止，为什么越来越多的海豹在美国的水域出现还没有一个明确的解释，同时Gordon Waring说，这些动物经常四处活动，它们是否是循着食物到南方或者什么其他原因，他们确实还不是很清楚。由此推断原因还不清楚，故应选A)。B)“和气候条件有关”，这只是一种猜测，并非确切原因，故排除；第五段最后一句中说Waring认为它们可能是受气候影响或是为了寻找食物而往南方移徙，但这都是猜测，故排除C)“在于它们在南方寻找食物”；D)“在于它们繁殖快速”，文中未提及，故排除。
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