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Now listen to part of lecture on the topic you just read about.
现在来听一段有关你刚刚阅读到的话题的演讲。
Well, ongoing investigations have revealed that predation is the most likely cause of sea otter decline after all.
持续的调查研究显示，掠食终究是海獭减少最可能的原因。
First, the pollution theory is weakened by the fact that no one can really find any dead sea otters washing off on Alaskan beaches.
首先，污染理论被没有人能真正找到被冲上阿拉斯加海滩的死海獭这个事实所弱化。
That's not what you would expect if infections caused by pollution started killing a lot of otters.
如果污染所引起的传染病开始杀死许多海獭的话，你看到的不会是这种情况。
On the other hand, the fact that it's so hard to find dead otters is consistent with the predator hypothesis.
另一方面，很难找到死海獭的事实与猎食者假说一致。
If an otter is killed by a predator, it's eaten immediately so it can't wash up on shore.
如果海獭被其猎食者杀死，它会马上被吃掉，所以不会被冲上岸。
Second, although orcas may prefer to hunt whales, whales have essentially disappeared from the area because of human hunters.
第二，虽然逆戟鲸更喜欢捕食鲸鱼，但是鲸鱼从这个地区消失本质上是因为人类捕猎者。
That means that orcas have had to change their diet to survive and since only smaller sea mammals are now available,
这意味着， 逆戟鲸为了生存必须改变它们的饮食，因为现在只有更小的海洋哺乳动物是可得到的，
orcas have probably started hunting those.
逆戟鲸可能已经开始捕食那些。
So it probably is the orcas that are causing the decline of all the smaller sea mammals mentioned in the passage — the seals, the sea lions and the sea otters.
所以，可能是逆戟鲸引起了文中所提到的小一点的海洋哺乳动物，海豹、海狮和海獭的减少。
And third, the uneven pattern of otter decline is better explained by the orca predation theory than by the pollution theory.
第三，捕猎假说比污染假说更好地解释了海獭减少不均匀的方式。
What happens to otters seems to depend on whether the location where they live is accessible to orcas or not.
发生在海獭身上的事似乎取决于它们生活的地方是不是逆戟鲸能接近的地方。
In those locations that orcas can access easily, the number of sea otters has declined greatly.
在那些逆戟鲸很容易就能接近的地方，海獭的数量大大减少。
However, because orcas are so large, they can't access shallow or rocky locations.
然而，因为逆戟鲸太大了，它们不能接近浅水或者是多岩石的地方。
And shallow and rocky locations are precisely the types of locations where sea otter populations have not declined.
而浅水和多岩石的地方正是海獭的数量没有减少的区域类型。
Summarize the points made in the lecture, being sure to explain how they respond to the specific points made in the reading passage.
总结演讲中的观点，准确解释他们如何对文章中提出的观点做出反应。
