Biologists speculate that the mostly likely cause was a shift in Pacific Ocean currents, but food availability, changing river conditions and predator-prey relationships could be affecting the fish.

生物学家推测，最有可能的成因是太平洋洋流的变化，不过食物的取得、河流环境的改变、生物掠夺关系等，也都可能对鲑鱼造成影响。

youdao

A river would not be one and the same river were it not for the fact that the water fowling in it is always changing, as are the river Banks and even the course of the river.

一条河流不会永远是这一条河流，不仅仅是因为它的河水总是不断变化，甚至河源和河道都在不断改变着。

youdao

Like I said, river conditions are always changing.

像我说的，河水总是在变。

youdao

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