Those that make it upstream develop into opaque elvers.

那些成功抵达上游的鱼变成了不透明的鳗鱼。

Having finally arrived in their hunting grounds, elvers begin to eat everything they can fit into their mouths.

在终于抵达狩猎场后，它们开始吞食任何能吃的东西。

Researchers were aware of leptocephali and glass eels, but no one guessed they were related to the elvers and yellow eels living hundreds of kilometers upstream.

研究人员知道细叶鳗和玻璃鳗，但没有人猜到它们与白叶鳗和黄鳗有关，后者生活在上游数百公里处。