Some, like the two Elwha dams, were built without fish ladders, meaning they serve as completely impenetrable barriers to fish migrations.

一些大坝和这两座埃尔瓦河大坝一样在建造的时候缺乏鱼梯设计，就是说它们完全阻碍了鱼群的洄游。

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The Australian grayling, a freshwater fish, graduated from "vulnerable" to "near threatened" thanks to fish ladders at dams and other protection measures.

澳大利亚的格雷林，一种淡水鱼，由“弱势”渐变为“濒临威胁”幸好是水坝里的鱼梯和其他保护措施才得以保全。

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Engineering solutions like fish ladders, water-velocity regulators, and careful site design can mitigate many of these concerns.

FORBES: Hydroelectric Revolution: A River Runs Through It

The Klamath river's dams, owned by PacifiCorp, a former subsidiary (remarkably enough) of Scottish Power, date back to 1918, and were built without fish ladders to help salmon returning to their natal waters.

ECONOMIST: Saving the fish of the Klamath river