what would happen to salmon if a dam was built across a river they......?

Question

what would happen to salmon if a dam was built across a river they went up to every year to lay there eggs?

Answer 1

Exactly such a dam was built across the River Tummel at Pitlochry in Scotland, to form Loch Faskally behind it.

The plans for the dam had to include a "fish ladder", a staircase of connected chambers through which the salmon could continue to migrate upstream and into the loch. One chamber has a glass front and a viewing gallery, which makes it a popular tourist attraction in the salmon migration season.

Answer 2

They literally bash themselves against the dam until they die.

If the dam is low enough, they can eventually jump over it. But if it is too high, they just slam against it until they damage themselves. And the ones behind them just create a logjam at that point. Big bloody mess.

But once the entire pod dies out, then there are no more salmon that know how to use that stream anymore, so next year, there should only be a fraction of the salmon there, and then the year after there should be none.

Answer 3

Exactly what HAS happened, many times. The salmon can't reach their spawning grounds and DIE!!