Fish ladders have been around for centuries. They have mixed results.

I went to Bonneville Dam on the Columbia River between Washington and Oregon and it was kind of like being in an aquarium watching the fish swim upstream. They seemed to get tired and would float backwards with the water current and then start swimming again against the current.

https://en.wikipedia.org/wiki/Fish_ladder

They also had a salmon hatchery literally right after the dam. But they had some stats showing that it also had mixed effectiveness.