>Less than a month after four towering dams on the Klamath River were demolished, hundreds of salmon made it into waters they have been cut off from for decades to spawn in cool creeks

Do we understand the mechanisms of this "genetic memory" (my words, no idea if its accurate or if there is a better word for it)? Butterflies knowing where to fly even though it was their grandparents that last did it - eels traveling thousands of miles to breed in a place theyve never seen - countless bird migrations - even something as simple as how it takes a human baby 12-18 months to walk but many animals walk as soon as they are born. I would love to understand better how this knowledge is inherited

Animal behavior usually has a weird combination of inborn instinct and learned behavior.

The one I've read about that stuck with me was dam building by beavers. Some part of the behavior is driven by a dislike of the sound of running water. Someone did an experiment with speakers playing the sound of running water and the beavers near the speakers would attempt to cover them with sticks and mud.

In my head I'm imaging that sound is like nails on a chalkboard to beaver.

Lots of discussion about salmon memory and such, but is it possible this is just Salmon finding "hey this is a great spot"? It is hard to imagine salmon not being flexible to some extent, and still surviving.

I read a fascinating article on this dam removal last week! https://hakaimagazine.com/features/the-other-side-of-the-wor...

The article tells both sides of the story of the dam removal in as fair a way as I think is possible. Many of the locals were against it and there was a strong advocacy group that fought for it, including a tribal constituency.

I came away from the article feeling I understood both sides better but with less certainty about what was the right choice.

All these dams on the Klamath river did have fish ladders where the salmon could go upstream and spawn. Removing the dams just increased the number of fish swimming upstream. Some of the fish ladders had glass walls and people could watch the fish going up & down the ladder.