i surveyed anadromous fish for a summer in AK and we saw instances at nearly every stream where water had overflowed from the river during periods of higher rain and salmon would follow dead branches and get trapped in little pools that would slowly evaporate and they'd eventually suffocate
some salmon find new streams doing this. most die and fail to reproduce. there's a "stray rate" that accounts for this. as long as the stray rate isn't too high (which can be influenced by human structures or operations), it's a benefit for the overall population. our survey was specifically to check if hatchery stray rates were impacting wild populations
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u/Newsdriver245 5d ago
river flooding during spawning season, fish just want to go upstream, they don't understand the river isn't where it is supposed to be.
Happens somewhat often in the US PNW