| ▲ | blackeyeblitzar 4 days ago |
| They swim towards where they feel water flowing from. They keep going until their bodies are breaking down. Fish at the spawn location often have rotting bodies, even as they still live - losing color and with their flesh changing consistency. |
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| ▲ | everyone 4 days ago | parent [-] |
| But what about at the start when they are in the ocean and water isn't flowing from anywhere in particular? + How do they end up in one particular river and not another? |
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| ▲ | blackeyeblitzar 4 days ago | parent | next [-] | | That part is not really known. Various things have been suspected like memory of magnetic fields, salinity, temperature patterns, odors, etc. Basically they may be memorizing those on the way out and end up coming back to the same shoreline. From there it’s following upstream water pressure (which is how salmon ladders induce them to follow the ladder). | |
| ▲ | 2OEH8eoCRo0 4 days ago | parent | prev [-] | | Do rivers have a smell? Animals have a keen sense of smell and the volume of rivers is enormous. Seems like a random-walk sniffing for rivers would be effective. |
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