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Biology

 

         Salmon are large fish that hatch in freshwater streams before migrating out to the ocean, where they live until it's time to reproduce. Then, during the period of time called "spawning", they come back to the same rivers they hatched at in order to mate and lay their eggs. This back and forth migratory behavior may not seem like a big change to us, but going from freshwater to saltwater is extremely difficult on the fish's morphology! Their entire body chemistry changes to adapt to a saltwater or freshwater environment.

Image by Marco Tjokro

Along with these chemical changes, salmon also experience physical changes during the spawning season. Different salmon change in different ways, but males typically grow a humped back, turn a vibrant red and green, and may even develop fangs or hooked jaws. To return to their spawning place, they have to travel upstream, even jumping over short waterfalls! This is where many salmon are caught by predators like bears, eagles, and wolves, who will wait at the top of the stream to catch fish mid-jump. People have called this season the "salmon run".

After spawning, most salmon will die. The journey from the sea to the river takes so much energy from them that their bodies simply cannot survive the return trip, and are thus programmed to die soon after their mission is complete. Mass die-offs of salmon are common right after breeding season, which provides ample food for scavengers both on land and in the water.

This website was created as part of the USDA National Institute for Food and Agriculture ENHANCEMENT Grant (2020-38422-32257)

CREATED BY

Cyrillus Sidhe - Jenavey Ivey - Mariangel Varela

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