Chum salmon migrate long distances from the ocean to their natal rivers to spawn. They navigate using a combination of olfactory cues and geomagnetic fields. After spawning, they die and their carcasses provide nutrients to the ecosystem.
During spawning, male chum salmon develop a distinctive hooked jaw, called a kype. They aggressively compete for females and establish dominance hierarchies. Males use their kypes to fight off rival males and defend their position on the redd.
