Sockeye salmon (Oncorhynchus nerka) migrate to their natal river or stream in the Fraser River watershed, which has one of the largest sockeye runs in the world. As they approach their spawning grounds, the bodies of the once silver fish turn bright red and their heads become green. Males develop a hump and hooked jaws, which play a role in competition and establishing hierarchies. Shortly after laying and fertilizing eggs, the salmon die, contributing to the ecosystem. Photograph by Paul Colangelo.