Animals

Female Pink Salmon (Oncorhynchus gorbuscha) probes her redd while her alpha male guards downstream, Alaska

Female Chum Salmon (Oncorhynchus keta) sniffing the water where she is building her redd as a male guards.

Male Pink Salmon (Oncorhynchus gorbuscha) using the gape threat to oust an alpha competitor while a small sneaker male approaches along the opposite side of the female in an intertidal stream that is a tributary of Prince William Sound, Alaska

Underwater view of a pink salmon (Oncorhynchus gorbuscha) spawning pair with an aggressive sneaker male gaping in Hartney Creek near Cordova, Alaska in the summer; Alaska, United States of America

Mature male Chum Salmon (Oncorhynchus keta) size each other while competing over a female in an Alaskan stream during the summer.

A Pink Salmon (Oncorhynchus gorbuscha) male comes alongside and quivers a female who is probing her redd in an Alaskan intertidal stream during the summer.

Underwater view of a sockeye salmon (Oncorhynchus nerka) spawning pair and a challenger male in Power Creek near Cordova, Alaska in the summer; Alaska, United States of America

Underwater view of a sockeye salmon (Oncorhynchus nerka) spawning pair and a sneaker male in Power Creek near Cordova, Alaska in the summer; Alaska, United States of America

Coho Salmon (Oncorhynchus keta) at various stages of final maturation alongside late Sockeye Salmon (O. nerka) in an Alaskan stream during autumn.

Three male Sockeye Salmon (Oncorhynchus nerka) competing to spawn with one female during early summer in an Alaskan stream.

Pink and Chum salmon (Oncorhynchus gorbuscha and O. keta) summer spawning migration in a tributary of Prince William Sound, Alaska.