Jack and normal male Sockeye Salmon (Oncorhynchus nerka) in an Alaskan stream during summer.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during autumn.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during late autumn.

Sockeye Salmon (Oncorhynchus nerka) spawning pair positioned over a redd that is under construction.

Coho Salmon (Oncorhynchus kisutch) in the act of spawning in an Alaska stream during late autumn.

Sockeye Salmon (Oncorhynchus nerka) spawning pair positioned over a redd that is under construction in an Alaskan stream during early summer.

Pink Salmon (Oncorhynchus gorbuscha) probes her redd in an Alaskan intertidal stream during summer.

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) spawning pair in an Alaskan stream during the summer; Alaska, United States of America

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) spawning pair in an Alaskan stream during the summer; Alaska, United States of America

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) spawning pair in an Alaska stream during the summer, South-central Alaska; Alaska, United States of America

Mature male Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) in an Alaskan stream during the summer, South-central Alaska; Alaska, United States of America

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) probes her redd while a male guards in an Alaskan stream during the summer; Alaska, United States of America

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) male threatening a challenger by also raising his snout in an Alaskan stream during the summer; Alaska, United States of America

Incidental tree branch bites can result from the aggressive behavior of male Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) competing to spawn in an Alaskan stream during the summer; Alaska, United States of America

A female Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) attacking a female who is excavating a redd that is too close to hers in an Alaskan stream during the summer; Alaska, United States of America

Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) spawning in an Alaskan stream during the summer. Two competing males are lurking nearby, one is visible at the right edge of the frame and the other, a jack or precocial male, is visible...

While her alpha male guards, a female Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka) excavates her redd in an Alaskan stream near Cordova, South-central Alaska; Alaska, United States of America

A red Sockeye Salmon spashes through shallow water as it heads upstream in the Russian River in Summer. Southcentral Alaska.

Red Salmon and fishermen in the Russian River with dead spawned out fish on shoreline, Summer, Southcentral Alaska.

Sockeye Salmon (Oncorhynchus nerka) in the act of spawning in an Alaska stream during summer.