Three competing males surround a female Sockeye Salmon (Oncorhynchus nerka) in an Alaskan stream during late summer.

A male Sockeye Salmon (Oncorhynchus nerka) holds a position high over a redd site as the female approaches from downstream in an Alaskan stream during early summer.

Pink salmon (Oncorhynchus gorbuscha) probes her redd while her alpha male guards in an Alaska stream during summer.

Female Sockeye Salmon (Oncorhynchus nerka) makes a dig while alpha male guards downstream in an Alaskan stream during summer.

A Sockeye Salmon (Oncorhynchus nerka) spawning pair Underwater view in an Alaskan stream during the summer.

A female Sockeye Salmon (Oncorhynchus nerka) fends off an intruding female with the gape threat in an underwater view in an Alaskan stream during early summer.

A female Sockeye Salmon (Oncohynchus nerka) nudges a male away from her redd so that she can work on it, underwater view in an Alaskan stream during summer.

A male Sockeye Salmon (Oncorhyncus nerka) holds position over a redd site while the female is away in an underwater view in an Alaskan stream during early summer.

Male Sockeye Salmon (Oncorhynchus nerka) threatens another male by raising his formidable jaws with this tilted head posture in an Alaskan stream during early summer.

Male Sockeye Salmon (Oncorhynchus nerka) threatens another male by raising his formidable jaws with this tilted head posture in an Alaskan stream during early summer.

Male Sockeye Salmon (Oncorhynchus nerka) threatens another male by raising his formidable jaws with this tilted head posture in an Alaskan stream during early 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.

A courting male Sockeye Salmon, also known as Red Salmon (Oncorhynchus nerka), crosses over a female in an Alaskan stream during the summer; Alaska, United States of America

Male Sockeye Salmon (also known as Red Salmon, Oncorhynchus nerka) digging in an Alaskan stream during the summer. This behavior is considered a displacement activity indicative of the male's frustration in not being able to spawn; Alaska, United...

Female Sockeye Salmon (Oncorhynchus nerka) digging her redd in an Alaskan stream during early summer.