[5] Two distinguishing features are their long, serrated gill rakers that range from 30 to 40 in number, and their lack of a spot on their tail or back.

They range as far north as the Bathurst Inlet in the Canadian Arctic in the east and the Anadyr River in Siberia in the west.

The farthest inland sockeye salmon travel is to Redfish Lake, Idaho, over 1,400 km (900 mi) by river from the ocean and 2,000 m (6,500 ft) in elevation.

Landlocked populations occur in the Yukon Territory and British Columbia in Canada, as well as, in Alaska, Washington, Oregon, California, New York, Utah, Idaho, Montana, Nevada, Colorado, New Mexico, and Wyoming in the United States.

[9] In Japan, a landlocked variety termed black kokanee, or "kunimasu" in Japanese, was deemed to be extinct after 1940, when a hydroelectric project made its native lake in northern Akita Prefecture more acidic.

They can change their position in the water column, timing and length of feeding, school formation, and choice of prey to minimize the likelihood of predation.

[19] Males partake in competitive and sneaking tactics, formation of hierarchies, and non-hierarchical groupings around females who are ready to mate.

[21] Male spatial distribution depends on shifts in reproductive opportunities, physical traits of breeding sites, as well as the operational sex ratio (OSR) of the environment.

[21] Males go through numerous morphological changes at maturation including, an increase in body depth, hump height, and snout length.

This could mean that longer snout sizes are sexually selected, but hump height and adipose fin length are not.

[25] Males choose females based on their readiness to spawn and their size in order to maximize their breeding opportunities.

[25] Other ecological factors like stranding effect select for smaller body size in sockeye salmon when present in a habitat.

Stranding is when salmon swim into dry land or shallow water during their migration for spawning and die from suffocation.

Fat, protein, and somatic energy stores decrease from the final moments in marine migration through freshwater entry, spawning, and death.

[22] Sockeye salmon with longer and more difficult migration routes produce fewer eggs on the spawning grounds.

[31] High water temperatures also increase the energy expenditure of sockeye salmon as they migrate upriver.

[22] These acts of aggression are important in terms of reproductive success, because they determine the quality of the nest site the female obtains and access to males.

[35] Commercial fishermen in Alaska net this species using seines and gillnets for fresh or frozen fillet sales and canning.

The annual catch can reach 30 million fish in Bristol Bay, Alaska, which is the site of the world's largest sockeye harvest.

[36] Sockeye salmon have long been important in the diet and culture of the Coast Salish people of British Columbia.

The Snake River sockeye salmon was listed as endangered in November 1991, after the Shoshone-Bannock Tribe at Fort Hall Indian Reservation petitioned the National Marine Fisheries Service.

[46] The return abundance (population) of Fraser River sockeye in 2009 was estimated at a very low 1,370,000,[47] 13% of the pre-season forecast of 10,488,000.

According to a consortium of scientists assembled to review the problem, the decline highlights the uncertainty in forecasting salmon returns.

[51][52] The Commission has been tasked with investigating all the factors which may affect Fraser River sockeye salmon throughout their life cycle.

According to the terms of reference,[51][52] the subjects of investigation are "the impact of environmental changes along the Fraser River, marine environmental conditions, aquaculture, predators, diseases, water temperature and other factors that may have affected the ability of sockeye salmon to reach traditional spawning grounds or reach the ocean."

Twelve technical reports were published using that information, looking at the possible impacts of diseases and parasites, hatchery diseases, contaminants, marine ecology, salmon farms, fisheries, predators, climate change and government management on the productivity of Fraser River sockeye runs.

[53][54] While the commission was holding public hearings, in the late summer of 2010, the largest run of sockeye since 1913 returned to the Fraser River system.

[57] There is high variation in thermal tolerance among the different sockeye salmon populations that migrate up the Fraser River.

In one study examining possible physiological mechanisms underlying these population differences in thermal tolerance, juvenile sockeye salmon from the Chilko River and Weaver Creek did not show any differences in force-frequency response of the heart or cardiac pumping capacity when reared in common garden temperatures at 5 °C and 14 °C.