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Sockeye Salmon (Oncorhynchus nerka)

Status | Taxonomy | Species Description | Habitat | Distribution |
Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info

  sockeye salmon underwater
Sockeye Salmon
(Oncorhynchus nerka)
Photo: Travis Nelson, Washington Dept. of Fish & Wildlife
 This link is an external site.

 

 

Status
ESA Endangered - 1 ESU
ESA Threatened - 1 ESU

Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Genus: Oncorhynchus
Species: nerka

Species Description
Weight: average of 8 pounds (3.6 kg)
Length: up to 3 feet (86 cm)
Appearance:  while spawning, they turn bright red with a green head;
while in the ocean, they are bluish back with silver sides
Lifespan: about 5 years
Diet: in freshwater, they feed on aquatic insects and plankton; in the ocean, they eat "amphipods", "copepods", squid, and some fishes
Behavior: migrate from a marine environment into freshwater streams and rivers or lakes of their birth in order to mate; they spawn only once and then die;
females spawn in 3 to 5 "redds" (nests)

The size of an adult returning to spawn may measure up to 2.8 feet (86 cm) in length and weigh an average of 8 pounds (3.6 kg).

The adult spawners are unique in appearance. They typically turn bright red, with a green head; hence they are commonly called "red" salmon in Alaska. During the ocean and adult migratory phase, sockeye often have a bluish back and silver sides, giving rise to another common name, "bluebacks."

The name "sockeye" is thought to have been a corruption of the various Indian tribes' word "sukkai."

Adults migrate from a marine environment into freshwater streams and rivers or lakes of their birth in order to mate (called anadromy). They spawn only once and then die (called semelparity). Sockeye salmon exhibit a wide variety of life history patterns that reflect varying dependency on the freshwater environment. With the exception of certain river-type and sea-type populations, the vast majority of sockeye salmon spawn in or near lakes, where the juveniles rear for 1 to 3 years prior to migrating to sea. For this reason, the major distribution and abundance of large sockeye salmon stocks are closely related to the location of rivers that have accessible lakes in their watersheds for juvenile rearing.

Females spawn in 3 to 5 redds (nests) over a couple of days. Hatching usually occurs after 6 to 9 weeks. Most sockeye fry then rear in lakes where they feed on aquatic insects and "plankton".

As the time for migration to the sea approaches for the anadromous forms, the juvenile loses its parr marks, which are a pattern of vertical bars and spots useful for camouflage. They then gain the dark back and light belly coloration used by fish living in open water. During this time their gills and kidneys begin to change so that they can process salt water. These "smolts", as they are called, initially stay close to the shore and feed on insects and plankton. Once they move offshore, their diet turns mainly to "amphipods", "copepods", squid, and some fishes.

Most sockeye salmon stay at sea for 2 years, returning to spawn at about age 4, but some may be 5-6 years old when they spawn.

There are some sockeye that are non-anadromous, meaning that they spend their entire lives in freshwater. Non-anadromous Oncorhynchus nerka in the Pacific Northwest are known as "kokanee." Occasionally, a proportion of the juveniles in an anadromous sockeye salmon population will remain in their rearing lake environment throughout life and will be observed on the spawning grounds together with their anadromous siblings. Taxonomically, the kokanee and sockeye salmon do not differ.

 
sockeye salmon critical habitat
Sockeye Salmon Critical Habitat
(click for larger view PDF)


sockeye salmon range map
Sockeye Salmon Range Map
(click for larger view PDF)


Habitat
Sockeye spend approximately the first half of their life cycle rearing in lakes. The remainder of the life cycle is spent foraging in estuarine and marine waters of the Pacific Ocean.

Critical habitat was designated for the Snake River ESU on December 28, 1993 and for the Ozette Lake ESU on September 2, 2005.

Distribution
On the Pacific coast, sockeye salmon inhabit riverine, marine, and lake environments from the Klamath River and its tributaries north and west to the Kuskokwim River in western Alaska. As they generally require lakes for part of their life cycle, their distribution in river systems depends on the presence of usable lakes in the system, and thus can be more intermittent than for other Pacific salmon. On the Asian side of the Pacific Ocean, sockeye salmon are also found from the Anadyr River in Siberia south to Hokkaido, Japan.

Population Trends
They are the third most abundant of the seven species of Pacific salmon, after pink salmon and chum salmon. However, the Snake River ESU has remained at very low levels of only a few hundred fish, though there have been recent increases in the number of hatchery reared fish returning to spawn. Data quality for the Ozette Lake ESU makes differentiating between the number of hatchery and natural spawners difficult, but in either case the size of the population is small, though possibly growing. The status review [pdf] [6.3 MB] provides more detailed information.

Threats
Salmonid species on the west coast of the United States have experienced dramatic declines in abundance during the past several decades as a result of various human-induced and natural factors.

There is no single factor solely responsible for this decline, given the complexity of the salmon species life history and the ecosystem in which they reside. For more information, please visit our Pacific salmonids threats page.

Conservation Efforts
A variety of conservation efforts have been undertaken with some of the most common initiatives including captive-rearing in hatcheries, removal and modification of dams that obstruct salmon migration, restoration of degraded habitat, acquisition of key habitat, and improved water quality and instream flow.

he Pacific Coast Salmon Recovery Fund (PCSRF) was established by Congress in 2000 to support the restoration of salmon species. The fund is overseen by NMFS and carried out by state and tribal governments. The 2006 PCSRF report summarizes their work in detail.

No Pacific salmon have been evaluated for IUCN Redlist This link is an external site. conservation status.

Regulatory Overview
The threatened and endangered ESUs of sockeye salmon were listed under the Endangered Species Act (ESA) on June 28, 2005. The Snake River ESU and Ozette Lake ESU had been previously listed in 1991 and 1999, but the listings were reaffirmed in 2005.

Critical habitat was designated for the Snake River ESU on December 28, 1993 and for the Ozette Lake ESU on September 2, 2005.

See Key Documents below for more details.

Key Documents
(All documents are in PDF format.)

Title Federal Register Date
5-year reviews   various
Final Recovery Plan for Lake Ozette ESU 74 FR 25706 05/29/2009
Draft Recovery Plan for Lake Ozette ESU 73 FR 21913 04/23/2008
Designation of Critical Habitat for Ozette Lake Sockeye 70 FR 52630 09/02/2005
ESA Listing Rule for Endangered and Threatened DPSs 70 FR 37160 06/28/2005
Status Review Update of All ESA-Listed DPSs n/a 06/2005
Designation of Critical Habitat for Snake River Sockeye 58 FR 68543 12/28/1993
More Sockeye Federal Register Notices various various
Recovery Plans and Related Documents n/a various

More Information

Updated: May 15, 2014

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