Sockeye Salmon – Oncorhynchus nerka
Spawning Phase – freshwater
Adults: No spots on the back, sides, or dorsal and caudal fins. In saltwater Sockeye are silver, in freshwater spawning adults become bright red on the body and green on the head.
Fry: Lack a dark stripe on the leading edge of the dorsal fin (in comparison to trout of the same size). Juveniles have small oval-shaped lateral parr marks roughly dived in half by the lateral line.
Sockeye are widely distributed in British Columbia and spawn in over 300 lakes and streams, including Lakelse Lake. In the Lakelse watershed, Sockeye utilize the following: Andalas Creek, Clearwater Creek, Sockeye Creek, Schulbuckhand Creek (Scully Creek), Williams Creek and Lakelse Lake for spawning and rearing.
Sockeye return to natal waters in the fall to spawn. Adult Sockeye migrate to spawning sites starts as early as July and spawning peaks from August to late October. Like other salmonines, females choose the spawning site. Sockeye females prefer shallow riffles, the outlets of lakes, or beaches in lakes where there is upwelling or subgravel flow. Ideal gravel diameters range from 1.0 to 2.5 cm however, in lakes Sockeye may spawn in cobble size substrate. As the female digs a nest, a male courts the female by nudging her with his snout and occasionally quivering at her side. Satellite males and jacks also take part in spawning by rushing in and fertilizing a variable number of eggs.
As with other salmonines, development rate is a function of incubation water temperature. On average incubating eggs hatch after 1.5 to 3.5 months and emerge from the gravel after 1.5 to 2.5 months.
Age, Growth and Maturity
A typical sockeye life history involves a lake-rearing phase lasting 1 – 2 years however, some populations rear in streams and rivers for 1- 2 years before migrating to the ocean. Temperature and food availability greatly influences the growth rate of newly emerged fry. Smolt size varies between 60 – 90 mm for age-1 smolts and 100 – 120mm for age-2 smolts. Juveniles spend 1 – 2 years in freshwater and 1 – 4 years in saltwater before returning to spawn. At sea Sockeye begin a counterclockwise migration to the Gulf of Alaska heading southwest along the Alaska Peninsula. In late fall/early winter their migration turns southeast and by the next summer they have completed the migration and are returning to the Gulf of Alaska again. This circular migration pattern is repeated each year. Upon maturity adults move towards the coast in June and July and return to their natal stream in late summer.
In freshwater, sockeye fry begin feeding shortly after emergence. Fry feed on zooplankton, chironomid larvae and pupae, copepods and cladocerans. In saltwater, sockeye feed primarily on macrozooplankton, small fish, and squid.
McPhail, J.D. (2007). The Freshwater Fishes of British Columbia. Edmonton, Alberta: The University of Alberta Press.