Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

The species exhibits riverine and lake life history strategies, the latter of which may be
either freshwater resident forms or anadromous forms. The vast majority of sockeye
salmon spawn in outlet streams of lakes or in the lakes themselves. These “lake-type”
sockeye use the lake environment for rearing for up to three years and then migrate to
sea, returning to their natal lake to spawn after one to four years at sea. Some sockeye
spawn in rivers, however, without lake habitat for juvenile rearing. Offspring of these
riverine spawners tend to use the lower velocity sections of rivers as the juvenile rearing
environment for one to two years, or may migrate to sea in their first year.
Certain populations of O. nerka become resident in the lake environment over long
periods of time and are called kokanee or little redfish (Burgner 1991). Kokanee and
sockeye often co-occur in many interior lakes, where access to the sea is possible but
energetically costly. On the other hand, coastal lakes where the migration to sea is
relatively short and energetic costs are minimal, rarely support kokanee populations.
Spawning generally occurs in late summer and autumn, but the precise time can vary
greatly among populations. Males often arrive earlier than females on the spawning
grounds, and will persist longer during the spawning period. Average fecundity ranges
from about 2,000 to 2,400 eggs per female to 5,000 eggs, depending upon the population
and average age of the female. Fecundity in kokanee is much lower and may range from
about 300 to less than 2,000 eggs.
Incubation is a function of water temperatures, but generally lasts between 100 and
roughly 200 days (Burgner 1991). After emergence, fry move rapidly downstream or
upstream along the banks to the lake rearing area. Fry emerging from lakeshore or island
spawning grounds may simply move along the shoreline of the lake (Burgner 1991).
Juvenile salmonids rely on a variety of non-main channel habitats that are critical to
rearing. All listed salmonids use shallow, low flow habitats at some point in their life
cycle. Examples of off-channel habitat include alcoves, channel edge sloughs, overflow
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