Chinook and coho salmon are
anadromous species and throughout their lives may be exposed to contaminants
in freshwater, estuarine, or marine areas. Although specific migratory
patterns of these two species vary, they both spawn in freshwater, live
there for 3 to 15 months after emergence as embryos from gravel nests,
and then migrate to marine waters. Contaminant concentrations in prey
they consume may vary in these habitats. In freshwater, the young salmon
consume aquatic insects and crustaceans but as they smolt and enter the
estuary they consume a wider variety of invertebrates and larval fish.
Adult salmon in marine waters continue to eat invertebrates but consume
more epipelagic 1 fish, increasing the likelihood
of contaminant biomagnification in their tissues. The amount of time each
species or population spends at sea varies widely but for both species
the majority of their growth occurs in marine waters before they return
to their natal streams to spawn. Short-lived fish like coho and chinook 2
salmon, reflect current environmental conditions in their habitats.
The muscle tissues of adult chinook and coho salmon have a relatively high in fat (lipid) content, thus they
may accumulate higher concentrations of contaminants in these tissues. Females may pass lipophilic
contaminants to their young along with the lipids used for egg development. Thus, the lipid content of the
muscle tissue, gender and the degree of sexual maturity may all affect the accumulation of contaminants
in these fish.
PSAMP began sampling coho and chinook salmon in 1990 and now samples fixed locations bi-annually. Click for sampling
- For both the coho and chinook salmon collected by the Fish Component, the maximum fish age was 5 years.
- Living or feeding on surface waters or at midwater to depths of 200 m.