The role of estuaries in the ecology of Pacific salmon and trout in Puget Sound
Each year, eight different species of salmon and trout migrate down rivers and into Puget Sound and other parts of the Salish Sea. They either migrate farther out to the Pacific Ocean or remain in the estuarine, nearshore, or open waters of the Salish Sea until they return and swim back upstream to spawn. These salmonid species vary in their size and age upon entering Puget Sound, and their use of estuaries and other nearshore marine habitats varies considerably between juveniles and adults, and among species and populations.
The use of estuary habitats by juveniles has been extensively studied, and restoration efforts have been completed or planned to improve habitat access and quality for juveniles. However, use of estuaries by adults has received much less attention. Adult behavior differs considerably among species and populations as they transition from salt to fresh water, from active feeding to anorexia, from immature to sexually mature fish, and from the orientation mechanisms that guided their migration in open water to those used during upriver migration. These complex factors and different behavior patterns cause salmonids to vary greatly in their duration in estuaries and exposure to fisheries, predators, and stressful environmental conditions.
Differences in estuary use among species are important for salmon ecology and conservation because humans have modified estuaries so extensively, and because of fishing pressures in nearshore, estuary, and lower river habitats. This variation makes some species more susceptible than others to natural and human-caused variation in habitat availability and quality.
Two comprehensive reports written by Thomas Quinn describe adult and juvenile salmonid use of estuaries in Puget Sound.
The role of estuaries in the ecology of juvenile Pacific salmon and trout in Puget Sound Published August 20, 2024
The role of estuaries in the ecology of adult Pacific salmon and trout in Puget Sound Published October 22, 2024