Diverse and changing use of the Salish Sea by Pacific salmon, trout, and char

Abstract

Each year, juveniles of eight salmonid species enter the Salish Sea - the inland marine waters between northwestern Washington, USA and British Columbia, Canada. These species vary in the proportions remaining there and migrating to feed in the Pacific Ocean. Such differential migration affects their growth rates, and exposure to habitat alteration, predators, fisheries, and contaminants. We review these diverse migration patterns and present data from Puget Sound illustrating the variation in downstream migration timing, residency in the Salish Sea, and upriver return timing. Recreational catch records indicate that proportionally fewer remain in the Salish Sea than in past decades for several species, and the declines began after peaks in the late 1970s – early 1980s. These declines resist easy explanation because the factors controlling residency are poorly understood, and the Salish Sea has changed over the past decades. Regardless of the cause, the diversity of migration patterns is important to the ecology of the salmon and trout species, and to the humans and other members of the Salish Sea community with which they interact.