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. 
 

Multidecadal Trends in Body Size of Puget Sound Chinook Salmon: Analysis of Data from the Tengu Derby, a Culturally Unique Fishery

“…Puget Sound and the entire Salish Sea have undergone many changes over the past decades in physical and ecological attributes (Quinn and Losee, in press), and we did not try to ascribe the observed changes in Chinook Salmon mass to specific causes. However, data such as these on the resident component, over such a long period, are unique and especially valuable.…”

“…The lack of correspondence between the Tengu Derby and purse seining data presented here spanning more than four decades, and the decreasing resident component in the populations, illustrates yet another important complexity in the analysis of temporal trends in salmonid body size. That is, the differential migration patterns observed in several species, especially Chinook Salmon and Coho Salmon (Quinn 2021; Quinn and Losee, in press), can cause differences in vulnerability to fisheries of contingents that migrate to different areas (Sharma and Quinn 2012). If those migratory contingents also differ in size, then the resulting data can be biased, depending on where and when the fish were sampled.…”

“…2014); thus, changes in the proportions of residents and migrants could strongly affect mean body size, depending on where and when the sampling took place. Indeed, the proportion of Chinook Salmon remaining as residents in Puget Sound has decreased over the period covered by the Tengu Derby data (Quinn and Losee, in press). The lack of correspondence between the Tengu Derby and purse seining data presented here spanning more than four decades, and the decreasing resident component in the populations, illustrates yet another important complexity in the analysis of temporal trends in salmonid body size.…”

In-Water Photo Identification, Site Fidelity, and Seasonal Presence of Harbor Seals (Phoca vitulina richardii) in Burrows Pass, Fidalgo Island, Washington

“…The end of January through the beginning of April is an important spawning season for herring, which have near-by spawning grounds in Fidalgo and Skagit Bays [48]. Each spring, juveniles of eight native salmonid species enter the marine waters of the Salish Sea [49], and during the late summer through fall there is a large influx of adult salmonids when they migrate from marine waters to their natal streams [35,37,38]. Consequently, harbor seal predation on salmonids increases during this time [38].…”

Prey Supply and Predation as Potential Limitations to Feasibility of Anadromous Salmonid Introductions in a Reservoir

“…Coho salmon-Coho salmon in the Salish Sea typically rear in freshwater for just over a year, migrating to the ocean during the following spring (primarily in May) where they spend approximately 18 months before returning to freshwater in September-November (peak in October) to spawn at age-3 [44,45]. A lake habitat is not commonly used by coho salmon during their freshwater rearing in Washington or further south, in contrast to observations of lake rearing reported in British Columbia and Alaska [26].…”