a. What are your focal species and their associated listing status?
Chinook salmon originating from within the Skagit River basin are the focal species of the Skagit IMW (Table 1). Skagit Chinook salmon make up six of the twenty-two independent populations of Chinook salmon within the Puget Sound ESU. Each population is listed as ‘threatened’ under Endangered Species Act (Federal Register on June 28, 2005; updated and reaffirmed Federal Register on April 14, 2014).
Skagit chum salmon and coho salmon are also expected to benefit from Skagit estuary restoration. Skagit chum salmon and coho salmon area not listed under ESA, however Skagit chum salmon like many other Puget Sound chum stocks are declining and at low abundance. In 2019, we leveraged the long
Limiting factors to Skagit Chinook salmon populations were identified assessing juvenile Chinook salmon population dynamics and habitat conditions. Separate studies examined three discrete life stages (egg to fry; freshwater rearing; estuary rearing). The influence of estuary habitat conditions on Skagit Chinook salmon populations were reported in Beamer et al. (2005) and are summarized in the current Skagit IMW Study Plan (Greene et al. 2015). In simplistic terms, Skagit Chinook salmon commonly exhibit extensive estuary rearing. Millions of fish typically out-migrate each year and rear in the tidal channels and marshes of the estuary as fry in late winter or early spring and leave approximately a month later after nearly doubling their length and increasing in weight by 10-fold. Successful estuary rearing likely increases survival to adulthood, because fish can grow quickly and attain a size at the right time of year to move to marine waters of the Salish Sea and capitalize on abundant marine prey. However, the current amount and connectivity of Skagit estuary habitat is limiting the number of Chinook salmon fry that can rear in the estuary. Observations suggests that both estuary residence
