Using salmon to sample the Salish Sea: diets of recreationally harvested Chinook and Coho salmon as an ecosystem monitoring tool

Abstract

In addition to their economic, social and cultural importance, Chinook and Coho Salmon are key players in the Salish Sea ecosystem. They are at times dominant predatory fish in epipelagic waters and are important prey for marine mammals. Chinook Salmon in particular are critically important as the primary prey of the endangered Southern Resident Killer Whales. Surprisingly, data on the diets of adult Chinook and Coho Salmon in the Canadian Salish Sea (Straits of Georgia and Juan de Fuca) are sparse, with no published work since the 1980s and a total lack of information on winter diets. We are seeking, in partnership with recreational anglers, to develop a low-cost, ongoing program to sample Chinook and Coho Salmon diets throughout the year from around the Canadian Salish Sea. We report results of our pilot year (2017) which indicate regional and seasonal variation in Chinook Salmon diet and corroborate recent observations of forage fish dynamics in the Salish Sea. This program has the potential to complement existing and future fishery-independent surveys in elucidating natural and anthropogenic changes in the ecosystem. We welcome input from, and collaborations with, other Salish Sea researchers to maximize the value of this citizen science initiative