The Salish Sea Marine Survival Project: Canadian Program Summaries summarizes findings from the Pacific Salmon Foundation’s five year study on salmon declines in the Strait of Georgia.
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14 This collaborative program is ongoing, providing ocean- ographic information at a temporal and spatial scale not achievable with large traditional research vessels. The data collected are allowing us to assess annual variation in physical/chemical oceanography, develop ecosystem models, validate satellite imagery and understand spatial and temporal changes in productivity of the Strait of Georgia (Figure 3). 2. Coho and Chinook Adult Diet Program What is it? PSF is also supporting a citizen science program coordin- ated by the University of Victoria (UVic), which aims to use food consumed by Coho and Chinook Salmon in the Strait of Georgia to better understand changes in marine ecosystems. This program addresses two key research gaps: the limited research on salmon diets in the Canadian Salish Sea since the 1980s, and winter diets which have never been described. The program involves recreational anglers as 'citizen scientists' to collect diet data year-round throughout the Canadian Salish Sea. The main objectives of the program are to develop an economical, long-term program to monitor the Salish Sea ecosystem, to charac- terize spatial and seasonal variation in Chinook and Coho diets, and to possibly develop an informative indicator of the abundance of small forage fishes within the Strait. How it works Forage fish are the fishy bedrock of the Strait's ecosystem, feeding most predatory marine creatures including salmon. But, while there are studies on commercially fished species like herring, a giant gap exists in our understanding of other forage fish species that are also important. The Adult Diet Program uses salmon stom- achs and volunteers to fill that gap. Stomachs of adult fish are collected and then processed by students and staff at UVic. Anglers freeze the stomachs of salmon they caught, fill out a data card for each fish, and drop stomach contents off at designated tackle shops. By engaging multiple volunteers with small vessels, the team is able to collect data from all over the Strait throughout the year. To date, over a thousand stomachs have been analyzed, and results so far indicate that Pacific Herring are by far the most important prey for both Chinook and Coho, providing a food source year-round. In June, small, recently born herring feed juvenile Chinook (Figure 4). But some observations indicate that these 'young-of-year' herring are getting too big for some juvenile Chinook to feed on, potentially having a negative impact on marine survival. Another finding observed a recent surge in anchovy populations in the southern Strait, with anchovies comprising up to 30 per cent of the adult salmon diet in areas of abundance. Why it's important While the data collected will be some of the first informa- tion obtained on the winter diets of Coho and Chinook, the insight it will give on the state of forage fish could prove equally valuable. Information from this cost-effec- tive, citizen science study could help us make important decisions around the protection of particular forage fish stocks and spawning habitats. As well, having good quality data on forage fish patterns comes with significant benefits to salmon. Figure 4. Index of mean partial fullness scores for Chinook Salmon in the Salish Sea from 2017-2019. Data from the Adult Diet Study, provided by Will Duguid, UVic. Figure 3. Oceanographic attributes, maps, animations and data available at the Strait of Georgia Data Centre www.sogdatacentre.ca.