Increases in synchrony among Central Coast salmon populations in British Columbia over the last 60 years

• Main Authors: Hertz, Eric, Connors, Brendan, Connors, Katrina, Reynolds, John
• Format: Text
• Language: English
• Published: Western CEDAR 2018
• Subjects: Salmon populations; Watersheds; Fresh Water Studies; Life Sciences; Marine Biology; Natural Resources and Conservation; Terrestrial and Aquatic Ecology; Sockeye; First Nations; Pink salmon
• Online Access: https://cedar.wwu.edu/ssec/2018ssec/allsessions/476; https://cedar.wwu.edu/cgi/viewcontent.cgi?article=2911&context=ssec

Understanding the dynamics of salmon populations is important for conservation and management, but the factors driving spatial and temporal variation in many salmon populations remain poorly understood. Understanding these patterns is important for many coastal First Nations, who play an important role in the monitoring and management of salmon in their traditional territories. Using data from 200 unique spawning locations on the Central Coast of British Columbia, we quantified patterns in abundance and coherence of salmon over space and time to measure the extent to which portfolio effects stabilize variation in stocks. We found strong declines in Sockeye Salmon abundance across the Central Coast. This decline was accompanied by an increase in population synchrony among stocks. Chum and Pink Salmon also showed generally similar patterns to Sockeye, though the odd-year lineage of Pink Salmon showed increased abundance in recent years. These changes in synchrony within salmon populations may be important as synchronization increases the risk of declines due to boom and bust dynamics. To explore possible drivers of changes, we test if factors such as changes in fishing rates, ocean conditions, or increased competition on the high seas explained changes in synchrony through time. To expand this work, over the next two years we will be working with First Nations throughout the Salish Sea to assess the status of salmon and their habitats. This future work will position us to better understand the drivers of changes in the synchrony among salmon populations on wider spatial scales.