Fish Migration

Science communication intern Avani Fachon joined the San Francisco Bay Inventory & Monitoring Network salmonoid monitoring team at Redwood and Olema Creeks in May 2023. Here, she shares her wonder at witnessing coho salmon's migration out to sea, and what she learns about the process of "smolt trapping" and its importance to better understanding and supporting coho salmon, a federally listed endangered species.

This has been a highly productive spawner season for the salmon in the Olema and Redwood Creek watersheds. The San Francisco Bay Area Network coho and steelhead monitoring crew spotted over 140 Chinook, coho, and steelhead redds (nests) in these creeks since November. These encouraging numbers are largely due to the heavy rainfall the Bay Area received in late fall and early winter. However, two months without significant rain has sounded some alarms for our coastal streams.

Summer migration patterns of Alewives in Acadia National Park. Research being done on fish passage helps to determine best practice for a population of river herring in Maine.

For the first time in the Coho and Steelhead Monitoring Program’s history, the monitoring crew had to stop outmigrant coho salmon smolt trapping early due to low flows. They removed the traps from both Olema and Redwood Creeks. This is just one of many indicators showing how severe the drought is this year.

Mass animal migrations are awe-inspiring sights. Every summer and fall, residents and visitors to Alaska can witness one of the great underwater migrations: Pacific salmon returning from the ocean to their home streams, rivers, and lakeshores to spawn. Hundreds of millions of salmon return to Alaska’s freshwaters annually. Alaska Park Science 17(1), 2018.