Migrating Puget Sound Steelhead Face Increased Predation at Hood Canal Bridge


Threatened Puget Sound steelhead face many challenges on their migration, including infrastructure barriers like the Hood Canal floating bridge.

The Hood River Canal Bridge is a major source of mortality for migrating steelhead smolts, according to new research in the peer-reviewed journal Ecosphere by NOAA Fisheries Northwest Fisheries Science Center scientists and the non-profit Long Live the Kings. Approximately half the smolts tracked by researchers died attempting to get past the bridge or soon after.

“We had no idea this bridge was causing such an impact on steelhead migrating out of Hood Canal,” says Megan Moore, a researcher biologist at the Northwest Fisheries Science Center and lead author of the study.

Using acoustic telemetry tags safely implanted in the fish and an array of more than 30 receivers at various points along their migration route, the researchers found the steelhead smolts slowed considerably at the bridge. The fish took one to two days on average to navigate past the bridge compared to just 5 to 7 hours to travel through open, unobstructed sections of the canal.

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