The Northwest Fisheries Science Center operates a study in the Columbia River estuary to collect data on migrating juvenile Pacific salmon implanted with passive integrated transponder (PIT) tags. This research employs a large surface pair trawl to guide fish through an array of PIT antennas mounted in the open cod end. Data on the species, tagging, and release time and location of detected fish is used to evaluate migration performance to the estuary, where the trawl operates. Since 1998, trawl detection data has been used to complete hydrosystem survival estimates to Bonneville Dam. These estimates provide managers with an annual metric to evaluate impacts and improvements to ESA listed stocks.

After cancelling the 2020 season due to COVID-19 restrictions, the trawl group is happy to be back on the water for the 2021 season. The trawl will operate 7 days per week beginning in mid-April, and will continue to sample through June when most spring-migrating juvenile salmon have passed through the estuary.
(Photos and content provided by OAI employee Erika Holcombe)