Fisheries managers are hoping to better understand the life cycle of steelhead to determine the status of the Skagit River run.
The Upper Skagit Tribe is implanting juvenile and adult steelhead with passive integrated transponder (PIT) tags that enable managers to collect data on fish survival and movement with minimal handling of the fish.
Unlike most species of salmon, steelhead can spawn repeatedly before they die. The timing of their migration to the ocean can vary, and they can stay at sea up to three years before returning to fresh water to spawn.
Upper Skagit natural resources staff are collecting, tagging and releasing juvenile steelhead from multiple locations on Hansen and Illabot creeks. Individuals that out-migrate from the creek have their tags read by receivers installed on the creek bottoms. Adult fish returning to spawn are collected in tangle nets and tagged before being released. The same receivers that detect out-migrating juveniles also detect returning tagged adults.
“The day we capture an adult fish that we tagged as a juvenile will be a big day,” said Josh Adams, one of the natural resources technicians working on the project.
PIT tags enable automatic detection of individual fish as they swim past a receiver, compared to coded-wire tags, which are best suited to mass-marking groups of fish and only tell managers where and when a hatchery fish was released. Coded-wire tags must be retrieved from a fish after it is harvested or recovered from the spawning grounds, while PIT tags can be read externally by a hand-held or instream receiver while the fish is still alive. The tribe is working with an automated electronic field database to record and centralize the large amounts of data gathered from tracking individual fish over their life cycles.
“With coded-wire tags, we know whether 100 out of 1,000 fish return, but with a PIT tag, we know what happened to Charlie,” said Jon-Paul Shannahan, Upper Skagit natural resources managing biologist.
The database was developed by Real Time Research, Inc., in close coordination with Upper Skagit Tribe biologist Rick Hartson. The Upper Skagit Tribe is hoping to collaborate with the state fisheries co-manager to track steelhead.
On the last day of adult tagging for the year, Upper Skagit staff were joined by Andrew Fowler, Washington Department of Fish and Wildlife biologist, who wanted to learn more about the effort.
“I’m here because I love steelhead,” Fowler said. “We all want to see more steelhead come back. The only way to do that is to learn more about what’s happening to them.”
The tribe has been monitoring Skagit River steelhead with this project for the past couple of years, taking scale samples to learn how long individual fish spent in fresh water before out-migrating and how long they spent at sea. The analysis also shows whether the steelhead migrated back out to sea after spawning in fresh water. Now, the scale sample data from PIT-tagged adults are being added to the database to get a more complete picture of the steelhead’s life span and history.
Both tribal and non-Indian fisheries have been reduced dramatically since the 2007 listing of Puget Sound steelhead as threatened under the Endangered Species Act. The primary causes of the decline of steelhead runs are believed to be degraded habitat, fish-blocking culverts, hydropower dams and unfavorable ocean conditions.