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ONP biologist monitor Elwha fish

July 17th, 2014 - 4:55am

(Port Angeles) -- For nearly a century, salmon migrations into Olympic National Park have been blocked on the Elwha River by the Elwha and Glines Canyon dams.

With Elwha Dam gone and approximately 30 feet of Glines Canyon Dam remaining, Pacific salmon will soon have access to over 70 miles of habitat protected within the park.

To understand, evaluate, and inform salmonid restoration in the Elwha River, biologists are monitoring fish populations to assess fish passage at the former dam sites and in the remote, upper canyons of the river.

In April, biologists from Olympic National Park, Lower Elwha Klallam Tribe, and U.S. Fish and Wildlife Service began a radio-tracking project to follow the movements of anadromous fish in the Elwha watershed.

Information gathered from this project will help illuminate how far, how fast, and where the first salmon recolonizers go after dam removal.

As of July 9th, biologists have captured and radio-tagged a total of 53 adult salmonids, including 23 bull trout, 16 steelhead, 12 Chinook salmon, and two sockeye salmon.

Each fish was equipped with a uniquely coded radio transmitter that differentiates it from all other tagged fish, even those transmitting on the exact same frequency.

This allows biologists to monitor large groups of fish using only a single radio frequency.

Radio signals from the tags are detected by a radio receiver and antenna.

To monitor the fish, six telemetry stations have been installed between the mouth of the river and just above Glines Canyon Dam.

These stations continually scan for and record data.

Additionally, biologists are manually tracking the fish between Glines Canyon Dam and the river mouth using handheld radio receivers and antennas.

After the removal of Glines Canyon Dam is complete, aerial surveys by a Cessna 172 outfitted with a wing mounted antennae will be used to track fish migration upstream of Glines Canyon Dam.

Information collected from the tagged fish is being used to map individual fish migrations in he Elwha watershed.

To date, eight bull trout and two wild steelhead have moved upstream of the Elwha Dam site.

Updates on the fish tagging project and fish migration maps, along with, radiotelemetry techniques, scientific processes, and methods of tracking, will be shared on regular Adopt-A-Fish posts on this blog.

This project is possible through partnerships with the Lower Elwha Klallam Tribe and U.S. Fish and Wildlife Service, and funding generously provided by Washington's National Park Fund.

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