Salmon smolts go 'high tech' in Grant PUD fish-survival study

EPHRATA — Thousands of juvenile salmon and steelhead will go “high tech” — figuratively and literally — in an upcoming study by Grant County PUD biologists of behavior and survival of the ocean-bound fish as they migrate down the Columbia River past the utility district’s Wanapum and Priest Rapids dams.

In an announcement last week, the PUD said 3,600 smolts — each measuring 4 to 8 inches in length — will be collected upriver at Chelan County PUD’s Rock Island Dam and transported by truck to Grant PUD’s fish tagging and husbandry facility at Wanapum Dam. There, the fish will be examined and their conditions documented before they’re anesthetized and surgically implanted with an electronic transmitter.

Once tagged and held for a 48-hour recovery period, the “acoustic” fish will be loaded into a “fly tank” suspended from a helicopter and flown to release points about one-half mile below both Rock Island and Priest Rapids dams.

PUD officials said special acoustic receivers have been strategically placed along a 58-mile section of the river that will track the young fish between Rock Island Dam and the Hanford Reach area near the Tri-Cities as they continue their spring migration down the Columbia River toward the Pacific Ocean.

The helicopter rides are expected to start in late April with fish releases continuing daily through the month of May. The implanted tags are considered harmless and send signals for about 30 days.

The smolts’ special mission provides valuable information to biologists engaged in a mandatory, 10-year survival study to ensure that at least 86.5% of the migratory fish make it safely past both Grant PUD dams. Similar studies are planned in 2027 for juvenile sockeye salmon.

According to the utility district, earlier studies have shown that Grant PUD has met or exceeded “performance standards” for survival of yearling Chinook, juvenile steelhead, and sockeye.

“Meeting performance standards for juvenile salmon and steelhead is extremely critical,” Tom Dresser, Grant PUD’s senior manager of Fish, Wildlife and Water Quality, said in a press statement. “Failure to meet these standards could mean costly modifications to Grant PUD’s environmental-stewardship program or even operational changes at the dams. We take these 10-year check-ins very seriously.”

Research conducted between 1999 and 2014 helped the district determine capital investments, operational measures, and programs needed to meet and improve survival standards. Those enhancements have since included:

—    Adding bypass systems – resembling giant “water slides” for juvenile fish – to ensure safer passage over both dams;

—    Developing “Fish Mode,” a safer way to operate the dams’ turbine/generator units to boost survival rates for fish passing through the in-river turbines;

—    “Predator controls” at the dams and their reservoirs to reduce losses to birds, fish and other natural predators which feast on migrating smolts.

Grant PUD partners with federal, state, and tribal representatives on the Priest Rapids Coordinating Committee to use scientific information and analyses in setting the survival targets and, when necessary, devising strategies to boost performance.