Incredible Journey

May 27, 2009

Release from: Annette Cary
News Tribune (Seattle)

More than 10,000 chinook and steelhead will be emitting a high-pitched beep every three seconds as they swim from John Day Dam on the Columbia River to the Pacific Ocean this spring and summer.

Data collected in the Pacific Northwest National Laboratory research will be used to better understand the behavior of the young fish and why some survive the journey to the ocean but others perish. The acoustic tagging system has become the primary tool used by the Army Corps of Engineers to assess juvenile salmon survival in the Columbia River.

"It allows us to select the best operation of the dam," balancing demands of fish, power and recreation, said Brad Eppard, Corps fisheries biologist.

Sound waves from acoustic tags implanted in each fish are picked up by underwater sensors that can distinguish the unique sound of each tag to track individual fish.

"It tells you how fast it is moving and which route it is taking," said Geoff McMichael, program manager for PNNL.

This year researchers are evaluating temporary weir systems at John Day Dam designed to direct the fish away from dam turbines and get them past the dam safely. As the Corps considers placing more permanent weirs at the dam, PNNL researchers are studying whether increasing water flow over two-day periods influences how the fish behave or makes a difference in how many survive the down-river trip.

Changes already have been made at John Day Dam as the result of information collected last year with the acoustic monitoring system developed by PNNL for the Corps.

The data showed fish passing through the dam were being eaten by gulls just below the dam. So this year the air over the water downstream of the dam is strung with long strands of parallel wires hung with fluttering ribbons that haze away gulls.

For 30 days this spring, researchers will release 60 tagged steelhead and 60 tagged chinook twice a day in various spots along the Columbia River near Arlington upstream from the dam.

The day before, an assembly line of workers at the Smolt Monitoring Facility at John Day Dam inserts acoustic tags into the bellies of anesthetized 6- to 8-inch steelhead and chinook that are collected from the dam's turbine bypass.

The workers have two to three minutes to perform surgery on each fish once it's been pulled from the water. They administer more anesthesia, insert a $215 transmitter the size of a couple of grains of rice through an incision and sew the wound shut with a few deft pulls of a needle.

Each transmitter has a battery that will last long enough to track the fate of the fish for 25 to 40 days. Fish that survive the trip usually require about two weeks to reach the ocean from John Day Dam.

Up to 97 percent make it through the dam, but just 75 percent to 85 percent make it to the ocean.

If a fish is eaten by a bird, the beeping is no longer detected once the transmitter is out of the water. The acoustic transmitters send a ripple of sound through the water that sensors detect.

Researchers picked a frequency of 417 kilohertz to make the beeps easy to differentiate from other underwater sounds. Humans can hear frequencies up to about 20 kilohertz and even McMichael's dog could not detect a sound as high-pitched as the transmitters' beeping.

As the tagged fish approach the dam, the transmitters' beeping may be picked up by detectors anchored in the river. About 200 are placed along the river to detect when fish pass. An array of 96 detectors near the dam determine exactly where each fish is swimming.

Detectors at the dam are hooked to cables that provide power and relay information to a computer. Researchers in a trailer atop the dam can watch a monitor as a burst of static every few seconds indicates a detector has caught the beeping of a fish.

That information can be used to create a three-dimensional view with dots representing where dozens of fish are swarming around the dam until each finds a way through a weir, a spillway, the powerhouse or the turbine bypass.

The fish also can be tracked with passive integrated transponder tags that don't send out a signal but can be read if they get close enough to an antenna. These tags are about half the size of the acoustic tags and much cheaper at about $3 each, but yield less information.

McMichael said the passive system typically detects 5 percent to 15 percent of tagged fish, while the acoustic system with its detection range up to 300 yards detects 99 percent of tagged fish.

PNNL began developing the acoustic sensor system, called Juvenile Salmon Acoustic Telemetry System, in 2001 for the Corps. In the five years through 2008, about 65,000 fish have been equipped with transmitters and released in the Columbia River. They've been released not only at John Day Dam but also as far upstream as Lewiston, Idaho. Later this summer, PNNL also will tag and release fall chinook at John Day Dam.

To see video of fish tracking information produced by the acoustic sensor system, go to www.youtube.com and search for JSATS.