Group studies Otsego Lake alewife stock

[STWA]

By Tom GraceThe

Daily Star Cooperstown News Bureau Wednesday, August 14, 2002

COOPERSTOWN - The alewives of Otsego Lake are being scrutinized this week by a team of international fish researchers. What they learn here, they hope to apply to studies of the Great Lakes and other bodies of water around the world.

Using sophisticated sonar equipment brought aboard the Biological Field Station's research boat and an underwater camera, researchers are studying alewives, small fish that have thrived in Otsego Lake in recent years.

The researchers already know what the alewives look like; they have a supply of them in a tank at the Biological Field Station. What they want to see is how the alewives appear in sonar and camera images when swimming in the depths.

By studying images generated by their sonar and computer equipment here and comparing them to X-rays of individual fish, the researchers are learning to interpret images more accurately, said Dave Warner, a visiting researcher from Cornell University and part of the project research team.

Bill Harman, director of the State University College at Oneonta's Biological Field Station, said the international team chose to use Otsego Lake as a laboratory "because we have calm water, serviceable equipment, and we're happy to help out with this project."

Scientists spent years figuring out the processes at work, creating a model that allowed them to predict how the lake would react to changes, and convincing society to control phosphorus.

Harman said the scientists are not here to learn more about Otsego Lake, where the fish populations are well-documented.

The team anchored in about 40 feet of water Tuesday and went fishing via computer screens. Individual alewives were put in cages, lowered into the water and studied with camera and sonar.

Warner said the spot the scientists selected Tuesday had many fish, perhaps attracted by their caged alewife.

The scientists worked until dusk, and Horne, a fisheries acoustician, said the project is going well. After returning to the BFS, Horne said, he planned to X-ray individual fish used during the day's research. The X-rays are being developed by Dr. Michael Power's Cooperstown Veterinary Association, he said.

Harman said the scientists plan to be at the BFS for a week. Coincidentally, he said, the alewife population seems to be lower this year than had been expected, as numbers likely died off months ago. Lower numbers of alewives can translate into clearer lake water because alewives feed on the zooplankton that feed on the algae clouding the water. However, the current trend may not last long, he said.

Along with Warner, the boat's research team includes Lars Ruostam of Cornell University, Tomas Didrikas and Thomas Axenrot of Stockholm University, John Horne of the University of Washington and Michael Jecks of the Northeast Fisheries Center at Woods Hole, Mass.

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