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Apr 4, 2012

State-of-the-art technology helps biologists “tag” hundreds of thousands of fish

WDNR - For the second consecutive year, a high-tech machine is helping tag hundreds of thousands of salmon as part of a multi-state effort to track the movement of the fish in the Great Lakes.

For 10 days, two mass marking trailers owned by the U.S. Fish and Wildlife Service are helping Wisconsin fish biologists do a job that was once done by hand. One trailer is at the Kettle Moraine Springs Hatchery and the other is at the Wild Rose Hatchery, tagging as many as 8,000 fish an hour at each facility. Later this spring, a trailer will be at the Les Voigt State Fish Hatchery in Bayfield.

“This state-of-the-art technology is an incredible advancement for us,” said Randy Larson, supervisor of the Wild Rose hatchery. “We used to tag and fin clip each fish by hand. Now the machine can process as many as 80,000 fish a day. Almost 740,000 fingerlings will make their way through this trailer in the next week and a half.”

The trailer is equipped with six stations that funnel the small salmon into a slot where a 1-millimeter imprinted metal tag is inserted into the snout of the fish. This tag contains a series of numbers that identifies individual fish or batches of fish. At the same time, the machine clips the adipose fin on the top of the salmon.

The million dollar trailers travel to states like Michigan, Illinois and Indiana doing the same process there. The fish clipped and tagged this spring were raised from eggs harvested from spawning salmon last fall as they came in from Lake Michigan.

Sport fishing for Lake Michigan trout and salmon depends on stocking by state fish hatcheries and on a growing number of naturally reproduced fish. Getting a handle on how many of those fish from hatcheries and how many are naturally produced is critical to helping match the number of trout and salmon out there with available prey fish, Larson said.

"The information we gather from the tagged fish is very important to all of us who live in the Great Lakes region,” he said. “Through the tagging process we can learn about the movement of salmon to and from Lake Huron and also determine how many chinook are naturally reproducing.

"It also helps us lay out a fish management plan in relation to predator numbers and abundance of alewife which are critical factors in the impact on salmon populations.”

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