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New Walleye Tagging Project Begins in Lakes Erie and Huron
April 6, 2005
When the friendly DNR creel census clerk asks you about your angling success after a day's fishing on Lake Erie or Lake Huron this summer, if your catch includes walleye, don't be surprised if the clerk pulls out a small handheld device (that looks something like a TV remote) and passes it over the head of the fish.
The clerk will be looking for an internal passive integrated transponder (PIT) tag.
A PIT tag is a radio frequency microchip about the size of a grain of rice that transmits a unique ID code or number to a special detection wand. Unlike the external, metal tag that biologists attach to the walleye's lower jaw, a PIT tag will not be noticeable to anglers. A syringe is used to place the PIT tag just under the skin in the head area.
Each year, thousands of walleye in Lake Erie and Lake Huron (Saginaw Bay) are tagged by the resource agencies who cooperatively manage these important fisheries.
According to Gary Towns, fisheries supervisor for the Michigan Department of Natural Resources' Lake Erie management unit, walleyes are captured at spawning sites during March and April. Each fish is measured, sexed and visually assessed for reproductive status, and a scale sample is collected for aging, before the jaw tag is applied. The fish is immediately released.
The lake-wide tagging program for Lake Erie, begun in the early 1990s, helps fisheries managers in Michigan, Ohio, Pennsylvania, New York and Ontario set the annual total allowable catch for the walleye fishery, which is based, in part, on measuring harvest rates through the voluntary reporting of tags by recreational and commercial fishers.
"We depend on anglers to report the jaw tag capture back to us," Towns said. "The jaw tags are used to estimate the exploitation rate of the fishery which is the percentage of the adult walleye population harvested by anglers."
Biologists also use the tag return rate to estimate the natural mortality level for walleye, which is another important factor in assessing the sustainability of the fishery. Tag returns also provide information regarding walleye movement patterns in the lake.
"Unfortunately, there are some disadvantages to using the external jaw tags because they can fall off and anglers often fail to report them," Towns said.
So beginning in 2005, adult walleyes from several stocks in Lake Erie and Lake Huron are being tagged with a PIT tag.
The goal of the lake-wide research project is to implant PIT tags in approximately 14,000 walleyes (3,000 in Michigan) each year for three years; both tag types will be applied to 4,500 fish. The project is being funded by the Great Lakes Restoration Act Fund.
The annual walleye tagging for Saginaw Bay takes place on the Tittabawassee River said David Fielder, research biologist at the DNR's Alpena Great Lakes Fisheries Research Station.
"A total 3,000 walleyes will be collected by electrofishing over a period of four or five days for jaw tagging by the DNR's Southern Lake Huron Management Unit," Fielder said. "Then we'll double tag 1,000 fish with both the jaw tag and the PIT tag." .
Since the Saginaw Bay walleye tagging effort began in 1981, the DNR has tagged more than 80,000 walleyes.
"Walleyes also are tagged in Lake Erie and we often see some of them as far north as Saginaw Bay," Fielder said. "Our Saginaw Bay tag returns will show up as far north as Thunder Bay and as far south as Lake Erie. This research will help us learn more about the movement patterns of these fish in each lake.".
For the Lake Erie part of the project, DNR biologists in southeast Michigan selected the Huron River because its spawning run of walleye is fairly easy to sample with an electrofishing boat. According to Mike Thomas, research biologist at the Lake St. Clair Fisheries Research Station, it will take about 10 days of shocking to reach the target number of 2,000 PIT-tagged fish.
"The size of the spawning run is small enough that we often recapture fish that we've tagged in previous years, but this provides more information about tag retention rates or patterns in tag loss," Thomas said.
Because the caught fish will be analyzed for tags by agency personnel rather than relying on anglers recognizing and reporting tags, Thomas said biologists hope to learn if enough harvested fish with the PIT tags can be checked to estimate exploitation.
"We also are very interested in looking at the comparison of tag retention between the standard jaw tags and the PIT tags," Thomas said.
In addition to the annual creel surveys, recreationally caught walleyes also will be scanned for tags at several fish cleaning facilities along Lake Erie, and commercially harvested fish in Ontario will be examined for PIT tags by port observers.
Results of this study will aid in decision analysis modeling, validate past tagging studies and improve understanding of mortality components for Lake Erie walleye.
"It is very important that anglers report the jaw tags if they get one on a walleye they've caught," Fielder said. "They can do this by writing to the address on the tag or going to the DNR Web site."
Anglers should report the tag number, date the fish was caught, location of the catch (both general and specific) and length of the fish. To report this information online, go to www.michigandnr.com/TAGGEDFISH.
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