Where have all the walleye gone?

May 24, 2010



A research project to track walleye could help explain why their population has declined for the past 30 years.

Several walleye were outfitted with transmitters last week as part of a project to track their movements during this year's spawning runs in Sandusky Bay and the Sandusky River.

For the third year, the Ohio Department of Natural Resources Division of Wildlife and The Ohio State University have tried to understand what is crippling an ever-decreasing walleye population.

"No. 1, we want to understand why it's declining and then explore avenues to rehabilitate the population," said Jeff Tyson, fisheries biologist supervisor for the ODNR Division of Wildlife Lake Erie Unit in Sandusky. "This particular study should give us some information to direct having an impact."

While it is difficult to determine the current population, the walleye harvest and population are linked.

In the mid-1970s, the walleye harvest was about 12,000 fish. In 2007, the harvest netted about 1,100 fish, or a 91 percent decline.

Walleye typically spawn in the Open Lake Reef Complex near Davis-Besse Nuclear Power Station and near the Maumee and Sandusky rivers.

During the first two years of the study, biologists tagged 50 walleye and learned only four fish were going up the Sandusky River to the Ballville Dam in Fremont, a historic spawning ground.

"It may be telling us that the spawning habitat is limited in Fremont," Tyson said.

With nowhere else to go, walleye have been spawning in Sandusky Bay, a "sub-optimal habitat" because of its turbid waters and muddy bottom, Tyson said. Clear water and gravel bottoms are ideal for walleye spawning.

The Division of Wildlife is looking at a few options to enhance production.

The Ballville Dam could be removed soon to provide additional spawning habitat, Tyson said. The Division of Wildlife is partnering with the city of Fremont and the Ohio Environmental Protection Agency to bring about its removal.

Tyson said they are also working on improving conditions in Sandusky Bay for walleye spawning.

The fish tracking program seems to be heading in the right direction, said Ray Petering, executive administrator of fish management for Division of Wildlife.

"We're very pleasantly surprised that we're able to keep up," Petering said. "These are small tags and short-ranged signal, but we've been able to keep up."

In the meantime, biologists are attaching test-tube sized transmitters to about 200 additional walleye this year.

The transmitters emit radio signals that can be tracked via stationary and mobile receivers in the bay, said Adam Thompson, an Ohio State University masters student in the Aquatic Ecology Lab.

"Understanding spawning location and migration is crucial to understanding how we can restore the stock in the future," Thompson said.

Walleye transmitter

*If you catch a walleye with a transmitter, call the Sandusky Fisheries Research Unit at 419-625-8062 and provide information on fish size, location, transmitter number and jaw tag number.