Lake Erie Walleye Problems Tied To Reproductive Failure, Not Overfishing - Plain Dealer

The schools of Lake Erie walleye have been dwindling over the past decade, and many anglers are demanding closed spring seasons rather than lower daily bag limits. Fisheries expert Roger Knight says changes in the environment, not the fishing rules, will help rejuvenate Ohio's favorite game fish.

The problem is not overfishing, said Knight, head of Lake Erie fishery management for the Ohio Division of Wildlife. It is the inability of walleye to successfully reproduce in today's version of Lake Erie. "We're learning what causes good hatches," said Knight. "But we can't explain it entirely. We do know Lake Erie is changing."

Knight said pollution, especially phosphate, nitrogen and iron, hinders walleye reproduction. Lake Erie of the 1960s had high concentrations of phosphate, triggering massive blooms of toxic blue-green algae, or Microcystis. Walleye reproduction was poor, the population was low and walleye didn't have the legion of fans they do today. Scientists found while green algae supports rapidly-growing young fish, blue-green algae is a killer. There are many theories for the recent spike in phosphate and nitrogen, but phosphate-spewing invasive species like quagga mussels are considered a culprit.

The Great Lakes states responded almost a half-century ago with changes under the Great Lakes Water Quality Act, including improved sewage treatment, a ban on phosphates in laundry detergent and better farming practices to reduce phosphate run-off. By the 1970s, blue-green algae disappeared. Despite fewer spawning walleye than exist today, Lake Erie walleye numbers blossomed in the 1980s. Fishing guides in Ohio grew from a handful to more than 1,400. Blue-green algae began to return in the mid-1990s, said Knight, with a corresponding decline in walleye spawning success over the last decade. In 2006, a new invasive algae, Lyngbya, was discovered in Lake Erie.

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