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Fisheries experts are preparing to crown the humble but popular walleye as the official king of the Lake Erie "fish community," in hopes of stabilizing an ecosystem that has been disrupted by pollution and foreign invaders.

In a series of fisheries-management goals expected to be completed later this spring, the walleye would be tabbed as the "terminal predator" in the lake's marine food chain, reigning over a hoped-for stable mix of perch and other species.

"Fish communities, in their pristine state, are largely controlled from the top down," Rob McGregor of the Ontario Ministry of Natural Resources reminded participants in a Great Lakes Fisheries Commission meeting that ended here Thursday.

"We have walleye back, and they could be considered rehabilitated," he added. "But we don't consider the fish community to be stable; it's unbalanced and unpredictable."

Walleye, a popular sport fish also known as pickerel, walleyed pike or pike-perch, was a major species in the "pristine" Lake Erie, McGregor noted.

But the lake changed drastically as fishing depleted some stocks and both pollution and cleanup efforts changed water quality.

Lake trout, lake sturgeon, lake herring and sauger all but disappeared from the lake, and blue pike are now considered extinct.

Yellow perch and white perch also suffered, and whitefish -- once caught off Dunkirk and shipped as a delicacy to the finest New York City hotels -- declined so badly that they disappeared from American commercial fisheries here until a small catch was logged again just last year.

"Forage fish" near the bottom of the food chain also were affected, as alewives and smelt invaded the lakes and displaced native species. A critically important food element, the burrowing mayfly, also vanished.

Stocking programs introduced salmon to Lake Erie to replace some vanished predators, with mixed success, and freighters unwittingly brought some new system-altering invaders -- the zebra mussel and a small fish known as the ruffe.

The lake's stable, inter-related fish community degenerated into an "unpredictable, unstable mass of fish species," McGregor noted.

"We now have concerns over the forage base in Lake Erie," he said.

A lengthy process has led to draft goals for the Lake Erie fish community, as part of the Fishery Commission's Lake Erie Committee research.

The draft goals seek a "harmonic" mix of fish types with walleye as the "keystone species" except for the deep-water basin in the eastern end of the lake.

Walleye would be encouraged as the dominant species in the lake's shallow western and central basins and in the shoreline areas off Western New York, but the deeper offshore waters between Long Point and Buffalo would likely be the realm of the lake trout.

Even that native mix of species poses problems for fishery management, McGregor noted.

Lake trout are not reproducing well in Lake Erie, and the zebra mussel may hurt walleye populations.

Part of the problem is that efforts to clean Lake Erie, declared "dead" in the 1960s when detergents and agricultural pollution loaded the waters with phosphorus and algae, may have been too successful.

The murkier waters of earlier times supported more microscopic and plankton food forms, the basis for fish communities. Cleanup efforts brought the nutrient levels back to the earlier, healthier levels, but then kept going.

Zebra mussels, which filter vast amounts of water, have accelerated the process in recent years and have made Lake Erie water's exceptionally clear -- too clear, say marine biologists. The clarity indicates an absence of food, and allows deeper sunlight penetration to the detriment of murk-loving fish species.

"The transparency has increased throughout Lake Erie to the point where it is becoming unfavorable to walleye," McGregor said.

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