"The more algae we have growing out there, the worse the problem is," Kayle said.

Throughout the summer, dead zones and the generally warming water in Lake Erie's western half push walleyes eastward. While anglers may still find good walleye fishing for out of the Port Clinton area and from the Sandusky area, mobile fishermen tend to move eastward as well.

In the extreme eastern edge of Ohio -- roughly from Ashtabula eastward and in western Pennsylvania -- walleye hotspots are influenced by different factors.

Water exchange, via currents between the central basin and the eastern basin, tends to attract forage fish, which in turn attract walleyes.

This area on both sides of the Ohio-Pennsylvania border usually offers some of the best summertime walleye fishing. Boaters launch out of Ashtabula and Conneaut in Ohio, and from the Walnut Creek Access in Pennsylvania.

The really serious fishermen carry fishing licenses for both states.

This area, lying near the Ohio-Pennsylvania border, has some of the more interesting bottom structure west of the Lake Erie islands area.

Whereas most of the central basin has a bowl-like structure, here there is more irregularity. Last summer, plenty of walleyes could be caught by trolling in depths of 26 feet to 55 feet -- relatively shallow water -- within a few miles of shore. But hard-core walleye fishermen knew that at times, going out farther into the "First Trench" or to the "Second Trench" resulted in catches that often included larger walleyes. It's not uncommon for boats launching from Ohio ports to have to run more than 20 miles to reach the better fishing.

The irregular structure near the Ohio-Pennsylvania border forms the eastern end of the central basin.

Approximately north from Presque Isle and the city of Erie, the eastern basin holds the deepest water in Lake Erie, dropping to a maximum depth of about 210 feet.

Moving eastward from Erie, the bottom drops rapidly. At the North East Marina -- the easternmost Lake Erie boat access in Pennsylvania -- the lake can reach depths of 100 feet within about four miles of shore.

Through this area the dominant structure is called "The Mountain." It rises just slightly as it moves away from shore, and then drops very steeply into the depths.

On the east side of Lake Erie, two distinctly different walleye populations become more evident:

• A local population, which tends to inhabit the shallower water inside The Mountain, and

• Another population that migrates from the western basin and generally inhabits deeper water outside The Mountain.

For the past couple of summers, most boaters have fished inside The Mountain, where locating fish was easier. But those relatively few boaters who ventured outside The Mountain often caught larger walleyes.

In the eastern basin, there is no lack of oxygen below the thermocline, so walleye are often are scattered at different depths. Some days they can be caught at 30 feet or 100 feet on the same troll.