Rumors floated at Mille Lacs recently suggested the Department of Natural Resources might expand the lake's 2-inch walleye harvest slot, liberalize its two-fish limit — or both.

The reason: Relatively few walleyes have been taken from Mille Lacs this summer, in part because of a shortage of anglers.

But the lake's limit won't be increased, at least not now, DNR regional treaty fisheries coordinator Tom Jones said Tuesday. Nor will its 18-20 inch harvest slot be expanded.

The reason: Mille Lacs walleye harvest numbers improved in the second half of June compared to the first half, and especially compared to May.

"The walleye harvest on Mille Lacs more than doubled the second half of June, from the first half," Jones said.

Angler effort was about the same for the two periods: about 150,000 hours (actually, effort was slightly less in the second half than the first).

Since open water fishing began on Mille Lacs in mid-May, only about 53,000 pounds of walleyes have been caught, Jones said, a figure that includes 17,000 pounds of estimated post-release mortality.

The latter figure as a percentage of the total catch is somewhat high, probably because the 2-inch harvest slot requires Mille Lacs anglers to release about nine fish for every one they keep.

Catching and releasing so many fish aside, this remains true about Mille Lacs walleyes: They're biting.

Which is good. And perhaps not so good.

"I've caught maybe 90 myself," Jones said. "But they've all been fairly skinny."

The lake's hot bite (on the flats and in the rocks) and the condition of its walleyes, Jones said, suggest prey fish such as perch and tullibees are fairly scarce.

Whether disproportionately consumed by the lake's larger walleyes, smallmouth bass, muskies, northerns or all of the above, or whether instead zebra mussels or other invasive species are at the root of the problem, is unknown.

"We're doing a study this year to see what walleyes here are eating, and so far we're seeing a lot of insects," Jones said, "when they should be eating mostly fish."

Another study intended to get a better handle on the size of the lake's walleye population is underway, Jones said. Meanwhile, the lake's hot bite continues.

Dennis Anderson danderson@startribune.com