Mille Lacs walleye fishing during the month of May nearly doubled in intensity this year under a regulation that allowed each angler one keeper if the fish was 21 to 23 inches long or longer than 28 inches.

Biologists for the Minnesota Department of Natural Resources (DNR) said the number of walleyes harvested throughout the duration of the special season was just under 4,000 fish and met expectations. That means chances are decent that Mille Lacs will be open to catch-and-release walleye fishing without closure for the rest of the summer.

“It does fall within right where we thought we’d be,’’ said Eric Jensen, one of the DNR’s large lake specialists. “So far, so good.’’

Jensen said cool water temperatures in May suppressed hooking mortality — the estimated number of walleyes that die after being caught and released. Estimates for harvest and hooking mortality count against the state’s yearly allocation of walleyes taken from Mille Lacs.

This year’s allocation for state license holders — based on estimated walleye abundance — is 87,800 pounds. Including winter ice-fishing totals, anglers so far have cut into the 2019 allocation by 35%, Jensen said.

He said May’s catch rate on Mille Lacs was strong — estimated at one fish for every two hours of fishing. The bite was enjoyed by thousands of anglers who put in a combined estimate of 195,000 fishing hours — nearly doubling the angling pressure for the same period in 2018 and 2017 when no keepers were allowed.

Mille Lacs Area Fisheries Supervisor Tom Heinrich said Mille Lacs fishing pressure would have been significantly higher for May if one of three weekends wasn’t spoiled by weather.

“The middle weekend was horrible,’’ he said. “Had we had a good weekend there, fishing pressure would have easily doubled.’’

Jensen said fisheries managers will be keeping an eye on the walleye catch rate and water temperatures. If June brings a big hatch of perch — a key forage fish for walleyes — the walleye bite could fall off, he said. Higher water temps and higher catch rates escalate the estimated rate of hooking mortality.

Heinrich said DNR research into last month’s fishing effort on Mille Lacs showed considerable interest in smallmouth bass. Twenty percent of anglers interviewed by the agency’s creel survey clerks were at Mille Lacs to target bass. Together, they caught and released an estimated 22,000 smallmouth, Heinrich said.

“The interest in smallmouth has been increasing,’’ he said.