The former rugby player dropped a Macho Minnow lure into 12 feet of water and let it sit on the bottom, occasionally jiggling it. He and four of his colleagues from the Department of Natural Resources (DNR) were on a receding ice shelf on the north end of the lake. Past study data suggested that walleyes might be staging there, before spawn.

Pow! The science was good. Pereira landed a 25-incher and the group landed a dozen other healthy specimens in less than two hours. Not long after sunset, he was back home in Cottage Grove, nodding again to the value of fisheries research.

“Based on stomach contents,” he said, “it turns out they were keying on burrowing mayfly larvae.”

When Pereira retires from the DNR on June 8, he will be remembered as a leader who based Minnesota fish management decisions on resource studies without fear or favor. The importance of his position has prompted DNR officials to contact fish and wildlife agencies in all 50 states in search of a successor.

“It’s a full-court press to get the best and the brightest to apply,” DNR Fish and Wildlife Director Jim Leach said. “It’s totally wide open, and the word is getting out.”

Leach said Pereira is credited within the agency for building a strong staff of regional fisheries managers and for making research and science a top priority. “Don really brought home that trait,” Leach said. “He solidified science-based decisionmaking.”

Pereira, a native New Englander who grew up in the Boston suburb of Woburn, Mass., originally studied biology at the University of Vermont. But he moved to Minnesota in the early 1980s to devote his education to fisheries science, joining the DNR in September 1983 as a research assistant and earning his fisheries Ph.D. in 1992 from the University of Minnesota.

Pereira turns 60 in August, but he has 35 years of experience at the DNR. He wants to spend more time with his wife, Lyn, and son, Leo. He’s also pursuing job leads for fisheries work in the private sector and is expanding his role with the Great Lakes Fisheries Commission, to which President Obama first appointed him in 2014 as a U.S. commissioner.

“I love my profession,” Pereira said. “It’s just that the day job is a grind.”

Pereira’s nearly five-year reign as the state’s leading manager of game fish populations coincided with high-level social disturbance around Mille Lacs. While a vocal group of local business owners and other community members assert that the Mille Lacs walleye fishery is healthy and capable of sustaining a bountiful harvest, Pereira and other biologists inside and outside the agency — including tribal officials who co-manage the fishery — are certain the lake has undergone serious ecological changes. The walleye population has declined and too many baby walleyes aren’t surviving, studies and external reviews have found.

Pereira said that while the state’s allocation of walleyes was reduced by court-mandated sharing of the resource with Chippewa bands, tribal spearing and netting of walleyes during the spawning period is “absolutely not the problem.”

Another misperception that has complicated fish management at Mille Lacs, he said, is community mistrust in the joint technical committee made up of state and tribal biologists. The committee sets an annual safe-harvest level — a baseline that has required catch-and-release walleye fishing and temporary fishing shutdowns. Disgruntled Mille Lacs stakeholders liken the arrangement to a “smoky back room,” Pereira said.

“The perceptions are way off the mark all around,” he said.

As chief, Pereira built on the foundation laid by predecessors Dirk Peterson and Ron Payer. Research grants were a constant pursuit, and he put a lot of DNR resources into studying Minnesota’s 10 largest sport fishing lakes. The payoff includes four detailed, freshly written lake management plans covering Leech Lake, Lake Vermilion, Lake Superior and Lake of the Woods.

“We stressed individual lake management planning,” he said.

As a young field scientist, Pereira was stationed at Lower and Upper Red lakes from 1987 to 1991 — before the combined walleye fishery crashed from overharvest and ecological factors. He witnessed what could be accomplished with research and management when state and tribal biologists pulled off a stunning turnaround in the system by closing it to fishing for seven years and stocking it.

Multispecies strong

During Pereira’s tenure as fisheries chief, the state began to promote Mille Lacs as a world-class destination for smallmouth bass fishing, and muskie fishing was expanded.

Those moves were in keeping with Pereira’s long-term vision of Minnesota as a haven for multispecies angling.

“I think that’s what puts Minnesota on the map for fishing,” Pereira said. “It’s our diversity.”

By his own assessment, Pereira said any success by DNR Fisheries while he was chief was achieved by allowing the section’s talented employees to work on projects free of political interference.

“That’s an important part of the job … let them work and get the hell out of the way,” he said.

Under Pereira, the 300-person Fisheries section produced a sweeping change in northern pike regulations; made history on Lake Superior by returning wild lake trout to prominence; protected North Shore steelhead by cutting the Kamloops rainbow trout stocking program; dumped ineffective walleye stocking to save $500,000 a year; closed the French River fish hatchery (saving another $500,000 per year); revamped the Crystal Springs hatchery; and recently started a muskie restoration in Gull Lake.