Mel Haugstad, the retired Department of Natural Resources trout manager whose knowledge of southeast Minnesota streams and their cold-water fisheries was encyclopedic, and who chronicled every trout he caught between 1959 and 2012 — all 32,795 of them — died Monday at Rochester Methodist Hospital at age 82.

The cause was cancer, a disease he fought for years.

“I had 42 radiation treatments at Mayo,’’ Haugstad told the Star Tribune in May, “then chemotherapy for a year, then hormone therapy, then a new type of chemotherapy they came up with, which I took here and twice in Florida.’’

Haugstad was similarly determined in defending trout and their habitats, particularly as fisheries manager in the southeast, a position he held from 1969 until retiring in 1990.

In that job, he regularly combated “big agriculture,’’ fly-fishing snobs (Haugstad was as capable with a fly rod as anyone, but also fished with bait and lures) and the DNR bureaucracy itself, believing the relative health of southeast streams and fish was a measure of the region’s vigor.

Haugstad, of Preston, Minn., was born Nov. 15, 1930, on a farm south of Spring Grove, Minn. He bought his first fly rod with cash he earned trapping gophers and worked on area farms after graduating high school to save money for college.Haugstad didn’t enroll as a fish and wildlife biology student at the University of Minnesota until 1956. But a year later, he was hired as a fisheries manager by the Minnesota Conservation Department, forerunner to the DNR.

“When I worked in St. Paul for the DNR in the early 1960s,’’ Haugstad said in May, “most of the native trout fishery down here [in the southeast] was lost due to logging, burning, clearing the land for agriculture and other poor land practices. Habitat work and education of landowners helped bring it back.”

Haugstad formed the Minnesota Trout Association in 1997 and edited its newsletter until his death.

Melford C. “Mel’’ Haugstad is survived by his wife, Vonnie; three sons and daughters-in-law, Jeffrey (Julie), Kevin (Jami) and Greg (Laurie); and various grandchildren, step-grandchildren and a great-grandchild, among other relatives.

A memorial service will be held at 10 a.m., Saturday, Oct. 5, at Christ Lutheran Church, Preston. Visitation will be an hour before the service and at Thauwald Funeral Home in Preston, 6-8 p.m., Friday, Oct. 4. Burial will be in Fort Snelling.