Effort to reintroduce these fish goes back nearly 20 years
With splashes and dashes, thousands of tiny brook trout swam free in several southeast Minnesota streams this August, representing a major milestone in a Minnesota Department of Natural Resources effort to restore a unique, native strain of brook trout.
“Our ability to produce these fish in our hatchery and stock them in the wild has been about 20 years in the making, and we are excited to share this historic success story,” said Melissa Wagner, Lanesboro area fisheries supervisor. “Anglers will have the chance to catch these beautiful fish in a couple of years.”
This strain of brook trout, called MN Driftless, came from the Minnesota DNR gathering the eggs and milt from remnant native populations of brook trout, then rearing the fish at the Minnesota DNR’s Peterson Hatchery. Brook trout are the only trout species native to southeast Minnesota.
The adult fish raised and held at the hatchery produced the tiny fingerlings that the Minnesota DNR started stocking into streams in August. The fingerlings are the result of genetics work the Minnesota DNR conducted that identified 37 streams in southeast Minnesota where brook trout retained original, heritage genetics.
“This strain is unique. Unlike most other trout in Minnesota streams, this strain is not imported from outside the state. The strain was produced by going out into the wild, collecting eggs and milt, and bringing them into the hatchery,” Wagner said.
The journey to this milestone began with some genetics detective work. In the early 2000s, Minnesota DNR fisheries staff began investigating whether the state had any remnant brook trout strains in southeast streams. It was already known that most trout present were a result of past stocking efforts of genetic strains originating in East Coast hatcheries. Through years of sampling and genetic testing, Minnesota DNR scientists compared the genetics of fish in 74 streams to the genetics of all the known fish stocked in the past. The result: there was a wild, remnant strain of brook trout still present in several southeast streams.
In the meantime, the Minnesota DNR was stocking a strain of brook trout raised in a hatchery, which was a mix of native and East Coast hatchery genetics. But in 2015, the agency lost the entire population of brood stock fish when a disease spread through the hatchery.
“Losing those fish was a setback, but also gave us a fresh start,” Wagner said. “At that point we knew all the genetics of the trout in all the southeast streams, so it was a chance to develop a completely new strain of heritage brook trout.”
Building the new strain didn’t happen overnight. Rigorous testing for disease was required before Minnesota DNR staff could bring eggs and milt into the hatchery. Then the Minnesota DNR examined the heritage strain genetics and took eggs and milt from trout where the populations were strongest.
“We’re taking genetics from populations that have enough adults in them. These are populations with really nice brook trout — 12-14 inch fish — and we’re going and spawning those,” Wagner said.
Now with the MN Driftless strain brood stock producing young fish, the Minnesota DNR is reintroducing brook trout to streams where they likely existed in the past, enhancing populations in streams lacking brook trout reproduction, and increasing fishing opportunities for people to catch brook trout. Minnesota DNR staff stocked 14 streams in August and will continue stocking the same streams for two more years to establish populations before selecting new streams.
MN Driftless fingerling stocking is not limited to southeast Minnesota. The Minnesota DNR plans to also stock them into streams including in the Detroit Lakes, Duluth, Fergus Falls and Little Falls areas, and the metro area, with the potential to evaluate the MN Driftless strain against past stocking efforts.
“So much effort has gone into this work from DNR Fisheries over the years,” Wagner said. “The history of the people involved is amazing, and a big thanks goes to those who had the vision toward where we are now. I feel special that I get to be a part of it.”
For more information on streams stocked and management goals, contact a Minnesota DNR area fisheries office.