GARVIN, Minn. — While southwest Minnesota may not be considered a destination for hooking the beloved state fish, Lake Sarah in northern Murray County is gaining notoriety for the particular strain of walleye finding reproductive success in its 1,200-acre turbid waters.
The lake, about 45 miles north of Worthington, has not been stocked with walleye since 1991, according to Ryan Doorenbos, area fisheries supervisor with the Minnesota Department of Natural Resources’ Windom office. That’s an anomaly in a fisheries district known for put-and-take walleyes (stocked by the DNR, taken by anglers).
Doorenbos said of the 80 lakes his office manages, Lake Sarah stands out for its natural production of walleyes year after year. His office is working to understand why.
“We started looking into genetics,” he said, adding that Dr. Loren Miller, DNR Fisheries geneticist, is helping lead the study.
Since southwest Minnesota lakes are commonly stocked with walleye fry and fingerlings from northern Minnesota fisheries, Doorenbos wondered if strains from certain lakes had more success in Lake Sarah. What Miller found was that the Lake Sarah strain wasn’t well matched with walleye from northern strains. Further testing revealed commonalities with other southern Minnesota walleye, continuing the quest for answers.
Through research, Miller discovered walleye stocking in Lake Sarah in the late 1980s and early 1990s with fry hatched from Cannon River walleye eggs harvested near Waterville, also in the southwest district. A comparison showed the genetics of Lake Sarah walleye were well matched with those in the Cannon River, thus resulting in naming the strain the Lower Mississippi Strain, or LMS.
The ideal walleye fishery takes care of itself with natural reproduction, Doorenbos said. If it can be done in Lake Sarah, he wants to know if it can be replicated in other southwest Minnesota lakes.
In 2015, fisheries staff conducted their first walleye egg take on Lake Sarah. Doorenbos said it was a learning experience. They weren’t sure if they could catch enough females to do an egg take or catch them at the right time, generally in mid-April.
“The typical egg take station up north is a river run, where you put out a trap and the fish come to you,” he explained. “In Lake Sarah, we don’t have a feeder stream into it. In order to capture the walleye, you have to go out and net them and bring them back to a location to spawn them.”
In their first attempt, Doorenbos said they harvested 52 quarts of walleye eggs.
“That’s not even a drop in the bucket,” he said. “Up north, they can get several hundred quarts in a day … and this was over the course of lots of days of trying this.
“We were floundering in unchartered territory, but learning and documenting,” he added.
The hatching process was also a trial. The southwest district’s fisheries hatchery is in Waterville, a roughly two-hour drive from Lake Sarah. At Waterville, the eggs incubate for 14 days and, when they hatch, the fry are distributed among the district’s lakes that are scheduled for restocking.
In the first two years of harvesting eggs from Lake Sarah walleye, Doorenbos said the hatch rate was just 30%. Greater success came with more knowledge, and in 2019, they harvested 175 quarts of walleye eggs and had a 70% hatch.
“We’re getting a lot more efficient, we’re getting more eggs and we’re getting a good hatch rate,” Doorenbos said. “We’re getting a fairly good trajectory … and then, of course, COVID hit.”
The global pandemic stopped all egg harvesting efforts by the DNR before it began this spring. As a result, no Minnesota lakes were restocked with walleye this year.
“It’s going to be an opportunity for us to evaluate natural reproduction in our lakes because we didn’t stock,” Doorenbos said.
That said, it’s still too soon to know if the egg harvests from Lake Sarah walleye will lead to improved natural reproduction in other lakes in the district. It’s believed to take up to six years for walleye to reach sexual maturity and begin reproducing. Doorenbos said tissue sampling collected during egg takes on Lake Sarah will be compared with fin clips on age zero walleyes during future netting activities to provide the answers.
“In the next couple of years, hopefully we’ll see some benefit to this,” he said.
Even if testing shows there isn’t an increase in natural reproduction of the LMS strain, it may reveal other reasons for stocking LMS versus other strains in southwest Minnesota lakes, such as survival rates.
A couple of years ago, the DNR began a paired stocking program by mixing walleye fry strains — half LMS with half northern strain — and putting them in the same lake. Doorenbos said initial data indicates the LMS walleye are outperforming the northern strain.
“It’s not that LMS is better, but that the conditions are such that this is where they’re supposed to be — this is where they thrive in their environment.”
To anglers, there’s no identifiable difference between the LMS walleye strain and those of other strains, although to Doorenbos and his staff, it’s a matter of appearance.
“We think the LMS strain seems to be more chunky — a little more volume to their body,” he said. “Typically we look at the bigger, chunkier fish and joke that it must be a LMS, but we have no way of knowing that.”
If you go: Lake Sarah, with a maximum depth of 10 feet, has three public access boat ramps, a county-operated campground and a few opportunities for shore fishing. Zebra mussels were found in the lake in 2018.
“Fishing can be on and off out there,” Doorenbos said, adding that boaters often have to battle the wind. “As a whole, it’s an impressive fishery. It’s the gem of our area in terms of a walleye fishery.”