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MN DNR conducts early fish survey on Lake Washington due to concerns of growing cormorant and pelican population at Pigeon Lake
Monday, Aug. 6, 2012

By Jennifer Kotila
Staff Writer

DASSEL, MN – Last week, the Hutchinson Area Fisheries Office of the Minnesota Department of Natural Resources (DNR) conducted a fish survey on Lake Washington.

The DNR decided to conduct the survey a year early due to the concerns of Lake Washington residents regarding the cormorant and pelican population increases at the Pigeon Lake rookery on Minnesota State Highway 15.

The fish survey began last Monday, and was expected to be completed by Friday or today. Preliminary results for the survey will be available from the DNR soon.

Final results will not be available until the data is completely analyzed over the winter.

When a fish survey is conducted, the results are compared to similar lakes throughout Minnesota.

The DNR expects that the fish population in lakes will fall within the 25th to 75th percentile range of lakes of similar size, quality, and depth, according to Lee Sundmark, area fisheries supervisor at the Hutchinson Area Fisheries Office.

Earlier this month, the DNR also conducted a fish survey on Collinwood Lake, which was scheduled for last year, but the state shutdown before it could take place, noted Hutchinson Area Fisheries Specialist Chris Foster.

Tuesday the Enterprise Dispatch joined two crews that were out on Lake Washington to pull in the gill nets and the trap nets that were set the previous day.

The first crew consisted of Foster and Chelsey Mickolichek, a summer intern with the Hutchinson Area Fisheries Office.

Mickolichek attends the University of Minnesota, were she is studying fisheries and wildlife management and has one year left to attend.

The second crew consisted of Brad Koenen, the Hutchinson Area Supervisors Office technician, and Gene Jeseritz, the assistant supervisor.

This was the last fish survey in which Koenen would take part, as he is retiring after 34 years with the DNR.

How a fish survey is conducted

To conduct a fish survey, the DNR sets a number of gill nets and trap nets in the lake, which capture fish.

A gill net is a mesh net 250 feet in length. It has five different sections, each 50 feet in length, with different size mesh.

The smallest mesh is three-quarters of an inch and the largest is 2 inches in order to capture fish in a range of sizes.

Gill nets are best used to capture northern pike, walleye, and yellow perch.

The gill net is stretched between two buoys in an area in the middle of the lake. Fish try to swim through, and their gills are caught in the net.

Due to the nature of a gill net, most of the fish the DNR pulls up in a gill net die. “Fish biologists don’t like to use gill nets, but we are only killing fish in relation to all fish in the lake,” Sundmark said.

Jeseritz used an agricultural analogy to compare sampling done with gill nets. “Say you have a 600-acre corn field, and you want to know what your corn crop is, so you go to the middle of the field and fill a five gallon bucket,” he said. “Does that five gallon bucket hurt how big the crop will be? No. It’s the same as we’re doing here.”

A trap net is a big rectangular mesh cage, with a 40-foot lead that channels fish into the cage. It is set near the shore, and the fish caught in the trap net are released once their data is gathered.

A trap net is best suited for capturing blue gill, crappie, bullhead, and carp.

Based on its size, Lake Washington is sampled using four gill nets and four trap nets.

The DNR sets the nets one day, then returns after 24 hours to pull in the nets, and collect data.

The nets are then reset for another 24 hours. So, for Lake Washington, data from 15 gill net and 15 trap net sets will be collected.

When collecting the data, each fish is measured for length and weighed. Scales are also collected to test the growth rate of the fish.

“It shows how old fish are and how quickly they grow, kind of like tree rings,” Foster said.

In larger walleye, the otolith is also collected to test the growth rate of the fish. The otolith is a bone located in the inner ear, which also grows from year to year, like tree rings.

Although the first gill net pulled in Tuesday did not have many fish in it, Foster said that may be due to the net being placed in a thick weed bed.

The next two gill nets pulled by Koenen and Jeseritz had better catches.

“It looks like the walleye numbers are good. Even though you can’t predict the president with only two precincts in, it looks good for walleye,” Jeseritz said.

He also noted that the number of carp caught was low, as well as the number of bullheads caught.

As the data was being collected, Foster commented that walleye from three different year classes were present in the data collected Tuesday.

A year class is the year the fish would have been hatched or stocked in the lake. For instance, there was a large number of walleye about 8 to 11 inches long that were probably from the 2010 year class.

The largest walleye caught Tuesday was 22 inches long, and 4 pounds.

One of the more interesting catches was a channel catfish, which is not something stocked by the DNR.

“Some probably came over the dam when the water was high, probably from the Crow River,” Foster noted.

Although there were no yellow perch caught, which is a staple of a walleye’s diet, Foster noted there was an abundant variety of minnow species and shiners available in Lake Washington for walleye to eat.

“So far the walleyes we have seen are not emaciated, they seem to be in good condition,” Foster said.

A nice size white crappie weighing just under two pounds and 14 inches long was also caught in a gill net Tuesday.

Preliminary fish survey results for Collinwood Lake

“By and large, most fish are within their normal range,” Sundmark said of the preliminary results for Collinwood Lake.

The last time a fish survey was completed on Collinwood Lake was 2006.

For trap net results, the blue gill numbers are at the fourth highest population they have ever been counted, Sundmark remarked.

Historically, blue gill numbers are higher than the median for lakes of similar size to Collinwood, he added.

He noted that black crappie tend to fluctuate a lot. For instance, in 2006 the number of black crappie was right at the 25th percentile for similar lakes.

However, this year they are above the 25th percentile. The highest year ever measured for crappies was 1981, when they were well above the 75th percentile.

The black bullhead and yellow perch numbers were a little low this year. “I’d like to see one or the other in higher numbers for the walleye to eat,” Sundmark noted.

However, although low, both were within the range expected by the DNR for lakes similar to Collinwood.

Also, bullhead numbers in Collinwood have been historically low for the last four surveys.

For some reason, the carp population in Collinwood Lake was a lot higher than the last survey. “It’s the second highest we have ever sampled in the lake,” Sundmark commented.

He noted that many of the carp were between 12 to 29 inches in length, and represented two age groups. Many of them were about 13 to 14 inches in length.

“Those would be about 1 year old, meaning last year there was a good hatch. Sometimes circumstances favor reproduction,” Sundmark said, noting that the water levels remained high last year.

With Collinwood having a large watershed covering a lot of wetlands, it is possible that carp made their way into the lake from other areas, Sundmark commented.

The number of walleye in Collinwood Lake were above the 75th percentile for similar lakes, which is at or just slightly below the median, Sundmark said.

The numbers of walleye are up slightly from the last survey in 2006.

One of the surprises on Collinwood is the northern pike populations, which really spiked this year. “[The northern pike population] is the highest I have ever seen,” Sundmark said. “Their numbers are way up, which may be part of the reason yellow perch and walleye numbers are down a little.”

The northern pike population was probably affected by the high water levels, as well.

Sundmark noted that northern pike move upstream to spawn in the flooded grassy areas in the spring. “We probably had a northern pike run last year that we haven’t seen for years,” Sundmark said.

A large number of the northern pike sampled were 17 to 21 inches in length, meaning they are probably all from last year, Sundmark said, noting they would know more after they are aged this winter.

Although the bass population in Collinwood Lake was extremely low, only one night of electrofishing was completed before the state shut down last summer, Sundmark said.

The DNR did not repeat the electrofishing this year, so that data is a little more unreliable than the other data.

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