90% of carp netted from Lake Susan

[Scott M]

Carp roundup is a net gain for Minnesota's lakes

By LAURIE BLAKE, Star Tribune

January 13, 2009

Talk about a great day of ice fishing.

Capitalizing on a quirk of nature -- carp congregate when it's cold -- University of Minnesota biologists pulled more than 3,000 of the unwelcome bottom feeders, some of them as old as 50 years, out of Chanhassen's Lake Susan on Monday.

Working under steadily pelting snowflakes, six commercial fishermen and 10 researchers located the cache of carp under the frozen surface by tracking radio tags placed on some of the fish during the summer.

A 2,000-foot skein net surrounded the fish under the ice as two tractors pulled the catch toward a 15-foot hole where the fish were scooped out onto a conveyer belt to be weighed, measured and counted.

"We probably caught 90 percent of the fish in that lake,'' said biologist Peter Sorensen of the university's Department of Fisheries, Wildlife and Conservation Biology. "This is an effort to remove the vast majority of the carp to see if we can improve the water quality of the lake."

And, he added, "A lot of these females being removed are just fat with eggs.''

The netting marked a milestone in an ongoing U study searching for ways to eliminate destructive carp populations, which dirty up the waters where they are found around Minnesota. The study has focused on three west-suburban lakes: Lake Susan in Chanhassen and Lake Riley and Rice Marsh Lake, both of which straddle the Eden Prairie-Chanhassen city line.

"We have been studying the carp in Lake Susan now for about three years,'' Sorensen said. "We know how many there are and have an idea about where they are coming from.''

The striking thing about Monday's catch, said Sorensen, was that "in that net there was almost nothing but carp -- 95 percent of the fish were carp. They were all large fish."

Game fish were thrown back, but the carp will be sold for food or used as compost at the university's Minnesota Landscape Arboretum.

Removing carp from lakes is nothing new. The key is keeping them from coming back, and that requires suppressing the birth of new fish and blocking the migration of adults between lakes, Sorensen said.

The researchers at lake Susan have made a key discovery, which raises hope for success: although some of the carp are 50 years old, young fish are scarce; the research team believes their numbers have been reduced by a predator, but they are not sure what that predator might be.

That means that if the older fish are removed, they may not be replaced by younger fish. (Age of the fish is determined by slicing open their ear bones to count their growth rings.)

The netting Monday again confirmed the scarcity of young fish, Sorensen said.

With the carp out, Sorensen's team will track the water quality for the next few years and experiment with barriers to prevent migration -- carp tend to move from lake to lake along streams and even drainage ditches. Success will depend upon suppressing the birth of young carp and blocking the migration of fish among the lakes, he said.

Sorensen, who distinguished himself by finding a way to reduce the number of sea lampreys in the Great Lakes, is using similar techniques in the study of carp.

Two-thirds of all Minnesota lakes and all metro-area lakes are infested with the common carp, and they are a national problem as well, Sorensen said.

Carp make clear waters murky by churning up clouds of sediment in their search for food. They can dig a foot into the muck at the bottom of a lake, uprooting good plants and stirring phosphorus on the lake floor back into the water, where it fertilizes algae and weeds. Their own excretions further foul the water.

Sorensen considers them the most damaging aquatic species in Minnesota and says water quality can't be improved until carp are under control.

He focused his research on the three west suburban lakes because they were home to thousands of carp -- some of them 2 to 4 feet long, as big as 18 inches in girth and weighing 10 to 20 pounds -- because they are connected in the same watershed.

On Lake Riley, which is bigger and deeper than Lake Susan, carp will be pulled out this winter to be counted and tagged and then thrown back to help the research team develop a good estimate of carp numbers there.

Once they know the size of the population scientists will determine a strategy for controlling it.

The study is funded by the west-suburban Riley Purgatory Bluff Creek Watershed District and the state's Environment and Natural Resources Trust Fund, with assistance from the Department of Natural Resources.

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It's a good start, but the trick is to close the loop. There are plenty of lakes that commercial netters could take better than 50% of the biomass, but carp always find a way back in or get off a massive spawn. If Dr. Sorensen can close the loop, his research will have been worth every million.

[Ralph Wiggum]

Very cool. I'd like to see this done sometime. I know they have netted carp from our lake in the winter in the past, but I've never been witness to it. Sounds like quite the operation.

[leech~~]

Sounds like a great way to help out Miss Paul get more fish sticks!! and clean up the lakes.

[HossFisher]

I can believe they said some of the fish were up to 4 feet long. A 4 foot carp would be 48 inches and the state record for a 55lber is only 42 inches.

[Ralph Wiggum]

Yes, but that is a hook and line record. There are bigger carp out there. I've seen photos of a 80-90 pounder that was arrowed a few years back.

Not saying that their fish were actually 4 feet long, but there are certainly carp out there that size.

[mainbutter]

I thought eventually carp stopped getting longer and just got fatter.. 48 inches is longer than what I thought the 80 lbers I've seen pictures of looked like.

[fishuhalik]

Awesome news! I love carp just as much as anyone, but ya gotta admit any kind of invasive species is a problem.

[goblueM]

I've personally seen carp (no exaggeration) that were 4 feet long. Lake Erie and Lake Michigan. Holy cow. We just couldn't believe how big these things were

[Selmer]

I remember getting to watch carp "round-ups" over in eastern SD back in the '90s. It was something else to see, semi-loads of carp leaving the lakes!

[mainbutter]

I've personally seen carp (no exaggeration) that were 4 feet long. Lake Erie and Lake Michigan. Holy cow. We just couldn't believe how big these things were

Were they fat too, like the big 'uns I've seen get?

I've seen a 32 lber as round as a dinner plate(and quite bigger than one) but it wasn't all that long, and I've also seen 30+ lbers that are more fish-shaped.

[chanfish]

they did this at lake susan awhile ago. i happened to be driving by and stopped to see it. semi fulls of brown carp. what i seen then and see from the newest pictures is all the carp were very, very similiar in size and shape. dark brown and round as a beach ball..exact same size..

i guess my question is it didnt do any good the last time they did it. now with leaving 10% in we will just see more of the same in about five years..wouldnt they be better of killing off the lake, putting fish barriers in and restocking??

[Ralph Wiggum]

I've seen a 32 lber as round as a dinner plate(and quite bigger than one) but it wasn't all that long, and I've also seen 30+ lbers that are more fish-shaped.

Like this? Not quite 32 lbs, but round as can be

[DEADhead]

that's a nice little piggie ryan.

[Dave S]

I know they did this in Lake Jefferson in Le Sueur County a couple years ago. I couldn't believe the number of carp they had. They appeared to be in the 5-10 lb range.

[Sassyshad]

thats awesome that they're getting rid of all the carp. and there are some monsters out there. my buddy and i shot 300+ with our bows last summer. we shot a ton in the 30-40lb range. most of them were shorter but fat. i couldnt even imagine getting a 4 footer!!!

[erickol]

I am going to be sure to fish Susan for carp in the next couple of years. what fish that are left are going to have less competition and I suppose in theory could get pretty big pretty fast.

[River Dan]

this one was 36#

[HossFisher]

I guess they did the same thing on Riley yesterday as they did on Susan.

[MinnesnowtaWild]

I enjoy catching Carp, but definitely realize the problems they bring to our lakes. Long Lake is a sad example of this.

[counter545]

... 50 years old some of these carp are.. amazing. .. i don't have a problem with the DNR trying to clear some lakes of carp, but mannnn, keep a lot of em around they're an awesome sport fish.

[tweedlap]

River Dan,

That is a monster. The longest I have seen in all of my years.

tweed

[SHAQ]

to bad they wouldent clean out some of the trash in tonka, like the dogfish & zillions of carp

[Ralph Wiggum]

to bad they wouldent clean out some of the trash in tonka, like the dogfish & zillions of carp

FYI, bowfin (AKA dogfish) are not trash. They were swimming in Lake Minnetonka long before your precious walleye, bass, and musky.

[erickol]

If you cleaned the "dogfish" (bowfin) out of tonka, the sunfish , crappie populations would be even more dominated by stunted fish than they are now. It would be a huge mistake. If you see folks killing them for the sake of killing them, ask them to put the things back alive! I gotta believe that if we put bowfin back into some of the waters where they have been removed, the panfish populations would support more trophies.

Just because they are ugly doesn't mean they are not vitally important to healthy fisheries. And like someone else said, they were swimming in the lake before the artificial walleye fisheries were made.

Ignorance destroys fisheries, not bowfin!

[fishuhalik]

well said fellas