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Colorado Lake Infested With Thousands of Koi

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November 20, 2012

Colorado Lake Infested With Thousands of Koi

By Chad Love

Officials in Boulder are electro-shocking a local lake that is apparently infested with..koi? Thousands and thouands of koi. Sounds like a job for the Flytalk guys. 

From this story on cbslocal.com:
It’s a fish that can brighten a backyard garden, but when koi take over a lake, it can be trouble. On Monday Colorado Parks and Wildlife removed close to 2,000 of the invasive fish from Thunderbird Lake in East Boulder. Where the goldfish came from is a mystery. “It wasn’t something we released; we had no knowledge of it, so it’s a big question mark,” Joy Master with Boulder Parks and Recreation said. It was earlier this year when officials with Boulder Parks and Recreation began to notice changes in the ponds ecosystem. That’s when the non-native goldfish were spotted. 

No more water gardens for them, these koi are destined to be fed to injured birds of prey at a nearby wildlife rehab facility. Anyone ever have a koi infestation in a local body of water?

 

Comments (15)

Top Rated
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from elkslayer wrote 1 year 21 weeks ago

Usually this happens when people want to get rid of their pet fish but are too emotional to kill them or flush them down the toilet. So they take the fish out to a local lake and let them go so they don't have to watch the fish die.

They can actually get pretty big.

+1 Good Comment? | | Report
from chuckles wrote 1 year 21 weeks ago

Nope we have northerns and muskie here in MN. Kinda hard on the Koi.

0 Good Comment? | | Report
from Koldkut wrote 1 year 21 weeks ago

I've caught a carp once that was really a big goldfish, you gotta look for the barbels on the side of the mouth to tell if it's a carp or not. I have heard of a single here or there, but never an infestation.

0 Good Comment? | | Report
from DSMbirddog wrote 1 year 21 weeks ago

Muskies and pike will not control Koi. Nor will electrofishing. They mught as well rotenone the lake and start over. And yes it is people turning them loose.

0 Good Comment? | | Report
from chuckles wrote 1 year 21 weeks ago

Well put one in your Koi pond and let me know how that works out for ya.

+2 Good Comment? | | Report
from DSMbirddog wrote 1 year 21 weeks ago

Carp in MN haven't been controlled by muskies and pike. Chuckles, do you have any good reasons to believe they would control koi? Your lakes are just as susceptible to exotic infestations as any where else.

0 Good Comment? | | Report
from habben97 wrote 1 year 21 weeks ago

what does one use to catch a koi?

0 Good Comment? | | Report
from jay wrote 1 year 20 weeks ago

I have a garden pond full of them. They are mucho dinero to buy. In my area, just a 12 inch koi and bring a couple hundred dollars.

0 Good Comment? | | Report
from chuckles wrote 1 year 20 weeks ago

Hey DSM, I wasn't trying to start an argument but here are my completely unscientific observations.
Lakes that support populations of northern or muskie may have carp in them but they do not dominate the ecosystem. In shallow lakes or warmer waters in the southern part of the state that do not have either fish the carp do become a problem.
I don't have any scientific data to back up my smartalecky comments. I fish several lakes in the Twin Cities metro where you do see a goldfish now and then that someone likely dumped but they do not seem to get out of control. That could be due to a lot of factors other than predation.
Brightly colored fish like Koi typically are at a disadvantage as they are highly visible to predators. Also pond raised and fed fish often do not have the same predator avoidance instincts and behaviors that make for successful populations in the wild.
Have a great Thanksgiving!

0 Good Comment? | | Report
from DSMbirddog wrote 1 year 20 weeks ago

Nor was I, Chuckles. Just making a statement. I fish northern MN at least three weeks a year and it is based rough fish populations in Leech, Cass, and Lake Bemidji. The rough fish may noy be increasing but they were able to get established and maintain their populations.

0 Good Comment? | | Report
from goin2themountains wrote 1 year 20 weeks ago

Blue Mountain reservoir in NM had a heavy population of goldfish. Planting tiger muskie seems to have taken care of the bulk of the problem there.

0 Good Comment? | | Report
from chuckles wrote 1 year 20 weeks ago

Well, hopefully people will make good choices and not release captive fish into the wild. Introducing predator fish is always a tricky subject especially in Colorado where much of the focus is on trout fishing.
There are a couple of studies I have read that show pike and muskie key on soft rayed fish like sucker, trout and carp if they have the chance. Probably a little easier on the palate than a bluegill or perch with its spines out.

0 Good Comment? | | Report
from Carl Huber wrote 1 year 20 weeks ago

We had the same problem with Alligators in NYC

+1 Good Comment? | | Report
from cracker81 wrote 1 year 20 weeks ago

I serviced ponds and aquariums for 6yrs in the Boulder area and I know exactly how they got there. I've been called by new homeowners to 'inspect' the pond that came with the house. Standard conversation:
"How much are they worth?"
"Some can get to the thousands. These, not much."
"how much to maintain the pond?"
"Not much, mostly just time spent cleaning, etc."
"What a pain. I'll just give them away."
What was funny though is that they never wanted to give them to me. My best guess is that they ended up in the golf course ponds or creeks that fed the surrounding watersheds like Thunderbird even after I explained not to do so. Boulderites do not like to kill things. Even when those 'things' screw up the natural 'things'. I even once saw a Koi about a foot long in Boulder creek while fishing! It came right up to me expecting to get fed. And it did, fed to the racoons in the bushes!

0 Good Comment? | | Report
from Buglmin wrote 1 year 20 weeks ago

Here in NM, they controlled those critters with Tiger Muskie. We are now one of the premier places for large tiger muskie. One was caught this summer weighing 36 lbs. and measured 53 inches. That's the best way to get rid of them.

0 Good Comment? | | Report

Post a Comment

from chuckles wrote 1 year 21 weeks ago

Well put one in your Koi pond and let me know how that works out for ya.

+2 Good Comment? | | Report
from elkslayer wrote 1 year 21 weeks ago

Usually this happens when people want to get rid of their pet fish but are too emotional to kill them or flush them down the toilet. So they take the fish out to a local lake and let them go so they don't have to watch the fish die.

They can actually get pretty big.

+1 Good Comment? | | Report
from Carl Huber wrote 1 year 20 weeks ago

We had the same problem with Alligators in NYC

+1 Good Comment? | | Report
from chuckles wrote 1 year 21 weeks ago

Nope we have northerns and muskie here in MN. Kinda hard on the Koi.

0 Good Comment? | | Report
from Koldkut wrote 1 year 21 weeks ago

I've caught a carp once that was really a big goldfish, you gotta look for the barbels on the side of the mouth to tell if it's a carp or not. I have heard of a single here or there, but never an infestation.

0 Good Comment? | | Report
from DSMbirddog wrote 1 year 21 weeks ago

Muskies and pike will not control Koi. Nor will electrofishing. They mught as well rotenone the lake and start over. And yes it is people turning them loose.

0 Good Comment? | | Report
from DSMbirddog wrote 1 year 21 weeks ago

Carp in MN haven't been controlled by muskies and pike. Chuckles, do you have any good reasons to believe they would control koi? Your lakes are just as susceptible to exotic infestations as any where else.

0 Good Comment? | | Report
from habben97 wrote 1 year 21 weeks ago

what does one use to catch a koi?

0 Good Comment? | | Report
from jay wrote 1 year 20 weeks ago

I have a garden pond full of them. They are mucho dinero to buy. In my area, just a 12 inch koi and bring a couple hundred dollars.

0 Good Comment? | | Report
from chuckles wrote 1 year 20 weeks ago

Hey DSM, I wasn't trying to start an argument but here are my completely unscientific observations.
Lakes that support populations of northern or muskie may have carp in them but they do not dominate the ecosystem. In shallow lakes or warmer waters in the southern part of the state that do not have either fish the carp do become a problem.
I don't have any scientific data to back up my smartalecky comments. I fish several lakes in the Twin Cities metro where you do see a goldfish now and then that someone likely dumped but they do not seem to get out of control. That could be due to a lot of factors other than predation.
Brightly colored fish like Koi typically are at a disadvantage as they are highly visible to predators. Also pond raised and fed fish often do not have the same predator avoidance instincts and behaviors that make for successful populations in the wild.
Have a great Thanksgiving!

0 Good Comment? | | Report
from DSMbirddog wrote 1 year 20 weeks ago

Nor was I, Chuckles. Just making a statement. I fish northern MN at least three weeks a year and it is based rough fish populations in Leech, Cass, and Lake Bemidji. The rough fish may noy be increasing but they were able to get established and maintain their populations.

0 Good Comment? | | Report
from goin2themountains wrote 1 year 20 weeks ago

Blue Mountain reservoir in NM had a heavy population of goldfish. Planting tiger muskie seems to have taken care of the bulk of the problem there.

0 Good Comment? | | Report
from chuckles wrote 1 year 20 weeks ago

Well, hopefully people will make good choices and not release captive fish into the wild. Introducing predator fish is always a tricky subject especially in Colorado where much of the focus is on trout fishing.
There are a couple of studies I have read that show pike and muskie key on soft rayed fish like sucker, trout and carp if they have the chance. Probably a little easier on the palate than a bluegill or perch with its spines out.

0 Good Comment? | | Report
from cracker81 wrote 1 year 20 weeks ago

I serviced ponds and aquariums for 6yrs in the Boulder area and I know exactly how they got there. I've been called by new homeowners to 'inspect' the pond that came with the house. Standard conversation:
"How much are they worth?"
"Some can get to the thousands. These, not much."
"how much to maintain the pond?"
"Not much, mostly just time spent cleaning, etc."
"What a pain. I'll just give them away."
What was funny though is that they never wanted to give them to me. My best guess is that they ended up in the golf course ponds or creeks that fed the surrounding watersheds like Thunderbird even after I explained not to do so. Boulderites do not like to kill things. Even when those 'things' screw up the natural 'things'. I even once saw a Koi about a foot long in Boulder creek while fishing! It came right up to me expecting to get fed. And it did, fed to the racoons in the bushes!

0 Good Comment? | | Report
from Buglmin wrote 1 year 20 weeks ago

Here in NM, they controlled those critters with Tiger Muskie. We are now one of the premier places for large tiger muskie. One was caught this summer weighing 36 lbs. and measured 53 inches. That's the best way to get rid of them.

0 Good Comment? | | Report

Post a Comment

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