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They caught 10 goldfish last week and 18 more this week – each one was over a foot long, the largest being 15 inches long and weighing around four pounds.
“We have had reports from residents of some growing groups of goldfish on the lake,” Ashling said. “People would see them from the shore or if they were kayaking, they would see them when they were in their boat.”
He said some of the fish were the size of a soccer ball.
I knew they were a pretty good size from some previous information but even knowing that it was a little surprising how giant some of these fish were, ”said Ashling. usual if you are used to seeing goldfish in pet stores. “
Goldfish take root on the bottom of lakes and ponds in search of food, which stirs up sediment and can uproot plants. This can impact water quality and native species diversity when goldfish become established, said Przemek Bajer, owner of Carp Solutions, an assistant research professor at the University of Minnesota.
“A lot of times they don’t eat aquatic plants, but the plants just can’t take root in these lakes, they’re just physically uprooted,” Bajer said. “So if you have a lot of goldfish and carp in the lake, usually the first thing that happens is all the aquatic plants are gone.”
Fish also lift up nutrients that had settled to the bottom and their wastes that can promote algae blooms that “turn clear lakes into green lakes.”
Goldfish are native to China and East Asia and have traveled the world, thanks to their popularity as pets and ornamental fish.
“All goldfish are invasive, basically all over the world,” Bajer said. “All over North America, Australia, parts of Europe, they’re really very widespread.”
They are closely related to the common carp, which is another non-native invasive species, Bajer said.
“It’s very likely that someone has just released them, but they can also reproduce in the wild,” Bajer said. “We don’t know if these were released by someone or if they were spawned in the lake by relatives who may have been introduced by someone.”
Bajer said the goldfish would have had to be in the water for several years to reach this size.
He said they will be collecting fish for testing in an investigation next week and will be able to tell exactly how old they are by looking at an inner ear bone that has growth rings, similar to a tree, which can be seen under a microscope.
Ashling said they have worked hard to improve the water quality at Keller Lake and the communities want to protect their investment. He said the cities will decide what to do next once Carp Solutions completes its assessment of the number of goldfish in the lake.
“We know it’s not good to have goldfish in the lake, but in some situations goldfish can be in a lake and not cause a lot of serious problems, but in the right lake in the good conditions, they can cause a lot of problems, ”Ashling said. “So we’re still trying to figure out what our situation is in Keller Lake.
Bajer said goldfish and carp are omnivorous and like seeds a lot, which is a bit unusual for fish in North America. He said they could bait certain areas of the lake with cracked corn to attract goldfish, then collect them in specialized nets without disturbing native fish.
“Because goldfish are smart, they can quickly know where food is, and also because they are social animals. Once a few of them know about food, that information passes through the rest of the world. population.”
Ashling says he hopes the attention the fish have received encourages residents to find a better home for their unwanted pets than Lake Keller.
“It seems there are a lot of people out there who don’t realize how big they can get and some of these situations, and that there are unintended environmental consequences of releasing goldfish or other types of fish. pets in the wild, ”he said.
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