About 30 more invasive carp were pulled out of the Mississippi River last week, suggesting that the destructive fish may have established a foothold in Minnesota.
The silver and grass carp were caught in shallow backwaters of the river's Pool 8, near La Crosse, Wis., just above the southernmost lock and dam in Minnesota.
More than 50 of the carp were caught in the same pool last spring, and another 14 were caught earlier this year.
Despite the high numbers, however, it's still unknown if enough invasive carp are above the dam to successfully breed or establish permanent populations in the state, said Ben Larson, invasive carp field lead for the Minnesota Department of Natural Resources (DNR).
All the fish caught were adults, he said.
"I don't think it indicates they're spawning," Larson said. "They're mass spawners that need a lot of fish together to successfully pull it off. That's why we came here to do this and why we're so excited about taking 29 of them away."
For the first time in Minnesota, state and federal agencies worked together over the course of the week to systematically hunt the carp.
The fish have been working their way north up the Mississippi River since the 1970s, when fish farms and sewage treatment managers in the American South brought them over from Asia to clean algae.
Some of the carp can grow to more than 100 pounds and upend native ecosystems by eating up to 20% of their body weight daily. Silver carp, which grow to about 20 pounds, gather in schools and leap out of the water en masse when they're scared, injuring boaters and water skiers.
An increasing number of the fish have been caught each spring in Minnesota.