Grass Carp Found in Lower Wisconsin River Confirmed Sterile

You may remember that on April 27^th the Wisconsin DNR stumbled upon two large grass carp just downstream of the Prairie du Sac dam. This was a significant finding because it was the first time an Asian Carp had been found in the Wisconsin River. See previous blog on April 29^th for more background.

The DNR biologists who found the carp sent a sliver of its head including a piece of its eye to a USGS lab in Louisiana to determine if this fish had been capable of breeding in our waters. They also sent a few bones to another USGS lab in Missouri to determine how old the fish was (we are still waiting for the results from the latter but WDNR biologists believe it to be at least 10 years old).

The results from Louisiana are in and are quite encouraging – the fish is triploid. A triploid fish is one that is modified to have an extra set of chromosomes that prevents the fish from forming glands necessary to reproduce. Triploid carp are still legally released in many states for use in aquatic plant management. Today, thanks to NR 40, it is ILLEGAL to release even triploid carp.

While we can all sigh in relief as we dodged this biological bullet, this remains to be a harsh reminder that Asian Carp are quite capable of invading Wisconsin through our western border, the Mississippi River. This is believed to be the way in which this pair of Grass Carp found their way to Wisconsin.

Join the River Alliance as we partner with Friends of the Lower Wisconsin Riverway, Sauk River PAL and many more to prevent the spread of invasives within the basin! »