Last year’s decision to take wolves off of the endangered species list left many animal rights activists concerned. Now, a lawsuit filed by the Humane Society of the United States and other animal welfare groups is calling the action “biologically reckless,” citing the more than 530 wolves killed in the Midwest’s first “open season” for wolf hunts.

As ABC News reports, the gray wolf used to roam nearly all of North America; since becoming endangered they have mostly been found in the Western Great Lakes region. While DNR representatives from Wisconsin and Michigan have released statements affirming their belief that the wolf population should continue to be hunted, Minnesota’s DNR spokesman declined to comment. Being placed back on the endangered species list (where they had been for many years) would be the best way to ensure their safety from the 2013 hunting season.