A national wildlife group is slamming a beaver-hunting derby underway in Saskatchewan.

It's the first year for the derby, which runs until May 10.

The competition offers cash prizes to hunters or trappers who kill the largest beaver or who come up with the most combined weight in beaver carcasses in 40 days.

The Association for the Protection of Fur-Bearing Animals says the event is inhumane and ecologically harmful.

The Saskatchewan Trappers Association says the derby helps eliminate bad hunting practices and teaches others how to utilize the entire animal carcass and fur.

It says at this time of year beavers are often killed and left in the field to rot.

"They're putting a price on wildlife like this, where basically we're just incentivizing people to go out and just shoot and kill as many beavers as they possibly can, just for a buck," said Adrian Nelson of the Vancouver-based wildlife association.

"It's really not sound management when it comes to dealing with wildlife populations, and it's just, in a lot ways, disrespectful to a lot of the management policies that we've been working so hard to put into place over the years."

The trappers' group said the wildlife group doesn't appreciate their intent.

"The main thing is that we don't want to see these animals left in the field of decay and rot without using the entire fur resource," said spokesman Ken Gartner.

Nelson said such culls could lead to beaver extinction and her group is calling on the Saskatchewan government to end the contest.