After 20 years of trying to phase out commercial turtle trapping in Minnesota, lawmakers have banned the practice.

Gov. Tim Walz signed legislation May 24 that outlaws commercial turtle trapping starting Jan. 1. At that time, the 21 companies and trappers in the state that have commercial licenses will no longer be able to harvest wild turtles.

"This is a huge conservation win after a 20-plus year effort," said Chris Smith, conservation chair of the Minnesota Herpetological Society. "By no means is the work done; there are still lots of turtle conservation needs. But this is a logical step to take."

The ban, part of a package of environmental bills, is only for commercial sellers. Individuals with recreational fishing licenses will be allowed to keep up to three turtles.

Minnesota was one of 13 states that allowed commercial turtle harvesting, and one of just six that put no restrictions on how many animals each licensee could take. In 2004, lawmakers barred the state from issuing any new licenses, but allowed the roughly 80 trappers that already had them to keep them and transfer their rights one time to an immediate family member.

"The intent was that these license holders would sunset and be reduced and eventually eliminated," said Bob Meier, assistant commissioner of the Minnesota Department of Natural Resources. "It wasn't estimated it'd take more than 19 years to get to that point in time."

In 2002, before new licenses were banned, a total of 79 trappers took 20,000 painted turtles and more than 2,000 snapping turtles. Within a few years, the plan seemed to be working. By 2009, there were just 30 license holders left and the harvest had fallen to 3,000 painted turtles and fewer than 1,000 snapping turtles.

But as turtle populations declined across the country, more states banned commercial harvesting or put stricter limits on it. DNR officials believe that put more pressure on Minnesota's turtle population as one of the only states without harvest limits. International demand for the animals has been rising for food and medicine, as well as for use in United States labs and in high school and college science classes, according to the DNR.

Since 2014, about 20 Minnesota license holders have been trapping about 10,000 turtles a year.

Painted, snapping and spiny softshell turtle populations have been falling across the state.

Turtle populations are in "grave danger," Meier said. "They face a significant threat, and we need to do whatever we can to protect them."

Part of the problem is that turtles evolved to rely on mature breeding adults surviving for decades, Smith said. It takes years for a turtle to lay enough eggs to produce one that will survive to adulthood.

"Crows, insects, snakes, raccoons — almost everything will eat a young turtle in a nest," Smith said.

But because very few predators go after turtles that make it to adulthood, they naturally get many chances to lay eggs. When commercial trappers remove adult turtles, they interrupt that process, putting entire populations at risk, Smith said.

State Rep. Jeff Backer, R-Browns Valley, objected to the ban at a committee hearing this spring, reading a letter from a constituent who said far more turtles are killed by cars, predators or even DNR fishing nets than by the remaining commercial harvesters.

The ban "may be focused on something that doesn't get to the true rift of the problem," Backer said.

Road mortalities, especially during spring as breeding turtles leave the water to find a place to lay eggs, are likely one of the biggest, if not the biggest, threats turtles face, Smith said.

"Road mortality is very significant," he said. "But the commercial harvest is significant, too."