Experts say the otter population is thriving — thanks in part to managed harvests — but animal welfare groups worry the expansion of trapping in the U.S. and Canada in recent decades isn’t sustainable. Trappers in North Dakota for years have pressed state wildlife officials to allow otter trapping as the animals have moved into the eastern part of the state from Minnesota, where the member of the furred weasel family is more established. River otters were once abundant throughout North America, but unregulated trapping, water pollution and habitat loss had depleted populations by the early 1900s, according to the Association of Fish and Wildlife Agencies. Bryant White, trapping policy program manager for the Association of Fish and Wildlife Agencies, said river otter trapping devices are generally considered humane by the scientific community. In North Dakota, Tucker said the only negative feedback she has received has been from two phone calls, despite Game and Wildlife officials discussing otter trapping at meetings around the state in the past year.