There were lots of snickers when a Chinese-Canadian man was caught trying to leave the United States with 51 turtles hidden in his sweatpants, but the case illustrated the serious threat facing native species from the booming international turtle trade, federal scientists said. To protect native species, the U.S. Fish and Wildlife Service proposed a rule on Wednesday that would put four kinds of freshwater turtle under the protection of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The common snapping turtle, the Florida softshell turtle, the smooth softshell turtle and the spiny softshell turtle, none of which are endangered yet, would be subject to a CITES rule that would let federal authorities begin collecting export data to determine whether limits on harvesters are warranted.   “We don’t know if they’re going into the wild and taking dozens, or hundreds of thousands of large, mature breeding females every year,” said Bruce Weissgold, a CITES specialist with the agency. More than 2 million live turtles caught in the wild are exported annually from the United States, according to the nonprofit Center for Biological Diversity, which supports the rule. Most supply meat and medicine markets in Asia where native turtle populations have been ravaged to meet growing demand, wildlife experts say. The wildlife service described the turtle trade as a boom-and-bust cycle in which a popular species is harvested until its numbers are decimated or regulated, after which a more populous species is targeted. Collette Adkins Giese of the diversity center said a harvester with a few wire-mesh traps can clear a large area of wetlands of turtles overnight. Weissgold said each state enforces its own regulations on turtle harvesting, with many turtle farms located in Louisiana. Kai Xu, the man caught in September and believed by federal agents to be a veteran smuggler, taped the turtles in baggies to his legs and groin and drove from Detroit through a border tunnel, according to the complaint filed in the U.S. District Court for the Eastern District of Michigan. (Reuters)