The federal government on Wednesday recommended an endangered-species listing for the loggerhead turtles in U.S. waters, a decision that could lead to tighter restrictions on fishing and other maritime trades.The massive, nomadic sea turtles have been listed since 1978 as threatened, a step below endangered, but federal scientists proposed ratcheting up the designation after reviewing the state of the species.Researchers said primary threats to the loggerheads include injury and death from fishing gear and damage to their nesting areas.The joint proposal by the National Oceanic and Atmospheric Administration's fisheries division and the U.S. Fish and Wildlife Service is not a final decision. If approved, it puts loggerheads on track for an endangered listing by the summer of 2011. The proposal now enters a public comment period.Environmental groups who'd been pushing an endangered listing said the proposal was a "turning point" they hope will lead to greater turtle protections."I think it's huge day for loggerhead sea turtles," said Elizabeth Griffin, a marine wildlife scientist at Oceana. "I think it really draws attention to the fact these turtles are not doing well and more needs to be done to protect them."No one really knows how many loggerheads there are, or how many are being killed by fishing gear or other activities. A species doesn't need falling numbers to be endangered, it can get the listing if it's shown to be threatened by one of five factors, such as disease or "manmade factors affecting its continued existence."Griffin cites a 40 percent drop in the number of nesting females in Florida over the last decade as evidence of trouble. But the Fisheries Survival Fund, an East Coast scallopers group, said in a letter early this month that nesting beach surveys can't provide good evidence of decline because they measure only mature females, who take at least 30 years to reach breeding age.Shaun Gehan, an attorney for the Fisheries Survival Fund, said an endangered listing is unneeded for a species there's no evidence is in danger of extinction. If new protections are mandated for the turtle, it could affect not only fishermen, but maritime traffic, coastal development and waterfront use, Gehan said."We are extremely disappointed that they've taken this approach," he said.Loggerheads are named for their large heads, which contain potent jaws that can crush the hard shells of prey such as conch. The turtles are about the size of a fist when they hatch and make a frenzied dash to the surf. But they typically grow to more than three feet in length and 250 pounds. The animal can log thousands of miles as it travels across oceans.Barbara Schroeder, national sea turtle coordinator for NOAA's fisheries division, said the biggest threats to the North Pacific loggerhead include damage to primary nesting sites, which are mainly in Japan, as well as accidental snaring of the turtles in fishing gear.Andrea Treece of San Francisco-based Center for Biological Diversity said the turtles get hooked by Hawaiian longline fishermen targeting swordfish and tuna and can be injured or drowned.On the East Coast, the main threat to turtles is gear from the region's various fisheries, Schroeder said.Gehan said that scallopers have developed dredges to keep the turtles out with a chain mat that covers the opening. Critics say the dredges keep turtles out, but also crush them, though survival fund officials say there's no evidence of that.A primary benefit of the endangered status would be increased public pressure on protecting the species, Griffin said. But the government would also have to determine "critical habitats," such as where the turtles reproduce or forage. Such places could be subject to additional protections for the turtles, including restrictions on maritime development or fishing.A balance needs to be found to help a species Griffin called "the ambassadors of our oceans" because they travel great distances and can be seen up close when they venture on land."I think that really gives people an appreciation for our turtles and marine life," she said.