The U.S. Navy wants to teach sailors how to hunt submarines off the coast of Jacksonville, but it's trying to prove its proposed undersea-warfare-training range won't hurt the world's most endangered whale. Concern about harm to the North Atlantic right whale from military sonar, vessels and torpedoes might pose a stumbling block to the proposed $100 million training range, which could be built near the whale's protected calving area. The U.S. Navy announced earlier this year that it wants to build the undersea-warfare-training range in a 662-square-mile zone nearly 58 miles off Jacksonville. Environmentalists fear whales could die from being run over by ships or becoming disoriented from the sonar. Under federal law, environmental issues have to be placed on par with other national interests, including economic concerns and military training," said Michelle B. Nowlin, supervising attorney for the Environmental Law and Policy Clinic at the Duke University School of Law. "The courts have been very clear there must be a balance of those interests." Federal reports say the death of even one pregnant female could risk the species' survival. That's why more than a dozen conservation groups have opposed a permanent range for the sonar-based warfare training near the calving grounds. Military sonar, broadcasting an active midfrequency signal at 235 decibels, has a lethal history, with a dozen cases worldwide of mass whale and dolphin strandings and evidence of damage to their hearing after underwater exercises.