In the blue-green surf, 11 endangered North Atlantic right whales surface, jump and shoot mist high into the air through their blow holes.Dozens of motorists pull over on A1A and grab their cameras and binoculars as the whales frolic in three groups near this north Florida town's pier."It's a good day," whale researcher Jim Hain said as he watched through binoculars from a restaurant's top deck.But this picture postcard scene is at the center of the latest debate over how to balance the protection of marine mammals with the military's need to use sonar for training.The right whale is among the world's most endangered mammals. Hain and other researchers believe there are only about 300 to 350 of them remaining and a loss of some breeding females could be devastating.Until now, their biggest threat has been ship strikes and entanglement in fishing lines. But researchers worry a new threat may be lurking in the waters off northwest Florida and south Georgia where the whales come each year from the North Atlantic to give birth — two Navy sonar projects.The National Marine Fisheries Service just approved the Navy's plan to do sonar training along the Eastern Seaboard — the right whales' habitat — but requires it to take precautions to protect the whales and other marine animals.The Navy also wants to locate an anti-submarine warfare training range on 75 miles off the north Florida coast. Kings Bay Naval Submarine Base and Mayport Naval Station are nearby. The facility, the Navy says, would enable it to train in a shallow-water environment. The affect on marine mammals would be negligible, the Navy said.But environmentalists argue that mid-frequency active sonar can disrupt whale feeding patterns, and in the most extreme cases can kill whales by causing them to beach themselves. Scientists don't fully know how it hurts whales."In proposing to locate the training range just outside of this federally designated right whale critical habitat, the Navy ignores or turns a willful blind eye to the various risks posed by its activities," said Catherine Wannamaker, an attorney with the Southern Environmental Law Center in Atlanta.The Georgia Department of Natural Resources and the Florida Fish and Wildlife Conservation Commission are also concerned about the sonar. Florida has asked the Navy to cancel the project or at least close the range from mid-October to mid-April. That's the period the whales are in the area.Environmental groups and the Navy have been at odds for years over sonar, but the U.S. Supreme Court ruled in a Southern California case in November that military training was more important than protecting whales.After that ruling, the Navy and the Natural Resources Council settled over the use of sonar in Hawaii. It requires the Navy to continue research on how sonar affects whales and other marine animals, but does not require sailors to adopt additional measures when they use sonar.A federal study determined Navy sonar tests likely caused the deaths of six beaked whales in the Bahamas in 2000. A necropsy determined the whales had bled heavily near their ears. The report said the wounds would not be fatal but could make the animals disoriented and beach themselves.Armed with a constantly ringing cell phone, a walkie talkie, a clipboard with whale sightings and cameras with long lenses, Hain has made an annual pilgrimage each January for 19 years, for his study of the whales as they return. He works with a team of about 200 volunteers and the Marineland Right Whale Project who come to the shore to spot the elusive whales and their calves.A quiet twin-engine, slow-flying aircraft is used to photograph the whales, which can be individually identified by the white markings or "callosities" on their heads and tracked."The thing we've learned, but we sort of knew ahead of time, is their variability," said Hain, a senior scientist with Associated Scientists at Woods Hole, Mass. "These whales have individual characteristics and preferences."It has been a good season for the right whales. Researchers have spotted 39 calves and mothers, the highest number recorded in about two decades of watching, and about 100 juveniles and sub-adults of the 165 whales spotted. They received their name because they were considered the right whales for whalers to pursue. They range from 45 to 55 feet and can weigh up to 70 tons. As baleen whales, they have plates to filter small crustaceans from the water instead of teeth. They swim close to shore, are slow and float when dead. The species takes about 10 years to reach sexual maturity and some females may be 20 before having their first calf. Hain estimates the whales have a 65-year or longer lifespan. Volunteer Becky Bush sighted the group of right whales off Flagler Beach. Like many of the watchers, she spends hours scanning the waters. She is thrilled when one is spotted and was amazed to see 11 at once. "It's so addictive. There are so few of them," she said. For now, Hain is reluctant to jump into the fray over the Navy's proposed anti-sub training range, which will take several years of study before it's built. "We look at the science and we look at what the facts tell us and we submit our comments based on that," he said. "There is no point in commenting until we have some facts on the table."