Large ships could threaten two lost whales

Rescuers were encouraged by progress in returning two lost whales to the ocean but were concerned about encounters the whales might have with large ships as they neared the San Francisco Bay। A mother humpback whale and her calf on Sunday made it down the Sacramento River as far as Honker Bay, roughly 50 miles from the sea, said Bernadette Fees, deputy director of the California Department of Fish and Game.The whales had been lingering for a week near a bridge about 70 miles from the sea.Thus far, the U.S. Coast Guard boats guarding the whales as they swim down river only have had to deal with recreational boats and windsurfers. But as the whales get closer to the bay, they will encounter large oceangoing vessels that could harm them."These larger vessels are a real concern to us," said Greg Hurner, a senior adviser with the California Department of Fish and Game. "We will try to keep a safe zone around them, and our enforcement vessels will reach (larger boats) on the marine channel."The whales are also at risk of taking a wrong turn and swimming up a number of tributaries and sloughs, where they could get stuck in shallow mudflats. Fees said rescuers will position boats to block the whales from heading in the wrong direction.Scientists did not know why the whales began moving down river again Sunday after frustrating biologists' efforts to urge them on using a variety of tactics, Renick said.The whales were first spotted in fresh water May 13 and drew large crowds to the Port of Sacramento before leaving and swimming to Rio Vista last week. Biologists speculated that a tugboat firing up its engines had triggered the sudden departure.The humpbacks' long exposure to fresh water has led to serious skin damage, biologists said, making them vulnerable to germs they would not face in their native saltwater habitat.Before the pair headed south, veterinarians used sponges attached to a long pole to swab skin cells from bumps resembling blisters or lesions on the mother and calf."We really need to try to get them back into a more appropriate environment so they can start healing," said Trevor Spradlin, a marine mammal biologist with the National Oceanic and Atmospheric Administration.The bumps could be the result of an infection from bacteria, a virus or fungus, but scientists wouldn't know for sure until they examine the skin cells under a microscope, Spradlin said.Deep gashes in both whales — likely suffered from a run-in with a boat's keel — have worsened during their river stay. But veterinarians believe antibiotics injected into both whales Saturday could slow the damage.Scientists have said the whales are not in immediate danger of starvation despite a lack of the saltwater foods that make up their diet, since humpbacks typically don't eat until the summer feeding season."Whales are not people. They don't need three square meals a day," said Brian Gorman, a spokesman for NOAA. Said Grygery