California After 10 days cruising the Sacramento River and its delta, two wayward humpback whales are showing the first signs of ill health from prolonged exposure to fresh water, experts said Tuesday.
Midafternoon Tuesday, the mother and calf put on a display of tail flipping - which biologists described as a potential sign of stress - as they continued to swim in a broad loop at the north edge of the Sacramento-San Joaquin River Delta near Rio Vista.
Biologists also noticed that the whales' wounds, believed to have come from a ship's propeller, were not healing as well as expected.
Dr. Frances Gulland, of the Marine Mammal Center in Sausalito, said the whales' skin, normally smooth and shiny, had begun to turn pitted and irregular. Fresh water can have a negative effect on the healing ability of skin cells in saltwater animals.
In continued efforts to coax the whales back to sea, a dozen vessels from the U.S. Coast Guard and the state Department of Fish and Game shadowed the creatures, occasionally banging steel pipes in the water to create a noise that might drive them downriver.