May 28 (Bloomberg) -- A humpback whale and her calf made progress in getting back to their normal migration route, moving closer to the Pacific Ocean after wandering in California's Sacramento River for more than two weeks.

The 45-foot (13.7-meter) mother and her 25-foot daughter, nicknamed Delta and Dawn, have moved past the Rio Vista branch of the Sacramento after refusing to cross under the bridge. They have traveled about 25 miles from yesterday's spot. Today, they are about 40 miles (64.4 kilometers) away from the open ocean and within a 200-yard area close to the Benecia Bridge.

``They took a leap of faith and went for it,'' said Joe Cordaro, a spokesman for the fisheries unit of the National Oceanic & Atmospheric Administration, after rescuers had unsuccessfully tried to drive the whales past the bridge. ``If they move at the same speed as yesterday, they could be out of the river and at San Francisco Bay by this evening.''

The humpback whales have been swimming up and down the river since about May 13, when they took a wrong turn into San Francisco Bay while migrating to Alaska. The pair suffered cuts to their backs from the propeller of a boat about 50 miles (83 kilometers) northeast of San Francisco Bay.

``Even though this is much progress there are still some hazards ahead of them,'' said Cordaro. ``There are tributaries they could swim up into where it gets very shallow. Then, once they are in San Francisco Bay, they have to deal with freight ships. We're trying to keep that buffer zone until they go through the Golden Gate Bridge and into the Pacific Ocean. That's when we shut down operations and they are on their own.''

Evaluating Their Health

Scientists yesterday were able to get swabs from the whales to assess the health of the mammals. They also were trying to obtain breath tests to determine whether the calf is still nursing and to assess the general welfare of the mother as both animals suffer from lesions on their backs that aren't healing in the fresh water.

Veterinarians put an antibiotic cocktail in custom-made syringes to inject into the muscle tissues of the whales, said Greg Renik, a spokesman for the state's Office of Emergency Services. The drugs were provided by the animal health units of Bayer AG and Pfizer Inc., and mixed by a local pharmacist.

Today, the whales are back in a section of the river, where the fresh water is replaced by the ocean's salt water, which should help their wounds to heal, Cordaro said.

``The animals are adaptive to a salt water environment, which makes the healing in fresh water difficult,'' said Carrie Wilson, marine biologist at the California Department of Fish and Game.

``The adult has two wounds, one of which is about 2 feet long and about 6 inches deep, just in the whale's blubber layer,'' Wilson said. ``The calf has an injury on its side.''

Recreational boaters were told to remain at least 500 yards away from the whales and to slow down as they moved through the area. Today, the U.S. Coast Guard and the Department of Fish and Game each have a vessel in the water to keep increased Memorial Day boat traffic away from the whales, Cordaro said.

To contact the reporter on this story: Nadja Brandt in Los Angeles at nbrandt@bloomberg.net

Last Updated: May 28, 2007 15:46 EDT