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Rescuers Back Off Injured Whales
Scientists this morning called off a plan to use sounds of killer whales to coax two lost humpback whales out of a northern California river and back to the Pacific Ocean.
The whales are hurt, and marine biologists don't want to add even more stress.
They played different underwater sounds last night, and found that a noisy mix of unnatural sounds caused the pair to back away. They didn't respond earlier in the day to recordings of banging metal pipes, or a small fleet of boats trying to herd them downstream.
Rescuers are planning to back off over the Memorial Day weekend if the whales have not moved downriver. The U.S. Coast Guard crews will keep a 500-yard buffer zone around the whales to keep boats away.
This morning, a News10 crew said the whales were swimming in the Sacramento River near the entrance to the deep water channel. They both have injuries that scientists say were likely caused by boats.
Trevor Spradlin with the National Oceanic & Atmospheric Administration Fisheries Service said experts tried three types of sounds. One group of sounds was that of killer whales attacking a gray whale calf. The killer whale was a natural predator of the humpbacks. A second set was a humpback feeding in Monterey Bay. The third group of sounds were man-made tones not heard in nature.
By 6 p.m. Wednesday the Coast Guard and NOAA research boats embarked on this phase of the rescue effort and continued until dark.
At noon Wednesday rescuers ceased what had been referred to as Plan B, the banging of metal pipes in the water in an attempt to repel the mother whale and calf from backtracking upstream. The whales did swim downstream Wednesday morning to about one-half mile north of the Rio Vista bridge but then turned back.
The Coast Guard wants to remind recreational boaters they will continue to enforce a 500-yard safety zone around the whales the upcoming Memorial Day holiday weekend.
Wednesday morning both whales were very active, slapping their tails on the surface of the water.
The whales first demonstrated the behavior Tuesday, which is concerning scientists. They say the change may indicate the whales are distressed. They noticed Tuesday that their injuries have worsened.
Veterinarians believe the freshwater is affecting the whales' skin and their ability to heal cuts they suffered, most likely from a boat propeller, according to Dr. Frances Gulland with the Marine Mammal Center.
"In particular, the wounds are not healing as we had hoped," Spradlin said.
The humpbacks' skin has also changed from smooth and shiny to irregular and pitted, veterinarians say.
Anyone with questions or suggestions on how to rescue the whales can email NOAA.