The health of two humpback whales that wandered into the Sacramento
River earlier this month continues to be a focus of rescue operations on Thursday.
Sounds of feeding whales and clanging pipes have been unsuccessful in luring the whales back to the ocean. Now scientists are letting the whales rest while they consider new rescue strategies and assess the health of the sea creatures.
"The feeding sounds have worked in past incidents. But for some reason, whether it was the incoming tide or the movement of vessels upstream, the whales took off down the channel and swam about 30 miles down to Rio Vista. The luring sounds were ineffective," said Jim Milbury, a National Oceanic and Atmospheric Administration spokesperson.
Wounded, Wayward Whales
The whales are not only wayward, they are also wounded. Dr. Frances Gulland, principal veterinarian of The Marine Mammal Center, reported changes in the whales' wounds and skin condition observed from her station on the Sacramento River at Rio Vista.
The wounds sustained by the mother and calf are presumed to have been caused by a run-in with a vessel. Biologists say fresh water from the river can impede the healing process for the whales. However, assessing the health of wild animals can be difficult because they have evolved to mask their injuries to protect themselves from predators.
"We continue to monitor the condition of both mother and calf, and have concerns about our recent observations," Gulland said in a statement. "The wounds appear to have worsened over time and their skin has changed from smooth and shiny to irregular and pitted."
Scare Tactics Fail
Scientists turned from their pipe-banging efforts to scare tactics on Wednesday: recordings of orcas attacking a mother whale and her calf. This strategy, too, failed. Next, scientists attempted to synthesize human sounds, likened to car alarms, but that did not work either.
"There seems to be some connection between the incoming tide and the whales swimming downstream against it," Milbury noted. "Scientists are planning to try some new sounds, depending on how the whales' health assessment goes today."
A sample of skin and blubber was taken from the adult whale yesterday and sent to
research labs at Oregon State University, the University of Tennessee, and the Northwest Fisheries Science Center in Seattle. The sample will be tested to reveal the whale's general health condition, her nutritional status, and help identify her population stock.
Unified rescue operations by federal, state, and local agencies are ongoing, but on Thursday scientists decided to let the whales rest. "At the end of the day, the whales are going to do what they want to do," Milbury said. "These are animals and their behavior is unpredictable."