Marine biologists planned to spray two lost, injured whales with fire hoses Friday in an attempt to evoke a reaction that would force the pair to head back to salt water.
The method has never been tried before, and biologists don’t know how the whales will respond. If they like the spray, crews will try to lure them back to the ocean; if they hate it, they’ll try to force them there.
Biologists planned to spray the whales both above water and underwater from the deck of a boat. The approach comes after attempts to lead them back to sea using the sounds of clanging pipes, feeding humpbacks and killer orcas failed.
The mother whale and her calf were last spotted about 70 miles from the ocean, in an area of the Sacramento River where they have been circling for several days, said Carrie Wilson, a biologist with the state Department of Fish and Game.
Officials gave the wayward pair a break Thursday. The physical condition of the whales had not changed much, but their wounds — apparently sustained during a collision with a boat’s propeller — continued to deteriorate.
“We don’t want to do anything that will impose stress on them today,” Wilson said. “We do not want them to become habituated or desensitized to the different types of things we’re doing to coax them down the river.”
The rescuers also are working on a plan to inject the whales with antibiotics to help their wounds heal. Scientists are still developing the compound and will likely use a syringe attached to a pole or a dartgun to administer it, said Frances Gulland, who is leading the campaign to move the whales back to the ocean.
Pair retreated from one recording
Scientists tried playing different underwater sounds on Wednesday evening. The lost whales did not respond to recordings of fellow humpback whales or blood-thirsty orcas, but a noisy mix of unnatural sounds caused the pair to back away, Wilson said.
The stranded whales also didn’t respond to the banging of banging metal pipes or a small fleet of boats trying to herd them downstream earlier Wednesday.
Both animals are injured, apparently from a run-in with a boat, and their wounds do not appear to be healing.
“It’s important that we get those animals back into salt water in order for them to heal properly,” Wilson said.
Rescuers had already planned to back off over the Memorial Day weekend as well if the stranded whales have not moved downriver. The U.S. Coast Guard crews would keep a 500-yard buffer zone around the whales to keep boats away. They expected crowds to gather along the riverbanks to catch a glimpse of the humpbacks.
The humpbacks apparently took a wrong turn during their annual migration to feeding grounds in the northern Pacific. They traveled 90 miles inland to the Port of Sacramento before turning around. They were making progress Monday until they reached the Rio Vista Bridge and began swimming in circles.
Skin becoming pitted
Although the freshwater delta is devoid of the whales' saltwater food sources like krill and plankton, starvation was not an immediate concern, biologists said, because humpbacks usually fast during the winter months.
Biologists would not estimate how long the whales could survive in the delta, but said tail-slapping behavior on Wednesday, known as "lobbing," was cause for concern.
The freshwater environment was taxing the whales physically, making their normally smooth and shiny skin become rough and pitted, "like when you sit in a bathtub for too long," said Trevor Spradlin, a NOAA whale biologist.