A wayward gray whale remained on California's Klamath River on Wednesday, even after its calf found its way back to sea and wildlife officials tried a scare tactic: blasting the sounds of its main predator, killer whales.
The audio blasts on Tuesday failed to drive her back to the sea three miles away, as did attempts on Sunday that included banging on pipes in the water, spraying a water cannon at her and slapping the water with tree branches, the Daily Triplicate reported.
Killer whales, also known as orcas, were given their menacing names by fishermen who saw them forming packs to attack whales, even ones as big as grays. The one on the Klamath is estimated to be 50 feet long and weigh 40 tons.
Given its whale-sized appetite for food, it's not clear how long the gray can survive, the Yurok Tribe, which retains fishing rights on the Klamath, said in a statement.
It's not known why she hasn't left. "There are some shallow parts but she could easily get out if she wants to," the tribe told msnbc.com.
One concern is that the river level is falling, which would make it harder for her to leave if she extends her visit much longer.
Officials planned to monitor her on Wednesday before deciding what, if any, next steps to take, the tribe said.
The mom and child were first spotted on the river in northern California a month ago, and soon drew locals and tourists, some who ventured too close.
"Some curious people in jet boats and kayaks have traveled too close ... some within feet — putting unnecessary stress on the animals," the tribe stated.
The calf was estimated to be around a year old, about the age that they separate from their moms. It was seen heading back to sea last Saturday but the mom did not follow.
Before the calf left, the pair swam past dozens of people lining the river in what looked like "a Sea World exhibit" complete with circular laps, the Triplicate stated.
The tribe was worried about the calf's condition, saying it appeared "to be relatively slim, at a time when it should be plump from feeding on fatty mother's milk."
Why would the pair have even entered the river in the first place? The tribe said they might have been trying to "avoid a predator such as a killer whale or a great white shark."
Or, it added, "the highly intelligent mammals could also simply be curious."
The last sighting of a whale on the Klamath was in 1989, the tribe said, and that one left without incident.
Gray whales travel long distances between calving and mating along the coasts and then feeding in the Arctic and sub-Arctic regions.
The population of gray whales off the Pacific coast are recovering after nearly being hunted to extinction for their blubber in the 1900s. Their population is estimated at around 20,000.