ANCHORAGE — Necropsies on two killer whales that died after spending weeks in an Alaska river have provided no obvious reasons for why the animals died.
Veterinarians on Wednesday completed a necropsy on a second killer whale found dead in the Nushagak River.
Two adult female whales were found dead in the river on Saturday, and a third whale, a juvenile, hasn’t been seen since.
NOAA’s National Marine Fisheries Service says over 100 samples were taken from the whales for analysis in hopes of providing a clearer picture of why they died.
A necropsy on the first whale revealed that the orca was carrying a late-term fetus, veterinarians said. That could indicate that she was having pregnancy complications and “that may have been a factor in the whale dying,” said Julie Speegle, spokeswoman for NOAA Fisheries Alaska Region.
The necropsy was done by veterinarians on a beach in Dillingham, where the carcass was taken after she was found floating Saturday in the river in southwestern Alaska, a remote and mostly unpopulated part of the state.
Federal biologists have said the rare sighting represented an unprecedented journey into fresh water for the killer whales in Alaska.
The necropsy showed no evidence that the whale died because of human interaction, such as a boat strike or entanglement in fishing gear, said Judy St. Leger, director of pathology and research at SeaWorld who is a member of the necropsy team.
The veterinarians took samples from the whale carcass for tests and hope to answer some basic questions about its age, health, and pod identity. A full report was expected to take a month or two to complete.
“Other than the slimy film that was on the skin surface, there was no other overt evidence of infection,” Speegle said.
The team also did not know yet why the whales were in the river. At one point, the distinctive black and white whales had ventured 30 miles upriver but were turned around and swam lethargically downriver toward Dillingham and the salt waters of Bristol Bay.