The juvenile whale was last spotted swimming downriver in the Nushagak River on Saturday, the same day the carcasses of two other adult orcas, believed to be females, were discovered in the river, Julie Speegle, a spokesman for NOAA Fisheries, said in a release.
Officials planned to fly the river Monday afternoon to confirm the location of where the two carcasses were found and to look again for the juvenile whale, she said.
Four veterinarians are scheduled to fly to Dillingham today to perform necropsies on the two adult whales. Leading the effort will be a killer whale specialist from SeaWorld in San Diego.
Speegle said it will likely take two days to complete the necropsies. According to NOAA, female killer whales can weigh up to 16,500 pounds and be 28 feet long. Preliminary results possibly could be ready later this week.
The whales have been swimming in the Nushagak River in Southwest Alaska for about three weeks in what federal biologists said was an unprecedented trek for Alaska killer whales.
The whales swam about 30 miles up the Nushagak to a spot just downriver from the village of Ekwok, which is about 285 miles southwest of Anchorage.
It had been hoped all three would swim downriver and eventually find their way back to Bristol Bay.
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