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Rio the humpback whale spotted last week in the Sacramento River appears to be on the move.
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The whale was first seen in the river on Wednesday, Sept. 16, by three men fishing near the Rio Vista Bridge. While humpback whales typically keep to the open sea, some have ventured into the Delta. The most famous example was Humphrey the humpback in 1985, whose trip to the Delta culminated in a high-stakes rescue by researchers and government agencies.
“Rio” is the nickname given to CRC-11620, a whale of unknown gender who has been seen migrating up and down the California coast since 2002. Researchers at the Cascadia Research Collective identified Rio based on the unique markings on its tail, or “fluke.”
Saturday, Sept. 21, the Marine Mammal Center reported Rio had been seen again on Friday afternoon, this time headed west, back towards the San Francisco Bay. A Coast Guard crew spotted Rio moving west near Port Chicago, in Suisun Bay. “This is the best news we could have received that afternoon, because that is the direction that we want Rio to go,” said Kathi George, director of Cetacean Conservation Biology at The Marine Mammal Center, in a statement on Monday.
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It’s unclear why Rio ventured into the Delta, and it is dangerous for the whale to linger there for too long. Hazards include freshwater environment, the narrowness of the waterways, and the potential for human interference.
According to the Center, no other sightings were reported over the weekend, though they are still on the lookout. Anyone who spots Rio is urged to stay 100 yards away, and to report any sightings to their website or the WhaleAlert app. “While we appreciate any new Rio sightings, we really want to make sure that you’re giving whales [their] space,” said George.
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