Selasa, 08 September 2020

A pair of stranded killer whales and a sick sea lion near Sitka have biologists looking for answers - KTOO

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An adult male Steller sea lion hauled out of Sitka Sound in 2018. The sea lion became a fixture over the weekend, attracting onlookers as it sought shelter near Mt. Edgecumbe Hospital and the surrounding woods. (Photo courtesy Sitka Fire Department)

Biologists are tracking some unusual stranding events around Sitka this summer, and hoping to learn more about what brought about the deaths of two killer whales, and what has made a sea lion gravely ill.

The most recent stranded killer whale was found beached on Pain Island, near Kake, in August. Back in June, another killer whale was found dead in Crawfish Inlet south of Sitka. This doesn’t feel normal for these animals, which occupy the top of the food chain in Southeast Alaska.

“For the killer whales, I honestly don’t know if this is normal or not,” said Mandy Keogh, the Regional Marine Mammal Stranding Coordinator for NOAA Fisheries in Alaska.

Dead killer whales simply aren’t seen that often.

“I think it’s kind of unusual to have killer whale strandings in general,” she said. “And some of that may just be there’s a lot of coastline, so if a killer whale does strand, you have to have the right timing of tides and people being in that area to report it. So there are strandings that we likely miss.”

The killer whale in Kake was found near the harbor, already significantly decomposed. Keogh says that community members collected some of the juvenile male’s teeth for traditional artistic purposes, and some of the teeth were forwarded to NOAA for aging. Killer whales put down a new layer of dentin every year on their teeth, which allows researchers to determine how old they are. Also, dietary isotopes can be extracted from the teeth to establish the killer whale’s ecotype: Whether it is a mostly fish-eating resident, or a marine-mammal eating transient.

It’s not as valuable as a full necropsy of a recently-deceased individual, but it helps.

“Even if it’s fairly decomposed — or very decomposed — we can still gain some information about it,” Keogh said.

The killer whale in Crawfish Inlet was also a young male. In neither case was NOAA’s Marine Mammal Stranding Network able to perform a necropsy and determine a cause of death.

Closer to Sitka, a sick sea lion may afford researchers a better opportunity. The large animal has been frequenting Eliason Harbor for a month or more. Keogh says it appears to be in bad shape.

“It looks slightly bloated, and it’s not using its hind legs or flippers like we would expect, but it is mobile and reactive to people being nearby,” said Keogh. “And it has some distinctive features on its back, the fungal patches, so we think it’s the same animal. The first report I’m aware of was August 5, and then it was not observed for a while, and then it was back this past week.”

A report of another dead sea lion not far from Sitka was initially thought to be this animal, but local members of the Stranding Network responded and concluded that it was another individual. There’s also a report of a sea lion around Sitka trailing a flasher, which Keogh says is unfortunately not unusual after the start of the commercial trolling season in July.

It sounds grim, but Keogh really wants to hear from anyone who sees this very distressed sea lion — especially if it is found dead. Learning what caused it to perish could help prevent similar events in the future.

“It’s so important to report strandings to the NOAA Hotline,” said Keogh. “We can track that, and look for unusual increases in a species or an area, and that might give us insight into whether something’s happening in the marine environment that might be of concern, and then we can start investigating that.”

The NOAA Marine Mammal Stranding Hotline number is 877-925-7773. Keogh adds that “photos are incredibly helpful.”

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September 08, 2020 at 12:27AM
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A pair of stranded killer whales and a sick sea lion near Sitka have biologists looking for answers - KTOO

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