•Strait Science

opsies from a whale seven miles south of St. Lawrence Island came back as from the eastern right whale population stock, and three weeks later was again sighted around Chukotka.

Crance explained that satellite tags were tried in 2004, 2008, and 2009, but while they were effective in showing location inside the Bering Sea or inside the Gulf of Alaska, all tags fell off before they could show migration routes.

Why is so little known about the North Pacific right whale?

Unlike the North Atlantic right whale, of which there are around 350 and live along the east coast of the USA, logistics in Alaska make full scale surveys few and far between.

And that is where Crance’s work as a bioacoustician comes in. She uses passive acoustics to identify and monitor right whales, which make three calls. Their predominant call sign is like a gunshot sound, but they also make up sweeps and a down sweep which sounds like a moan. In the short-term, she uses sonobuoys, which have a series of hydrophones, and when using ones in multiple locations, they can triangulate the whale’s location. In longer-term studies, they have year-long passive recorders at 20 sites. Crance explained that these are a useful tool for population monitoring because they are usable year-round when vessels aren’t.

Their results show a consistent annual detection in the Bering Sea, and increasingly in the North Bering Sea, too. The distribution correlates with temperature, and in warmer years, there are more soundings in the north. Crance thought that this had to do with the cold pool, and the distribution of the right whale’s food.

Unfortunately, bowheads make some of the same calls, too, and they can be impossible to differentiate. They hope to solve this by studying the song itself. The song has a hierarchical structure similar to humpbacks, and they have found four unique song types in the Bering Sea. Remarkably, these songs have remained the same for the last eight years, too, and Crance said it might be a reproductive display. The songs in the Bering Sea and the songs in the Gulf of Alaska are slightly different, but as it appears as if only the eastern population of only the North Pacific right whale sings, there is still much to study.

Crance also took the time to explain some of the research happening around her, including proof of concept collaborations with Canadian Dept. of Fish and Oceans researchers. Dana Wright is doing a PhD at Duke University looking to uncover calving grounds through isotopes in baleen. This is similar to the genomic sequencing that a previous Strait Science speaker talked about in identifying Alaskan Hare range through pellet samples. There are also studies looking to use machine learning to analyze the soundings, which warp over time and distance.

Before opening up the talk to questions, Crance talked about the February 7, 2022 sighting by commercial fishermen of right whales just north of Unimak Pass in the Aleutian Islands. This was the first documented sighting of winter feeding. The sighting was reported by the fishermen, and a notice went out through the U.S. Coast Guard and an automatic AIS notice to ships going through the region to be cautious. This kind of shared information from people out in the sea “really does help us piece together this puzzle,” Crance said.

The talk generated a lot of comments and questions, including from as far as Utqiagvik. One caller asked how close the cod fishermen were when they sighted them in February. Crance explained that they were a couple hundred yards away, and that the photos were good enough to identify the species, but not the individuals. Right whales frequently associate with other species of whales, and in this case, they were seen with 8-10 other pairs of humpback whales. The humpbacks came much closer than the rights.

Asked about life expectancy, Crance said that “short answer, we don’t fully know,” but it is thought to be at least 70 years. Bowheads are known to live to 150 years old. Entanglement and vessel strikes are certainly threats to the longevity of whales.

Many people asked about another threat, noise pollution. This is big issue, Crance said, because right whales rely heavily on acoustics to communicate, and more noise makes it harder to be heard for any marine mammal. It also can hinder detection of whales inside of louder waters, and as traffic increases through the Bering Strait, noise will, too.

If you see a right whale, with a wide, flat back and no dorsal fin, or the distinctive V-shaped blow, please report it. If possible, include time and date, location, number, and their behavior. Photos and videos would also help with the cataloging of the North Pacific right whale.