Humpback whales sightings suggest breeding ground in Marianas


At least 12 humpback whales, including mother and calf pairs, were spotted during lookout and vessel surveys in February and March this year, suggesting humpback whales are breeding in the Marianas, according to a whale researcher.

Dr. Erin Oleson, a National Oceanic and Atmospheric Administration scientist, spoke at the American Memorial Park on Monday night about their recent efforts to spot and sample tissue of humpback whales off Saipan.

Compared to other landmark research done on whales in the Northern Pacific or elsewhere in the world, the Western Pacific, where the Marianas lies, is “isolated” in terms of research done.

There has been “speculation that there is a whole breeding area missed,” Oleson told the audience gathered on Monday.

In February to March this year, NOAA researchers set up a rooftop lookout at the Hyatt Regency Saipan, and according to Oleson, 12 whales were spotted, including four mother whales with their calves.

She said four biopsy samples were taken through the vessel surveys, which used a modified crossbow that “bounced back” off the whales with a layer of skin and fatty tissue.

From these surveys, she said, they can say “at least” 12 humpback whales are in the area. She also noted that all the search efforts were conducted in just one area, what is called “CK reef.”

“They probably are more broadly distributed,” Oleson said.

“We had three mom and calf pairs…suggesting that it’s likely that humpback whales are actually breeding and giving birth to their calves here or nearby, and not transiting from some more distant breeding ground with their calf.

“That’s a fun finding,” she added. “We know they are actually using this area as a likely breeding area, and now we want to know that links to the other breeding areas” in Asia and west and north Pacific.

Cetaceans research continued

In 2014, a survey of cetaceans in waters of the CNMI, including the Islands Unit of the Marianas Trench Marine National Monument, from the NOAA Ship Oscar Elton Sette was delayed due to maintenance issues with the ship.

But according to Oleson, they recently completed—from earlier research in the southern Mariana Islands—surveys continuing up the archipelago chain.

Minus Asuncion and Farallon De Medinilla, they now have done surveys of the southern islands like Guam and Saipan and the Northern Islands.

“The goals were to understand distribution [of whales] throughout the archipelago,” she said. “And also to collect tissue samples and photos for comparison to other information we already have.”

NOAA researchers used standard and non-standard methods, meaning they did broader scale surveys up the island chain and smaller, more-focused surveys near the shore of islands.

“In our systematic effort, we had relatively few sightings, about 10 [cetaceans],” she said, while the non-standard efforts, which took place near or about one mile off shore, revealed generally more sightings.

With the newly collected data, NOAA researchers can now compare genetic samples to ones already collected in southern islands like Guam and Saipan. Their initial cruise results reveal 42 sightings. Over 10,000 photographs were taken. Forty-five biopsy samples were taken from spinner dolphins, melon-headed whales, false killer whales, sperm whales, and other cetaceans. Cetaceans were also tagged and tracked to show them distributed quite broadly in the Marianas. As of Monday, they were still tracking these cetaceans. Results of genetic sample tests are not in yet.

Dennis B. Chan | Reporter
Dennis Chan covers education, environment, utilities, and air and seaport issues in the CNMI. He graduated with a degree in English Literature from the University of Guam. Contact him at

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