Sperm whales found traveling together, dining alone

Source: Xinhua| 2017-09-17 06:56:48|Editor: Yamei
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SAN FRANCISCO, Sept. 16 (Xinhua) -- A new study confirms that when a group of sperm whales travel, the highly social creatures tend to hang pretty close together.

Researchers from Oregon State University (OSU) in the U.S. Pacific Northwest and the Autonomous University of Baja California Sur in Mexico reported their finding that sperm whales spent about 30 percent of their time at the surface resting and socializing.

However, when a group of such whales with 27 so-called Advanced Dive Behavior, or ADB, tags would dive in search of their preferred food, namely the Humboldt squid, they would sometimes reach depths of 1,500 meters, or nearly a mile below the surface, and would each went their own way.

During one such dive, according to the researchers who recently published a paper in the journal Ecology and Evolution, a whale remained submerged for more than 77 minutes in the Gulf of California.

The sophisticated ADB tags allowed the researchers to gather unprecedented amounts of data on sperm whale movement, socialization and feeding and diving behavior that previously had been difficult, if not impossible, to obtain.

Sperm whales have been notoriously hard to study in part because they spend a lot of time underwater and dive to great depths.

Technological limitations had precluded researchers from gathering continuous behavior data on them for more than 24 hours at a time until the ADB tags were developed by OSU and Wildlife Computers.

The tags can record high-resolution diving depth data as well as Global Positioning System, or GPS, locations, and can enable the researchers to track individual sperm whales for as long as 35 days.

As results, among their findings, the researchers discovered that whales make six different types of dives, including two shallow dive types and four deep dive types.

About three out of every four dives were deep dives, likely related to foraging, and tracked sperm whales diving to the ocean bottom probably more common than scientists previously thought.

"This information is extremely valuable as it reveals how sperm whales allocate their energy resources to different activities such as feeding, resting and socializing over time," Ladd Irvine, a researcher with OSU's Marine Mammal Institute in Newport, Oregon, and lead author on the study, said in a news release from the U.S. university this week.