Sperm whales are social animals that travel in groups, but when it comes to eating, they prefer a table for one.

That's one of the takeaways from a study conducted by researchers at Oregon State University's Marine Mammal Institute. The research was published in late August in the journal "Ecology and Evolution."

Researchers from OSU and the Autonomous University of Baja California Sur in Mexico tagged and tracked 27 sperm whales in the Gulf of California in 2007 and 2008 with special devices that chronicled the most detailed look at the deep-sea diver's activity to date.

The famously difficult to track divers have historically been followed visually or with devices that typically track behavior for no more than a day.

But OSU's research revealed the massive mammals, which can dive more than a mile underwater, spent nearly 30 percent of their time on the surface hanging out with other whales.

But when they went in search of Humboldt squid and other sustenance, they went alone.

"We are now learning things about sperm whales that we just didn't have access to before," said Ladd Irvine, an OSU researcher and lead author of the study, said in a statement. "Unlike many other terrestrial and marine mammals that form social groups, sperm whales seem to prefer foraging as individuals. They would stagger both the starting time and the depths of their dives."

Researchers have struggled to study sperm whales in the past because the animals spend so much time underwater and at extraordinary depths. One of the whales studied stayed underwater for more than 77 minutes, and another descended nearly 1,500 meters, or about a mile, below the water's surface.

The tagging beacons allowed researchers to gather data from multiple dives, in some case over a span of several weeks, before they slipped off the whale.

Bruce Mate, the director of OSU's Marine Mammal Institute and co-author on the study, called the devices "revolutionary."

"The technology has made whales our partners in acquiring data to better understand ocean conditions and climate change," he said in a statement. "It shows us what the whales do underwater; when, where and how they feed; what water temperatures they prefer; and how they might be affected by passing ships or other noises."

The tags are effective up to 35 days, and researchers plotted a variety of dives performed by the whales at various depths.

The U.S. Navy, International Association of Oil and Gas Producers and Naval research office funded the research, according to a statement.

In an interview, Irvine said that researchers are now studying sperm whales in the Gulf of Mexico and have been investigating the effect of the gulf's rapid oil and gas exploration on whale populations for the past several years.

-- Andrew Theen

atheen@oregonian.com

503-294-4026

@andrewtheen