West Coast Research Expedition Tracks Elusive Beaked Whales

Cuvier’s beaked whale
Cuvier’s beaked whale. Bahamas Marine Mammal Research Organization/Charlotte Dunn.

Marine mammal scientists are beginning a research expedition in search of the least known, most mysterious and deepest diving whales off the West Coast.

The expedition on NOAA Ship Bell M. Shimada will employ a newly-developed system of about 20 drifting buoys that will quietly listen for whales hundreds of feet below the ocean surface. Researchers from NOAA Fisheries’ Southwest Fisheries Science Center will deploy the low-cost buoys up to 300 miles offshore as the ship traverses waters off California, Oregon and Washington.

The research survey is called PASCAL, for Passive Acoustic Survey of Cetacean Abundance Levels. The primary focus is on beaked whales, which are so deep diving and elusive that some species have never been seen alive. They often travel in small groups, staying underwater for an hour or more at a time.

“These animals are so well-hidden we just don’t know much about them,” said Jeff Moore, leader of the California Current Marine Mammal Assessment Program and one of two chief scientists for the survey. “This is a rare opportunity to look in on these animals and their very deep-water habitats in a very unique way.”

A 2013 study by Moore and Jay Barlow, also chief scientist of the survey, examined decades’ worth of survey data and about a century of stranding records and concluded that the number of beaked whales is declining in the California Current. The scientists estimated that Cuvier’s beaked whale, one of the better known species of beaked whale, had declined from more than 10,700 in 1981 to about 7,500 in 2008.

Blainsville’s beaked whale
Blainsville’s beaked whale. NOAA Fisheries/Southwest Fisheries Science Center & Bahamas Marine Mammal Research organization/John Durban.

The reason for the decline is a mystery. The scientists suggested in the paper that it could involve shifting distributions, changes in the deep-water food web or human impacts such as increasing ocean noise and the use of underwater sonar. They expect the survey will help understand the current status of populations of different beaked whales and other types of whales.

“This should produce unprecedented data on beaked whale abundance, which is something that has been a big question mark for us,” Moore said. The Marine Mammal Protection Act calls for NOAA Fisheries to assess whale populations, and the better scientists understand the status of whale populations the more effectively they can assess potential threats to the species.

The Shimada will also tow an array of hydrophones that will constantly listen for whales, with software programmed to recognize the calls of different species.

Another goal of the cruise is to better identify which calls belong to which species of whales, with the help of the hydrophones and an observing team on the ship.

The ship will drop off the recording buoys, called drifting acoustic spar buoy recorders, or DASBRs, in a pre-planned pattern off the U.S. West Coast from the Canadian border south to San Diego. Suspended 330 feet (100 meters) below each buoy is a hydrophone that listens for whales. As the buoys drift, they record whale vocalizations for scientists to download and analyze once they retrieve each buoy later in the expedition.

“The great advantage of the buoys is that their collective 400 days at sea is like increasing our ship effort by a factor of 10 with very little increase in cost,” Barlow said. “The quality of the recordings is also much better because we don't have any ship noise, so we can hear farther.”

Baird’s beaked whale
Baird’s beaked whale. NOAA Fisheries/Southwest Fisheries Science Center/Robert Pitman.

The survey will be the first large-scale deployment of the listening buoys developed at the Southwest Fisheries Science Center. Researchers expect each buoy to drift as much as 10 nautical miles a day, covering about 100 to 200 miles over their 20-day deployments. Scientists can then retrieve the data and convert the number of times the buoys detect beaked whales into a much clearer picture of their populations off the West Coast.

“We’ll have all these extra ears out there listening for the whales while we also look for them,” Moore said. “No doubt we’ll get many more detections of beaked whales this way than we ever could visually because they’re so cryptic and hard to find.”

This study was funded in part by the U.S. Department of the Interior, Bureau of Ocean Energy Management through Interagency Agreement Ml6PG000l1 with the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center.

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