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News | Sept. 5, 2017

Navy Sonobuoys Facilitate Endangered Whale Sighting

By Chief of Naval Operations Energy and Environmental Readiness Division Chief of Naval Operations Energy and Environmental Readiness Division

Thanks to sonobuoys provided by the U.S. Navy, the National Marine Fisheries Services (NMFS) recently spotted two endangered North Pacific right whales in the Bering Sea near Bristol Bay, Alaska, Aug. 6. 

Sightings of right whales in the eastern North Pacific are extremely rare and any encounter represents an important opportunity to gather information about this critically endangered population.

The sonobuoys were dropped into the water at regular intervals by a Pacific Ocean Whale and Ecosystem Research (POWER) program ship. This particular survey is a collaborative project by the International Whaling Commission, the Government of Japan and NMFS. Jessica Crance, a NMFS research biologist aboard, heard whale vocalizations via the sonobuoys and helped the ship chart a course to locate the animals. Navy sonobuoys use passive acoustic technology to listen for underwater sounds, in contrast to active acoustic devices which generate a "ping" and locate objects based on the echo. 

Researchers captured photographs of the whales, along with a biopsy sample. According to researchers, the biopsy sample collected from the whale can help establish the identity of the whale, its sex, whether it's pregnant and can also provide data about diet and reproduction. Right whales can be identified by the unique pattern of growths on their heads, termed callosities; both of the animals in this sighting were known from previous years' work in the Bering Sea. 

"Today, the eastern North Pacific population is estimated at around 30 animals, and we know too little about their status, biology and behavior," says Dr. Phillip Clapham of the Marine Mammal Laboratory Alaska Fisheries Science Center. "The POWER cruise offers a unique opportunity to conduct a systematic sighting survey which has been designed and approved by the IWC's Scientific Committee for this critically endangered whale, and the Navy's sonobuoys have been instrumental in locating them through detection of the whales' vocalizations - often beyond visual sighting distance."

The population of North Pacific right whales initially plummeted due to whaling from 1835 through 1930s, at which point official protections were put in place. Despite these protections, illegal whaling removed the bulk of what was thought to be a small but slowly recovering population. Today, the primary threats for North Pacific right whales include hazards caused by fishing gear entanglements and ship strikes. 

Programs receive sonobuoys when the Navy's Living Marine Resources (LMR) program assesses the requirements worldwide to perform mission tasks and issues surplus, unexpired buoys to outside organizations sharing the Navy's research interests, which include marine mammal protection projects and studies. The sonobuoy's shelf life is typically several years and the Navy's distribution varies annually. In 2017, 480 sonobuoys were allocated to, most notably, multiple National Oceanic and Atmospheric Administration (NOAA) programs and the Marine Mammal Laboratory at the Alaska Fisheries Science Center. 

"We are extremely grateful to the Navy for providing these sonobuoys," says Dr. Catherine Berchok, a research biologist with NOAA. "We couldn't do our work without them!"

Crance and her colleagues will continue to search for more North Pacific right whales in the area through mid-September.

For more information on sonobuoys and the LMR program, visit