Sharks could serve as ocean watchdogs

CHICAGO — The same gray triangles that peek above ocean waves to terrify beachgoers could prove a boon for climate scientists. By strapping sophisticated sensors to sharks’ otherwise ominous fins, researchers can now collect temperature and other environmental data from the far reaches of the Pacific.

Maintaining devices that monitor conditions in the ocean is expensive, says marine scientist Kim Holland of the University of Hawaii at Manoa; a crucial network of buoys in the tropical Pacific is currently operating at reduced capacity due to budget problems. Using sharks as ocean surveyors could provide a new source of data for scientists developing weather and climate simulations.

 “Sending sharks to do the heavy lifting makes a lot of sense,” Holland said.

Although other animals have proven useful as data collectors, including Arctic seals (SN: 11/6/10, p. 12) , sharks represent an untapped resource. Holland and his team recently discovered that sharks take nightly dives up to 800 meters down as well as 1,000-kilometer-long unexplained excursions to the center of the Pacific. The sharks’ deep and long jaunts provide unprecedented access to ocean waters unplumbed by scientists, Holland says. He presented his latest findings February 14 at the annual meeting of the American Association for the Advancement of Science.

Off the coast of Hawaii, Holland and his team have begun fitting the fins of tiger and hammerhead sharks with sensors about the size and shape of an ice cream cone. Holland began the project to study the behavior of the ferocious fish, but realized the data could be more widely applied. Future shark-mounted gadgets will record water oxygen levels and conductivity, which researchers use to estimate saltiness and other chemical properties.  The data from the sensors are beamed to a satellite system above the ocean when the sharks surface.

“It’s a great idea,” said oceanographer James Overland of the National Oceanic and Atmospheric Administration who is based in Seattle. Additional data are always useful, he said, noting that some of the research ships used for ocean monitoring cost $10,000 to $20,000 a day to operate.

Budget problems have jeopardized the Tropical Atmosphere Ocean array, a set of buoys across the Pacific set up by federal researchers to collect data and monitor El Niño and La Niña events. Around half of the buoys are in need of repair and no longer collecting data. 

Holland also notes that curious, chomping sharks often destroy robotic vehicles that monitor the ocean, such as gliders.

Animals such as sharks are absolutely helpful in monitoring the ocean, says oceanographer Jennifer Francis of Rutgers University in New Brunswick, N.J. In addition to providing inexpensive oceanographic data, the method also tracks variations in their behavior, habitat and feeding spots, she adds.

“All of this gives us clues as to how the ocean is changing,” said Zdenka Willis, director of the U.S. Integrated Ocean Observing System in Silver Spring, Md., which is currently building a national network for collecting data from tagged animals.  

“It is hard to pinpoint a single data stream as being most important,” Willis said. But given that the Pacific is large and undersampled, she added, data from tagged animals are poised to become more important.