CHICAGO — Those gray triangles that peek above ocean waves can terrify beachgoers. They flag a cruising shark. But those same fins could mark science at work for climate researchers. Some scientists have begun strapping sensors to the sharks’ otherwise ominous fins. Now when those fish travel the seas, they can collect a rich trove of data from the far reaches of the Pacific.
Maintaining devices that monitor conditions in the ocean is expensive, notes Kim Holland. He’s a marine scientist of the University of Hawaii at Manoa. Using sharks instead could provide a new and less costly source of data for those scientists who use computers to try to understand and anticipate weather and climate conditions.
“Sending sharks to do the heavy lifting makes a lot of sense,” Holland says.
Other animals have proven useful as climate-data collectors. These include elephant seals. But to date, sharks represent an untapped resource.
Holland and his team recently discovered that sharks take nightly dives to depths of as much as 800 meters (2,600 feet). Some of the fish also embark on unexplained 1,000-kilometer (620-mile) cruises to the center of the Pacific. These long and deep jaunts provide unmatched access to parts of the subsea world that scientists never visit, Holland says. He presented his latest findings February 14, here, 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, called tags. Each device, which doesn’t hurt the fish, is about the size and shape of an ice cream cone. Holland began tagging sharks to get information on their behavior. Soon, however, he realized the data that these ferocious fishes were bringing back could help scientists in other fields as well.
His team’s tagged sharks are now collecting ocean temperature data. These can help map how those temps vary with depth.
Future shark tags will record oxygen levels in the water. Some will measure other chemical properties, including electrical conductivity, a gauge of the water’s saltiness. Every time a shark surfaces, its sensors can beam data it has collected to a satellite system above the ocean.
Sharks: A relatively inexpensive alternative
Tagging sharks? “It’s a great idea,” said James Overland at the Chicago meeting. An oceanographer, he works for the National Oceanic and Atmospheric Administration in Seattle, Wash. The bonus ocean data that sharks glean will certainly be useful, he says. Using tags also is relatively cheap. By comparison, the cost each day to operate some of the research ships used for ocean monitoring is $10,000 to $20,000 each.
U.S. scientists had set up an array of buoys across the Pacific to collect data and to monitor El Niños and La Niñas. (These common, years-long climate events get their start in the Pacific.) But recently, money problems have put the usefulness of this Tropical Atmosphere Ocean array in jeopardy. Right now, roughly half of the buoys are in need of repair and are no longer collecting data.
Overland also notes that curious, chomping sharks can destroy robotic vehicles that monitor the ocean, such as gliders. But putting those sharks to work by ferrying tags around the ocean makes sense.
Jennifer Francis agrees. An oceanographer at Rutgers University in New Brunswick, N.J., she has not been part of the shark-monitoring team. In addition to providing inexpensive ocean data, she says, tagging also can track variations in shark behavior, where the fish hang out and where they dine.
“All of this gives us clues as to how the ocean is changing,” said Zdenka Willis. She is director of the U.S. Integrated Ocean Observing System in Silver Spring, Md. It’s a government project involving many U.S. agencies. And this system is building a broad 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 sampled nowhere nearly enough, she argues that data from tagged animals are certainly poised to become more important.
array A broad and organized group of objects. Sometimes they are instruments placed in a systematic fashion to collect information in a coordinated way. Other times, an array can refer to things that are laid out or displayed in a way that can make a broad range of related things, such as colors, visible at once.
behavior The way a person or animal acts towards others, or conducts itself.
climate The weather conditions prevailing in an area in general or over a long period.
data Facts and statistics collected together for analysis but not necessarily organized in a way that give them meaning.
El Niño Extended periods when the surface water around the equator in the eastern and central Pacific warms. Scientists declare the arrival of an El Niño when that water warms by at least 0.4 degree Celsius (0.72 degree Fahrenheit) above average for five or more months in a row. El Niños can bring heavy rainfall and flooding to the West Coast of South America. Meanwhile, Australia and Southeast Asia may face a drought and high risk of wildfires. In North America, scientists have linked the arrival of El Niños to unusual weather events — including ice storms, droughts and mudslides.
glider A vehicle (such as a plane in air or uninhabited submarine) that takes advantage of currents to travel long distances using little or no fuel. It also tends to move smoothly, creating few disruptions in the fluid or airstream through which it moves.
habitat The area or natural environment in which an animal or plant normally lives, such as a desert, coral reef or freshwater lake. A habitat can be home to thousands of different species.
La Niña Extended periods when the surface water around the equator in the eastern Pacific cools for long stretches of time. Scientists will announce the arrival of a La Niña (lah NEEN yah) when the average temperature there drops by at least 0.4° C (0.72° degree F). Impacts on global weather during a La Niña tend to be the reverse of those triggered by an El Niño: Now, Central and South America may face severe droughts while Australia floods.
oceanography The branch of science that deals with the physical and biological properties and phenomena of the oceans. People who work in this field are known as oceanographers.
electrical conductivity The ability of some substance (such as water or metals) to transport an electrical charge or current.
sensor A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.
shark A type of predatory fish that has survived in one form or other for hundreds of millions of years. Cartilage, not bone, gives its body structure.
tagging (in biology) Attaching some rugged band or package of instruments onto an animal. Sometimes the tag is used to give each individual a unique identification number. Once attached to the leg, ear or other part of the body of a critter, it can effectively become the animal’s “name.” In some instances, a tag can collect information from the environment around the animal as well. This helps scientists understand both the environment and the animal’s role within it.
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