For the past quarter-century or so, the U.S. Navy has been training beluga whales (Delphinapterus leucas), along with dolphins and sea lions, to carry out various military exercises. These animals' innate abilities to swim long distances without fatiguing, to dive to great depths and to navigate even the most turbid waters make them ideal agents for such tasks as locating mines, retrieving lost equipment and protecting moored ships from hostile divers. Now it seems that the use of such marine creatures is expanding from the realm of naval warfare to that of science: Recently oceanographers enlisted wild belugas to chart the physical properties of the icy waters of a freezing Arctic fjord in Svalbard, an inhospitable place for conventional oceanographic surveys.
The new beluga-based oceanographic study was published in the December 1, 2002, issue of the journal Geophysical Research Letters. Scientists from Scotland and Norway outfitted two beluga whales with miniature instruments able to measure and record the electrical conductivity of seawater along with the prevailing temperature and the pressure. (Conductivity is useful because it indicates salinity, and pressure is proportional to depth.) The electronic payload also included a radio transmitter, which allowed the data collected during a dive to be sent to a satellite overhead after the animal surfaced.
Although two whales were outfitted in this way, one of the instruments malfunctioned before the water started freezing, so the published study depended on just one beluga's roaming. Yet even with only the one whale working for them, in just 17 days, the scientists were able to gather measurements from 540 positions, spread over an area of roughly 8,000 square kilometers. This feat is especially impressive given that these waters were largely covered with ice.
The survey provided some much-needed information about the state of the water in this fjord as it freezes over. Previous studies of ice formation there had assumed that at this time of the year (mid-November) the fjord is filled with near-freezing water from the Arctic Ocean. The new beluga data, however, showed that there is a considerable influx of comparatively balmy water from the North Atlantic. This finding perhaps reflects recent global warming. So having the means to collect such information about the warming of far northern waters in coming years should be of considerable value to scientists trying to evaluate changes in the climate.
This is not the first time a marine animal has gathered useful oceanographic data. For example, in 2001, George W. Boehlert of the National Oceanic and Atmospheric Administration and six colleagues published a study that presented oceanographic data collected from the North Pacific using instrumented elephant seals. The recently published beluga work does, however, represent the first time such a program has been mounted with the express intent to study some aspect of physical oceanography rather than to discern the behavior of the instrumented animal as its prime objective.
"It's a fantastic piece of work," says Barbara A. Block of Stanford University. She is in a good position to judge, having spent much of her career outfitting tuna with electronic sensors. "This group is taking us beyond where anyone has been," she says, noting that this is the first time anyone has instrumented a marine animal with a device as complex as a conductivity-temperature-depth sensor package.
Christian Lydersen of the Norwegian Polar Institute was lead author of the beluga study. He explains the logistics of pressing a beluga whale into oceanographic service. According to him, it's not that difficult: One needs only to erect some nets near shore and then to steer whales into them. "These are pretty easy to herd," he says. The instruments are then attached using nylon bolts, which screw into a corklike layer of skin on the whale's back. "It sounds pretty bad," Lydersen admits, but he points out that this thick, leathery skin on the animal's dorsal ridge stands up to it and that the units normally fall off on their own in just two to three months.
As the newly collected records show, beluga whales can remain submerged for 20 minutes at a stretch. And they routinely dive to depths that are deeper than the deepest parts of the Barents Sea, so they provided full coverage for the fjord examined. These whales are thus well suited to the task of probing such chilly corners of the ocean. The economics of this approach to oceanography is also attractive, given that it takes perhaps one day for a team of scientists to outfit a whale with instruments, whereas it would take them many days to collect an equivalent amount of oceanographic data from an ice-breaking research vessel, which might lease for $10,000 or more a day. The biggest advantage, though, is that the whales are there all year long, whereas oceanographic research vessels typically visit these waters only in the summer and autumn. As Lyderson says, "In the ice, in winter—there's nobody doing any oceanography." Or, as his thick-skinned helpers might say: nobody but us whales.—David Schneider