An Army of Animal Oceanographers

The tags used on the elephant seals are small computers—about the size and weight of a New York strip steak—with several sensors to collect data on the animals’ surroundings. The tags have memory to store data, a clock and a transmitter that allows them to send data to a satellite. All of this runs on battery power. Costa’s team has conducted extensive testing to make sure the tags do not affect the seals’ behavior in any way. “The size of the tag is not an issue because the [elephant] seals are so big,” he said. “We haven’t found any changes in terms of how much time they spend at sea, how far they go, weight gains or breeding behavior.”

He added that the elephant seals are already providing important data on some obvious effects of climate change. In March of 2008, a giant chunk of the 6,000-square-mile Wilkins Ice Shelf broke off the western side of Antarctica, and the rest of the shelf is hanging on by only a thread. The seals tracked by Costa and colleagues were swimming around and under that shelf both before and after the break and have provided information on water conditions that may lead to such events.

Foley, along with Costa, has done work tagging the sooty shearwater, a small seabird that has a round-trip migration of more than 40,000 miles in a figure-eight pattern around the Pacific. The shearwaters cover such a vast area that scientists can comprehensively measure ocean surface temperatures along the seabirds’ routes, with data recorded every time they land on the water. Researchers are also tracking several types of albatross around the Pacific, which has proved useful because the legendary seabirds “go to particularly cloudy places where satellites can’t generally see,” Foley said.

Marine biologist Barbara Block, who tags giant bluefin tuna and several species of sharks at Stanford University’s Hopkins Marine Station in Pacific Grove, said that the original goal of animal tagging was to collect biological information. The recent ability to learn about the oceans, however, fills in an important knowledge gap. “The animals are adding to the data coming from this large portion of our planet that we haven’t been sampling in a very comprehensive way over the last 200 years,” she said.

Clearly, retroactively predicting storms by watching a turtle dive is only the tip of the proverbial iceberg. Filling in the gaps in oceanographic information will allow for better predictions of ice formation and melting as well as a clearer understanding of the structure of the world’s oceans. “By getting all these numbers, our friends at NOAA and NASA are able to build predictive models of the ocean,” Block said. “That helps us better understand how our planet works at a time when information about the climate is vital.”

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