Seals Are Scientists’ Little Helpers for Collecting Ocean Data

For the past 10 years, hundreds of seals equipped with special headgear have collected crucial data on ocean temperature and salinity for scientists

An elephant seal from the Kerguelen islands with a logger device attached to his head, just before his departure back to sea. Photo: C. Guinet (CEBC/Chize, France)

In recruiting a research team, some scientists would do well to include a few seals. Over the past ten years, around 350 of these blubbery mammals—mostly elephant seals, but also Weddell and crabeater seals—have been outfitted as data-collecting helpers in the Southern Ocean. These animals’ role in producing quality research is not trivial, either. According to new research published in Geophysical Research Letters, including seal data in an ocean model paints a significantly more accurate picture of the local environment than relying on buoy-derived information alone.

Over the past decade, a small army of sensor-equipped seals has produced more than 150,000 environmental profiles. Special gear that sits like a small party hat atop the animals’ heads collects information about depth, temperature, conductivity and salinity of the surrounding water. The instruments are glued to seals' heads using epoxy; they are either recovered the next year, or they fall off naturally when the animals moult in the fall. In case you're wondering, no evidence points to these instruments harming the animals in any way.

Originally, these sensors were invented to gain insight into seal foraging and behavior patterns. When climate and oceanography researchers caught wind of the new development, however, they realized the method could also prove a valuable tool in their own work and enthusiastically signed up for some seal data of their own. A seal-sharing program called “Marine Mammals Exploring the Oceans Pole to Pole” was created to facilitate mutual collaboration, and the authors of this new paper just published the calibrated data collected from 2004 to 2010 in the program’s joint database. 

So what makes seals so special and indispensable for research? Studying the sea ice and ocean currents surrounding Antarctica provides invaluable insight into climate change, but those experiments are tricky to pull off due to the nearly inaccessible nature of some of those study sites.

“The presence of sea ice, remoteness and harshness of the climate make it difficult to observe these oceanic changes,” says Fabien Roquet, a researcher in the department of meteorology at Stockholm University and lead author of the paper. “Seal-derived data efficiently fills dramatic observational gaps in several regions of the Southern Ocean, especially in poorly sampled, ice-covered places.”

To verify the importance of seal-collected data, Roquet and his colleagues undertook two circulation experiments in the Southern Ocean. In one, they relied only on a network of floats to gather their oceanic information over the course of a year and a half, but in the other they added seal-gathered data to the float data. The seals, they found, not only bolstered their data set’s level of detail but also significantly modified the entire model, including changing its representation of sea ice and ocean currents. To make sure their results did indeed correlate with reality rather than reflect some strange seal world, they compared the models to satellite data showing sea ice concentrations. The seal model, they confirmed, did indeed better reflect reality than the buoys alone.

While the study emphasizes the reliability and importance of instrument-carrying seals, Roquet says much more work is needed in the coming years in a continued effort to better understand and monitor climate change. Seals, no doubt, will play a role in that work.

“Instrumented seals represent the most promising technology to fill the Southern Ocean observational gaps, so we hope that this study can promote a wider use of seal-derived data in oceanographic and climate [research] communities,” Roquet says. Furthermore, he hopes the study “can provide strong arguments to sustain and further develop this remarkable technology in the coming years.” 

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