Tracking Project Reveals Secret Lives of Marine Animals

The black-footed albatross is among the many marine species researchers have been able to track using satellite tags. (Dan Costa)

(CN) – Researchers tracking a wide array of marine creatures discovered surprising similarities in how the different animals move.

In the report, published Monday in the journal the Proceedings of the National Academy of Sciences, researchers use tracking data collected across the world to examine how marine species move throughout the ocean.

Besides revealing unexpected behaviors and migratory patterns, the findings show similar movement patterns among different marine species, including those widely separated by evolutionary history, geography or mode of travel.

The starkest contrasts were between different habitats.

In coastal areas, species had more complex movement patterns that were dominated by search behavior while they showed simpler, more predictable movements over extended distances in the open ocean, according to the data.

“It makes sense, because the coast is a much more complicated environment, whereas the open ocean is more homogeneous and the features are more spread out in space and time,” said co-author Daniela Costa, a distinguished professor of ecology and evolutionary biology at the University of California, Santa Cruz (UCSC).

“Regardless of what species it is, the movement patterns match the oceanographic features of their environment.”

Costa noted these insights can useful for determining how marine species will respond to climate change, as well as for predicting the movements of animals for which tracking data are lacking.

“Many of these species are endangered and we have no tracking data, but we can extrapolate from other species to understand how they are likely to interact with fisheries, shipping, or other human activities,” he said.

Costa has helped to spearhead the development of high-tech tracking devices – like the ones used to collect these data – and their use in marine animal research. UCSC’s Long Marine Laboratory is considered a leading hub for research on marine vertebrates, such as dolphins, whales, seals, sea lions and sea otters.

“This paper is the result of a big international effort. We realized that if we all share our data and work together in a concerted manner, we can learn a lot more about these animals,” he said.

Costa and other UCSC research deployed the first satellite tracking tags on elephant seals at the Ano Nuevo rookery, or colony of breeding animals, in the 1990s.

“Before we put tags on elephant seals, all the books said they were limited to the California Current. We had no idea they were traveling these incredible distances and using the entire North Pacific Ocean,” Costa said. “We went from studying them where we could watch them to having the animals tell us where they were going.”

Costa teamed up with Barbara Block of Stanford University and others in 2000 to start the Tagging of Pacific Predators (TOPP) program, a decade-long effort to track the movements of the Pacific Ocean’s top marine predators. For TOPP, Costa oversaw the tracking of marine mammals, birds, sharks, turtles and tuna.

Costa’s lab has led groundbreaking tracking studies of many marine species around the planet, such as sooty shearwaters, albatrosses, California sea lions, Galapagos sea lions, southern elephant seals, crabeater seals, and Weddell seals.

His team has also continued to learn about elephant seal biology from ongoing research at UCSC’s Ano Nuevo Natural Reserve.

A study published Feb. 14 in the journal Biology Letters demonstrated the effects of pregnancy on the diving habits of female elephant seals. Led by postdoctoral researcher Luis Huckstadt, the team found that the dives of pregnant seals became shorter, likely due to a growing demand for oxygen for the fetus.

“The only way we could do that is because we now have over 500 tracks of female elephant seals, and a small number of them didn’t have a pup or lost it at sea, so we could compare and see the effects of pregnancy,” Costa said. “It’s not surprising, but nobody had been able to document it.”

 

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