Nav: Home

Tracking data reveal the secret lives of marine animals

February 26, 2018

The movements of marine mammals and other large animals that spend their lives in the ocean were largely unknown prior to the development of sophisticated tracking devices researchers could deploy on animals in the wild. Insights gained from this technology have revealed unexpected behaviors and migratory patterns in marine animals ranging from sharks and seals to turtles and albatrosses.

Researchers from around the world have now pooled their data on the movements of a wide array of marine animals, enabling them to look for common features in how animals move throughout the world's oceans. The results, published February 26 in Proceedings of the National Academy of Sciences, show remarkable convergence in the movement patterns of different species, even those widely separated by geography, phylogeny (evolutionary history), or mode of travel.

The biggest differences were between different habitats rather than between different species. In coastal areas, tracking tags revealed complex movement patterns dominated by search behavior, while in the open ocean they showed simpler, more predictable movements over longer distances.

"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 coauthor Daniel Costa, a distinguished professor of ecology and evolutionary biology at UC Santa Cruz. "Regardless of what species it is, the movement patterns match the oceanographic features of their environment."

These insights can be useful, he said, for understanding how marine life will respond to climate change and for predicting the movements of species 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," Costa said.

Costa has been at the forefront of developing high-tech tracking devices and using them to study marine animals. UCSC's Long Marine Laboratory is known as a leading center for research on marine vertebrates, including seals, sea lions, sea otters, dolphins, and whales. The coauthors of the PNAS paper include six other UC Santa Cruz researchers in addition to Costa.

"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 researchers deployed the first satellite tracking tags on elephant seals at the Año Nuevo rookery north of Santa Cruz in the 1990s. The initial results were astonishing.

"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."

In 2000, Costa joined forces with Barbara Block at Stanford University and others to launch the Tagging of Pacific Predators (TOPP) program, a decade-long effort to track the movements of top marine predators in the Pacific Ocean. Costa oversaw the tracking of marine mammals, birds, and turtles for TOPP, which also included tracking of sharks and tunas.

Costa's lab has carried out groundbreaking tracking studies of a wide range of species around the world, including albatrosses, sooty shearwaters, California sea lions, Galapagos sea lions, crabeater seals, Weddell seals, and southern elephant seals. Meanwhile, his team has continued to learn new things about elephant seal biology from ongoing studies of the northern elephant seals at UC's Año Nuevo Natural Reserve.

One recent study, published February 14 in Biology Letters, revealed the effects of pregnancy on the diving behavior of female elephant seals. Led by postdoctoral researcher Luis Huckstadt, the researchers found that the dives of pregnant seals became shorter, probably due to an increasing 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. It's not surprising, but nobody had been able to document it," Costa said.
Huckstadt is also a coauthor of the PNAS paper, as is doctoral candidate Anthony Pagano, whose research on polar bears in the Arctic was recently published in Science, and associate researcher Ari Friedlaender, who has led tracking studies of blue whales. Other UCSC contributors include coauthors Patrick Robinson, Stella Villegas, and Elizabeth McHuron.

The PNAS paper was led by first authors Ana Sequeira at the University of Western Australia and Jorge Rodriguez at the Institute for Cross-Disciplinary Physics and Complex Systems in Spain.

University of California - Santa Cruz

Related Sharks Articles:

Caribbean sharks in need of large marine protected areas
Governments must provide larger spatial protections in the Greater Caribbean for threatened, highly migratory species such as sharks, is the call from a diverse group of marine scientists including Stony Brook University School of Marine and Atmospheric Sciences (SoMAS) PhD Candidate, Oliver Shipley.
Recreational fishers catching more sharks and rays
Recreational fishers are increasingly targeting sharks and rays, a situation that is causing concern among researchers.
Large marine parks can save sharks from overfishing threat
'No-take' marine reserves -- where fishing is banned -- can reverse the decline in the world's coral reef shark populations caused by overfishing, according to an Australian study.
Walking sharks discovered in the tropics
Four new species of tropical sharks that use their fins to walk are causing a stir in waters off northern Australia and New Guinea.
Lonesome no more: White sharks hang with buddies
White sharks form communities, researchers have revealed. Although normally solitary predators, white sharks (Carcharodon carcharias) gather in large numbers at certain times of year in order to feast on baby seals.
The private lives of sharks
White sharks are top predators in the marine environment, but unlike their terrestrial counterparts, very little is known about their predatory activity underwater, with current knowledge limited to surface predation events.
Basking sharks exhibit different diving behavior depending on the season
Tracking the world's second-largest shark species has revealed that it moves to different depths depending on the time of year.
These sharks use unique molecules to glow green
In the depths of the sea, certain shark species transform the ocean's blue light into a bright green color that only other sharks can see -- but how they biofluoresce has previously been unclear.
Blue sharks use eddies for fast track to food
Blue sharks use large, swirling ocean currents, known as eddies, to fast-track their way down to feed in the ocean twilight zone.
Hundreds of sharks and rays tangled in plastic
Hundreds of sharks and rays have become tangled in plastic waste in the world's oceans, new research shows.
More Sharks News and Sharks Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.