Shark Tracking

Shark Tracking
courtesy of US Air Force

In the morning hours, while many of us are reading the newspaper or downing cereal, shark expert Barbara Block takes care of an important chore. "I like to check on the position of the sharks with my coffee every morning," said the Stanford Hopkins Marine Station professor.

Block is just one of many scientists who are benefiting from technological innovations in shark research that have occurred over recent years. In her case, she can remotely track the position of tagged sharks by simply going online. Anyone can do something similar by directing a Web browser to http://www.topp.org.

Shark tagging has become a growing high-tech industry, with a few different companies selling tags to researchers and institutions worldwide. According to fellow shark tagger Josh Loefer, "Tagging improvements really took off in the late '90s." The biggest boom has been for satellite tags. Loefer, a marine biologist with the South Carolina Department of Natural Resources, explained that there are two principal types. The Smart Position-Only Tag, or SPOT, tracks individual sharks in real time. This data transfers to satellites.

Pop-Up Archival Tags, or PAT, record water pressure, temperature and light. Unlike SPOTs, PATs pop off the shark at a preprogrammed date. Once they float to the surface, they too begin transmitting their data to orbiting satellites.

Block used both types of tags to study salmon sharks. "By using two types of tags, we're able to accumulate a larger data set on the sharks' habitat and preferences with a greater accuracy than we've been able to do before." Already, Block and her team determined that salmon sharks migrate from the glacial waters of Alaska all the way to the warm seas off Hawaii.

Loefer said even the metal toggling device he harpoons onto sharks has seen improvements over the years. This object, which is what can attach a tag to a shark, used to be made out of various types of metal. Now, like a nickel-free earring — or perhaps fin ring would be a better analogy — it is made out of titanium. "Titanium reduces biorejection," Loefer explained.

He is using satellite tags to track sharks off the South Carolina coast, particularly around a deep-water bottom feature known as the Charleston Bump. At depths of over 2,300 feet, the bottom of the bank rises to a shallow scarp and then plunges around 410 feet, yielding rocky cliffs, overhangs and caves that attract sharks and other fish.

There, and in nearby regions, Loefer has tagged scalloped hammerhead, night, silky, mako and big-nose sharks. While he said it will take another three to four years to analyze the collected data, already the information is suggesting that marine species divide themselves into underwater neighborhoods, with scalloped and silky sharks at around 66 feet under the water at certain times in particular locations and blue billfish closer to the surface. Loefer thinks such partitioning "could help to reduce competition among predators."

In addition to tagging innovations, genetic sequencing and DNA analysis methods, similar to those used in stem cell research and in the mapping of the human genome, recently were applied to elephant sharks, the subject of a PLoS Biology [Public Library of Science] study. Like a biochemical family tree, the shark's DNA revealed how this species relates to other sharks and animals, including humans. Overall, the findings illustrate how sharks remain our distant cousins.

New biological and medical-related study methods also are unraveling puzzles about how sharks move, breathe, eat and even smell. A recent Boston University study published in the Journal of Experimental Biology found that sharks use both the nose and skin to locate prey. Again there is a human connection, since humans can sense airflow with small hairs located on the face. Sharks accomplish something similar for odors, utilizing a part of their skin known as the lateral line. This enables them to fish out prey, like squid, by processing incoming information from squid stink gathered by their olfactory, vision and skin systems.

Genetic and computer technologies, along with many other research advancements, are still in their relative infancy, so many more revelations about sharks are possible in the years to come.

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