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Expedition White Shark:
By Claire Discenza
New dangers constantly threaten marine wildlife, yet humans don’t understand enough about the lives of many of these species to protect them, said National Oceanic and Atmospheric Administration fisheries biologist Heidi Dewar at the Jeffrey B. Graham “Perspectives on Ocean Science” lecture hosted by the Birch Aquarium on Feb. 13.
During her talk titled, “Fish and Chips: Using High-Tech Tools to Learn More About Fish,” Dewar presented the new tracking technologies that she and others use to map behaviors of at-risk species.
She also gave an overview of the problems that marine animals face, and the insights humans can glean from new tracking technologies.
“While knowing something about fish has been important throughout the 40,000 years we’ve been hunting them for food, understanding fish behavior is even more crucial now. A lot more people are on the planet, and our concerns are more complex,” Dewar explained.
Changing oceans, overfishing, poaching, and accidental death have dramatically reduced many populations throughout the Pacific in recent years. “The Southern Bluefin Tuna is pretty much in the toilet,” Dewar reported, as one of many examples. In order to help protect and revive Pacific populations, researchers need to know more about their habitats and migrations.
“We need to be able to make better predictions about what will happen to our species after different changes. Information is important in helping us to understand what patterns we see out there,” said Dewar.
To gather this information, Dewar and her colleagues use three high-tech tracking devices: the Archival tag, the SPOT tag, and the PAT tag, each of which collect different types of information about fish location and water conditions.
The Archival tag, an information-storage “personal computer for a fish,” must be retrieved to collect the data. “There are two ways to get them back,” explained Dewar. “The first is a large educational and outreach program, and the second is a large reward. We use both.”
The other two tags transmit their data via satellite, and therefore don’t need to be recovered. The Smart Position and Temperature (SPOT) tag specializes in the tracking of surface species, whereas the Pop-Up Archival (PAT) tag is best suited to deeper-swimming creatures.
Using these devices, researchers have been able to track dozens of species, including 27 Mako Sharks. “Individual sharks went back to the same location on subsequent years,” Dewar noted. “They have neighborhoods that they like to hang out in.” Among many possible applications, scientists can use this data to develop plans for avoiding bycatch, or the unintentional capture and injury of non-target species during fishing.
Through tagging, researchers have learned that swordfish dive deep during daylight hours, whereas Leatherback Seaturtles, a common bycatch, stay within the top 40 meters of the ocean.
“Our idea is that maybe we can catch swordfish during the day, when they are deep and all the turtles are at the surface,” Dewar explained. “We are developing incredibly powerful complex modeling to tell where you have overlap between the species you do want to catch and the species you don’t want to catch.”
In a final call to action, Dewar emphasized the importance of education and outreach.
“If anyone sees a shark, make a phone call,” Dewar insisted. She discussed “Expedition White Shark,” an iphone app that allows anyone to track tagged sharks, as well as the Tagging of Pacific Pelagics (TOPP) project website on which visitors can follow several migrating species in real-time.
When it comes to conservation, “bringing the public in is so important,” Dewar stressed. “We need political power, so we need people who are out there and interested.”