Sightings | Alumni Profile

Tagging Giants for Research
Barbara Block Takes on One of the World's Premier Conservation Challenges by Pursuing the 'Most Majestic Fish in the Sea' p.4

Although bluefins must resurface, Block’s group also learned that bluefin hearts can make use of a special muscle protein and enzyme action to keep beating at blood temperatures as low as about 39 degrees Fahrenheit.

“So I think it’s fascinating that a tuna can go from the warm waters of the Carolina Gulf Stream, at about 78 degrees Fahrenheit, travel 10 days later to waters as cool as 45 degrees, and then when it dives occasionally go to waters as cool as 39,” she says. “Your heart couldn’t do it. Mine couldn’t do it. It’s a unique aspect of this animal.”

Block has now moved beyond her Atlantic Ocean tagging work by also agreeing to organize an electronic tagging program for the massive Census of Marine Life (CoML), an estimated $1 billion venture by universities, institutions and governments from 40 nations to advance understanding of life throughout the oceans. (Read about another CoML project based in the Nicholas School here >.)

As a first phase, she is spearheading a program called the Tagging of Pacific Pelagics (TOPP) that is focusing on 20 target species, including tuna, sharks, dolphins, whales, marine turtles and seabirds.

“What we began to realize is: what if albatross, sea turtle, shark, tuna and marine mammal researchers all worked together?” she explains. “What if we thought the way that genome science works? What if we shared tools and stopped being proprietary?”

So the same types of tags that Block’s team has used in the Atlantic are now also being used in another, larger ocean, and not only on tuna. The electronic monitors are being fitted onto some seabirds, and are being considered for use on marine mammals. And a new type of tag is being attached to sharks that swim close enough to the surface to directly transmit data to satellites.

As an early result of using such tags, researchers studying a Pacific diving bird called the shearwater have learned that those animals descend as deep as 30 to 50 meters. “The secrets of animals that we didn’t know anything about are now being revealed,” she says.

From her own tuna archival tagging work in the Pacific, Block has now learned for the first time that a smaller first cousin of the Atlantic bluefin may be “born in the light of the Coral Sea or the Sea of Japan and one day decide to swim as a two-year-old to Baja California,” she exclaims excitedly.

“That’s a journey that’s three times longer than in the Atlantic by a fish that’s smaller,” she says. “It implies that everything we’re hypothesizing in the Atlantic is true. Naturally spawned Mediterranean Atlantic bluefins don’t think twice about coming over and spending five years in North Carolina.”

Check out Block’s talk at the National Geographic Society Dinner for honoring Nicholas School and Duke Marine Lab members of the William Preston Few Society online >

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