So where is she now? The good news is that she did very well on release, traveling from Monterey Bay to Baja California, a distance of more than 500 miles. The last time we heard from her, she was near Ensenada, Mexico.
But about two months ago, her satellite tracking tag “started talking on land,” according to John O’Sullivan, the Aquarium’s curator of field operations. The white shark had been incidentally caught in a gillnet and died. She is the only one of the five white sharks exhibited at the Aquarium known to have died following its release.
Still, that shark, and the more than 180 others that have been tagged and tracked as part of the Aquarium’s White Shark Program, have provided invaluable information on where juvenile and adult great white sharks are traveling and how we might better protect them from overfishing, habitat destruction and other human activities.Future Plans
So what can white shark watchers expect this summer, the time when we normally collect and display seasonal “young of the year?” The million-gallon Outer Bay exhibit is scheduled for renovation starting in August, and that means we won’t be hosting another white wonder until 2011 at the earliest.
For the Aquarium’s White Shark Project, however, it’s full speed ahead. “Our field research continues even though there will be no exhibit white shark this year,” says John.
Working with colleagues at Tagging of Pacific Predators, as well as colleagues in Mexico and southern California, Aquarium staff hopes to answer one looming question: Where do young white sharks go? “Many of our released sharks have gone south to Mexico,” says John. “But we don’t know where they came from before that, and we don’t know where they’re bred or pupped.” Further tagging efforts can help answer these questions.
Data from other tagged sharks indicate that there are “two major population centers in the Eastern Pacific—one in central California, off the Farallon Islands; and one off of Guadalupe Island in southern California,” says John. The adults of these two distinct populations appear to travel back and forth to Hawaii and the “Shark Café,” a remote area between Baja and Hawaii known as winter and spring habitat for adult great whites.
“It’s a huge migration, and there must be an important reason they’re doing it, possibly related to feeding or breeding,” says John. “But no one knows for sure. Continued tagging will help us determine that.”Tagging Technology
To help solve these mysteries, researchers will employ satellite tagging technologies. Currently, before a shark is returned to the wild, it’s fitted with two types of electronic tags. The first is an externally attached pop-up satellite (PAT) tag that eventually pops off, floats to the surface and transmits data via satellite. A second type, the smart position-only (SPOT) tag, sends data every time the shark’s dorsal fin breaks the surface. But these tags have limited lifespans and don’t supply information past six months.
Now, to track shark movement for periods up to five years and closer to shore, researchers will be using implanted acoustic tags. This technology requires underwater “listening stations” to record the “pings” emitted by the tags. “The adult white shark program uses these extensively off the Farallones and Point Reyes, near San Francisco Bay,” says John. “But we’ll be deploying 11 more listening stations off southern California and Mexico’s Baja Peninsula in the next year.”
A fourth type of tag, the archival tag, may also be used. These are surgically implanted and can record temperature, compass heading and depth, and last up to seven years. The shark must be caught in order to recover the tag and its storehouse of data.
It’s all part of solving the mystery of the white shark.
“They’re a big piece of the ecosystem, and yet we know so little about them,” says Dr. Chris Harrold, the Aquarium’s director of conservation research. “What we do know is that there are not many of them. And that alone is cause for concern. We’re trying to learn as much as we can, so we know their role in the marine ecosystem, and what kind of protection they need.”
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