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Little Shark Helps Pierce Great White Mystery


mrmoshe

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Little shark helps pierce great white mystery

The great white shark is one of the oceans' greatest predators, an animal feared by man and fish alike, an object of public fascination even before that campy hit movie Jaws. Yet only recently have we begun acquiring the skimpiest of knowledge about the species.

A little guy in a 1.3-million-gallon tank here at Monterey Bay Aquarium is crucial to that effort. An instant celebrity when he went on display Sept. 1, already the second-longest great white shark to survive in captivity, the juvenile is doing more than drawing visitors to one of the world's top aquariums.

SWIMMING WITH SHARKS: Keep track of sharks via this website

Swimming with huge tunas, Pacific barracudas, a giant green sea turtle and other denizens of deep offshore waters, the shark is bringing in revenue that goes back into research. He's helping to educate the public about the plight of sharks — many species are depleted by overfishing — and he's beefing up a growing body of work on white shark habits.

"There's no doubt we'll learn a lot about white shark behavior, biology and physiology from captive animals," says Chris Lowe, a marine biology professor and director of SharkLab at California State University, Long Beach. "But the biggest value is these little sharks are ambassadors. The aquarium's ability to keep them will be a key turning point in getting people to look at white sharks not just as a threat."

Great whites are king of their natural environment but become delicate creatures when confined. A few dozen attempts have been made since the 1950s. None was successful until two years ago when the aquarium here kept a young female for 198 days, releasing it only after it killed two soupfin sharks in the big tank.

The aquarium's first try, in 1984, ended badly when a 5-foot great white, caught by a fisherman in Bodega Bay north of here, refused to eat and died after 11 days. In 2000, curators decided to try again, but only after careful study of what would put a great white at ease.

By then other aquariums, including SeaWorld in San Diego, had learned that a great white needs a big space because it must swim constantly to breathe. A tank had to have rounded sides, so a shark wouldn't bump into a corner and injure its nose.

Starting small

Tanks had to be cleared of pumps because electrical currents disorient sharks. A key step, copied from a world-class facility in Okinawa that keeps whale sharks, was building a 4-million-gallon pen in Monterey Bay outside the aquarium to mimic open-ocean conditions. That provided a sea-to-tank transition where curators could observe a shark and make sure it was healthy and eating food they offered.

The aquarium sought small whites after early attempts with large ones failed at SeaWorld and San Francisco's Steinhart Aquarium. The new resident is 5 feet, 8 inches long, weighs 100 pounds and is about a year old.

"We're not trying to display a large 18-foot animal," curator Jon Hoech says. "We believe starting small gives us our best chances."

The unnamed male appears to be as big a hit as his female predecessor. She attracted 1 million visitors and $3 million in revenue during the winter 2004-05 tourist offseason. The aquarium has spent nearly $4 million since 2000 on its white shark project; $840,000 of that went back into field conservation research, spokesman Ken Peterson says. The young male, a resident for 53 days as of today, has brought in 250,000 extra visitors.

The aquarium's success has won over critics such the Pelagic Shark Research Foundation, a Santa Cruz, Calif., group that opposes confining certain deep-ocean animals.

"Their program has evolved," director Sean Van Sommeran says. "We stick to our policy, but we're supportive of the project, and it's bringing in a lot of money that can be used on behalf of the shark."

Visitors linger in front of the tank's 15-foot-tall, 13-inch-thick acrylic viewing wall, startled by 500-pound bluefin tuna but mostly waiting for the star to cruise by. He'll swim high and low, glide along the walls, keep to himself. The big tuna ignore him, but a school of sardines stays out of his way.

Twice-daily feedings are a big draw. From above, a worker lowers a pole and chunk of black cod, albacore tuna, salmon or other delicacy into the water. Another handler shoos away other fish.

Soon the shark, as he would in the wild, moves swiftly up from below toward the food, grabs it in his jaws, pivots and swims away.

Most of what had been known about white sharks came from fishermen. The sharks' migratory movements were mysterious, though it was assumed they hung out mostly in coastal waters.

"We don't even begin to understand how animals use the 'blue' part of the planet," says Barbara Block, a professor at Stanford University's marine station here.

In recent years, a lot of effort went into tagging whites and tracking them by satellite. Findings, still limited in scope, were surprising. Whites had long been found in the Farallon Islands west of San Francisco, in the Marin Headlands to the north and at the rocky coastal point Año Nuevo to the south, gorging on seals and sea lions.

Tracking by satellite

Whites also were known to be around Mexico's Guadalupe Island, on the Chilean coast, in Spencer Bay in southern Australia and off South Africa. They like chilly waters associated with Mediterranean climates, says Peter Klimley, a marine biology professor at the University of California, Davis.

Satellite tracking showed adults traveling much farther: from coastal California to the Hawaiian Islands, from Northern California to Baja, from South Africa to Australia. Scientists don't know why. Block says whites may swim to Hawaii in winter for its marine mammal buffet, including baby humpback whales.

"Are there populations at these places" so you can calculate a total, Klimley says, "or are they moving between these sites so there may be even fewer, which is perhaps the likely scenario?"

A graduate student of Klimley's is working on what's hoped is the first reliable estimate of the global white shark population. "There aren't going to be a lot of them," Klimley says, because the top-of-the-food-chain predator reaches sexual maturity late in life and bears a single pup every other year. One hypothesis is that no more than 5,000 exist, he says.

Knowing the population and whether it's going up or down helps predict effects on other marine life, Klimley says. If the white shark is depressing the seal population, that could increase the population of a fish humans eat.

Scientists were perplexed when tracking found white sharks going to a place about halfway between California and Hawaii. It's the ocean equivalent of a desert — no mountains, no valleys, no food, just an aquatic wasteland. Yet the sharks were showing up. Researchers called it the Shark Cafe.

At first they thought that if the cafe had nothing to do with food, it must be about reproduction. "Adult males and females were showing up, so that would sound like sex," Block says. "But then young ones showed up, too, which makes everybody wonder what's going on."

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Guest fishrunner

Thanks for that MallacootaPete,

Very interesting to read they have another in captivity,,,, hope this one survives to undo some of the mysteries that surround this species, :biggrin2:

Greatwhites , still little known about them :biggrin2:

cheers

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