ATLANTA -- One of the original whale sharks at the Georgia Aquarium has died -- the aquarium's second whale shark death in five months.

GUEST BOOK: Share Your Thoughts On Norton's Death

Aquarium officials said in a statement that Norton had stopped eating in the past few months and showed erratic swimming behavior.

Husbandry staff noticed a decline in Norton's swimming behavior yesterday, and blood work confirmed a decline in his health.

Norton had been placed on a 24-hour watch. Aquarium officials say early this morning, the whale shark stopped swimming and settled to the bottom of his tank.

Divers took him to a stretcher. The aquarium says, "after every option had been exhausted to improve Norton's health, the team made the decision to humanely euthanize him."

In January, Ralph, another whale shark, died.

Aquarium officials say Ralph had stomach problems that led to an inflammation of a membrane in his abdomen. But some animal rights groups have questioned whether his death involved a chemical used in the tank to treat parasites.

Earlier this month, two new whale sharks -- Yushan, which means "jade mountain" and Taroko, named for a national park in Taiwan, arrived to the aquarium from Taiwan.

The Georgia whale sharks are the only whale sharks on display outside of Asia.

The United Kingdom-based Captive Animals' Protection Society, the New Jersey-based Shark Research Institute and at least one scientist who has conducted whale shark research have raised varying degrees of concern about the aquarium's decision to display the gentle giants, which eat plankton, not people.

Others, including Robert Hueter — one of the nation's leading shark experts — have applauded the plan to bring the big fish to the public. Exposing huge numbers of people to the giant fish through the aquarium will, they contend, help protect the animal in the wild and increase our understanding of the creature.

"This kind of display can engage the public and help protect the ocean, and there are two ways to go about that," Hueter said. "One is to take people to whale sharks in the wild. The other is to bring whale sharks to people.

"You can only take so many people to the sharks without adversely impacting the sharks' behavior. And most people just can't afford to go on those kinds of trips."

But Craig Redmond of the Captive Animals' Protection Society, which lobbies on behalf of animals in circuses, zoos and the entertainment industry, has labeled the Georgia Aquarium's move as "dangerous." He has called for a shutdown of the aquarium industry.

"CAPS believes that Georgia Aquarium's capture and display of species like whale sharks is increasing the pressure on other aquariums across the U.S., and the world, to capture thousands of animals from the wild and put them on display," Redmond said. "Many of these animals will not live long in captivity and will be replaced by yet more wild-caught animals."