Georgia Aquarium looks for answers in whale shark death

January 12, 2007

NEW: Aquarium conducting necropsy on Ralph
NEW: Other whale sharks appear to be fine
Ralph stopped swimming and received treatment before dying hours later
Aquarium euthanized ill beluga whale Gasper earlier this month

ATLANTA, Georgia -- Scientists worked Friday to determine what killed Ralph, one of the four giant whale sharks at the Georgia Aquarium.

The 22-foot-long fish stopped swimming Thursday afternoon and divers whisked it from the bottom of its football field-sized tank to an exam area. Teams worked to save him for about eight hours before he died at 9:30 p.m.

"When we found him sitting on the bottom we immediately knew that he was in trouble," said Jeff Swanagan, the aquarium's executive director. (Watch Ralph before he died and how the staff responded )

http://www.cnn.com/video/player/player.html?url=/video/tech/2007/01/12/sotvo.ga.jeff.swanagan.on.ralph.the.whale.
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Swanagan said a necropsy, or animal autopsy, was under way to try to determine the cause of death. Aquarium employees are also monitoring the other animals.

He said whale sharks Norton, Alice and Trixie all seem to be swimming normally.

"We're watching it very carefully, but there's nothing indicating any other problems in the exhibit or anywhere else in the aquarium and no problems with any of the water chemistries," he said.

Ralph was the second popular animal to die at the aquarium in a nine-day period.

On January 2, Gasper the beluga whale was euthanized. He had suffered from a string of chronic illness even before he came to the aquarium.

Swanagan said the deaths were unrelated and that the animals lived in separate tanks with different water supplies.

"To have two big charismatic animals [die] creates a linkage that's probably not there," he said. "I've been doing this since 1979 and I've had cases where I've had two days in a row of births and two days in a row of deaths. Nature just sometimes doesn't give you a schedule of tragedies that's convenient."

Ralph had a physical exam in November with about 50 people taking part -- including veterinarians, biologists, divers and photographers.

Swanagan said the staff was concerned about some unusual swimming behavior a couple of months ago, but that had improved. Ralph's appetite also had been on and off. (Full story)

"There was nothing we could see that would define that this animal was as sick as he turned out to be," he said. Swanagan said there was no indication that stress from the exam could have contributed to Ralph's death but said that was one of the things they would look into.

Saved from the dinner table
Ralph and Norton have been the biggest stars at the aquarium since it opened in November 2005. They were joined by females Alice and Trixie in June.

The aquarium got the whale sharks by negotiating with Taiwan, which catches the animals for food. It is the only aquarium outside of Asia to showcase whale sharks.

The World Conservation Union lists the whale shark as a vulnerable species. Heavy fishing of the whale shark in several areas of Asia is believed to be one reason for its population decline.

Scientists hope to breed the sharks, but Swanagan said that's years down the road.

"The animals are all pre-teenagers and it would be many years before they would be ready to breed," he said. "Our friends in Okinawa, Japan, have had three whale sharks for 10 years in an exhibit that's two-and-a-half times smaller than ours and their animals are not yet breeding."

Mysterious giants
Whale sharks are the world's largest fish and can grow up to 66 feet in length. They are gentle animals that feed on plankton and small fish that they filter into their wide, flat mouths.

Swanagan said the Georgia Aquarium has been working with whale shark researchers for four years, but there are still a lot of things that they don't know.

He said some leading marine scientists worked for years without seeing a whale shark in the wild.

"No one knows, comprehensively, the life cycle of these animals," he said.

Swanagan said he's glad that more than 4 million visitors got to see Ralph.

"People have such an aversion to sharks, so to have these sort of friendly sharks, like whale sharks be ambassadors to get people to want to learn more about sharks is a very important reason to have them," he said.


Note: this is very sad. I visited the Georgia Aquirium last March and it just amazing there. I hope they learn more and more about these beautiful animals and can find out why he died.

I saw the Bulugas last year also and it was sad they could not get the one that died recently cured of the illness it had when it was rescued.


HERE'S RALPHS STORY BELOW WHEN HE HAS HIS LAST PHYSICAL.
Huge whale shark Ralph gets a once over
November 9, 2006

ATLANTA, Georgia -- -- Physical exams are a lot more complicated when the patient weighs about a ton. And lives in salt water.

A well-choreographed team of about 50 people, including veterinarians, biologists, engineers, divers and photographers took part in an examination of Ralph, one of four whale sharks at the Georgia Aquarium.

"There are extraordinary challenges. We're talking about the world's largest fish," said Ray Davis, Vice President of Zoological Operations.

"You want to be safe for the animal and the staff handling him," he said.

Ralph is 22 feet long. He's grown six feet since arriving at the aquarium in June 2005.

Divers used nets and ropes to guide Ralph, believed to weigh between 1700 and 2500 pounds, into a sort of floating stretcher. During the exam, engineers could raise, lower, or tilt the contraption so the staff could access the proper body parts.

Anesthesia drugs diluted in nearly 1500 gallons of water were force-flowed into the whale shark's mouth and across the gills during the two-hour procedure.

While Ralph was "out," aquarium veterinarian Dr. Tonya Clauss drew blood for a number of different studies. Scientists know that red and white blood cells are significantly larger in whale sharks than in other sharks, or their relatives, skates and rays.

"In a normal field of view for a smaller shark, you would see 30 to 40 smaller red blood cells. For whale sharks we saw 10 huge cells," said Davis.

Another crucial area of study is the animal's reproductive system. Very little is known about when whale sharks become sexually mature, and exactly how they reproduce. So the blood will also be studied for hormones, to help determine if Ralph is beginning to sexually mature. The same tests are being conducted on his cohorts in the 6.2 million gallon habitat -- Norton, Alice, and Trixie.

Whale sharks are ovoviviparous, meaning that eggs hatch within the mother's body, and then are released. The species is so little studied that researchers did not learn this until 1995, when a female whale shark that had been harvested for food was found to have both eggs and live young inside.

"This female had 350 offspring, that's an extraordinary number, and in different stages of development," said Davis.

Some newborns have been found measuring 21 to 25 inches.

Also during the exam, images were taken under the gill flaps and inside the whale shark's mouth, to add to knowledge about feeding mechanics. A whale shark's mouth can reach four feet across. In the wild, it feeds on sardines, anchovies, mackerel, small tuna, small crustaceans and squids that it strains from the water through its gills. Usually the food consumed is small, because the fish's throat is small and makes a right angle to its stomach. Whale sharks move slowly, and often feed near the ocean's surface.

The medical team also took DNA samples to add to a database of the species, and examined Ralph's gastrointestinal tract.

While the team took extensive measurements to track Ralph's growth, it is considered too dangerous to try to weigh him.

Little is known about the migratory habits of these huge fish. The aquarium has partnered with Mote Marine Laboratory in Sarasota, Florida, to conduct long-term studies of its biology and habitat. Whale sharks are found worldwide, generally about 30 degrees north and south of the equator.

Finding answers to some of the mysteries of this big fish is one of the aquarium's missions.

"Every time we answer a question, we end up with 25 more questions. That's what motivates our team," said Jeff Swanagan, Georgia Aquarium Executive Director.

The World Conservation Union lists the whale shark as a vulnerable species. Heavy fishing of the whale shark in several areas of Asia is believed to be one reason for its population decline.

The Georgia Aquarium has had more than 3 million visitors since it opened a year ago.