AmbergrisCaye.com Home Forums About Belize Nature Secrets of the Belize Whale Sharks Revealed

Thanks for the collaboratin Simon.

And by the way, the whale shark steaks you had waiting for me in my refrigerator when I arrived were excellent.

OK bywarren had to be something stronger than a few Belikins prior to the dive you "saw" a Whale shark engulfing tuna? Something mind alterring by any chance?? As Warner Wolf would say - "gimme me a break"!!!!

Show us a picture of that one and I'll buy the first round of Whale shark steaks for every person on the island!!

Be careful what you offer. Look me up when you are in AC and I will show the pictures and a video. If I am not there when you are, just look up Jose Gonzales (fishing guide) phone number 226-2344. He also has copies.

To quote Walter Brennan, "no brag, just facts."

PS: and it was not "a whale shark." I used the term "them" and "their" i.e. plural. Have been diving with them many years seeing it many times.

bywarren: You're on!

High-Tech Tags Reveal Whale Sharks
By Rossella Lorenzi, Discovery News


AP Photo/Beatrice Larco

Oct. 6, 2005- Whale sharks, the world's largest fish, dive nearly a mile in search of food, according to high-tech electronic tags that have recorded every aspect of the fish's life.

Rachel Graham, of the U.S.-based Wildlife Conservation Society (WCS) and colleagues from the University of York, U.K., attached electronic tags to nine whale sharks swimming at the Gladden Spit reef off Belize, the world's second-largest barrier reef system.

Thousands of snappers gather there under full moons in the spring to spawn, turning the sea a milky color and drawing normally solitary whale sharks, which feast on snapper fish "caviar."

Part of the folklore of the reef's fishermen, the spectacle has proved to be a unique possibility for the researchers to attach satellite-controlled tagging devices to the fish's thick skin.

The tags made regular recordings of temperature, water pressure and light level for 206 days. After this preprogrammed period, they automatically detached from the fish, floating to the surface and sending their data back via satellite.

Downloaded to a computer, the recorded information showed that whale sharks made dives beyond 979.5 meters (3,213 feet) - the tag's maximum depth recording - to temperatures below 7.6° Celsius (46° Fahrenheit).

"A whale shark may be able to withstand low temperatures due to its subcutaneous fat layer," the researchers wrote in the current issue of the Royal Society's journal Interface.

While at night the sharks remained in shallow waters, they made deep dives during the day. These often ended with fast ascents, to re-oxygenate the gills after time spent in less-oxygenated depths.

Growing up to 65 feet (20 meters) long and weighing up to 15 tons, the nonaggressive whale shark (Rhincodon typus) lives in tropical seas and feeds mainly on plankton.

Contrary to its name, the fish is not related to whales, which are mammals.

A highly migratory species capable of transoceanic movements, whale sharks, threatened by overfishing, are one of the species listed as vulnerable to extinction.

"We now know how the world's largest fish behaves night and day and that their behavior is not random; it has patterns that are geared to food availability," Graham told Discovery News.

"This has conservation implications whereby we need to focus more on protection of their key feeding sites where they are most vulnerable to capture," she said.

Indeed, the data from tags revealed that whale sharks' dives are influenced by food sources, with shallower dives made during fish spawning periods. Even the different diving patterns during the night and daytime are related to food.

"They may be linked to migration of zooplankton that usually aggregate near the surface by night and descend to deeper depths during the day," said the researchers.

According to Heidi Dewar, a marine biologist at the TOPP program - Tagging of the Pacific Pelagics - in La Jolla, Calif., the study "provides valuable data on a very poorly understood and endangered species."

"It also takes the analysis to a new level using a novel approach to quantifying patterns, rather than just describe them qualitatively. Rigorous quantitative analysis is critical to developing any models that will predict the distribution of whale sharks for conservation efforts," Dewar told Discovery News.

http://dsc.discovery.com/news/briefs/20051003/whaleshark.html

Hmmm, filets or steaks, grilled -butter,garlic YUM! YUM!

Very cool program, been to their base on the Silk Cayes, twice during tagging, which is as difficult as it sounds. Treat yourself to a whale shark dive with Julie Berry, who worked with Rachel and is now runing the dive shop at Turtle Inn in Placencia.