Guess who's back?

Photo by Instructor Shane Anderson

Scientists with the federal government and from 3 Gulf of Mexico states say efforts to find out more about whale sharks, the world's largest fish, are picking up steam.

Biologist Eric Hoffmayer of the National Oceanic and Atmospheric Administration fisheries service says 2 trips into the Gulf during September resulted in 10 taggings, significantly more than earlier efforts. The tags will provide information on the animals' movements.

In the summer, schools of the harmless animals laze about at the surface, where they can be tagged easily. But as fall approaches, they split off to hang out with schools of tuna that herd baitfish to the surface for an easy meal.

Relatively little is known about whale sharks. Scientists don't have a handle on population numbers, or know much about their breeding and migratory patterns.

Researchers from Louisiana, Texas and Mississippi joined for the September tagging expedition. They were aided in their search by a spotter plane provided by a California-based nonprofit, On the Wings of Care.

On one trip to the Flower Garden Banks National Marine Sanctuary off Texas, Hoffmayer said the Gulf seethed as whale sharks leaped about, gulping mouthfuls of tiny fish. Screaming seabirds dove to grab some of the bounty.

Photo Josh Blair Oriskany

The scientists had 30 seconds to get photographs, anchor a GPS tag in the thick, sandpaper-like skin of one of the sharks and take a DNA sample.

Hoffmayer said the trips were successful — they tagged five whale sharks on each of two such trips. That's more per day than ever before.

The tags will beam information back to labs to track the sharks whereabouts.

"We pretty much doubled the amount tagged in the northern Gulf in one week," said Hoffmayer, who has studied whale sharks for nearly a decade.

The newly tagged animals range from 15-foot-long juveniles to 35-foot adults.

Photo by Shane Anderson 6 miles off shore

Whale sharks can grow as long as a school bus and are on the World Conservation Union's "red list" of threatened species.

"We're interested in how long they stay here in the Gulf, and where they go in winter," Hoffmayer said.

But to find out requires swimming with the sharks.

Fortunately, they're a docile species. They cruise the gulf sucking into tiny teeth meals of small fish and plankton. They lack the fearsome jaws of Gulf predator species such as the mako, tiger and bull shark.

Getting close to the gentle giants isn't as easy as it seems, even as they glide slowly through the warm waters.

"Though it looks like it's swimming nice and slow, it's a lot faster than we are. We try to put ourselves in front of the animal and let the animal swim to us," Hoffmayer said.

Once their boat was in position near a shark, Jennifer McKinney, a research technician at the University of Mississippi's Gulf Coast Research Laboratory, and Hoffmayer slipped into the water. A photographer went to the head — the spot pattern behind each whale shark's gills is unique. Hoffmayer was in the middle to attach a tag, and McKinney got DNA samples from the tail.

Photo Josh Blair Oriskany

Seven sharks tagged in September have tags that store months of temperature and depth data. They're designed to pop off and rise to the surface — adding a straight-line travel distance from the spot where the fish was tagged — either after a set time or if the shark dives so deep that water pressure would crush the electronics.

Two have "spot tags," designed to transmit an animal's location each time it surfaces. One has both.

The International Foundation for Animal Welfare and World Wildlife Fund provided money for the tags, which cost about $2,000 for spot tags and $3,500 to $4,200 for the pop-off tags.

Two are set to pop off in four months, two in six months and two in eight months, Hoffmayer said.

"Two of the spot tags that we put out have reported," Hoffmayer said. "Both sharks were moving east."

Photo Down Under Diver

In about 12 days, he said, one had moved about 120 miles and the other about 130 miles. One was south of Pensacola, Fla., near an underwater area called the DeSoto Canyon. The other was south of Mississippi.

The trips grew out of a larger effort to tag fish such as tuna and billfish, said Louisiana Wildlife and Fisheries Assistant Secretary Randy Pausina.

Pausina said a multispecies tagging plan may be ready to submit to NOAA within a few months.