Scientists say they are baffled by the large number of whale shark sightings reported this summer in the northern Gulf of Mexico. Reports have been pouring in from all over; from Clearwater to the Florida Panhandle and along the Alabama, Mississippi and Louisiana coasts.

“The sheer number of anecdotal reports from the public is amazing. There’s obviously something going on,” says shark scientist Bob Hueter who heads the Shark Research Center at Mote Marine Laboratory.

It is common for Whale sharks to gather in the plankton-rich waters off the Yucatan Peninsula during the summer, but this year numerous whale shark sightings have been reported from the eastern and northern parts of the Gulf as well. The concentrations spotted off the Yucatan Peninsula are also higher than before with hundreds of Whale sharks being seen in a single location.

According to Mote Marine Laboratory records, there were just three Whale shark sightings in the Florida Gulf in 2005, two in 2006, five in 2007, and three in 2008. This year, there have been 12 sightings just from July to mid-August.

According to Heuter, the large Whale sharks may have been attracted by a change in the massive “loop current” in the Gulf that took place this year, and there is also a stronger than usual upwelling of cold, nutrient-rich water off the Yucatan that may play a role.

“That changed the oceanography a bit, and it could have driven some of these animals up into the northern Gulf,” Hueter explained.

Eric Hoffmayer, a biologist with the Gulf Coast Research Laboratory on the Mississippi coast, said his lab has gotten reports of 30 sightings in just the last two weeks. On Aug. 1, there was a reported sighting of more than 100 whale sharks congregating about 60 miles off the Louisiana coast.

“We don’t know what’s going on,” said a baffled Hoffmayer.

Many of the sightings have occurred when there was a full moon.

As mentioned above, record sightings are being reported from the waters off Yucatan as well. An aerial survey last week did for instance reveal over 400 whale sharks in a relatively small area near the Isla Mujeres. The Yucatan aggregation is an annual phenomenon, but it usually takes place near Isla Holbox and the group tends to be much smaller.

Alabama fishermen and scuba divers will receive a welcome present from the state of Alabama in a few years: the coordinates to a series of man-made coral reefs teaming with fish and other reef creatures.

In order to promote coral growth, the state has placed 100 federally funded concrete pyramids at depths ranging from 150 to 250 feet (45 to 75 metres). Each pyramid is 9 feet (3 metres) tall and weighs about 7,500 lbs (3,400 kg).

The pyramids have now been resting off the coast of Alabama for three years and will continue to be studied by scientists and regulators for a few years more before their exact location is made public.

In order to find out differences when it comes to fish-attracting power, some pyramids have been placed alone while others stand in groups of up to six pyramids. Some reefs have also been fitted with so called FADs – Fish Attracting Devices. These FADs are essentially chains rising up from the reef to buoys suspended underwater. Scientists hope to determine if the use of FADs has any effect on the number of snapper and grouper; both highly priced food fishes that are becoming increasingly rare along the Atlantic coast of the Americas.

Early settlers and late followers

Some species of fish arrived to check out the pyramids in no time, such as grunt and spadefish. Other species, like sculpins and blennies, didn’t like the habitat until corals and barnacles began to spread over the concrete.

“The red snapper and the red porgies are the two initial species that you see,” says Bob Shipp, head of marine sciences at the University of South Alabama. After that, you see vermilion snapper and triggerfish as the next order of abundance. Groupers are the last fish to set in.”

Both the University of South Alabama and the Alabama state Marine Resources division are using tiny unmanned submarines fitted with underwater video cameras to keep an eye on the reefs and their videos show dense congregations of spadefish, porgies, snapper, soap fish, queen angelfish and grouper.

“My gut feeling is that fish populations on the reefs are a reflection of relative local abundance in the adjacent habitat,” says Shipp. “Red snapper and red porgy are the most abundant fish in that depth. They forage away from their home reefs and find new areas. That’s why they are first and the most abundant.”

What if anyone finds out?

So, how can you keep one hundred 7,500 pound concrete structures a secret for years and years in the extremely busy Mexican Gulf? Shipp says he believes at least one of the reefs has been discovered, since they got only a few fish when they sampled that reef using rod and reel. Compared to other nearby pyramid reefs, that yield was miniscule which may indicate that fishermen are on to the secret. As Shipp and his crew approached the reef, a commercial fishing boat could be seen motoring away from the spot.