DUBAI // "It is a game of patience," says Juan Romero, pointing to four silhouettes swimming on the other side of a thick acrylic wall.
Although it is only 9am and shoppers are few and far between in Dubai Mall, the spectacle has already attracted a sizable crowd. They gather outside the vast transparent wall of the Dubai Aquarium and Underwater Zoo to watch as the divers try to catch a shark.
The plan is to have 31 of the aquarium's larger sharks - there are 50 in total - briefly taken to the surface so blood samples can be taken and quick health checks carried out. The smaller sharks are easier to handle, and do not need to be caught and brought to the surface for their examinations.
It is the first time the sharks have been tested since the aquarium opened in November 2008.
Mr Romero, the curator, believes the examinations are necessary both for the individual wellbeing of the fish and to maintain the health of the world's largest collection of captive sharks and rays.
The fish, however, do not appear to have read the e-mail. "The sharks know something is coming up and they are hiding," says Mr Romero.
Two of the divers try to attract the shark into a large, cone-shaped bag, while the others try to guide the fish by placing plastic poles on each side of the its head.
The poles, says Mr Romero, stimulate sensors and create the illusion that the shark is surrounded by walls, helping to guide it in the desired direction. But once the fish looks around, it can see there are no walls and swims away. That is exactly what was happening yesterday morning.
After 15 minutes of manoeuvres, a male sand tiger shark is finally in the bag and the four divers head to the surface. Mr Romero runs two floors up to the aquarium's back rooms where a team is ready to work on the fish.
A pipe with oxygenated water runs in front of the shark's mouth, ensuring it can breathe whenever its head is out of the water. Water is sprayed on any exposed flesh.
Three of the divers - Alessandro Marchi, Mark Dimzon and Nazrin Rusli - hold the shark as the fourth, Ariel Torres, a veterinary technician, extends a hand for an empty syringe.
"Torch," Mr Torres instructs, disinfecting an area near the shark's tail.
Under the beam he expertly inserts the syringe and begins drawing blood.
Unlike mammals, sharks are not easy to take blood samples from, Mr Romero explains later. Their skin is as thick as that of a crocodile and blood vessels are hard to find.
After measuring the fish - it is more than two metres long - the team takes a sample from the area around its gills to see if it is infected by parasites. Before it is allowed to swim back, the fish also receives an injection of vitamin B12 complex and vitamin C.
"It is like giving someone a good breakfast," Mr Romero says.
The shark's behaviour during the entire procedure counters the species' image as a voracious predator, hostile to humans. Although it appears agitated, at no point does it seem hostile towards its handlers.
"The shark will only attack if it feels in danger," says Mr Romero. "If you are swimming or diving with one, do not panic, just leave it alone."
Recent shark attacks in the Red Sea may have been caused by previous interactions with humans, he says. As many divers aim to see sharks in the wild, some dive operators pour blood and meat in the water to attract sharks.
"My personal opinion is that they relate humans with food," he says.
Only one other shark is caught for the rest of the day. The effort continues next week and is expected to be finished at the end of January.
The team will test the samples they obtain to determine if the fish is healthy. The information is also entered into a database, which can be monitored and exchanged with other aquariums around the world - helping to create comparative data in captive populations.
Eventually, it could help the facility to breed sharks in captivity.
This may be necessary, considering the dire conservation status of sharks in the wild, says Mr Romero.
By eating fish one step down the food chain, sharks keep entire eco-systems in balance. If sharks go, so will coral reefs and commercial fisheries.
"We have managed to wipe out between 93 and 95 per cent of the world's entire shark population through shark finning and by-catch," he said. "And no one seems to understand how important they are."