Nature’s MR. BIG
The fin was in front of me just as it broke the surface of the water. Behind the fin, a tail moved. The boat that brought us was a short distance away; everyone on it was pointing at the shape that seemed to be heading straight towards me.
It was dawn when we boarded the fishing boat and left Isla Holbox, northwest of Cancun. Isla Holbox is separated from the mainland by a lagoon.
The mixture of currents in this area causes plankton to bloom profusely. Plankton attracts a variety of marine life forms, including an elusive creature.
When the boat’s engine stopped, I dove into the water.
After adjusting my snorkel, I peered under the surface to see what lay ahead. Visibility wasn’t good but I sensed something big very close. The water around me seemed empty when suddenly I saw an enormous mouth, over a yard wide. I could do little but stare at this larger-than-life creature as it sucked in whatever came between its enormous jaws.
The whale shark (Rhincodon typus), a filter-feeder, is the largest fish species on earth. The name ‘whale shark’ comes from the fish’s physiology: a shark bigger than most whales, which shares a similar filter feeding technique.
The largest specimen ever recorded was caught on November 11 1947 off the island of Baba, near Karachi, Pakistan. It was 41ft long, weighed 47,300lb and had a girth of 23ft.
The creature’s enormous mouth holds 300 rows of tiny teeth. Two small eyes are located towards the front of the wide, flat head. The skin is marked with a ‘checkerboard’ pattern of pale yellow spots and stripes. The spots are unique to each whale shark.
Whale sharks have a varied menu. They scoop up plankton that drifts in great numbers in salt water, along with small fish that happen to be around. Sometimes whale sharks eat garbage by mistake. Buckets, boots, oars and tires have all been found in the autopsied stomachs of Mr. Big.
Whale sharks are found in temperate and tropical seas around the world, except the Mediterranean. Telemetry studies indicate they are a highly nomadic species.
Seasonal feeding aggregations of whale sharks occur at several sites, including Ningaloo Reef off Western Australia, Utila off Honduras, Isla Holbox off the Yucatan, and near the island of Zanzibar, in the Indian Ocean. Though occasionally seen far offshore, the creature has also been observed close to land.
The species is considered vulnerable. Once targeted by commercial fisheries in areas where they seasonally congregate, all fishing and exporting of whale sharks for commercial purposes has been banned.
What do whale sharks and the night sky have in common? Much, it seems. They are both on the large side. Both are physically attractive, if daunting to look at. And both whale sharks and the night sky have the same complexion: a sprinkling of light spots against a dark background.
This last characteristic has caught the attention of Ecocean, an Australian marine conservation agency. Using a star recognition computational procedure, the agency has developed computer software that can assign a specific whale shark a ‘digital fingerprint’. These are based on photographs of the precise and specific pattern of spots on the animals back.
The goal is to discover whether whale sharks are experiencing the same population decline that we’re seeing in other shark species all over the world. Observers send in snapshots, which are fed into a database called the ‘Whale Shark Photo-Identification Library’. This allows Ecocean to track the movements of individual whale sharks.
The results are ominous. For instance, the number of whale sharks observed around Ningaloo Reef in Western Australia declined by 19% from 2001 to 2005. The species may in fact be swimming through its twilight years. Let us pray that that does not happen and that this magnificent creature remains forever a part of the natural world.
Joe Zentner is a retired professor and a freelance writer.
Diving with Whale Sharks
Whale sharks are often cited when educating the public about the misconception that all sharks are ‘man-eaters’. Humans can swim alongside this giant fish without risk. Enjoy, but please exercise prudence when around Mr. Big.
Mature whale sharks, which are three times the size of the larges great white shark, are peaceable creatures unfazed by visits from curious humans. As noted in this article, the creatures visit the Yucatan Peninsula’s coast during the summer to feed. This situation presents an ideal opportunity to observe whale sharks up close. Mexico’s Caribbean coast is one of the few places on earth where people can swim alongside whale sharks. This is an incredible marine experience that puts a person just a few yards away from a natural wonder of the world. Tours are held between June 1st and mid-September.
For more information concerning Yucatan whale shark swimming tours, contact: [email protected]