Holbox Whale Shark Expedition

July 3, 2009

Join us as we visit one of the most important whale shark feeding areas in the world. During July 11th – 15th, Dr. Sylvia Earle’s Deep Search Foundation will be on the island of Holbox as part of a research expedition to better understand the largest fish on earth.

Whale sharks are widely distributed in all tropical and warm temperate seas throughout the world. Their distribution in these warm tropical waters is linked to the high productivity of these areas, i.e. dense concentrations of plankton. One particular island off the coast of Mexico boasts a large population of migratory whale sharks. Isla Holbox (pronounced “hole-bosh”) was a well-kept secret until 6 years ago when whale sharks were discovered right off its coast. Once a small island with just 1600 year-round residents, Holbox has since become a popular summer tourist destination. Although whale sharks are generally considered solitary animals, they congregate in the waters surrounding Holbox to feed and mate from May through September, earning the island’s designation as the top place in the world to see and swim with these ‘gentle giants’.

Whale sharks are currently listed as a threatened species by the International Union for the Conservation of Nature (IUCN) and significant attention has been given to protecting them from overexposure to humans at Holbox. The Mexican government has listed Holbox as the only port that can offer tourism trips and strict regulations are in place against the use of scuba equipment to view the sharks. In addition, local tour guides have been provided with training to ensure no whale sharks are harmed during trips. Unfortunately, the sharks are under increasing pressure from the ‘loving them to death’ syndrome. This year the Mexican Government granted 220 permits. Last year only 40 permits were issued.

Whale sharks (Rhincodon typus) have earned the descriptions of being both ‘Harmless Heavyweights’ and ‘Gentle Giants’ due to their enormous size yet docile and serene temperament. Although their name implies differently, whale sharks are actually a species of shark and the largest living fish in the world, reaching lengths of up to 40 ft and weighing upwards of 15 tons! However, despite this huge size, whale sharks are filter feeders that eat the tiniest plants and animals in the ocean, called plankton. During feeding, a whale shark’s mouth can open to an astounding 5 feet wide and creates a strong suction that essentially vacuums food into its mouth. Unlike other filter feeders that need to constantly swim to filter food out of the water column, whale sharks are able to suck in food from a stationary position.

Please join Dr. Sylvia Earle and the Deep Search team as we work to highlight the important research being conducted in Holbox. We will be making daily posts from the island and developing new content for Google Ocean’s “Explore the Ocean” layer.

Kip Evans, Deep Search