St Helena’s Unique Whale Sharks

Every year, from December until May, whale sharks (*Rhincodon typus*) – the world’s largest fish – gather in numbers around the island of St Helena.

Although the exact number of sharks that visit the island every year is not known, more than 30 individual animals have been sighted during a single week, although not at the same time in the same place.

As with all marine encounters, sightings cannot be guaranteed, but the chance of spotting one of these magnificent fish during a visit to St Helena at this time of year is very high indeed. Just being at sea when they are in the area brings a decent chance of seeing one at the surface, and the experienced captains of the snorkelling boats who run dedicated trips to find the sharks know where to look.

While there are other whale shark aggregations in different locations around the world, the annual gathering around St Helena is possibly one of the most important. The island is unique in the fact that it is the only known location in the world’s oceans where adult male and female whale sharks gather in equal numbers.

Satellite tags track the whale sharks as they gather and then disperse (pic: Georgia Aquarium)

It is the only place in the world where whale sharks have been observed mating, and for more than ten years, the islanders collected data from each gathering with the guidance of St Helena’s Environmental Management Division. It was not until 2015 that the first ‘official’ scientific expedition to the island occurred, in partnership with the Georgia Aquarium, based in Atlanta, America.

Satellite tagging projects sponsored by Georgia Aquarium and implemented by the Marine Conservation officers of St Helena, have shown that the whale sharks remain in the area between three and four months, before dispersing into the open ocean.

The Saints have for many years recognised the significance of this gathering, and strict guidelines have been produced governing the interaction of humans with the whale sharks. Only two boats are allowed in the area where there have been sightings, only eight people are allowed into the water to interact with an individual shark, and snorkelers must remain at least 3m from the shark, and at least 4m from its powerful tail.

Diving is not permitted among the whale sharks, only snorkelling, but as they often approach the shore quite closely, it is not uncommon for the sharks to be seen during a dive when they are in the area. Visitors will have a better chance of a close-up experience with these fantastic animals near to the surface when they are feeding or basking in the sun, before they dive to deeper waters, where they have been recorded reaching depths of up to 600m.