Madagascar Emerges as New Whale Shark Hotspot

Josh Wright

29 Aug 2018

85 different sharks identified over a 4-month period

Having split from the Indian Subcontinent some 88 million years ago, Madagascar – the world’s fourth-largest island – is a biodiversity hotspot, with its flora and fauna evolving in relative isolation from the rest of the world. Lemurs are undoubtedly the country’s most famous residents, but in fact over 90% of Madagascar’s wildlife is found nowhere else on earth. As a result, travellers here are assured of a unique safari experience, and tourism has become an important part of the Madagascan economy. Now new research has identified another animal – this time a migrant to Madagascar’s shores – that is providing another avenue for wildlife tourism in the country: the whale shark.

With the largest confirmed specimen measuring just over 40 ft in length and tipping the scales at more than 20 tonnes, there is no bigger fish in the ocean than the whale shark. Although usually solitary creatures that spend most of their lives in the open ocean, these huge filter-feeding animals are known to congregate in significant numbers at a few select locations around the world, including Djibouti, St Helena and the Galápagos Islands.

In May of this year, marine biologists published the results of research undertaken back in 2016, when a remarkable 85 individual whale sharks were identified in a single season close to the island of Nosy Be, off northwest Madagascar. “No-one thought there were that many [whale] sharks,” said Stella Diamant of the Madagascar Whale Shark Project, lead author and project leader of the study. Intriguingly, all of the whale sharks recorded were juveniles, ranging from 11 to 26 ft in length. They had also all arrived in Madagascar’s waters from further afield, although cross-referencing with a global database indicated that they had not migrated from Mozambique or other neighbouring areas. “They come back for the food,” said Diamant, whose findings have established Madagascar as “an important seasonal habitat” for these young sharks.

Diamant and her fellow scientists attached satellite tags to eight of the whale sharks, and the team were pleased to find that half of the tagged sharks visited a second hotspot 180km to the south of Nosy Be, with five swimming northwest to Mayotte and the Comoros islands. One shark even swam right to the southern end of Madagascar, before returning to Nosy Be. Some were present in the area for several months, while three were spotted again during the 2017 season, having lost their tags. These findings cement Madagascar's role as a vital refuge for this endangered species. The population of Rhincodon typus has declined by around 50% over the past 75 years, reports the IUCN. In the Indo-Pacific, where the vast majority of whale sharks are found, this rate is thought to be even higher.

Whale sharks are currently afforded no formal protection in Madagascar, except in two Marine Protected Areas located to the southwest and northeast of Nosy Be. “'Over the last decade, shark populations have declined dramatically in Madagascar due to overfishing,” said Dr. Jeremy J. Kiszka, a marine biologist and co-author of the recent study. “However, the most significant threat to this species is the incidental catch in coastal gillnets and industrial purse seiners operating offshore.”

The reliable arrival of the whale sharks to Nosy Be between September and December has created a growing ecotourism industry, but to ensure this continues, protection for whale sharks must become more of a priority for Madagascar’s lawmakers.

The aforementioned protected areas around Nosy Be are also home to a number of other large marine species, including manta rays, sea turtles and humpback whales. But the migratory nature of many of these creatures – as evidenced by the tagged whale sharks’ movements – shows that many more such protected areas must be established if these marine species are to be safeguarded effectively.

Whale shark safaris are a great way of ensuring the species is worth more alive to local economies than it is dead. Study co-author Dr. Simon Pierce, co-founder and principal scientist at the Marine Megafauna Foundation, believes the sharks “can be a major asset” for Madagascar. To improve public perception of the species, the Madagascar Whale Shark Project also incorporates community engagement and education programs in their work.

If you’d like to travel to Nosy Be and take to the waters with the world’s largest fish, you can speak to one of our Destination Specialists to start designing your own bespoke safari to this burgeoning whale shark destination. With Natural World Safaris, enthusiasts can also embark on a whale shark safari to St Helena or join marine photographer Joshua Barton on a free diving trip to Djibouti.

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