By Stella Diamant
Images by Simon Pierce

2016 saw the first successful season of whale shark research completed by the Madagascar Whale Shark Project. They aim to protect the dwindling numbers of this gentle giant in the Indian Ocean. 

Swimming with whale sharks is on most divers’ bucket lists, and a once-in-a-lifetime experience for those who have the chance to interact with one of these gentle giants.
While the world’s biggest fish is seasonally found in large groups or “aggregations” in places such as Mozambique, Tanzania and the Seychelles in the western Indian Ocean, its numbers are decreasing.

The species was recently downgraded to an endangered species on the IUCN’s Red List, due to observed declines such as a 79% decline in Tofo, Mozambique since 2005. The reasons behind the disappearance of this slow-growing fish could be overfishing, pollution and boat collisions, combined with the effects of climate change and changing feeding grounds.
Nevertheless, other places such as the island of Nosy Be in north-west Madagascar have witnessed whale sharks year after year, leading to growing marine tourism in the area from September to December. A fantastic diving spot, the blue waters of Nosy Be also attract humpback whales, turtles, manta rays, countless dolphin species and the very rare and elusive Omura’s whale.

Yet little was known about the whale sharks; their population size, structure, residency and
movement patterns remained a mystery until 2016, which saw the first field season of the Madagascar Whale Shark Project (MWSP). The MWSP is a collaborative research and conservation project between the Marine Megafauna Foundation (MMF), Florida International University, the National Center for Oceanographic Research in Madagascar and local whale-watching company Les Baleines Rand’eau (LBR).

Led by Belgian biologist Stella Diamant, a passionate 27-year-old who initially contacted all the project partners in 2014 about the need to study the unknown whale shark population, the project finally came to fruition and is the first attempt to quantify the number of whale sharks visiting the waters of Nosy Be each year. By working together with LBR, Stella and her team were guaranteed daily trips out on the water together with tourists, where they could successfully collect data such as photo-identification pictures, gender, size and GPS location each time a whale shark was encountered. Thanks to their unique spot pattern, each shark can be readily identified by comparing photographs of the same area, a user-friendly process available to anyone who captures one of these photo-IDs and uploads it onto the Wildbook for Whale Sharks’ website, whaleshark.org
Stella also collected skin samples to better understand diet and population genetics, and together with Dr Simon Pierce, the project’s scientific supervisor and a renowned whale shark expert, deployed eight satellite tags to track the whale sharks’ movements through the season.

As the season came to a close in mid-December 2016, preliminary results unveiled the existence of a significant population with a whopping 84 different whale sharks spotted since September. Some individuals such as the team’s favourite “Michel”, a small, shy, 5m-long male, were seen as many as 15 times. This first season also allowed Dr Pierce to share his experience in implementing a Code of Conduct, a set of guidelines followed on the water in an attempt to minimise any possible impacts of tourism on whale sharks, while also improving client satisfaction. This Code is already successfully established in the MMF’s field sites such as Mozambique and Tanzania; with it, the team hopes to reduce the occurrence of boat collisions and the lifelong physical scarring that follows, a death trap for slow-growing whale sharks.

While data analysis is ongoing, the MWSP’s team is already planning its 2017 season, and plans to widen its objectives with outreach events and ambitious research objectives. Stay tuned on madagascarwhalesharks.org

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Image: BBC Earth