Mafia Island, situated off the coast of Tanzania, stands out as one of the most unique sites for observing whale sharks (Rhincodon typus). These gentle giants, the largest fish species on Earth, have found a stable, year-round haven in Kilindoni Bay, where their predictable aggregations offer a valuable opportunity for both tourism and scientific research.
Whale Shark Movement and Residency Patterns
Whale sharks are known for their remarkable ability to travel thousands of kilometers across the ocean, often aggregating in tropical and subtropical regions where food is abundant. However, what sets Mafia Island apart is the unusually high level of residency observed among the local whale sharks. Unlike many other populations, the whale sharks in Mafia do not disperse widely after their sighting season (October-February). Instead, they remain in the deeper waters of Kilindoni Bay during the “off-season” (March-September)
This image shows sea-surface temperatures in the Eastern Equatorial Pacific during October and November 2012. Warm water is red and yellow; colder water is blue and purple. The dots show the locations of whale sharks tracked during this period. Credit: Monterey Bay Aquarium Research Institute
Photo-ID surveys have been conducted over eight years, identifying around 200 individual whale sharks in the areaThese studies, along with the use of acoustic telemetry tagging, reveal fascinating insights into the year-round movement patterns of whale sharks. Researchers use movement network analyses to map the connectivity between different acoustic monitoring stations, identifying core habitats that are critical to the sharks’ activity
Whale Shark Surveys and Data Collection
From 2012 to 2017, over 318 boat-based surveys were conducted in Kilindoni Bay, focusing on visual and acoustic tracking of whale sharks. These surveys are complemented by photo-ID techniques, which allow scientists to re-identify individual sharks using their unique spot patterns .This method is crucial for long-term tracking, helping researchers understand individual residency, movement, and behavior over time.
One of the most important findings from these surveys is the use of Kernel Utilization Distribution (KUD) to highlight core home ranges and high-use areas for the whale sharks in Mafia Island These hotspot areas are identified using node strength and eigenvector centrality, advanced metrics from movement network analyses that show the intensity of use for particular locations within the bay
Conservation Challenges and Management
While whale sharks are legally protected in Tanzania, they face significant threats, including boat strikes and entanglement in fishing gear. The high residency of whale sharks in Mafia Island means that they are more exposed to these risks compared to migratory populations Efforts are underway to integrate whale shark conservation into Tanzania’s National Plan of Action for shark management, which aims to address these local threats and ensure the sustainability of whale shark tourism in the area.
In addition to direct conservation efforts, the sustainable management of whale shark tourism plays a critical role in protecting this iconic species. Whale sharks contribute significantly to the local economy by attracting tourists to Mafia Island, making it essential to balance conservation with eco-tourism initiatives
Join the Journey of Whale Shark Conservation
Visiting Mafia Island offers the rare chance to swim alongside these majestic creatures in a responsible and eco-friendly manner. Licensed tour operators adhere to strict guidelines to ensure minimal impact on the whale sharks while providing an unforgettable experience for tourists. The continued success of these conservation efforts depends on the collaboration between researchers, local communities, and visitors.
Whether you are a diving enthusiast, a marine biologist, or simply an eco-conscious traveler, Mafia Island offers a unique window into the world of whale sharks. Through advanced tracking technologies, conservation initiatives, and responsible tourism, Mafia Island remains a vital sanctuary for these endangered species.
Visit Blue World Diving website for more information.
