Dhidhdhoo - Whale sharks of South Ari Atoll

The southern tip of South Ari Atoll is a 12km stretch of reef that hosts whale sharks year round - unlike most other Whale Sharks hotspots around the world, which are seasonal and usually coincide with feeding opportunities such as a coral or fish spawning events. It was declared a Marine Protected Area in 2009 and attracts a large and growing number of visitors. The Maldives Whale Shark Research Programme (MWSRP) is a long term monitoring program that began in 2006 and has since had over 1000 separate Whale Shark encounters. Using a technique called photo-identification, which uses images of the shark's unique spot patterns as "fingerprints", over 170 different individual sharks have been identified. The number of "known" versus "new" sharks has enabled researchers to estimate how many whale sharks are in these waters at any one time - surprisingly few with less than 200 estimated to be in South Ari waters at any one time.

The average length is just under 6 m, and since whale sharks are thought to mature at approximately 9 m in length, all are considered juveniles. Surprisingly, almost all are males with only 5% of the individuals found in South Ari being female.

Telemetry tagging work carried out in 2008 and 2009 showed whale sharks are highly mobile animals; constantly moving around the Maldivian archipelago and occasionally travelling thousands of miles south to the Chagos Bank and north to the Laccadives. Whale sharks are feeding less than 10% of the time at South Ari and tagging shows they dive incredibly deep, exploring layers in the water column as deep as 1600 m. At these depths water is not only cold (3°C) but also low in oxygen. The Whale Shark is a huge cold-blooded animal that requires ambient warmth and highly oxygenated water to keep functioning. South Ari, with its long, wide and shallow reef shelf, which drops off into very deep water, makes it the perfect haven to return and recharge after deep diving. Consequently, South Ari is a vitally important habitat for whale sharks, which also makes their predicted time at the surface especially attractive to the thousands of visitor who watch them every year.

Currently the main threats to the whale sharks in the Maldives are collision with vessels and disturbance of their natural behaviour by unregulated tourism. Careful management and continued research should ensure whale sharks of South Ari can be enjoyed for generations to come.

Richard Rees

Maldives Whale Shark Research Programme


Dhidhdhoo, Alifu Dhaalu Atoll/South Ari Atoll (Maldives)


Dhidhdhoo, Alifu Dhaalu Atoll/South Ari Atoll (Maldives); The inhabited island Dhidhdhoo lies on the southeast coral shelf of South Ari Atoll (Alifu Dhaalu Atoll). Shallow waters of the outer coral reef near Dhidhdhoo are the perfect habitat for whale sharks.