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Very little is known about whale shark movements and migrations in the Indian ocean. The earliest evidence showing that whale sharks travel large distances was from the 1996 whale Shark Tagging Pilot Project conducted in Seychelles. A shark tagged in November 1996 was re-sighted by a diver off Mozambique in October 1997 showing that the species migrates between the waters of Seychelles and the South East African mainland. Since then, there have been major advances in tag technology, with satellite tags being used to track sharks.
With funding from the Global Environment Facility
(GEF) in 2001 MCSS was able purchase Smart Position Only Tags (Spot2), to track the movements of three sharks as they traversed the Indian Ocean. Initial analysis of the data from the SPOT2 tags has indicated that the shark’s migration patterns are far more extensive than had previously been thought.
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| A Spot2
tag before deployment |
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One Spot2 was deployed during the first whale shark peak season (Jul – Aug), two more during the second season (Oct - Dec). All three tags began transmitting on the day of deployment and continued to do so for varying periods. The data showed that the sharks initially remained within the coastal areas of Mahe or on the surrounding shallow water plateau known as the Seychelles Banks before heading in divergent directions.
Shark 1 swam north west to the equator, off the Kenyan coast then continued north to a spot off the coast of Somalia. Shark 2 proceeded south west across the Seychelles Bank almost immediately after it was tagged. From there, the tag continued with sporadic transmissions in a westerly direction to a position off the island of Zanzibar, Tanzania. This was very similar to the pattern indicated the by earlier passive tag re-sighting off Mozambique.
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| Tracks
from the 3 Spot2 satellite tags |
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