CH5 Nature Shock - The Blacktip Shark Mystery (2013)

In 2006, dive boat operator Mark Addison witnessed the mysterious arrival of 60 Blacktip sharks off the coast of South Africa. Even more unusual, the migratory Blacktips stayed, taking over the reef and chasing off the larger Tiger sharks that had been the focus of Mark's dive operation. He decided to study the invading sharks and discovered that his group was 100% female and over 200 strong. More remarkable still, they seemed to be operating a hierarchy and communicating using sound, both theories new to shark science.

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