Swimming with the whales tourism in northern Tonga is disturbing the natural behaviour of nursing Humpbacks who are there to give birth, bond and nurse.
New research from New Zealand's AUT University shows tourism intensification is forcing mothers away from their calves as they dive to avoid tour boats.
They're also providing an unnatural attraction for infants.
Dominic Godfrey reports.
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This photograph taken on August 4, 2008 shows a humpback whale diving near the island of Vava'u in Tonga. Photo: DAVID BROOKS / AFP