Sydney - The moon and water temperature affect the diving behaviour of sharks, researchers reported on Tuesday, in a discovery that could help prevent fishermen from catching the marine predators inadvertently.
A team from the University of Western Australia's Oceans Institute and the government-run Australian Institute of Marine Science spent nearly three years monitoring grey reef sharks off Palau in the Pacific.
They tagged 39 sharks - common on coral reefs throughout the Indo-Pacific region - and used acoustic telemetry to follow them, finding they stayed in deep water on full moon nights but rose to the shallows with the new moon.
Similar patterns have previously been recorded in species such as swordfish, yellowfin and big eye tuna, suggesting the reef shark behaviour was related to feeding.
The study also said it may be an anti-predator response where reef sharks seek to avoid increased light nearer the surface that may aid the hunting abilities of larger sharks.