Researchers from the Wildlife Conservation Society (WCS) and the University of Western Australia used baited underwater 3D video systems to record data at eight sites within the reserve and at eight outside its boundaries.
Marine life was observed at both shallow and deeper depths. Writing in the journal Coral Reefs, researchers say they found two to four times the number of sharks inside the sanctuary than outside, where fishing is allowed.
The most likely reason for higher shark densities within the reserve is a significantly higher availability of prey fish compared to adjacent, unprotected areas, the researchers said.
Shark populations have recently plunged in many areas of the world, mainly due to the demand for shark fins in Asian cuisine.
“The news from Fiji gives us solid proof that marine reserves can have positive effects on reef shark populations,” said Caleb McClennen, director of the WCS Marine Program.