When a dark shape glides past in the surf, the inevitable heart-stopping question confronts beachgoers: is that a shark or dolphin?
But rest assured, says Professor Brendan Kelaher from Southern Cross University whose team has counted the marine wildlife off beaches in two years' worth of drone footage.
"Our extensive data suggests it is up to 135 times more likely to be a dolphin than a shark. But if you are concerned, it's best to get out of the water," Professor Kelaher said.
Professor Kelaher and his team from the University's National Marine Science Centre and the NSW Department of Primary Industries have been using drones to monitor our beaches for the past three years as part of the NSW Shark Management Strategy.
The University's research team carefully analysed the drone footage and counted more than 4100 large marine animals.
"As well as contributing to beach safety, our drone program has been quantifying the diverse marine wildlife off our beaches," Professor Kelaher said.
"Our beaches provide habitat for amazing marine animals including dolphins, sharks, rays, turtles, seabirds, game fish and the occasional whale.
"Over the last three years, we have routinely captured footage of fevers of rays exceeding 100 animals, whales feeding on bait balls in the shallows and incredible chases between sharks, rays and dolphins."
Professor Kelaher said the results can give some comfort to ocean users.
"We do see potentially dangerous sharks in the shallows, but our data show they are much less common than people would have you believe.
"Our oceans are teeming with life and the fact that you can see dolphins regularly by just simply going to the beach is fantastic. We are really lucky to have such a wonderful marine environment on our doorstep.
"Further, the findings confirm that emerging drone technology can make a valuable contribution to the ecological information required to ensure the long-term sustainability of beach ecosystems."
The results have been published online in a special 70th year edition of the journal Marine and Freshwater Research.
