When is a dark shape in the surf shark or dolphin? 

The turbulent waters off ocean beaches provide habitat for large marine fauna, including dolphins, sharks, rays, turtles and game fish.

“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 Brendan Kelaher from Southern Cross University 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 over 4,000 large marine animals. In total, 4388 individual large marine animals were identified from 216 drone flights.

The most common – bottlenose dolphins (Tursiops spp.) and Australian cownose rays (Rhinoptera neglecta) -  occurred in 25.5 and 19.9% of flights respectively. White (Carcharodon carcharias), bull (Carcharhinus leucas) and other whaler (Carcharhinus spp.) sharks were observed in <1% of flights.

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 are published online ($$!) in a special 70th year edition of the journal Marine and Freshwater Research.