In 2021 Council agreed to support additional shark mitigation measures including SMART drumlines and listening stations to catch, tag and release target sharks and monitor for the presence of tagged sharks in our area. In February this year, these tools were deployed along our coastline. So, what are they and how do they work?
What’s most surprising about sharks is that they travel further than you would expect – and certainly further than most of us have in the past two years. Dr Paul Butcher, Principal Research Scientist with the NSW Department of Primary Industries (DPI), has been tracking sharks as part of the NSW Government’s Shark Management Strategy since 2015 and has seen sharks move from New Zealand, up the coast of Australia to Papua New Guinea and back again.
“They don’t often stick to one beach and ‘lurk’,” he says. “They move quite vast distances. We’ve seen one white shark travel to WA and back three times. It’s covered more than 40,000kms since it was first tagged in 2016.”
The research that Paul and the DPI team have been undertaking these past seven years is filling in a lot of knowledge gaps about sharks, which all goes to paint a bigger, better picture about their behaviour and how we can exist alongside them in the water.
The tools that are providing DPI with this information are SMART drumlines (which stands for Shark Management Alert in Real Time) and tagged shark listening stations, which are currently deployed along 21 locations half a kilometre off the Randwick City coastline by the DPI. A listening station will soon be deployed off Maroubra Beach.
In 2021, Council agreed to support DPI deploying SMART drumlines and listening stations, to be used in addition to the two shark nets already in place in Maroubra and Coogee. Previous research has shown that SMART drumlines are 15 times more efficient than nets for catching target sharks, catch significantly fewer non-target animals than nets, and result in a 99% survival rate of animals caught on the SMART drumlines compared to about 40% in nets.
The drumlines consist of a hook baited with one large sea mullet, which is attached to two buoys and a satellite-linked GPS communications unit that alerts contract boats when the bait has been taken. Within 30 minutes the contractor will pull up alongside the shark and spend the next 12-17 minutes tagging them with an acoustic tag, then will take them a further 1km offshore and release the shark. Non-target animals are given an identification tag and released in situ.
“One thing we do know from our satellite tagging is that when a target shark is caught they’re often 15 to 25km offshore within 24 hours of being tagged, they don’t hang around,” Paul confirms.
Shark listening stations are buoys that provide a real-time alert when a tagged shark swims within 500 metres. “Any time a tagged shark is detected on any one of the listening stations, it sends information to the SharkSmart app, website and Twitter account with
a date and time, where the shark was previously detected and where it was originally tagged, so people can see the movements of sharks in the area.”
The target sharks that Paul and his team are most interested in finding out about are white, tiger and bull sharks, though they also catch dusky whalers, hammerheads, makos, bronze whalers and other non-target animals.
“The benefit of this program is that we primarily catch the species that are responsible for most serious shark bites in NSW.”
To see where SMART drumlines and shark listening stations are located in our area, please see this map.
This multifaceted approach to shark mitigation also includes the use of drones. Fifty of NSW’s beaches, including Maroubra Beach, now have drones as an eye in the sky. Another program that Paul is currently working on, could see these drones become autonomous and fly over beaches using image recognition software to detect sharks swimming close to beaches and send an alert to beach authorities, such as Lifeguards, who would sound an alert and clear people from the water.
What Paul would really like to see – but is still in the early stages of research – is a method that would avoid the need to capture sharks at all. “We’re working on some environmental DNA projects now that would allow us to take a sample of the water column and detect spikes or troughs that would indicate the presence or absence of white, tiger and bull sharks,” he explains. “A one-litre sample of water would be enough to let us know if there are any dangerous sharks in the region so there would be no need to tag the animals. It’s one of those blue-sky technologies that would be great to use in the future."
How many sharks have you tagged since this program began? We’ve tagged 700 white sharks so far, 232 tigers and 135 bull sharks along the NSW coast since the program began in 2015.
What are you more like to encounter while swimming, a shark or a dolphin? A dolphin. From the drone research we’ve done, you are 140 times more likely to see a dolphin in the water than a shark.
Are sharks a sign of a healthy marine eco system? Certainly. They are top end predators, so if there are sharks around then it is a healthy ecosystem and if we can have programs in place that allows us to live alongside them, then that’s great.
Will the bait attract sharks to the area? We’re not attracting sharks to the area – we are intercepting them as they travel along the coast. We don’t use burley and the bait we use is one sea mullet. We’re only setting the lines during daylight hours and we take the bait out of the water at the end of the day and dispose of it on-shore.
What’s it like handling an apex predator in the water? It’s not the rodeo that everyone thinks it will be because sharks are fairly timid animals and don’t play up very much. The odd tiger shark likes to “croc roll” but the rest of the animals are fine being alongside the boat and are happy to swim away once tagged.