Keeping sharks and humans safe; drumline effectiveness ‘highly debated’

In this photo taken on January 15, 2019, Ocean Ramsey, a shark researcher and advocate, swims with a large great white shark off the shore of Oahu. It could be one of the largest great whites ever recorded. Picture: Juan Oliphant via AP
In this photo taken on January 15, 2019, Ocean Ramsey, a shark researcher and advocate, swims with a large great white shark off the shore of Oahu. It could be one of the largest great whites ever recorded. Picture: Juan Oliphant via AP

While SMART drumlines cause less damage to marine life than shark nets, a social scientist has said questions remained over how effective the technology was at protecting people from the predators of the oceans. 

The NSW Department of Primary Industries has proposed a trial of the drumlines at beaches across Tathra, Pambula and Merimbula to begin this summer, but is yet to confirm whether or not the operation will take place. 

SMART (Shark-Management-Alert-in-Real-Time) drumlines are a new technology. When a shark is caught an alarm is triggered to alert authorities which allows them to be tagged, relocated 1km offshore and released alive.

But Dr Leah Gibbs, a senior lecturer in geography at the University of Wollongong whose field is people’s relationships with nature including environmental governance, said there was not enough research to state whether or not they were effective at keeping people safe from potentially dangerous sharks.

“Their effectiveness is really highly debated,” she said. 

She said authorities should be looking at a “patchwork strategy” involving multiple types of approaches at the same time. 

“There’s not one strategy that will work all the time in all the places, that’s important to note,” she said.

“But there’s lots of different strategies proving to be very successful in different places.”

If we approach the challenge in a patchwork way, I think that’s much more effective rather than looking for one silver bullet solution.

Dr Leah Gibbs

These included land or air-based human observation, tagging and satellite monitoring, electronic deterrents such as Shark Shields, visual deterrents like wetsuits using camouflage or warning designs, and installing artificial kelp forests as sharks do not like being in such forests. 

Exclusion barriers could be suitable for some places, but not where there was large surf. Also, a very new approach was suspending a blimp above a beach to look for sharks – a project currently being developed in Kiama by a UOW PhD student.  

“If we approach the challenge in a patchwork way, I think that’s much more effective rather than looking for one silver bullet solution,” Dr Gibbs said. 

She said the shark nets in use between Newcastle and Wollongong could catch whatever swam past them. Traditional drumlines were more targeted, but often resulted in the deaths of animals including non-target animals. 

The new SMART drumline system aimed to alert authorities when an animal had been caught, allowing them to release it alive. Tagging sharks caught on the drumlines could actually assist scientists in studying the animals. 

But Dr Gibbs said there were a number of concerns over the use of such technology.

“I think there is a pretty high level of community concern over the ethics of catching animals and the potential harm that can be done to them,” she said. 

Picture: Tourism Australia

Picture: Tourism Australia

“Some of the animals caught on the drumlines will die. The survival rate after their release is unknown. And the SMART drumlines will still catch animals that pose no threat to people.” 

Dr Gibbs said so far the DPI appeared to be fairly successful with their aim of releasing target animals of white, tiger and bull sharks 1km from the shore after they had been caught.

Releasing the animals alive was a contrast to a program she studied in Western Australia a few years ago, and the existing program in Queensland, where the target animals were shot.

Some of the animals caught on the drumlines will die. The survival rate after their release is unknown. And the SMART drumlines will still catch animals that pose no threat to people.

Dr Leah Gibbs

In her findings that were published in the journal Marine Policy, she found “the effectiveness of lethal approaches to reduce risk of shark bite is not supported by consistent, convincing evidence”.

Also, she said far more people were opposed to drumlines than supported them, stating in her findings “killing sharks does not make ocean-users feel safer, and they do not think it will reduce risk for themselves or others”.

But she did not want to suggest the same results would occur on the Far South Coast. 

“I do think it’s really important to listen to what the people who live in the place think,” she said.

She said the results appeared to be much better for SMART drumlines than they were for the established shark nets in terms of reducing bycatch, which was the catch of non-target species - the ones that pose no threat to people.

“So I think there is great promise for replacing the existing nets – used between Newcastle and Wollongong – with SMART drumlines,” she said.  

“But there is still a question about why drumlines would be introduced to a place, like the Bega Valley, that has never before had a technique like this in operation.”