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Alternatives to Shark Nets and Drumlines

Wednesday, May 02, 2018

Non-lethal Shark Bite Mitigation Technologies

Different states in Australia are researching, trialing and testing various shark bite mitigation strategies. Millions are being poured into initiatives such as helicopter patrols, tagging and tracking sharks, shark nets, masking the sounds of people in the ocean, broadcasting Orca sounds underwater, drum lines and various repellents.

In addition to what the governments are looking into, private investors are also trialing various programs such as electronic deterrents, drones, the Eco Shark Barrier at a local beach in Perth, and smart phone applications which use social media to advise the community of where sharks are spotted.

Around the world, shark mitigation strategies that do not harm delicate marine ecosystems are also being explored. In Brazil, the government has partnered with scientists to catch sharks around 2kms from shore, tag and tow them about 8kms away from popular beaches, resulting in a reduction of shark incidents by 97%. In South Africa, the popular Shark Spotters program, started in 2006 by the surfing community, uses a flag and alarm system to keep watch on swimmers and surfers at popular beaches in Cape Town, for a minimum of 10 hours or more, 365 days a year.

Evidence from Hawaii, where more than 4,500 sharks were killed between 1956 and 1976 in a state-imposed shark cull, illustrated that there was no significant decreased in the rate of shark bites as a result of the cull. Additionally, a 2012 report, commissioned by the Western Australian Government rejected the use of drum lines as an effective option to reduce shark bite risk. In fact, drum lines may actually increase safety issue where they are deployed near the coastline. The round-the-clock deployment, close to the shoreline, means that catches are unattended for long periods of time. These injured or dead sharks can potentially attract larger sharks; which was seen during the drum line trial when a juvenile shark was pulled up with its stomach torn open and its tail missing.

When provided with the knowledge of each of the different alternatives to drum lines and shark nets, the community favored the Eco Shark Barrier and the Shark Spotters program in the short term. These alternative measures are relatively cheap to introduce into the coastline and are not harmful to the marine environment. They can also provide beach goers peace of mind, 365 days a year.

All sharks have highly sensitive electrical receptors located in their snouts called the ‘ampullae of Lorenzini’. Used for finding food, they sense tiny electrical currents from prey less than a metre away. (Over longer distances, they use their sense of smell, sight, and hearing).

​Surfers are also being urged to consider buying the new surfer specific device, which from today can be purchased through the personal shark deterrent subsidy in WA.

The Ocean Guardian's Surf+ device was tested and proven to reduce the risk of a shark interaction by Flinders University in extreme circumstances - chummed and baited waters in a known shark aggregation area. In more normal surfing conditions, the device is likely to produce an even higher level of deterrence.

In the long term tagging and tracking along with shark behaviour education were favored. Additionally, participants involved in providing feedback advised that eco tourism would alter the way sharks are perceived.

South Africa's Shark Spotters is an example of a non-lethal shark bite mitigation program.

Finally, the feedback provided indicates that the community would like more funding to be put into magnetic and electronic deterrents, as well as the utilisation of technology such as unmanned aerial devices, such as drones.

There is a clear distinction between what the community believes is the way forward in reducing shark incidents and the approach undertaken by state governments in Australia.

Sea Shepherd knows from its various discussions with different community groups affected by the shark cull, that the main areas the state governments are failing, is a complete lack of community consultation.

It is a blight on these governments that not-for-profit organisations such as Sea Shepherd have had to undertake their own community consultation. Regardless, we are determined to ensure that the governments of Western Australia, Queensland and New South Wales hear the voices of their constituents and the scientific community and act accordingly.

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