SA invention looks to save sharks while protecting bathers
Shark nets and drum lines, to protect beachgoers, are a direct threat to the lives of sharks and other marine life.
Tourism operators want aerial shark patrols to be introduced in Australia’s Whitsunday Islands as they try to stem falling visitor numbers following a spate of attacks along the Great Barrier Reef. © RamonCarretero / IStock.com
Humankind is a direct threat for some of the world’s deadliest apex predators and due to human interference, the number of sharks in the oceans is declining.
Ensuring that marine species thrive is a difficult balancing act, said Sustainable Seas Trust researcher Lesley Bloy.
Shark Spotters reported that up to 30% of sharks are close to extinction, mainly due to commercial fishing resulting in the accidental netting of sharks.
Shark nets, to protect beachgoers, are another direct threat to the lives of sharks and other marine life. The KwaZulu-Natal Sharks Board (KZNSB) said these nets threaten dolphins, turtles, whales and large fish. The board has prioritised developing alternative methods to stop sharks coming too close to shore.
SA Association for Marine Biological Research conservation strategist Dr Judy Mann said municipalities appeared to want to keep shark nets at protected beaches.
“We need to work very hard at communicating the importance of sharks in the ocean and at building people’s understanding of the role of shark nets.”
She said that until people stopped wanting shark nets to protect them, a change in policies to reduce the shark and marine life fatalities due to the nets was unlikely.
But in some areas, almost 50% of shark nets have been lifted and replaced with drum lines. This is especially prevalent on the KwaZulu-Natal coast, with the KZNSB reporting a total of 107 drumlines off the coast.
Drum lines consist of a large float anchored from a suspended baited hook. Since these were introduced in 2007, the KZNSB reported a 47.5% reduction in non-target species being caught.
Neither drum lines nor shark nets are 100% safe, however. The only way to ensure no attacks is to build a physical barrier and this is far from practical.
The KZNSB has, since 2014, been exploring shark repellent cables, which emit low-frequency electronic signals that repel sharks.
But a South African invention called the SharkSafe Barrier may prove to be the most successful, least invasive solution yet.
SA Environmental Observation Network Elwandle Node manager Professor Tommy Bornman said this new technology was made to look like a kelp forest and would keep sharks out, without injuring any marine life. It includes permanent magnetic stimuli which forms a barrier that discourages sharks from passing through.
– nicas@citizen.co.za
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