New teeth to debate over use of shark nets

09 February 2016 - 02:23 By Nivashni Nair

New research has taken a bite out of the age-old argument that shark nets reduce the chance of attacks. Laurie Laurenson, an associate professor at the Deakin University School of Life and Environmental Science in Australia, has analysed 50 years of data about shark mitigation and coastal populations in South Africa and New South Wales, Australia, and has found that shark nets "do nothing".He said that reducing the number of sharks in an area did not reduce the likelihood of shark attacks."I can show statistically that there is no relationship between the number of sharks out there and the number of shark attacks," he said.But KwaZulu-Natal Sharks Board head of research Geremy Cliff disagreed."Durban's beachfront suffered 21 shark attacks - with seven fatal - in the decade 1942 to 1951. Shark nets were installed in 1952. In the ensuing 63 years there has not been a significant shark-inflicted injury at any of the beaches protected by shark nets in Durban."I defy anyone to come up with more convincing evidence that shark nets do or do not work in KwaZulu-Natal."But marine enthusiasts, who have been opposing the culling of sharks for years, were not surprised by Laurenson's findings."Sixty years is a long time and many truths have suffered. Among those truths would be every single whale, dolphin, turtle, fish, shark, ray and sea bird that suffocated or drowned in this tangled web of deceit," contended marine enthusiast Mark Addison."At best shark nets were a hare-brained scheme and at worst a crime against nature of epic proportions that has scarred our coastline . with the aggravation of drum lines being introduced and the damage they are doing."Study data showed that mostly juvenile sharks were caught in the nets and drum lines, said Addison."They can't even feed on hard food types as their dentition hasn't developed sufficiently and the average size is less than 1.2m. I don't know of a single documented white shark of 1.2m that is recorded as attacking anyone."Amanda Barratt, one of the organisers of The Paddle Out for Sharks - an annual event to highlight the plight of sharks - said nets did not offer full protection because 30% of the sharks were caught on the shore side."If the premise for shark nets were true, we'd see more attacks in unnetted areas," she said.How they workShark nets and drumlines catch sharks to reduce their numbers near beaches.Nets - 214m long, 6m deep and secured at each end by two 35kg anchors - are laid in two parallel rows about 400m offshore and at depths of 10m to 14m. Sharks can, therefore, swim over and around them.Drumlines - single baited hooks - were introduced to reduce the numbers of harmless species being caught, but whales, dolphins and turtles still get caught in shark nets.

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