A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa)
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文摘
The shark control programs of New South Wales (NSW), Queensland and KwaZulu-Natal (KZN) are compared in an attempt to determine whether the fishing effort applied in the KZN program could be reduced. The stated mechanism in all three programs is to reduce shark numbers, and thereby the probability of an encounter between a shark and a bather. Large-mesh (50-60 cm stretched) gill nets are used in each program, and in Queensland these are supplemented by baited drumlines. The number of standard (100 m net) net-days per protected (meshed) bathing area per month is about 26 in NSW, 57 in Queensland and 192 in KZN. There is a four-month closed season (i.e. no control measures) in winter in NSW, a six-week closed season at some Queensland beaches and no closed season in KZN. Despite these differences, the apparent successes of the programs in reducing the total number of shark attacks recorded at meshed beaches are impressive and comparable. The same shark species are believed to have been responsible for most of the attacks in the three regions, these being the great white shark Carcharodon carcharias, the bull shark Carcharhinus leucas and the tiger shark Galeocerdo cuvier. After comparing factors such as the nearshore physical environment and trends in shark catch and catch rate, it is concluded that there is a case for reducing the number of nets in KZN.