Shark Nets, Drumlines, and Safe Swimming
Most of the shark nets deployed by the KZNSB are 214 m long and 6 m deep and are secured at each end by two 35 kg anchors; all have a stretched mesh of 51 cm. The nets are laid in two parallel rows approximately 400 m offshore and in water depths of 10-14 m.
A drumline consists of a large, anchored float (originally a drum) from which a single baited hook is suspended. Most beaches are protected either by two nets or one net and four drumlines, but the quantity of gear varies from beach to beach. Durban, the largest coastal city and holiday resort in South Africa, has 17 nets, each 305 m in length, which cover all the popular swimming beaches between the mouth of the Umgeni River and the harbour entrance. The KZNSB boats service the nets every...
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How do nets and drumlines work?
Shark nets do not form a complete barrier and sharks can swim over, under or around the ends of the nets. Neither, of course, do drumlines form a physical barrier. Both function by reducing shark numbers in the vicinity of protected beaches, thereby lowering the probability of encounters between sharks and people at those beaches. The nets may have a limited physical barrier effect as well, but the fact that about 1/3 of the catch is caught on the shoreward side of the nets is evidence that such an effect is only partial. Drumlines are a recent introduction on the KwaZulu-Natal coast, but their successful use in Queensland, Australia, indicates that the fishing effect of the equipment is of primary importance.
Are nets and drumlines fail-safe?
It was recognised before shark netting was introduced in Sydney, Australia, in 1937 that only a complete enclosure would provide complete protection from shark attacks. Despite this, the safety record of shark nets off the coasts of New South Wales, Queensland (Australia) and KwaZulu-Natal has been very good. At Durban, from 1943 until the installation of nets in 1952, there were seven fatal attacks. Since the installation of nets there have been no fatalities at Durban and no incidents resulting in serious injury. At KwaZulu-Natal's other protected beaches....
Read more: Sharks Nets Continued