DRUM lines have replaced some of the shark nets in service on the Upper South Coast shore as of 1 March.
The large red buoys have been spotted floating on the surface of the water in the vicinity of the Warner Beach shark nets.
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The use of drum lines is being implemented by the KZN Sharks Board, which services both devices as a means to ensure bathers’ safety.
The transition follows a growing groundswell of environmental opposition to the use of shark nets. The global trend away from the use of traditional net installations has seen a change to the use of a mixture of nets and drum lines at protected beaches along the KZN coast.
KZN Sharks Board’s head of operations, Greg Thompson explained that while shark nets protected bathers from potentially dangerous sharks, it came at an environmental cost. “Not only do the nets catch potentially dangerous sharks, they also catch certain shark species which pose no threat to bathers, as well as various species of dolphin, whale, ray, turtle and large bony fish,” he said.
The Sharks Board continually seeks ways of reducing catches, without compromising the safety of bathers.
“The deployment of drum lines in conjunction with the nets, is one such initiative,” said Thompson. “In 2007 the board replaced nearly half of its existing shark nets with drum lines at 20 protected beaches between Hibberdene and Port Edward in the Ray Nkonyeni Municipality (Hibiscus Coast) and more recently at five protected beaches between Zinkwazi and Ballito.
As of 1 March, drum lines replaced some of the nets at eThekwini beaches between Westbrook and Umgababa. Drum lines have an excellent track record and have been used in conjunction with shark nets in KZN for over a decade, with no shark incidents occurring at any of these 17 beaches.”
Thompson explained that a drum line consists of a single, large baited hook suspended from an anchored float which is an alternative method of fishing for potentially dangerous sharks. They are positioned around existing net lines, some 400m out to sea, at a water depth of 15m. They are re-baited when the gear is serviced daily. Target species are great white, Zambezi and tiger sharks. They will remain in the water year-round but the hooks will be detached when netting is removed for the sardine run.
Drum lines are baited with fish species which are taken as a bycatch in SA’s hake fishery.
Asked if baited drum lines wouldn’t attract more sharks to an area, Thompson explained that the distance over which sharks are thought to be sensitive to smell is around a few hundred metres, as opposed to kilometres.
“The baits are likely to attract only those sharks already in the vicinity of the drum lines. Each drum line has one baited hook and most installations will only have between four and eight drum lines, so the total quantity of bait present is not large,” he said.
While scavenging by small sharks and fish does occur, potentially dangerous sharks have been caught on the drum lines deployed at beaches north and south of eThekwini.
“Both nets and drum lines achieve their protective function by fishing over the long term in the vicinity of each protected beach and so the effectiveness of the drum lines is not dependent on the hooks having bait on them at all times,” he said.
“Drum lines have been in use in the bather protection programme of Queensland, Australia since 1962. They are far more selective than nets in terms of their catch. Both shark nets and drum lines have an excellent safety record, but neither provide absolute protection from shark attack. Only a physical enclosure can achieve that, and the construction of such enclosures at surf beaches is impractical,” he added.
While drum lines are intended to catch larger, dangerous species of sharks, there are reports of turtles and other species such as hammerheads, being caught and killed. Thompson countered that there is minimal bycatch on drum lines compared to that of shark nets. “Where we have reduced the length of netting by 50% and introduced drum lines, the bycatch is down by 47%,” he said.
“We do not anticipate a large difference in the number of sharks caught in the mixed gear in comparison to when only nets were used. The species composition will change as very few ragged tooth, spinner and blacktips are taken on drum lines, but more dusky sharks will likely be caught, outside the sardine run.” Looking to the future,
Thompson explained the KZNSB is actively pursuing the development of alternate methods of shark mitigation.
“This has involved developing an electrical shark repellent cable (SRC) system, based on the well-known fact that sharks are extremely sensitive to electrical fields. We hope such a cable can be deployed as a system to protect bathers at swimming beaches.”
The public is reminded that drum lines constitute life-protecting equipment and are the property of the Sharks Board. Their introduction is an initiative aimed solely at reducing the environmental impact associated with the provision of safe bathing.
Thompson emphasised that bather protection remains the priority and appealled to the public not to tamper with the drum line equipment and to report the presence of any displaced shark safety gear found along the KZN coast. Reports can be made to KZNSB on 031-566-0400.
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