Reducing Mortalities

Between 2005-2009 the average annual catch was 591 sharks (the bulk of the catch comprising 14 species, 13.3% released alive), 201 rays (mostly comprising seven species, 50.8% released alive), 60 turtles (mostly comprising two species, 54.3% released alive), 43 dolphins (three species) and 30 teleosts (bony fish). Although the KZNSB, through monitoring trends in catch rates of each species, believes that catches of most of the species concerned are sustainable, it is committed to minimising any environmental impact associated with its mandate of protecting sea users from shark attack. Several initiatives have been implemented or are being evaluated in an attempt to reduce mortalities without jeopardising bather safety.

Permanent removal of all nets from selected beaches

The provision of a shark netting service is expensive and historically certain beaches were poorly utilised for a number of reasons. It was therefore decided in 1994 that the cost of providing the netting service at these beaches could not be justified and that all the nets should be removed. Such localities included Tinley Manor and La Mercy to the north of Durban and Ifafa and Mtwalume to the south.

Net reduction

A major initiative has been directed at reducing the number of nets at individual beaches. Logically, given that the nets are fishing devices, fewer nets will catch fewer animals. The initial impetus for this research was provided by a comparison of the KZNSB’s operation with those of its counterparts in New South Wales and Queensland, Australia. In both Australian states, considerably less shark fishing equipment is deployed per protected beach than in KwaZulu-Natal.

Drumlines – an alternative to nets

Another means of reducing environmental impact is the introduction of drumlines in place of some of the remaining nets, such that beaches are protected with a combination of nets and drumlines. A drumline consists of a shark hook suspended from a large anchored float. Drumlines take a reduced catch of harmless animals, compared to a net.

Dolphin pingers

Unfortunately, the shark nets catch dolphins. An annual average of 12.6 common dolphins (Delphinus capensis), 23.4 bottlenose dolphins (Tursiops aduncus), and six Indo-Pacific humpback dolphins (Sousa chinensis) were caught between 2005-2009. Due to a relatively small population size, it is actually the catch of humpback dolphins that is of most concern.The KZNSB has initiated two research projects aimed at determining the efficacy of dolphin deterrent devices in reducing catches. This work has been conducted through generous support from the Endangered Wildlife Trust.

Other options to replace shark nets

The KZNSB has been experimenting with electrical shark repellents for some years.

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