Shark netting along the Kwazulu-Natal Coast
The main
management issue: The shark netting practice that has evolved in South
Africa has placed heavy emphasis on the use of large numbers of nets at bathing
beaches, in the belief that these operate as barriers to sharks. This is in
sharp contrast to the Australian situation, where far fewer nets are used, on a
more intermittent basis and in conjunction with drumlines, based on the belief
that the population of sharks, especially local shark populations, needs to be
controlled by a fishing down process in order to minimise shark attacks. The
Australian approach appears to work as well as the South African approach and is
far cheaper.
OLRAC's involvement: OLRAC's involvement with the
Natal Sharks Board (NSB) started in 1994 when they were asked to carry out a
study on the feasibility of predicting the risk of reducing or altering shark
net configurations on the Natal coast. OLRAC has carried out exhaustive
quantitative studies on shark net catch records dating back to the 1960's, and
has developed a computer based model of shark movement and the response of
sharks to nets. OLRAC's research has provided a valuable conceptual framework
for management thinking, in which there are three components of the way that
shark nets operate:
- As a barrier to shark movement onto bathing beaches
- As a fishing device which reduces the overall population of sharks, and the
local population of sharks
- As a device that reduces the time that sharks are able to spend in the vicinity of bathing beaches by capturing them at an early stage.
- the experimental design of netting experiments
- comparing the efficiency of shark nets to drumlines
- further spatial models of shark movement and interactions with nets
- more in-depth analyses of the shark capture database to determine whether shark net CPUE trends should be taken as indices of shark abundance or not
- further analyses of the mark-recapture database for sharks
Future research efforts by OLRAC will probably be directed at sonic tagging to develop a better understanding of the movement behaviour of sharks.
