When V.M. Coppleson published Shark Attack in 1959 he recounted many attacks in Australia and elsewhere and particularly the war experiences of downed airmen and shipwreck survivors. These accounts captured the fear that people have of shark attack. Surf bathing became popular after the First World War but shark attacks discouraged the activity and netting enclosures had proven ineffective. The Shark Menace Advisory Committee was formed in 1934 to investigated the issue, and meshing was adopted as the most effective method of control (Coppleson 1959).
Meshing of sharks as a protective measure for swimmers and surfers was introduced to the New South Wales metropolitan beaches of Sydney in 1937, Newcastle in 1950 and, to Queensland beaches in 1962. These are the only two states in Australia that employ this protection measure (Krogh & Reid 1996; Paterson 1990). At the time shark control activities were being introduced, other activities now banned, such as abattoirs discharging offal into the ocean, could have led to a higher incidence of shark attacks.
Shark nets do not completely enclose beaches but are usually 150 m long and 6 m high, with a mesh size of 50 to 60 cm (Krogh 1994). The nets are set parallel to the shore in around 10 to 15 m depth with the bottom of the net resting on the ocean floor and the top supported by a series of floats (Krogh 1994). The purpose of the nets is not to stop sharks coming to the beaches but to intercept and catch them on their regular feeding and territorial runs (Eckersley 1996). There are currently a total of 49 meshed beaches set offshore between Newcastle and Wollongong in New South Wales (approximately 200 km of coastline). In Queensland, a mixture of baited drumlines and nets are used. Drumlines consist of a marker buoy and float supporting a trace and baited hooks anchored to the bottom, and are intended to target dangerous species of sharks and reduce the bycatch of non-target species.
White sharks caught by beach meshing programs are usually small (less than 3 metres), and in many cases, particularly off eastern Australia, are smaller than 2 metres. This suggests that these programs operate close to pupping grounds or in juvenile nursery habitats. However, while beach meshing undoubtedly is detrimental to smaller specimens, the widespread occurrence of similar small sized White Sharks in areas where beach meshing is not undertaken suggests that nursery habitats are also probably widespread in Australia (B.Bruce, CSIRO, pers. comm.).
If the catch per unit effort (CPUE) equates to some measure of abundance then there has been a significant decline in White Shark abundance in both programs. The trend would be more pronounced for New South Wales if the whole time series were available (White Shark data are only specifically available from the New South Wales program since 1950) as larger numbers of White Sharks were almost certainly caught in the first few years of the program. The average size of White Sharks caught in New South Wales meshing operations has also declined over the period, though this is apparently not evidenced in the Queensland data.
Reid and Krogh (1992) observed that there has been a steady decline of White Sharks in New South Wales meshing data since 1950. Since then and up until the 1998/99 meshing season, a total of 509 White Sharks have been captured in shark mesh nets in NSW (Dennis Reid, NSW Fisheries, pers. comm.). The annual average number of White Sharks caught has declined from 13 for the first 20 years of recorded meshing to 4 caught per year in the last 10 years (Dennis Reid, NSW Fisheries, pers comm.). New South Wales increased the meshing effort in the early 1970s and this is also reflected in the increase in shark captures around that time (Reid and Krogh 1992).
Since 1962 a total of 670 White Sharks have been caught in the Queensland Shark Control Program. During the first 20 years of beach meshing in Queensland an average of about 20 White Sharks per year were caught by the nets. This rate of capture has dropped to an average of 10 White Sharks per year over the last 10 years (Shark Control Program, QDPI). Paterson (1990) observed that nearly 90 percent of White Shark captures occurred in southern Queensland off the Gold and Sunshine Coasts. The peak in captures also occurred when water temperatures were low (Paterson 1990).
The degree to which beach meshing is impacting on White Shark populations is unknown although the decline in captures suggests it is significant. The New South Wales meshing contract was reviewed in 1972-73, leading to an increase in the number of beaches meshed, the introduction of requirements for nets to be bottom-set, and for the net material to be of synthetic filament (Reid & Krogh 1992). It is interesting to note that from 1972 - 73 to 1989 - 90 the number of catches in three major netting areas in New South Wales showed a reduction to about a quarter of the 1972-73 catch. A similar trend has also been detected in Queensland and South Africa (Queensland Department of Primary Industries 1992).
These data may reflect a decline in the overall abundance of White Sharks along the New South Wales coast or may represent localised depletion. Most of the sharks were caught soon after the meshing was commenced, and further catches consist of sharks moving into the area for opportunistic feeding, breeding, and/or colonisation of vacant territories (Reid & Krogh 1992). A suggested possibility is that White Sharks are actively avoiding the nets but this seems unlikely as many of the nets are set in random locations throughout the year (Reid & Krogh 1992).
Non-target species that are captured in the shark nets include whales, dugongs, turtles and dolphins (Gribble et al. 1998). Beach meshing to reduce the threat to humans from shark attack was nominated as a key threatening process under the Endangered Species Protection Act 1992 in May 1997. This nomination was unsuccessful.
There are indications that drumlines are more species selective than nets (Department of Primary Industries 1992) and that they provide similar levels of shark protection. The biggest problem with drumlines is that they can move in heavy seas (Department of Primary Industries 1992). Experiments using electrical fields to repel sharks have been carried out in South Africa since 1965 (Cliff and Dudley 1992), however practical trials have encountered many logistical problems (Gribble et al 1996).
There have been several changes to the structure of nets and the amount of fishing effort over time. To make accurate statements about the degree of impact beach meshing has on White Shark populations, factors such as fishing effort, catch levels and environmental fluctuations need to be recorded (BRS 1996; Reid & Krogh 1992). In addition, given that White Sharks will be caught occasionally there needs to be some capacity to either tag and release the shark if it is alive and autopsy all dead animals. Continued monitoring of the take of White Sharks is desirable. The need for a broader, coordinated monitoring program is discussed under Research Activities.
Western Australia has considered the issue of shark control and recently adopted the Shark Response Plan which is detailed in the Shark Hazard Report Western Australia 2001.
This report considers the matter of shark hazards in terms of three main issues including prevention, response mechanisms and education. The Response Plan provides that in the event of a shark attacking, or attempting to attack, a person, fisheries officers would, upon verification of the identity of the animal, immediately attempt to kill the shark. To be able to kill a great white in the interests of public safety, the Minister for Fisheries has issued a Standing Order, which authorises Western Australian Police and Department of Fisheries officers, in the event of an attack, or attempted attack, to immediately kill the shark responsible for the attack. The Response Plan also outlines the process for capturing and destroying a shark using a firearm by a Western Australian Police Service Officer, or where this is not possible, by a Department of Fisheries officer. The exemption to kill sharks only applies in Western Australian State waters that is in an area up to three nautical miles off shore). There is no such exemption in Commonwealth waters. (The Department of Local Government Nov 2001).