The Australian Senate: Prevent proactive killing of white sharks in Australia
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We, the undersigned, urge you to use your legislative power to ensure ongoing protection of white sharks in both Commonwealth and state waters, including Western Australia, so that no sharks can be killed proactively. We are asking for this based on the following facts:
White sharks are protected both under the EPBC Act (in commonwealth waters) and in Western Australian state waters. They were protected because long term catches of white sharks showed declines (1) and there is currently no scientific evidence showing that populations have recovered (2-4).
White sharks can travel up to 120 km per day (5). As such, the likelihood of catching and killing a shark responsible for an attack on a human is very low. The likelihood of identifying that a shark is going to attack a human and catching and killing the right shark pre-emptively is even lower and cannot be proven.
The increase of shark attacks (including those by white sharks) over the last century, are related to human behaviour and not an increase in shark numbers. Increases are very likely a result of human population growth, increased communication of attacks, and more people using the ocean for recreational activities (6,7). They are unlikely caused by rising number of sharks in the area as some of the species implemented in the attacks have declined significantly both locally and globally (8-10). Moreover, there is no scientific evidence showing that white shark populations have increased (2-4).
Populations of white sharks of South Africa, Australia, New Zealand, and the South Pacific are connected. Both genders regularly return to the same sites and also make oceanic excursions (11,12), e.g. from South Australia to Tasmania and New Zealand (13). Juvenile and adult sharks can traverse whole oceans, e.g. from South Africa to Western Australia (14), from New Zealand to Vanuatu and Queensland (12,15). Thus, selective killing of sharks in Western Australia can influence white shark populations on a large geographic and international scale.
White sharks of South-western Australia are genetically distinct from sharks of eastern Australia and New Zealand, indicating a very limited gene flow (11). Genetic estimates indicate that at present only about 700 white sharks in South-western Australia contribute genetic material to the next generation (11). Generally, there should be about 500 - 1000 breeding animals in a population to ensure its sustainability (11). Historically however, the ‘effective population size’ was much larger (11). As a result, culling could easily cause a decimation of the population below sustainable levels, and even the removal of particular age or sex classes could have dramatic effects on already endangered population (16).
White sharks are slow growing, have a reproductive cycle of three years and reach sexual maturity at large sizes, at an age of 7 - 9 yrs (males > 3.6 m length), 12-17 yrs (females > 4.8 m length) (4). As a result, selectively killing of large sharks could impact on immature as well as mature animals, and could in the worst case scenario even target gravid females, as these are the largest white sharks out there. As mentioned above, removal of one sex or size grouping could have dramatic effects on the population (16).
A study of juvenile white sharks on the east coast of Australia found that the abundance and presence of white sharks is not a good indicator for the likelihood of an attack on a human (1). In eastern Australia, juvenile white sharks (< 3 m length) are found either in residency areas or in transit between those areas. Attacks are more likely to happen when sharks are in transit (1). But interestingly, sharks are more abundant in residency areas, where they remain over extended periods of time and spend most of their time in surf zones1. It is believed that sharks spend time in residency areas because here they feed on locally abundant prey (1).
Your petitioners ask the senate to use their legislative powers to ensure Western Australia adopts a non-lethal approach of bather protection based on scientific research and public education, including the measures listed below. Some of these measures are already in place but can be extended with funds taken from the $2million set aside by the WA government to “track, catch and destroy sharks in close proximity to beachgoers”:
- Provision of continuous information about the presence of sharks and how to prevent interactions with sharks to the public. This can be done through Surf Lifesavers, sharkalarm.com.au and temporary as well as permanent information stands (e.g. at beach cleanup days)
- Increased aerial patrols of populated beaches. Testing of the effectiveness and costs of drones for surveillance.
- Erecting permanent signs on beaches where sharks have been seen, to inform the public about their potential presence and when to avoid the waters.
- Closure of beaches when sharks have been sighted. This also includes fast reaction to the presence of whale carcasses.
- Support for community based approaches like sharkalarm.com.au which enables members of the public and tourists to make informed decisions on where and when to enter the water.
- Creation of public swimming enclosures but not shark nets. We oppose the use of shark nets as they are lethal to many marine species and could not only affect shark populations in Western Australia but also seals and other marine mammals and turtles.
- Study on the feasibility of shark spotters in Western Australia. This system is used in South Africa, where it not only serves to alert people to the presence of a shark, but also provides continuous information on the movement of sharks (7).
- Study and identification of aggregation sites of white sharks in Western Australian waters. To date, no such sites are known, but knowledge about them could provide information on locations with an above average likelihood of attacks on humans.
1. Werry, J. M., Bruce, B. D., Sumpton, W., Reid, D. & Mayer, D. G. in Global perspectives on the biology and life history of the white shark (ed Domeier, M. L.) 271-286 (CRC Press, Boca Raton, 2012).
2. Anonymous. Review of the white shark recovery plan 2002 (Department of the Environment, Water, Heritage and the Arts, 2008).
3. Bradford, R. W., Hobday, A. J. & Bruce, B. D. in Habitat use and spatial dynamics of juvenile white sharks, Carcharodon carcharias, in eastern Australia (ed Domeier, M. L.) 255-270 (CRC Press, Boca Raton, 2012).
4. Bruce, B. D. & Bradford, R. W. in Global perspectives on the biology and life history of the white shark (ed Domeier, M. L.) 225-253 (CRC Press, Boca Raton, 2012).
5. Bonfil, R., Francis, M. P., Duffy, C., Manning, M. J. & O?Brien, S. Large-scale tropical movements and diving behavior of white sharks Carcharodon carcharias tagged off New Zealand. Aquat Biol 8, 115-123 (2010).
6. West, J. G. Changing patterns of shark attacks in Australian waters. Mar. Freshwater Res. 62, 744 (2011).
7. Curtis, T. H. et al. in Identifying juvenile white shark behaviour from electronic tag data (ed Domeier, M. L.) 477-509 (CRC Press, Boca Raton, 2012).
8. Baum, J. K. et al. Collapse and conservation of shark populations in the Northwest Atlantic. Science 299, 389 (2003).
9. Myers, R. A. & Worm, B. Rapid worldwide depletion of predatory fish communities. Nature 423, 280-283 (2003).
10. Ferretti, F., Myers, R. A., Serena, F. & Lotze, H. K. Loss of large predatory sharks from the Mediterranean Sea. Conserv Biol 22, 952-964 (2008).
11. Blower, D. C., Pandolfi, J. M., Bruce, B. D., Gomez-Cabrera, M. & Ovenden, J. R. Population genetics of Australian white sharks reveals fine-scale spatial structure, transoceanic dispersal events and low effective population sizes. Mar Ecol Prog Ser 455, 229-244 (2012).
12. Clua, E. & Seret, B. in Global perspectives on the biology and life history of the white shark (ed Domeier, M. L.) 343-353 (CRC Press, Boca Raton, 2012).
13. Bruce, B. D., Stevens, J. D. & Malcolm, H. Movements and swimming behaviour of white sharks (Carcharodon carcharias) in Australian waters. Mar Biol 150, 161-172 (2006).
14. Bonfil, R. et al. Transoceanic migration, spatial dynamics, and population linkages of white sharks. Science 310, 100-103 (2005).
15. Duffy, C. A. J., Francis, M. P., Manning, M. J. & Bonfil, R. in Global perspectives on the biology and life history of the white shark (ed Domeier, M. L.) 301-318 (CRC Press, Boca Raton, 2012).
16. Robbins, R. L. & Booth, D. J. in Global perspectives on the biology and life history of the white shark (ed Domeier, M. L.) 287-299 (CRC Press, Boca Raton, 2012).
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