A POPULATION concentrated near the coastline and a love of ocean-based activities means that sharks are part of the Australian psyche.
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Unfortunately, most shark information that is available to the public is based on myths and untruths, which leads to an unfounded fear of these majestic creatures.
Sharks have been part of our oceans for around 400 million years and today there are more than 500 different species inhabiting the world’s oceans, estuaries and freshwater systems. The most recent authoritative text, Australian Sharks and Rays (2009) by Last and Stevens, recognised 182 shark species in Australian waters, with just over half of these found only in Australia. This rich and diverse collection of sharks, along with their close relatives the skates, rays and stingarees, play very important roles in our unique marine environments. These roles include keeping prey species’ populations in balance, enhancing genetic fitness by removing sick and weak individuals, structuring habitats through their predatory activities and even serving as prey for other marine organisms.
Although our understanding of their ecological roles is not yet complete enough to fully predict the effects on marine ecosystems of their removal or significant population declines, the best evidence suggests that the effects are likely to be far reaching and profound.
Despite this, shark populations are generally low or declining, mainly as a result of fishing pressures and particularly due to the shark fin trade.
Clarke and colleagues reported in the journal Ecology Letters(2006) that the global shark fin trade alone is responsible for the death of 26 to 73 million sharks each year.
The IUCN currently recognises 73 shark species globally, and 29 in Australian waters, that are threatened. Although fisheries management and other conservation measures in Australia are better than much of the world, we still have threatened species and declining populations in our waters.
The typical public reaction to sharks is one of fear and every summer this is whipped up by reports of shark sightings, shark attacks and stories of ‘‘man-eaters’’. Fortunately, this is improving and people are slowly beginning to recognise the truth about sharks and the vital roles they play in our seas.
However, is there any justification for the fear and hysteria that is an almost traditional part of an Australian summer?
I’d argue that there isn’t, as it is largely based on misunderstanding, misrepresentation and the irrational fear this generates.
Each summer, hundreds of thousands of people swim, surf, dive, snorkel and participate in other water-based activities in NSW alone.
Across Australia this figure would extend well into the millions.
However, detailed records maintained by the Australian Shark Attack File (ASAF) at Taronga Zoo indicate that Australia averages around one shark fatality each year, compared with an average of 121 beach drowning deaths annually.
Of course this is not meant to downplay the tragedy of these incidents, rather, my intention is to provide the facts and place the risk in perspective.
Of the 182 species occurring in Australian waters, only three are considered to pose a potential threat to people, while several other species, such as bronze whalers and hammerheads, have been involved in a small number of incidents but are not generally considered dangerous.
The potentially dangerous sharks are the white shark, bull shark and tiger shark, with only the first two regularly occurring off the Sydney-Newcastle coastline.
These species feed on fish and will also consume large prey, such as seals, dolphins and whale carcasses. They are highly mobile species that follow ocean currents and fish movements and there is no evidence that they establish territories in any specific location.
Tracking studies on white sharks by the CSIRO have shown extensive movements, including sharks from South Australia seasonally travelling as far as southern Queensland and north-west Western Australia and even to New Zealand and back.
Sharks are ever present in our coastal waters and pose a negligible risk to humans.
For example, over the 2009-10 summer school holiday period, NSW Primary Industries conducted an aerial shark patrol trial on weekends and public holidays.
The patrols covered 51 beaches between Newcastle and Wollongong and a total of 221 sharks and over 100 schools of fish were sighted. However no attacks occurred and no beaches were closed as a result of these sightings.
The reality is that humans are not ‘‘on the menu’’ and sharks are not the ‘‘man-eaters’’ portrayed in movies like Jaws and often implied in media reports each summer.
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Instead they are magnificent animals, superbly adapted to their environments, in which they play critical roles.
We need to respect the ocean and use common sense when we enter it, but an irrational fear of sharks should not be a part of this.
Dr David Powter is a marine ecologist and senior lecturer in biology, ecology and conservation at the University of Newcastle.
http://www.theherald.com.au/story/122 ... nd-man-eater-myth/?cs=308
