STOP KILLING WESTERN AUSTRALIAN SHARKS!!!
BBC NEWS:A shark cull divides a nation http://www.bbc.com/news/magazine-26937924
◎What’s the real risk of being bitten by a
shark in Western Australia?
Statistics show us that even a spate of deaths like that in WA could be a simple quirk of fate. But assuming there are underlying factors at play, what might they be?
The fact that white sharks prey on humpback whales suggests that a key risk factor for shark bites is their attraction to the region during the annual humpback whale migration. In early winter, mature humpbacks travel north along the WA coast to the Kimberley region, before returning to Antarctica in late winter and spring. Mothers who have calved during this time lag a few months behind the main migration, resting from time to time in shallow coastal bays with their young.
My analysis – which, it must be stressed, is undergoing peer review at the time of writing – shows that shark bite frequency has grown exponentially between 1973 and 2013. During this time, humpback whale populations along the WA coast have grown at 10% per year. My work suggests that these two factors are closely linked.
The theory is bolstered by the fact that two-thirds of white shark bites occur during months when humpback whales are migrating through the local area. Roughly half of white shark bites on humans happen in spring, when humpback mothers and calves are migrating south.
Coupled with this circumstantial evidence is the fact that whale meat, usually obtained by scavenging dead whales rather than by direct hunting, contributes more than any other food by mass to the diet of large white sharks.
Has the shark population grown?
The true size of WA’s white shark population remains largely a mystery.
What we can say is that white sharks have been protected in most Australian states since the mid to late 1990s, meaning that the first group of white sharks that could have benefited from this protection will now be maturing to adulthood and increasingly preying upon marine mammals as part of their diet. Unfortunately, given the lack of reliable population data, we can’t say much more than that.
Meanwhile, it’s surprising to note that WA’s booming population over the past decade does not appear to be a significant factor in the rate of shark bites.
Participation in surf sports and diving have, if anything, declined slightly over the past decade.
What are the real risks?
In estimating the personal risk of white shark bite, the WA Department of Fisheries has identified water depth, choice of water activity, distance from shore, water temperature, and the presence of marine mammals as important risk factors.
Based on these factors, the risk of a fatal white shark bite varies hugely. My analysis shows that for Perth beachgoers bathing within 25 metres of shore during summer (which is outside the whales' migration period), the risk is no more than 1 in 30 million per swim.
In contrast, for a diver more than 50 metres from shore, in cool waters more than 5 metres deep off WA’s southern coast, in the springtime when whales and their calves are close to shore, the risk may be as high as 1 in 15,000.
To put this in perspective, the risk of being bitten by a shark while swimming at a Perth beach in summer is about 50 times smaller than the risk of a serious or fatal recreational cycling injury in WA, and about 30 times smaller than the risk of being struck by lightning in Australia.
Lightning over Perth - where you’re more likely to be struck by a lightning bolt than bitten by a shark. beninfreo/Flickr, CC BY-NC
Click to enlarge
Shark bite is an emotive topic, which evokes less-than-rational responses by both individuals and governments.
Based on what we know about the personal risk, the current summer shark culling policy in WA would appear to be unnecessary and at the time of writing is yet to catch or cull a large white shark.
Baiting during summer is very unlikely to reduce the risk of white shark bite during the higher-risk winter and spring months.
Although it may be expected that bite risk will increase as whale abundance continues to grow, for the foreseeable future, for the majority of bathers, it is likely that the risk of shark bite over WA’s summer will remain very low.
For those who choose to participate in higher-risk water activities such as diving, a better understanding of personal risk and the factors that influence shark bites could help people make informed choices about where, when and how to enjoy WA’s superb climate and its beautiful coastline.
13 February 2014 by CONVERSATION http://theconversation.com/uk
◎State Government asks Commonwealth to
approve its shark-kill program until 2017
Australian waters usually see about one fatal shark attack per year; but these waters are the primary home of the great white shark, a large species that can grow up to 20 feet (6 meters) long. Last year, 14 unprovoked shark attacks on humans were reported in Australia, only one of which was fatal.
Shark attacks went up last year — the highest amount of attacks seen worldwide in a decade, researchers say.
The spike in attacks is most likely due to the growth of the human population, coupled with the increasingly large amount of time people spend in the sea, which raises the odds of human-shark interactions.
Scientists investigated 115 alleged incidents of struggles between humans and sharks worldwide in 2010. They confirmed that 79 of these were unprovoked shark attacks on live humans.
Unprovoked attacks are ones that occurred with the predators in their natural habitats without human instigation. The other 36 incidents included 22 provoked attacks — such as assaults after divers grabbed sharks — including three cases of sharks biting boats, four incidents dismissed as non-shark attacks, five scavenging incidents of human corpses and two cases where there was not enough information to determine if an unprovoked shark attack had occurred.
The Australian Senate: Prevent proactive killing of white sharks in Australia https://www.change.org/petitions/the-australian-senate-prevent-proactive-killing-of-white-sharks-in-australia-2
Save WA Sharks - Stop the Cull. http://www.marineconservation.org.au/petitions.php/9/save-wa-sharks-stop-the-cull
SAVE OUR SHARKS green peace https://www.greenpeace.org.au/action/?cid=60
Shark cull policy in Western Australia faces fresh challenge from Greens
Common Names: Great White Shark, White Shark, White Pointer
Scientific Name: Carcharodon carcharias
Size: Av. 4-5m. Max size 6.5m
Found: Worldwide along continental margins of temperate and some tropical seas.
Population Status: Vulnerable to Extinction (IUCN 2007)
Tooth ShapeGreat White teeth are triangular in shape with serrated edges for tearing.
Egg sacs develop and hatch inside the mother, young are
then born live. Females can give birth to 7-9 pups measuring
around 1.5m at birth.
It is thought that Great White Sharks only give birth 4-6 times
during their life. Juveniles can take 10-12 years to reach maturity.
Great White Sharks can reach speeds of up to 25mph and can weigh up to 3 tonne.
Great Whites can have around 3000 teeth at any one time.
After a large meal, a Great White can go without food for up to 2 months.