The West AustralianWA Fisheries experts have revealed there are as many as 5400 great white sharks off the State's coast and say up to 25 of them could be caught to protect surfers, swimmers and divers over the next three years.
WA Fisheries experts have revealed there are as many as 5400 great white sharks off the State's coast and say up to 25 of them could be caught to protect surfers, swimmers and divers over the next three years.
Their research shows the average annual rate of great white shark attacks in WA has more than doubled in the past 20 years.
The significant increase takes into account the State's growing population and a drop in the number of people doing surf- related sports.
The insight into WA's great white sharks and their impact has been revealed in the State Government's environmental review into its drum-line program, released yesterday.
The Government is seeking environmental approval from the Federal Government and WA's Environment Protection Authority for the program.
Under the policy, up to 72 baited drum lines will be used to catch great white, tiger and bull sharks bigger than 3m off beaches in Perth and the South West between November 15 and April 30 for the next three years.
As many as 25 great whites could be captured over that time, the Government said, though any smaller than 3m would be released if found alive.
The Government concluded the drum lines posed a "negligible risk" to WA's great white shark population, which is protected by law.
Fisheries experts said the great white shark population had increased, or at least stabilised, over the past decade and numbers had reached between 70 and 85 per cent of what they were before they were hunted or fished.
There were now between 3400 and 5400 of them between Victoria and North West Cape off WA.
With an estimated 50 to 100 great whites killed as bycatch in WA, South Australia and Victoria every year, the review said the lines had a "remote" chance of having a "minor" effect on the great white shark population.
It noted no great whites were caught in WA's 14-week drum-line trial this year. In comparison, drum lines will catch 900 tiger sharks over the next three years, the Government estimated.
Far more tiger sharks were caught in the drum-line trial - 64 compared with 10 to 20 expected by Fisheries experts.
Scientists have been surprised by the high number of tiger sharks in the ocean off the Perth metropolitan area and the South West. Warmer ocean temperatures are thought to be attracting tiger sharks further south.
In its review, the Government said it was "possible" the tiger shark death toll in drum lines over the next three years would have a "minor consequence" on the population. It said tiger sharks would need a "higher level of monitoring" and there would be a specific assessment of tiger sharks at the end of the three years of drum lines.
A study found the annual rate of shark attacks in WA increased from 0.4 per million in 1995-96 to more than one per million in 2010-11.
The WA Fisheries report said this increase was unlikely to have been caused by more people in the ocean because Australian Bureau of Statistics data showed fewer were doing surf-related sports.
The public can make submissions on the Government's environmental review of its drum-lines proposal until July 7.