Researchers say shark numbers are dropping in Queensland

Despite Townsville anglers saying shark numbers have exploded in the region, new research says the opposite is true.

DESPITE Townsville anglers saying shark numbers have exploded in the region, new research says the opposite is true.

Anecdotally fishers say the numbers of sharks off the coast are out of control, with the grey coats often taking fish from lines.

In September two people were attacked by sharks in Cid Harbour in the Whitsundays, while in November a Melbourne doctor was killed in an attack in the same area.

However, analysis by University of Queensland and Griffith University researchers of Queensland Shark Control Program data, found the state’s coastal shark numbers were continuing a 50-year decline.

Baited drumlines and nets are used as part of the program, which has run since 1962 to minimise human-shark interactions.

UQ School of Biological Sciences researcher Dr George Roff said historical baselines of shark populations were largely unknown.

“Explorers in the 19th century once described Australian coastlines as being ‘chock-full of sharks’, yet we don’t have a clear idea of how many sharks there used to be on Queensland beaches,” he said.

“Shark populations around the world have declined in recent decades, with many species being listed as vulnerable and endangered.”

Dr Roff said researchers found large apex sharks such as hammerheads, tigers and white sharks, had declined by 74-92 per cent along Queensland’s coast.

“And the chance of zero catch – catching no sharks at any given beach per year – has increased by as much as seven-fold,” he said.

“The average size of sharks has also declined; tiger sharks and hammerhead sharks are getting smaller.

“We will never know the exact numbers of sharks in our oceans more than half a century ago, but the data points to radical changes in our coastal ecosystems since the 1960s.”

Dr Chris Brown from Griffith University’s Australian Rivers Institute said they were surprised at how rapid the declines were, especially in the early years of the shark control program.

“We were also surprised to find the declines were so consistent across different regions,” he said.

Last financial year there were 114 sharks caught on baited drum lines off Townsville and Magnetic Island – which equalled half of all sharks caught between Gladstone and Cairns. Of the sharks killed, 36 were tiger sharks, and 58 were different varieties of whalers.

Dr Roff said what might appear to be an increase in sharks was in “reality a fraction of past baselines” with the long-term trend showing ongoing declines.

Originally published as Researchers say shark numbers are dropping in Queensland