The less salty water and supplies of mullet turn out to be the perfect habitat for young bull sharks. Australian researcher finds that bull sharks are using Gold Coast rivers and canals as nurseries.
Ground-breaking research by Jonathan Werry, from the School of Environment at Griffith University, found the Nerang River upstream with its less salty water and supplies of mullet to be the perfect creche for young bull sharks.
"The sharks' strategy to have their juveniles in a river is a good one," Mr Werry said. "They're safe from predators. The adults will eat the babies. Once they become teenagers it's a different story. "They use the river and canals, they know it well, but they're confident enough to risk going out into the outside world."
He is yet to quantify the number of sharks but believes it is more conservative than widely thought, adding that "it's definitely not thousands".
Another local marine scientist, Trevor Long, Sea World agrees with the findings and has welcomed the research after several fatalities occurred in Coast canals. Gold Coast resident Beau Martin was killed by a shark in Miami Lake in December 2002, and six weeks later champion bowler Bob Purcell was attacked and killed in Burleigh Lake.
Mr Long warns the predators are likely to be more of a problem during summer months and at night when they move from the deep of canals to the surface for food. The adult female bull sharks moved up the river to have their pups in summer, and they needed extra food to sustain them on their way out to the Seaway.