CHIMPS OF THE OCEAN
MYSTERY OF HAMMERHEAD INTELLIGENCE
SCIENTISTS are looking into why the number of hammerhead sharks caught in nets has halved – and it could be because they are too damn smart.
Griffith University researcher and PhD student Johann Gustafson has been commissioned to look at the behaviour of the wide-eyed species, considered the chimpanzees of the shark world.
The number of hammerheads caught in shark nets has dropped from 77 in 2001 to 38 last year.
Researchers want to know if their intelligence has steered them away from the barriers.
“We’re trying to find out where they are in the scheme of intelligence and see what their behaviour is, see where they go in certain seasons,” Mr Gustafson said.
“The intelligence thing is related to their behaviour and sociability. They have 180-degree vision on both sides – they can’t see in front of them – but this is made up for with a sensory system that can detect electrical impulses in front of them.
“Hammerheads hunt in the open ocean, in murky waters. They have more sensors and turn on sharper angles (as opposed to other sharks which are more rigid).”
Mr Gustafson said previous research funding into sharks had predominantly concentrated on man-eating species such as great white, tiger and bull sharks so little is known about hammerheads.
“We pretty much know nothing about them,” he said. “For the past 15 years numbers have declined in the Queensland shark nets and some reports say there was a 90 per cent decline in catch data globally,” he said.
“Hammerheads are the most advanced species and they’re also the youngest (on the evolutionary timeline).
“They have more sensory adaptations and more neural linkages in the brain which is why they gather socially, unlike other sharks. They’re kind of like chimpanzees of the shark world.
Mr Gustafson said he planned to track three juvenile and five adult hammerheads to determine their feeding and breeding patterns.
Along with tagging, Mr Gustafson will examine hammerheads caught as bycatch to determine if they are Gold Coast residents by examining organs and cartilage.
He said one theory for why the sharks numbers were dwindling in catch data was because they are not as resilient as other shark species.
“Even though there are more advanced they die very fast if they are caught in nets or drum lines, usually within an hour. They’re not as hardy as other sharks.”