If you are studying animals, one of the best ways to get data is to spend time with them – but what if those animals are sharks?
Dr Pete Klimley, who visits Ireland next week, has spent plenty of time in the company of sharks and he has come up with some assumption-challenging findings during his career as a marine ecologist.
For one, he believes that white sharks – the type portrayed in the film Jaws – do not like to eat humans because we don't have enough fat.
"White sharks are not human eaters, they are seal eaters, and seals have lots of fat," explains Klimley, who directs the Biotelemetry laboratory at the department of wildlife, fish and conservation biology at University of California, Davis.
“We find sea otters washed up on the shore and they have shark tooth marks [and fragments], but they have not been eaten. Like us they they are lean and the shark doesn’t eat them.”
He also believes that the majority of attacks by other sharks on humans happen because the fish has been frightened or mistaken and that sharks need to beware of human practices.
“Sharks have evolved all these ways of surviving in the marine environment,” he says, “but then along comes homo sapiens with long lines and hooks and nets.”
Swimming with sharks
Klimley has made numerous discoveries about shark migration and behaviour.
Throughout his career he went free-diving (with no scuba gear) with hammerhead sharks to tag the fish for study. “At that time, everybody felt they were dangerous and suddenly they are an arm’s length away and then you look up and there are silhouettes above you and then you swim back through them with a little trepidation,” he recalls.
“But after a while I realised that their mouths are really small and they feed on small fish and squid and when they are in a school they want to be a body-length apart from each other and swimming in the same direction, so that allows you to get close enough to put a tag in them.”
When tracking scalloped hammerhead sharks in the Gulf of California, he discovered the fish seem to navigate using magnetic fields produced by magnetic materials in lava flows that form offshore seamounts and islands in the eastern Pacific Ocean.
“The sharks were using these lava flows as magnetic highways,” he says. “It would be like us using a road with lines on it – that is their version in the ocean.”
His time with sharks has also led to observations of social behaviour and communication through “acrobatic” movements. Klimley – who has been dubbed Dr Hammerhead – now wants to develop “shark parks” where fishing is prohibited.
He will be in Ireland next week to give a series of lectures hosted by the Irish Basking Shark Study Group, the RDS and the US embassy in Ireland (see baskingshark.ie for details).
The talks start in the RDS, Ballsbridge, on Monday, September 29th, at 6.30pm with The Conservation of Sharks: Sharks Beware of Humans not Humans Beware of Sharks. Admission is free but booking is essential. See rds.ie/speakerseries
