Grey Nomads With Gills

By Pascal Geraghty on July 23, 2015 in Other

When the term ‘grey nomad’ caresses your cochlea, what springs immediately to mind? Be honest now.

Is it images of weathered baby-boomers lapping up new leases on life? Is it well-seasoned beards, khaki short shorts and caramelised chicken legs? Do you picture dual-axle caravans scurrying in convoy to warmer latitudes? How about offensive television satellite dishes erected in the most unlikely of outposts? Or do you simply cringe at inheritances being squandered?

Either way, a recent study by local marine scientists suggests that a more appropriate depiction of a grey nomad may in fact be the notorious bull shark, Carcharhinus leucas!

Eminent shark researchers, and colleagues of mine, from NSW and Queensland agreed to put their respective State of Origin quips aside long enough to collaborate on a project examining the movements of bull sharks along Australia’s east coast. They did this using acoustic telemetry technology. Bull sharks were captured at a range of locations (including Sydney Harbour) using various fishing techniques, tagged with electronic transmitters, released unharmed, and their movements monitored as they swam past underwater receivers deployed in waters up and down the east coast.

It was discovered that these extraordinary, formidable and misunderstood creatures were embarking on long-distance migrations, including movements in excess of 1,700km! Much like their human counterparts, a large proportion of the adult sharks tagged in NSW headed north to the warmer, tropical waters of Queensland. In fact, they displayed rather luxuriant tastes when it came to their choice of destination with many individuals being sprung sampling Queensland‘s finest, most exclusive holiday hamlets including Orpheus Island and surrounding Townsville reefs, and the paradisiacal Capricorn-Bunker Group. Many said travellers remained in cane toad country for the duration of the study; however, an equal amount were observed moving repeatedly backwards and forwards across the state border. Interestingly, only one shark tagged in Queensland waters tried to emigrate south to NSW. It turned back, no doubt having been informed Queenslanders were not welcome.

Long-distance movements by sharks are not a new discovery. Great white, tiger, sandbar and common blacktip sharks, just to name a few, have all been shown to swim impressive distances. Nor are bull sharks in Sydney Harbour, or on the Great Barrier Reef for that matter, a brand new concept. These tagged sharks have simply given us an insight into the routes bull sharks have plied since the sea rose to its present-day level some 12,000 years ago.

Bull shark attacks are grisly, violent and tragic events, there’s no doubt. Nevertheless, my hope is that one day these sharks attract respect rather than fear and are considered first and foremost for their marine ecosystem value rather than as indiscriminate killers of innocent people.

Perhaps if we put the recent irrational, and somewhat embarrassing, bull shark hysteria behind us, and instead captured, tagged and monitored some people’s movements, we may just discover we have a whole lot more in common with sharks than we care to admit.
Who knows, maybe this is exactly what the Mad Monk and his gang have in mind for our metadata?