Shark’s travel tale stirs up frenzy

ARECENT newspaper headline announced: “As great white shark Lydia closes in on UK, Brits brace for bloody mayhem on holiday beaches.” The “man-eater” with “razor-sharp teeth” will soon arrive here, we were told. She was “on course for Ireland”.

What nonsense.

Lydia seems to have abandoned her plan to visit Europe; latest reports say she is heading northwards towards Greenland but, if she does veer south again and turns up at Salthill or Ballybunion, no one is likely to be harmed.

In March 2013 Lydia, 4.27m long and weighing 900kg, was tagged off the coast of Jacksonville, Florida, by a team from Ocearch, a research organisation studying “great white sharks and other apex predators”. The fitting of the monitoring and satellite tracking devices can be seen on YouTube (youtu.be/-IJ0uLh9UAs). Hooked from a boat on a baited fishing line, the huge fish was manoeuvred into a floating enclosure erected beside the vessel. Divers and scientists jumped into the water to help control her. The wooden base of the corral was then raised, lifting the shark out of the water. The head was covered with a blanket, calming her. Seawater, pumped through her mouth and gills, kept her oxygenated. Next, a brightly coloured data-recorder and a satellite-tracker were attached to the huge dorsal fin. Her measurements taken, she was released, seemingly none the worse for her experience.

Great whites lift their heads above the water occasionally; perhaps they locate prey by smell. When a dorsal fin carrying a monitoring device clears the surface, the pinger sends a signal to satellites, enabling its position to be pinpointed. Lydia has meandered all over the Western North Atlantic, travelling more than 30,000km. At one stage, she was about 1,200km from Ireland. If she had continued towards Europe, she would have been the first great white known to have crossed our ocean. It would not be the first recorded crossing by a shark, however, a few years ago a member of a related species, a porbeagle tagged off Ireland, travelled to Canadian waters 4,260km away.

Great whites frequent the Bay of Biscay. As our seas become warmer, with climate change, it is increasing likely that these sharks will turn up here. If they do, bathers and surfers, despite sensational tabloid headlines, have nothing to fear. The risk of shark attack is tiny. According to the Florida Museum of Natural History, there were 72 incidents worldwide, resulting in 10 fatalities, during 2013. Your life-time risk of being killed by a shark, according to the Museum, is about 1 in 3,700,000. Compare that to the risk of drowning; 1 in 1,100. You have one chance in 80,000 of being killed by lightning. More people die falling off their toilets than are attacked by sharks.

Great whites like to eat seals, not people. Attacks on humans may be cases of mistaken identity, often the result of poor visibility. Sharks seem to “test-bite” a swimmer, releasing the victim immediately, so only a minority of strikes are fatal. Either they don’t relish human flesh or they find us too bony. The layers of protein-rich fat and blubber on seals are much more to their liking. An irrational fear of sharks, therefore, may be no bad thing if you are overweight.

If you like bathing in sunny climes, cut down on junk food lest a shark takes a fancy to you! It will help to reduce your risk, not from sharks, but from heart attack. 1 in 5 of us dies of coronary disease.

So what has Lydia taught us so far? It’s unlikely that her wanderings are a once off; great whites almost certainly range widely in the Atlantic.

This is no surprise; a tagged shark crossed the Indian Ocean in both directions, so why shouldn’t Atlantic sharks also travel.

That Lydia ventured into colder waters than her species normally frequents is a surprise; the great white’s range seems to be greater than was thought. More tagging will be required, however, before the ecology of this vulnerable species is well understood.