Canada and the World
Current Events with a Canadian Perspective
Last update
31 December 2010
Great White Sharks
Stalk like Serial Killers
Researchers say that great white sharks off the coast of South Africa stalk their prey methodically before striking
Seal Island is in False Bay, off the coast of South Africa, about 30 minutes from Cape Town. It is home to about 64,000 Cape fur seals, a primary food source for great white sharks.
Great White Shark Attacks on Humans are Rare
At an average of 4.6 metres (15 feet) in length, great white sharks are the biggest predatory fish on Earth.
According to The National Geographic, “Of the 100-
The naturally curious animals are testing to see if they like what they are tasting, and usually they don’t.
So, that’s between 30 and 50 great white attacks a year and most of them survived by the victim. That’s hardly enough to warrant the widespread fear these animals conjure up.
However, The National Geographic describes what clearly gives ocean swimmers and surfers the shudders: “…their mouths are lined with up to 300 serrated, triangular teeth arranged in several rows, and they have an exceptional sense of smell to detect prey. They even have organs that can sense the tiny electromagnetic fields generated by animals.”
Seals are the Great White’s Favourite Food
Great white sharks are efficient hunters and ruthless killers when it comes to their favourite menu items.
Neil Hammerschlag of the University of Miami in Florida, and Aiden Martin of the University of British Columbia in Vancouver, have been studying the techniques great whites use to get their next meal.
BBC News reported on their work on June 22, 2009: “During the winter of 2004, the researchers observed 340 attacks by great whites on fur seals within two kilometres of [Seal Island].
“After each attack, the scientists recorded the precise geographical location and the depth of the water, as well as whether the attack was successful or not.”
Research Data Analyzed by Crime Profiler
Hammerschlag and Martin have drawn on the expertise of Kim Rossmo, a criminal justice expert based at Texas State University’s Center for Geospatial Intelligence and Investigation.
Rossmo uses a technique law enforcement officials call geographical profiling. By carefully plotting the times and places of similar crimes such as arson or murder, it’s possible to narrow down the location of the perpetrator’s “anchor point.” This is usually their place of work or home.
It turns out the great white sharks in False Bay exhibit similar behaviours to those of human serial killers.
“The largest most dominant sharks,” writes the BBC’s Matt Walker, “would regularly pick a particular anchor point, and search for their next victim close to this location.
Most large sharks regularly returned to a spot some 100 metres due south of the main place where seals came ashore on to the island.”
Image credit
Sources
“Great White Shark.” Brian J. Skerry, National Geographic
“Great Whites ‘Plan’ Seal Attacks.” Matt Walker, BBC Earth News, June 22, 2009.
© Canada and the World, July 2010
All rights reserved
Great white sharks grow to an average of 4.6 metres (15 feet) in length, though specimens exceeding six metres 920 feet) and weighing up to 2,268 kilograms (5,000 pounds) have been recorded. They can travel at up to 24 km/h (15 mph).
A five-