Counting Sharks

October 17, 2011
By Damond Benningfield

If the fear of great white sharks has kept you out of the water, then get splashin’. It turns out there are probably no more than a few hundred of them in the northern Pacific Ocean.

Great whites inhabit just three regions of the world’s oceans: off the coast of South Africa, around Australia and New Zealand, and in the northeastern Pacific. During the summer, a bit more than half of those congregate off central California, while the others circle around an island off the coast of Baja California. And during winter, they head westward, either all the way to Hawaii, or to a feeding ground about halfway to Hawaii.

Great white shark. Credit: Wikipedia

From 2006 to 2008, marine biologists conducted the first census of these great whites.

They took hundreds of pictures of sharks in their California feeding grounds, and used the unique shapes of their dorsal fins to count them. The scientists then used statistical techniques to estimate the total number. They found that there probably are around 219 adults and near-adults in the group. And from that, they estimated the total population of great whites in the northeastern Pacific at around 400.

That’s fewer than the researchers had expected to find. But since no one had ever counted the sharks before, there’s no way to know if the number of great whites has changed much over the last few decades.

The census will help researchers keep track of future population changes, though, to see if fishing and global climate change have any effect on these scary but rare creatures.