Great White Shark Sightings

Winter in the Southern Hemisphere is known as the best season to view Great White Sharks. Here in Gansbaai, we have sharks all-year-round, but Winter is still traditionally considered as the best season. There are a few contributing factors, such as the fact that there are more sharks hanging around Shark Alley during Winter, the water visibility improves and the water temperature is a few degrees warmer than in Summer. Thanks to the Great White Shark’s rete mirabile, they are able to raise their body temperature about 10’C warmer than that of the surrounding water, which in layman’s terms relates to the sharks being a little lazy when the water is cold and when the water is warmer, they feel a little friskier. The big males make their appearance in winter, just in time for the Cape Fur Seal pups to take their first plunge into the Atlantic and test their aquatic skills. Generally, we see more females than males during Summer and more adult males during Winter.

If you look at our data from 2015 however, you will notice a pattern that does not support what I’ve just told you. Now, I understand that when it comes to the collection of Biological data, it is not as clean and neat as pure statisticians would like it to be; the variables are all over the place! I am all for statistics, it is fascinating, it gives us insight and better understanding, but sometimes it also gives us more questions than answers. And 2015’s data is very intriguing indeed…

The Western Cape of South Africa did not get its nickname “The Cape of Storms” for no reason; Winter in the Western Cape is infamous for its gale force winds and feisty cold fronts, which whips the Atlantic Ocean up into a frenzy and of course, has a direct impact on the amount of days we can go out to sea. Therefore, one could deduce a direct correlation between the amount of trips done per month and the number of sharks spotted. Which is probably why we saw nearly 330 Great Whites in February and only a 140 in May. We did not have good weather in January, so we had quite a few “no sea days”, but January is not known as a good shark-month, so one could expect a low number of sightings. September is still considered good shark-viewing season, but the weather did not permit many trips out to sea, which then gives us the self-explanatory low figure of 84 Great White Shark sightings.

But this is where it gets intriguing: why did we see so many males in February, if traditionally we see more females than males in Summer? And why do we generally see more adult females than adult males? The males we do see tend to be juveniles, which brings me to another question: why do we see so many juvenile sharks in our area? Could one be blamed, if one came to the conclusion that there may well be a Great White Shark nursery in our waters? I mean think about it: Lots of adult females, not so many adult males, and loads of little juveniles of about 1.2m in length, which is practically newborn size. Hmmm, it does make you wonder, doesn’t it?

Now if you consider the strange phenomena we experienced during January and February of 2016, where we had no shark sightings for 5 weeks; could these hiccups in our 2015 pattern have been the warning signs of the impending crisis, much like cumulus clouds are the forerunners of a storm? Were these hiccups caused by the El Nino and can we indeed blame the El Nino for making our sharks disappear for those weeks? Guess we will have to wait until all the data has been accumulated and assessed – will keep you posted!