The sharks that we see are the ones who "specialise" in seals. This means that we don't typically see juvenile sharks who, in their early years, feed mostly on fish, but see the sharks that have grown enough to shift to a diet of mammals, usually at around 2.5m in length. We see a lot of sub-adult and fully mature sharks in both seasons, typically around the 3.5-4.5m length and in winter from May-August is when we see the giant female sharks! At their maturity they are over 5.5m a truly a sight to behold! To read more about shark size, click here.
So why do the sharks visit the islands seasonally? The seals have an annual breeding cycle that the white sharks seem to have worked out! In December, pups are being born and, not long afterwards, the mums are ready to mate again and so the large bull seals visit the islands from November, with chocolates and flowers in hand....hmmm well maybe not... it is this seal activity that effectively gives us our "summer season" with the great white sharks.
The pups who grow up to be big and strong start their swimming lessons around May, also the time of the year that the giant female sharks turn up.... the shallow waters in the bays around the islands are full of sleek, black, slippery forms practicing their diving and hunting skills, and are easy pickings on the white sharks' dinner menu. Once these cuties have mastered everything they need to know to make their own way in the world, they leave the islands and their mums around October time.