Shark Chronicles 016 - Seal survey

Cape fur seals are readily abundant here in the chilly waters off the coast of South Africa. In the heart of Mossel Bay lies an island that 4400 seals have colonized and made their resting spot. Unfortunately for the fur seals, there is a constant patrol of great white sharks. The seals have to be extremely agile and quick to avoid the stealth and teeth of the white sharks and therefore watching their behaviour as they travel to and from the island can be quite difficult.

SAMPLA came up with the idea to get a bird’s eye view of the island to observe seal movement, which is actually much more efficient than taking observations from the boat. The scientists and interns take shifts throughout the day from atop the Dias Hotel on the western inland side of Mossel Bay, which gives the observer a complete view of the island and the entire bay. From here, researchers can observe the number of seals leaving and arriving at the island, the various boating and shark activity around the island and the weather and sea conditions. With the island being a focal point, the rest of the bay is divided into sectors to make recording seal movement more accurate.

At first, seal observation was restricted only to daylight hours. Researchers arrive before sunrise and leave shortly after sunset. Recently, SAMPLA has received some cutting-edge night vision equipment to make 24 hour and night time observations possible. Never before have 24 hour observations on seal movement been recorded in such a way. SAMPLA research has also uncovered that white sharks in Mossel Bay are able to hunt at night as well, with no ambient light, first time ever documented. The night time observations are crucial in order for SAMPLA to gain a complete understanding of the cape fur seal behaviour. It also helps complete the picture of the predator-prey behavioural games between the white shark and the Cape fur seal.