December 2003 Shark Bytes
Posted on Wednesday, 31 December 2003
Wishing everyone the best for 2004. Apologies for the delay in the newsletter, but I have found it difficult to get back into work mode, as I am sure many of you have too!
During this time of the year up until about early June we concentrate our efforts on pelagic trips. We are fortunate to have a very rich area of marine life in our waters off Cape Point. Cape Point is a notorious area for extreme weather and many ships have come unstuck here, including the legendry Flying Dutchman. Factors attributing to these rough seas and often strong winds are mixing currents, jagged coastline and the first landfall of the mountainous Southern Ocean swells generated thousands of miles away.
The past 6 weeks we have only been out to sea on two occasions, making me wonder what I was actually going to write about this month! We have not only been experiencing the usual Summer South Easter winds, but an abnormal amount of cold fronts pushing through bringing with them strong North westerly winds and large swells. When we venture off Cape Point we are travelling anywhere from 20 to 40 miles off shore so the weather has to really be good for us to go especially in order to dive with the sharks. We are basically looking to find the warm Agulhas Current that comes from Mozambique and merges with The Benguela Current that sweeps northward along our western coastline.
These mixing currents are contusive to producing high-density feeding grounds for a variety of fish species. These in turn attract the predators.
Most Capetonians wont believe this to be true, but the water can get gin clear and is a beautiful blue/purple colour with the visibility on some days infinite. The water is also very warm for our part of the world and is usually between 20 and 23 degrees Celsius.
It is no wonder we go to such efforts to find the pelagic sharks that are found out here! We are diving over waters anything from 500 meters to 2 000 meters in depth and the most common shark we see is the Mako and Blue shark. We have on several occasions seen common Thresher shark (Alopias vulpinus) and very large smooth hammerheads.
The blue sharks usually come in their numbers as they tend to swim in schools. I always say to divers we are taking out that if they have not dived with sharks before the blue shark is a great “first shark” to start with. The blues in our area are usually small, but this definitely does not stop them from making close passes and bumping divers to find out what they are. This probably sounds hypocritical, but we find them to be completely non-threatening. Once we have gently pushed them away a few times they seem to understand that we are not for eating! They still continue with their close passes and a fantastic encounter with an open ocean shark can be had. Blue sharks have been recorded as large as 3.8 meters in length. As I mentioned earlier we usually encounter sharks from about 60cm to 1,5 meters. On one of our trips this month we had a 2,5 meter male up at the boat. It was really exciting for us to see a large blue shark, the largest we have seen off Cape Point. He had a bite from anther shark behind his mouth making us wonder what the sharks are doing for this to happen! I guess it is the mystery of sharks that captivates people around the world.
Blue sharks have very long pectoral fins. These are designed specially for gliding in ocean currents and can do this at a rate of around 1 knot. This will help to conserve energy as well as cover immense distances. Chris once tagged a blue in the Cape Point area and was later caught in The Azores, Portugal less than a year later, several thousand kilometres away.
Being in the water with a Mako shark is a completely different feeling. This magnificent shark is built for speed with a perfect hydrodynamic proportioned body similar to that of a jet fighter aircraft. With its magnificent blue dorsal surface and snow-white underbelly this shark is truly Master in the realm of the open ocean. Does this somehow sound like it could be one of our favourite sharks?!
We see Mako’s on most of our trips and, like the blue sharks, they tend to be small. On the way back to Cape point last week Chris spotted a large Mako basking on the surface. After much coaxing the shark was eventually lured up to our boat with the aid of a fresh tuna. We estimated the shark to be at least 2,5 meters also the biggest Mako we have seen. He was extremely cautious around the bait and only tried to take a bite once he was absolutely sure as to what is was. This is probably how he got to be so large. We just watched the shark from the boat in case we scared him off by getting in the water. Seeing him was definitely one of the highlights of last year!