Monday, June 7, 2010

Shark Activity for May 2010



The return of Nemo!
As we get in to May we are consistently having trips were we are viewing on average more than 10 different great whites per trip. Over the years some of our sharks have been given names that help us identify them when they arrive at the boat. The Great White Shark is nomadic therefore they are not residential, whenever a shark migrates out of the area we always hope that we will get to see it again someday and that it has not fell foul of the hooks and nets that man has placed in the ocean. On the 4th of May a shark which was last seen on the 20th October 2009 in the inshore area called Jouberts Dam “Nemo” returned to our boat alive and well. As soon as we spotted her distinct rolled dorsal fin and the missing right pectoral fin at the Geldsteen area a wave of excitement passed through the crew, “Hey it’s NEMO!!!”At around 2.6 M this little female continues to grow and doesn’t seem to be significantly disadvantaged in her ability to manoeuvre through the water. She has so far been spotted around the Geldsteen area near shark alley and also around the channel mouth area. Her behaviour is like that of the majority of our sharks. Nemo is calm, curious and inquisitive often taking more of an interest in the cage or the boat than the roped tuna line bait in the water. Nemo was last seen on 29/05/2010 on our afternoon trip. It was a beautiful clear winter’s day and Nemo was on form, twice in quick succession she popped up right next to the cage from under the boat and then moved very slowly to the bow of the boat with her head out of the water. A behaviour referred to as “spy hopping”, checking out the boat and the clients. Spy hopping behaviour more than likely evolved as a result of the Great White Shark observing pinniped (i.e. seal) haul outs. The Great white Shark has phenomenal eye sight that it is able to use both in and out of the water. Within the eye rod cells and cone cells are present, guess which other species else has these cells? You’re using them right now to read this, yes that’s right humans. That means as Nemo was spy hopping moving along side our boat she was viewing her environment (and the clients) in colour! Another misconception about Great Whites coined from the movie Jaws is that they have “eyes as black as coal”. If you are ever privileged enough to see a great White’s eye the pupil may be black but the iris is the most amazing and beautiful magenta-blue colour that you will ever see. When captured in the right light it is breathtaking!
No sea days!
From the 5th of May to the 16th of May we were unable to go to sea. We had 3 cold fronts pass through the area in that we work in, high wind speeds, rain and large swells that were on some days in excess of 8m. This meant that any scheduled trips were cancelled immediately. Our highly professional and experienced skippers will cancel if they feel that clients and the crew’s health and safety would be compromised by going to sea. We can always reschedule bookings so that you can come and view the beautiful Great Whites when it is safe to do so.



Back to sea!
On the 17th May we returned to sea! The cold fronts had passed and swells had calmed, and we have had clear sunny weather, it made a welcome change from the howling winds and rain that we were subjected to. We are viewing whales with increasing frequency on our trips; all three species have been spotted during May. On the 17th as we headed over to the Geldsteen area a Bryde’s Whale was spotted 50m off the port side. Bryde’s whales can grow up to 17m and weigh as much as 41 tonnes, as we continued our journey the Bryde’s whale broke the surface allowing us to see its distinct dorsal fin which is located ¾ of the way down its body and resembles a similar shape as a dolphin dorsal. We have also observed small numbers of southern right whales and humpbacks in the area, no doubt as we move into June these sighting will increase. Last year in June 2009 a group of clients were able to observe 3 Great White Sharks all around 3m in length from the cage, then to make their trip unforgettable behind the 3 sharks a humpback and her calf passed by giving them an amazing spectacle.
During our trip on the 17th we had good visibility and 11 different sharks visited the boat (including Nemo). Whilst chumming we could see one shape in the water coming up from the depths that was definitely not a shark, but it was staying deep. Eventually it came closer to the surface and revealed itself to be a short tailed stingray with a diameter of around 2m! The stingray came up to investigate the chum trail but quickly changed its mind after it saw the competition. The sharks didn’t attempt to predate upon the stingray keeping a distance of at least 3 meters until the stingray descended back to the ocean floor. After we had finished our trip we made a pass though shark alley to see the seals on Geyser Rock. In the summer months the seals will happily come along side the boat, during winter time however they know the Great Whites are patrolling close by and hug the shore very closely. We were able to observe 2 Great Whites naturally patrolling shark alley looking for a potential meal. Not all predation attempts are successful; a good analogy for the blubber that surrounds the cape fur seal would be that of a thick coat. During some attacks the Great White is unable to get a good grip of the seal and the seal is able to struggle free and make its way back to Geyser Rock and back to safety. We observed a large seal that had managed to survive an attack. Though the wound looks severe and chronic the damage inflicted is superficial, on the flip side the Great Whites is sometimes on the receiving end of defensive attacks from seals. It is not uncommon for us to observe Great Whites with deep scratches around their eyes and bite marks that have clearly been inflicted by the seals!

During our trip on the 19th we observed an unusual conspecies interaction at the Geldsteen area. The Great White Shark has so many highly tuned senses that what took place almost defies belief. Two females one +/- 2.7m and one +/- 3.0m both approached the bait from opposite directions. As the bait was removed the two sharks which had both been behaving very calmly the whole trip continued slowly towards each other and collided. It was more of a delicate bump than a big impact, upon this taking place the sharks very calmly moved away from each other in opposite directions. At the risk of making an anthropomorphic comment (attributing human behaviour to something non human) it was almost as if the two sharks had bumped into each other and apologised before going their separate ways. As evidence for this we were lucky enough to have one of our White Shark Project volunteers James Green from London in the cage when the incident took place. He was able to get a fantastic shot of the two sharks bumping into each other! Nice one James!
On the 23rd we were reminded that not all conspecies interactions result in an amicable ending. Generally the behaviour we observe with sharks is that they utilise mutual personal spacing i.e. they have an area of space around them that they will defend vigorously and if necessary aggressively. The Great White like other shark species will go to great lengths to signal to other sharks that enter its personal space that it is uncomfortable. Pectoral fins may be pointed straight down, the shark may gape showing its teeth to the shark that has entered its personal space. All of this is done to communicate to the other shark to move away. In most cases this works as we do not observe a great number of white sharks with bite wounds that have been inflicted by other white sharks. On the 21st however we were able to photograph a 3.1m female that had a bite inflicted upon her right hand side around the gill area. The bite has resulted in gill filaments being exposed on the 1st and 2nd gill slits. Once again our volunteer James was in the right place at the right time and was able to capture the photograph from the cage!
On another trip within the last week we were able to view a “bird bashing” event. We had been working at the Geldsteen area and several sharks had stayed with us for the whole trip when a Cape Gannet (Morus capensis) landed and decided that it would like to pick up a few small pieces of tuna that were floating down in our chum line. Landing in a chum line is not a good idea, especially when you have inquisitive white sharks around! To start with the 3 sharks didn’t approach the cape gannet, keeping a distance, but after a couple of unsuccessful attempts at the roped tuna bait that we had in the water the shark decided that it would try a different target, one that was gannet shaped. On the 1st and 2nd passes a male great white of around 2.5m in length circled closely from underneath and bumped the gannet twice, the gannet didn’t take the hint. On the 3rd pass the white shark decided to investigate the object using its mouth and it mouthed the gannet. The Great White has highly sensitive taste buds in its mouth and on tasting a mouth full of feathers it decided to spit the gannet back out of its mouth. The gannet then looking rather dishevelled and confused as to what had just happened finally made a good decision and tried to fly away. The same shark returned to the gannet and bumped it again twice before the bird was able to take flight. Again we had one of our volunteers in the right place to capture the action Joshua Peck from the Falklands was able to capture these amazing shots.

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