August & September 2009 Shark Bytes
Posted on Wednesday, 30 September 2009
My apologies as the shark news this month is a little delayed and you are going to get August and September in one shot!
I can only describe the last 6 weeks at Seal Island and in False Bay as peculiar. For the last few years we have found activity in the first half as August as normally part of the best of the season with good numbers of sharks around the boat and intense predatory behaviour. This past August has been the slowest for all activity in the last 15 years. So, the sharks have certainly been keeping us on our toes with a very short 3 month season this year. We completely understand how nature works but it has just been disappointing that we have not had more quality moments with the sharks as time spent with them is always precious.
Seal Diving & Slow Sharks
In early August shark activity was so slow that we resorted to diving with the seals close to Seal Island. This was a pretty special second prize and I have to say it was one of the highlights this season for me. It was really wonderful to be able to spend time with the seals in their domain. They were so tolerant and one aspect of their behaviour that really stood out was how comfortable they seem to be with close contact with each other. Under the water it is absolute mayhem with ten’s of seals cavorting around and constantly intertwining with each other. I would guess that these animals have very strong social bonds and would know each other very well. It was a true privilege to spend time with them like this and certainly gave me an even stronger bond with the seals…it was well worth the rather daunting swim to the Island with dark shadows lurking in the back of my mind!
It was interesting to note that Gansbaai also experienced slow shark activity in early August. I guess this says to me that there must have been some change that we were not aware off that severely affected the sharks. The Southern Right Whales that migrate from Antarctica to the South African shores each year have also been late, yet another sign that something is up.
Despite the slow activity we hosted a Discovery Channel film crew for a couple weeks in August and I am not sure how (!) but we managed to pull off capturing some pretty spectacular shots of the great whites. This show is only going to air next August but will definitely be worth looking out for during Shark Week. It is very balanced so please don’t expect the almost normal killer-shark type shark week documentary!
From the middle towards the end of August the activity did pick up a little bit and we did see sharks on almost all trips. What is a little distressing to note is that the natural predation activity was down by almost 40% compared with what we normally see. I am not sure what to make of this but again it just goes to show how different each season can be and how inaccurate it can be to draw conclusions over short periods.
Our season historically ends around mid September and although due to bad weather we did not do a lot of trips in September we still had good sightings of predations and a couple sharks up at the boat.
It was not a good time period for seeing any sharks that we know but a really nice surprise towards the end of the season was the second sighting of “Shy Guy” on a successful kill. We last saw him in June so it was exciting to note him again nearly 3 months later. Also on our last trip to the Island in mid September Chris managed to identify “Bumps” on a kill. We have not seen her since mid July and certainly did not expect to see her now!
Mossel Bay Great White Sharks
We had a great opportunity of spending 5 days with the great whites at Seal Island in Mossel Bay. Mossel Bay is located about 4 hours from Cape Town up the Garden Route and very close to shore there is a seal colony of about 2000 to 3000 Cape fur seals. Of course this small breeding colony does attract Great white sharks and is one of South Africa’s hot spots for them.
We had not spent anytime with the sharks here so both Chris & I were really excited to visit and spend time in a different shark area. It certainly was a nice, but strange feeling just arriving in the morning and having a boat ready to drive us to the Island. We had no need to worry about fuel, bait etc and the shark operation here was a great host.
The great whites in Mossel Bay have also been observed to breach out of the water as they do in our “home” waters. My first feeling on arrival at the island was that it was not a “breachy” kind of place. There is not a lot of seal movement and the small colony of seals does not give the impression of supporting a lot of great white sharks. We did not observe any natural predatory events but over a 5 day period we did manage 3 breaches on the decoy.(after a lot of towing!)
Breaches are always spectacular but what left the greatest impression on us was how close to shore these sharks are. It is a crazy sight watching a great white shark swim around the boat and then to look up and see people walking on the beach.
Upon anchoring up we really had great interactions with the sharks and this gave us the impression of a very healthy population of great whites along this stretch of coast. Another interesting observation was that all sharks were a lot smaller than the sharks we see at Seal Island and the average sizes we were seeing were between 2 and 2.8 meters. Considering the average size shark at Seal Island is 3.5 meters this is a great size difference.
I certainly am not an expert of the Mossel Bay sharks but it would seem to me that these younger sharks may possibly be feeding mainly of fish species found close to the shore and then going for the occasional seal feeding sortie.
Younger great whites have dentition that is more tri-cusped and thus more suited to feeding on fish (by using a grasping rather than sawing motion). As they become older the teeth become more triangular which would be more suited to feeding on seals as a sawing motion is needed.
After having great sightings of sharks around the boat Chris was lucky enough to do an observation of the shoreline from a helicopter. From the air they spotted 6 great whites sharks just behind the shore break. We have heard that over our summer months the numbers of great white sharks close to shore are far greater than this time of year. We are really excited to visit this area again during the up coming summer months and see what the shark movements are like.
Back to False Bay, and some Awesome Cetacean Sightings
On our return back to False Bay we found the bay to be teeming with life. In the early mornings very large shoals of bait fish on the surface and on most trips we were sightings schools of common dolphins. We were also seeing large numbers of Brydes whales and even had one encounter where 2 of them spent a good 15 minutes almost rubbing up against the boat. These whales are typically shy so it was an exiting experience and actually the second time this season that we have had such a case.
Now, I am sure that many of you will remember that back in April I wrote about Killer Whale sightings that Chris had, I had such a tremendous response to that piece of news that I was starting think it may be a good business decision to open up Killer Whale charters!
Well, even though I was so excited for Chris & Poenas I was bitterly disappointed to have missed this sighting as this was a life’s dream of mine.
So anyway, on a trip in early September we were heading out to the Island when Chris spotted some rather large dorsal fins in the distance. He immediately knew what they were and within a few moments we were surrounded by 6 Killer whales!
There were 4 adults and 2 small juveniles and they were just magnificent as they cruised the False Bay waters. In an instant their behaviour changed and they disappeared for a long period underwater.
Low and behold on the distance we spotted a school of common dolphin that the Killer whales were obviously already well aware of. On the last encounter the killer whales were observed hunting a large school of dolphins and it appeared that we would witness this yet again. The dolphins were completely unaware of their hunters and we made sure to keep our distance so as not to disturb or distract them and shut down our engines while we waited to see what would happen. During this time there was no sign of the killer whales for a number of minutes as they were underwater. Suddenly a killer whale blasted through the water culminating in a full breach as it stunned the dolphin, knocking it too into the air.
I am sure the dolphin was severely injured after that and the killer whale was is no rush to chase it down quickly after that. In fact the 2 juveniles also participated in the hunt and sadly for the dolphin the whole end part of this took rather a long time, including the actual consuming of the dolphin.
Chris & Poenas had got a really good look at both killer whale sightings and they reckoned these were definitely different pods. We did some research afterwards as our knowledge of killer whales is not very impressive! Both pods displayed behaviour that is normally attributed to transient killer whales. These included hunting techniques as well as prey choice, in this case mammals. It was also interesting to note that on both occasions the seals in the area were quite comfortable to be in close proximity. This is strange as in other locations around the world killer whales do hunt seals. Here the killer whales showed absolutely no interest in the seals so both species seemed to be tolerant of each other. The research we read also stated that it was very rare for killer whales to bow ride or interact with boats so we were extremely lucky to have had this experience and the quality of both sightings.
So the common denominator for slow sharks in April and August just so happens to coincide with our killer whale sightings. I wonder..!