July 2017 Shark Bytes
Posted on Thursday, 10 August 2017
We started the month of July at Seal Island on a real high but as July draws to a close it’s becoming evident that things are slowing down quite significantly.
The strange shark year in South Africa just keeps continuing and the news from Gansbaai is not good either.
I would however like to start with the good news…
Seal Island, False Bay
In June Shark Bytes, I reported that things were on the up and right through to about the middle of July we were getting some fantastic sightings of the great white sharks around the boat. On our best trips we were recording up to 7 individual sharks per trip and on most trips we were seeing between 3 and 5 different sharks.
After a long “shark drought” it was a relief to have such great views of the sharks. I felt like I made the most of every moment and really took in these magnificent animals. I suppose it is good to be reminded sometimes of how grateful we should be to see these rare super predators.
All of these sharks were incredibly interactive and most of the time it was nonstop shark activity around the boat for the duration of the trips.
The water visibility was also very good and being 10 meters plus on most days over this 2 week period, the shark cage diving was the best we have had in a long while.
Most of the sharks we were recording were much smaller than we normally see at Seal Island but there were also a couple of bigger sharks in the 4 meter range.
July is normally our absolute peak time for seeing the sharks hunt the cape fur seals. It would be correct to say that most morning trips this time of the season would see a spectacular breach or 2 as well as some fascinating sequences of sharks chasing seals on the surface.
At the peak of the shark activity around the boat we were seeing between 3 and 8 events per morning trip so although predation activity was a bit slower than normal we expected things to keep picking up the deeper we got into July.
Unfortunately this was not to be.
False Bay was hit by 5 days of very strong South Easterly winds and on the other side of this the shark activity seemed to take a tumble.
Over the last 2 weeks in July, we only recorded a total of 8 predatory events. And this is at a time of the season where seeing between 15 and 20 events per day is not uncommon.
Even the events we did see were mostly half hearted attempts with small lunges on the surface as opposed to the spectacular aerial acrobatics the great white sharks are so capable of.
Whilst on anchor over the last 2 weeks it became apparent there was a total of 5 different sharks at Seal Island. We recorded the same sharks each day and there was no sign of new sharks arriving at Seal Island.
The really odd thing was that all these sharks were tiny and in the size range of between 2m and 2.8m in length. This is not the size class of shark we normally see with our average shark size at Seal Island being 3.5 meters. In fact, it’s a rare to see such small great white sharks at Seal Island.
There is quite a bit more I would like to say on this particular topic and will discuss this further when I bring you news from Gansbaai.
Some interesting behaviour at Seal Island
There are 2 interesting bits of behaviour that stand out from July.
The first one is the high presence of red-bandit jellyfish in the waters around Seal Island.
These beautiful jellies have dark red streaking on the top of their mantels and are about 30cms in diameter with their trailing tentacles. The water must have been very rich in nutrients which would have been the draw card for the jellyfish. The interesting observation for us was how interested the sharks were in the surface swimming jellyfish. They would often swim up to them for a closer inspection and on a couple of occasion they even swallowed them. This was met with an unpleasant reaction of spitting out the jellyfish and doing a bit of a jig after finding out the jellies were not their normal food item! We termed them shark chilli poppers.
A Giant Petrel also had a very lucky escape after a close encounter with a great white shark. This open ocean scavenging bird does not visit Seal Island too often and thus is obviously not in tune as to the danger posed by a great white shark. This particular bird spent most of the morning sitting around our vessel and the sharks would often approach it as it sat on the ocean surface. Its only reaction was to flare its wings and participate in a half-hearted scamper on the surface to evade the big predator that was checking it out and on occasions actively trying to catch it.
Chris and the crew made many attempts to chase it off as they were all worried it might get taken. But, time and time again it came back to the boat.
At the very end of the trip the crew had just brought the shark cage back on board and were preparing to head back to Simons Town when the inevitable happened.
A great white approached the Petrel at high speed, lunged and took it down in one huge gulp. Whilst the bird was in the shark’s jaw, it thrashed around shaking the bird from side to side before eventually letting it go.
The bird floated up to the surface in a bedraggled state and all on board felt sure it had not survived.
Incredibly the bird shook itself and limply put its head up.
Never one to leave a living animal in distress, Chris and Ryan caught the bird and 2 of our guests were able to act as an ambulance and get the bird to SANCCOB (a sea bird rehabilitation centre) immediately after the trip.
It turns out this giant petrel is an extremely lucky bird having “only” sustained four puncture wounds and a ruptured air sac. He has taken 5 weeks to recover under the watchful eye of the amazing staff at SANCCOB and a successful release took place 40km off Cape Point this past weekend! Hopefully he flies south and never sees another great white again as it is doubtful any bird will ever be given such an incredible second chance.
This really is an incredible story as he was breached on, completely swallowed, thrashed around in the same manner great whites tear a seal in half, and then spat out by a shark that was nearly 3.8m long and would have weighed close to 800kg, probably 120 times more than the bird.
In June Shark Bytes I had reported that another great white shark carcass had washed up in the Gansbaai area and an orca predation had been confirmed. The few sharks that had started to return to Gansbaai after the May orca attacks almost immediately departed these waters once more.
We are now nearly 6 weeks down the line and still not a single shark has been seen here.
The sharks are most certainly missing in action…
The resulting dynamic is interesting. We think that most of the sharks have moved in an easterly direction up the Coast with Mossel Bay seeing a high number of sharks on their current trips.
A lot of great whites have also been spotted off Plettenberg Bay and as far up as Jeffreys Bay.
We also think a few of the sharks moved down to False Bay and Seal Island.
I have already mentioned that many of our sharks seen over July were small animals that we don’t normally see and this indicated to us that they could be Gansbaai sharks. (Gansbaai does record a high percentage of sharks in this size class).
Another pertinent detail to consider is the obvious lack of predatory behaviour at Seal Island this season.
For quite a few years now we have surmised that Seal Island may consist of a segregated population of great white sharks that are seal hunting specialists. Gansbaai does not see nearly the same amount of hunting behaviour that we do at Seal Island so we feel that this adds weight to our assumption that we have been seeing Gansbaai sharks.
Unfortunately this begs the question as to where are all the Seal Island sharks?
Looking back at our data it appears that between 20% and 30% of the sharks we have seen between 2004 and 2014 are what we call “Seal Island regulars”. We see these animals season to season and for weeks at a time at Seal Island.
Since 2014 we think this figure of regular sharks has gone down to 10%.
All this aside, it also means there is a very high percentage of sharks that merely come in and out of the area and stay for short periods of time. In other words Seal Island normally experiences a high turnover of sharks.
So, an even bigger question is….where are all these sharks?
There certainly is a lot to think about but one thing for sure is that the answers are not coming very easily.
Sadly another factor that could be playing a part is that whale entanglements, either in experimental Octopus long line pods which are strewn all over False Bay and crayfish traps which are in their hundreds at the mouth of the bay, have been responsible for at least 15 whale entanglements and possibly as many as 5 brydes whale and 1 humpback whale death in just over a year and a half. What this means is that when the sharks find one of these floating carcasses they gorge themselves to the point of saturation, having over the years personally witnessed this on 5 separate occasions, and don’t resume normal feeding for weeks at a time. This tragic and completely unnecessary loss of the lives of our bays whales could therefore also be having an impact on our sharks.
As we head into August we can only hope that the sharks stay on at Seal Island for a while longer, whales stop needlessly being killed, and that the sharks begin to return to Gansbaai.
Until next month,