July 2013 Shark Bytes
Posted on Wednesday, 31 July 2013
Dear Shark Lovers,
Wow, wow, wow …. That pretty much sums up the last few weeks’ activity at Seal Island, reminding us all once again what an incredibly unique and spectacular place this is.
Most of our news this month is focused on the natural predation activity and also the return of more of our favourite and regular Seal Island sharks.
Great Water Visibility
Shark sightings around the boat and predatory activity had been building towards the end of June but a 5 day period of bad weather in early July did cause some decrease in activity.
Once the weather started to settle down again we found that the water visibility at The Island was fantastic and was averaging at 10 meters plus (very good for us!). The settled weather made for perfect cage diving conditions and all guests were having fantastic views from underwater.
However, the great water visibility seemed to have a huge effect on seeing breaches on the decoy and these were very few and far between.
We are not entirely sure but we think that with the water visibility being so good the sharks may be able to pick up in the last split second moment before hitting the decoy that it is not exactly what they are looking for. Rather than waste unnecessary energy they seem to pull out of the final attack.
The great water visibility has stayed with us the whole of July and so the low rate of success on the decoy has continued for the whole month.
This was no problem at all though and we focused our attention on great cage dives and the intense natural predation activity that was to follow…
An Intense Amount of Predation Activity
Due to the huge demand of our Predation Specialty 10 Day Expedition each year we decided to host 2 trips for the 2013 Season.
We could not have picked more appropriate dates as the intense activity kicked off right from 16 July, day number 1!
We arrived to light winds and 38 predatory events in 3 hours, including a spectacular full breach on a group of seals. Our guests could not quite believe what they were seeing as for some this was their first ever Great White Shark sighting!
Over the next 4 days we recorded just over 120 events…These kinds of mornings are hard to describe. Everyone is focusing really hard on looking for seals and splashes that indicate an event is in progress or just scanning the sea-scape hoping to catch the sight of a Great white shark in full flight. The crew is calling out seal movement, what direction they are and how far from the boat … the skipper is reacting to the directions and the energy is high. It must sometimes sound like a military operation to those who are new on the boat.
But, to do this properly, it is the only way. The events are incredibly sensitive and if you are not paying attention it is very easy to run over seals that have not been spotted or approach too close to an event. Everyone has to be on their game in order to have the least amount of impact on the area and at the same time witness amazing natural history and behaviour.
These 4 intense days took place leading up to bad weather and peaked just before a short winter storm hit Cape Town.
Weather seems to play a vital role in predation activity and we do see these activity spikes with the build up to bad weather. It could be that more seals are returning to haul out on Seal Island and this in turn attracts more hunting Great white sharks to the Island.
Just after the bad weather we had a few quiet days with little hunting activity. It could have been that the batch of sharks that had been at Seal Island for the previous few days had eaten and had their full.
It was time for them to move out and a new batch of sharks was yet to move in…
There were still a couple of sharks around, including Deux Rossi, and since the great water visibility was still present we made the most of some fantastic cage diving and getting a different perspective of the sharks underwater.
As the wind began to turn round to a moderate northerly direction so too did the predatory activity start to increase again and the next cycle began. In the following 3 days we were back up to recording 20 plus events per day.
When it is so intense like this it is sometimes important to step back and digest exactly what we are seeing and what is taking place. There are few places on earth where natural predation or predator/prey interactions take place on such an intense level.
When a lot of sharks are present at Seal Island and are in hunting mode there is tremendous competition between sharks. The pressure means that they most likely push each other to hunt even when they maybe don’t feel they have the advantage. As such on these busy days it more than likely that the sharks are trying to hunt multiple times on a morning, a lot of times without success.
When they are successful they need to consume the seal very quickly as there is a very high chance of losing their meal to another shark. There is often a lot of splashing going on with each event and other sharks will be cued into these sounds. Likewise if one shark is unsuccessful the seal will move off from the predation event but another hunting shark will be waiting and another event will take place… so it makes sense that the pressure between the sharks creates these extremely high predation days.