REPORT – 26 April 2009-05-07
 
Weather Conditions:
Wind: 1 - 4 Kt SE
Sea Conditions: Calm
Weather: Light coastal fog
 
 
Observation period:
11:25 am to 12:45 pm
 
Account:
At 11:00 am, I received a call from Chris Fallows informing me that he had encountered a school of dolphins being hunted by a small pod of Orcas. His position at that time was indicated at 1.5 NM West of Seal Island.
I immediately grabbed my camera & proceeded out on vessel “Awesome” – an 8m semi rigid inflatable.
 
On arrival at 11:25 am (position: 4 Nm SW of Sea Island), I noted the following:
 
A school of Approx 800 Common Dolphins, approx 6 Orcas (one calf) & a small number a Cape Fur Seals.

The dolphins were moving in a SW direction at approx 6 Kts (feeding), with the pod of Orcas following on the surface about 150 metres behind them.

The Orcas were tracking them & progressively moving closer to the rear of the group. It appeared as if the Orcas were observing their feeding behaviour and waiting for just the right moment to close in. This was evident from the behaviour of the dolphins which appeared unaware of the potential danger & only reacted when the Orcas were right in amongst them.

At this stage the Orca pod split up and launched individual attacks – mostly approaching from just below the surface (dorsal fin visible most of the time) and in a few instances breached & descended on the dolphins. Throughout the predatory event, the Orcas remained at the rear of the school, perhaps seeking out a weaker animal. The dolphins remained as a group throughout the attacks & maintained a linear formation, rather than the semi circular to large oval feeding formation that I regularly see.

Even though I witnessed a number of successful predatory attacks, I did not notice any blood in the water or any Cape Gulls feeding on the surface as with Great White Shark predations.

The duration of the event lasted no longer than 5 minutes and the Orcas moved off in a Westerly direction. The dolphins continued feeding as if nothing had happened (heading in the direction of Whittle Rock).
 
For the next 40 minutes the Orcas swam around in a relaxed manner in random directions, showing no interest in the dolphins whatsoever.

By 12:00 the distance between the 2 groups had extended to over 1 NM & the dolphins were approaching Whittle Rock.

At about 12:10 there was a sudden change in the behaviour of the Orcas. They re-grouped and started moving in the direction of the dolphins - increasing their speed to about 8-10 Kts until they again reached a distance of 200 metres from the rear of the dolphins. Then exactly as per the first encounter, they maintained an approximately 150 metre tracking distance and moved in again for the second attack.
 
This took place at 12.28 and was virtually a carbon copy of the first – lasting about 5 minutes (off Whittle Rock).
It was during this event that I just missed capturing a breach attack and took the picture of the surface predation.
 
Interesting Observations:

• There were a total of 3 predatory events, all at 50 minute intervals.
  
• The Cape Fur Seals in the vicinity were happily swimming alongside and approaching the Orcas.
  
• The dolphins maintained a very narrow & linear formation when under attack.