Great white sharks scarcity in Gansbaai February 2017
Last year in January 2016, the great white shark diving industry based in Gansbaai South Africa experienced a challenging period where practically no white sharks were observed at any boat-for almost an entire month. This hit the industry hard, financially, with over four weeks of cancelled trips and some very disappointed tourists. The below article was written to discuss some possible reasons behind the paucity of white shark sightings at this time.
This year, white shark sightings had been steady averaging at 6-8 sharks per boat per trip, until much to the operators dismay on the 8th of February 2017, all the shark diving boats returned to shore with no- or minimal white shark sightings. A minimal shark sighting can be defined as a fleeting glimpse of a shark- with no interaction and no possibility of a dive in the cage or decent surface view of the animal.
As always, there are currently many theories flying around from various sources as to why the white sharks- which can be so reliably sighted throughout the year, should all of a sudden appear to have vanished from the Gansbaai region. Is it just conincidence or is there something else happening? The truth is, we cannot say the sharks have completely fled the Gansbaai area but they certainly may have dropped in number and those sharks remaining are not responding to the boats.
At the Dyer Island Conservation Trust we have a long term monitoring project where we tag and track the white sharks movements in Gansbaai. We used this gap of fewer sharks in the area recently to dive out and download our underwater receivers. The data we retrieved showed us that even though not sighted at the boats some white sharks were actually still in the area, where the operators were attempting to attract them but failing to do so.
The fact is, we have no conclusive evidence to explain what may have caused the sudden apparent drop in shark numbers and their sudden lack of response to the WSCD boats. Similar to last year, there could be various factors at play in this scenario, such as more favourable environmental conditions or an abundance of prey species further along the coast. Just 50km away in Struisbaai fishermen were recently catching large amounts of yellow tail and often seeing white sharks while doing so. Subsequently on the 8th of February 2017, two transient Orcas frequented the exact same reef system the white sharks aggregate in Gansbaai. The pair of Orcas moved through the area quickly and were tracked by Marine Dynamics crew until they continued South West offshore of Dangerpoint. Interestingly the next day a young 2.6m female white shark washed up on Pearly beach (the bay adjacent to Kleinbaai). Various media avenues tried to correlate the drop of white sharks with the presence of the two orcas.
See link: http://www.grindtv.com/wildlife/mysterious-great-white-shark-death-off-south-africa-orcas-involved/
Even though we know that Orcas are a possible predator of great whites and have potentially caused them to disperse away from aggregation sites in California and South Australia (see link: http://www.sharkattacknews.org/2013/11/hd-video-orca-kills-great-white-30.html) we have no solid evidence such as bite marks on the recent carcass of the deceased shark to suggest this was the case in Gansbaai.
It has been over two weeks since shark operators have seen white sharks in Gansbaai. Cage diving clients are being referred to the only operator in Mossel Bay, another aggregation site, where sightings of white sharks have remained good.
As much as it is frustrating from a tourism perspective, and we hope the shark activity picks up again, it is also quite humbling and just a stark reminder of how privileged we are to have such remarkable sightings of white sharks throughout the year in Gansbaai. It also highlights that despite the white sharks iconic reputation, there is still so much we need to understand about how this species responds to different ecological pressures.