Whale Shark stranding
December 27, 2012 by dyertrust
On Thursday, 14th December 2012,
the DICT was notified of a Whale Shark which has stranded in Pearly Beach.
DICT Biologists and Volunteers rushed out to the site to assess the situation. We are always optimistic about strandings, hoping that we can manage to help the animal back into the ocean. Unfortunately, upon arrival, we found a dead 8.5m Whale Shark, estimated at 2 tons, stranded on the high tide mark on Castle Beach.
Our team collected data, measurements and samples of this animal, and during this process they observed no obvious signs of damage externally. It might be possible that this specimen stranded from thermal shock, or lack of thermal tolerance to the icy 10 degrees water temperature which was recorded off of this area on this day.
In 2010, a Whale Shark stranded in the same area on Pearly Beach. This happened under similar environmental conditions, also during a dramatic drop in water temperature caused by vigorous upwelling and driven by and intense south easterly which is characteristic of our December wind patterns.
Strandings and sightings of this species are uncommon in our waters and area. Whale Sharks are predominantly tropical and sub tropical species reported mostly from our South African East Coast up into the Indian Ocean off the coast of Mozambique and Tanzaniahowever, a few specimens have been recorded off of Cape Point historically.
It is always a sad sight to see such a magnificent animal stranded. Very little is known about their breeding habits and where large females go. Due to this data deficiency it is imperative that pictures taken of the whale sharks flanks, just behind the gills, is sent off
to researchers who can positively identify the individual through their unique spot patterns on these sections.
Special thanks to Alison Kock from SharkSpotters for notifying us of this stranded animalany member of the public who encounters any form of stranded creatures on our Overberg Coastline can contact the DICT to enable us to gather, record and document these strandings on 082 907 5607, or for any queries please contact us at The 17th of December 2012 was a very special day for Alison Towner, Senior Biologist for the Dyer Island Conservation Trust. She graduated in MSc Zoology from the University of Cape Town, this 2 year project was a research based masters with the department of Zoology and the Animal Demography Department.
Achieving your MSc Zoology is no easy featespecially if your project revolves around the infamous Great White Shark. Her thesis looked at boat based sightings data of Great White Sharks in Gansbaai with environmental influences. Over 6000 sightings were consistently collated and statistically modeled between 2007-2011, which amounted to a solid data set for analysis. The results found white shark sexual composition in the bay is strongly influenced by ENSO (climatic phase) and water temperature.
Alisons love of our oceans is tangible when you are in her company and she was the first researcher to present this regional water temp/ENSO hypothesis in the Western Cape at the Durban shark and ray meeting in 2010, and at SAMMS (South African Marine Science Symposium) in 2011. She has submitted this work for publication and look forward to continuing with this research towards her PhD in 2013.
The study was challenging but super rewarding at the same time. I’m very grateful to my mentors and colleagues, especially Prof Les Underhill (UCT) and Dr. Malcolm Smale (PE Museum and University) as well as Wilfred Chivell (DICT) for their support. I feel that I have gained some vital skills during the MSc which has equipped me for the next stage in my career. As in most scientific projects, once we have some answers to questions a whole bunch more emerge, and that’s exactly the case with white sharks in this area! was Alisons reply when asked how she felt about her achievement.
Alisons future is very bright, her Great White Shark tagging work is giving very interesting insights in the behavior of the sharks in our bay, and were looking forward to seeing this bright young lady tackle her PhD with the same vigor she approached her MSc.