White sharks of Gansbaai
Working with large predatory sharks that migrate impressive distances, think Nicole's epic journey in 2003 from Gansbaai to Australia and back, means that we have White sharks moving in and out of the area on a regular basis and with this comes the chance to encounter particular sharks multiple times a year, once a year or maybe only once every few years. The Winter season in the Greater Dyer Island area has come and gone for 2016 and with it some of our best known and studied White sharks. These previous months have seen some of those sharks we have become familiar with return to the area, some of the most interesting sightings of which you can learn of below.
The White sharks that visit multiple times a year are those that are generally smaller and do not migrate as far as the larger ones. Pieter is one such shark, a juvenile male that was tagged on the 1st of December, 2015, he was fitted with a continuous transmitter which allowed the Dyer Island Conservation Trust (DICT) team to manually track this shark for close to 20 hours in the shallow system of the Joubertsdam. This shark also became part of the biopsy program DICT in collaboration with University of Cape Town, Stellenbosh University and Sussex Univeristy in the United Kingdom undertook during 2015 and a small tissue sample was taken for genetic and toxicology studies. Now onto 2016, as many in the Gansbaai area and White shark world would know, 2016 did not start well for sightings with sightings scarce in the area for approximately 21 days, more of which you can read about in a blog written by DICT's Marine Biologist Alison Towner here. The first shark to be spotted in the Joubertsdam after this period of shark absence was none other than Pieter! Furthermore Pieter has just returned to the bay after our Winter season and is yet again a favourite with our visitors. Not only is this shark looking healthy with the small areas of scarring we reported on this shark at the end of last year and start of this year healed over but also a little larger than when previously seen.
The end of 2015 saw some great success with the Dyer Island Conservation Trust's tagging program with not just Pieter tagged but a number of acoustic r-coded or continuous tags attached to sharks. One such deployment was on a female just over the 3.0m length in size that we affectionately refer to as Paisley. This shark was tagged on the 1st of December 2015 and was yet to be seen back in the bay up until the change in our season from Winter to Summer. It was fantastic to see this animal after nearly 9 months of absence and even more so with her tag still nicely in place. Our hopes are that with the retrieval of the 10 ATAP's (Acoustic Tracking Array Platforms) at the beginning of 2017 we will better understand Paisley's movements and utilisation of the area.
Not only have we been lucky enough to see some of our own acoustically tagged sharks back in the area from 2015 but some of those fitted with satellite tags in 2012 by Ocearch. One such animal was Sellendilloh. A smaller male that was tagged in Gansbaai on the 13th of April, 2012, this shark is seen to revisit the area approximately two times a year and is fantastic to have around our boat Slashfin to show our guests the ways in which the movements of these animals can be monitored. The journey Sellendilloh has made can be seen on the Ocearch tracking page along with all the other sharks that are part of their tagging program.
It is not just the tagged sharks that are monitored but also those with signifigant wounds or scarring (please see DICT's past studies specifically on White shark wound healing abilities here). Scarlett is a large female that we have been documenting in the bay since 2014. She is one of the White sharks that utilise the entire area, with sightings of this animal during our Winter months at the Islands and during the Summer months in the Shallows. This shark gets its name from the many scars that cover her body, many of which appeared in 2015, when she was seen from the boat with bite marks all over her head, gills and jaws as well as the tip of the caudal fin missing. This is believed to be the work of another shark. The truly exciting thing about having Scarlett's return this year is that those wounds have completely healed and are barely noticable with dark, zigzag scars now seen over her head section and can only be detected on close inspection and furthermore the dermal denticles have regrown over the tip of the tail.
Whilst Scarlett's wounds were inflicted by another shark we also have multiple sharks with injuries sustained from human contact including one of our favourites that has been sighted in the area since 2012 and who unfortunately is now sporting what appears to be a propellor injury to her dorsal fin. Well known by many in the area due to her unique fin, Ingrid is a large female that was observed in 2015 with fresh injuries to the dorsal fin. This Winter saw Ingrid back in the bay for the first time since last year and to our delight her dorsal fin was looking substantially better than it had previously and whilst she did not appear very often during her visit to the bay we are pleased to have been able to keep tabs on this shark and hopefully see her again in 2017.
Now to end our sightings update on a BIG note...the largest shark sighted around our boat during these last few months was a shark that has been documented by the Marine Dynamics team since 2009 yet had not been observed in the area since 2013. This incredibly impressive specimen of a White shark was nicknamed all those years ago as Steamtrain due to her sheer size and presence so you may well be able to imagine just how large she is now. This female was estimated during her visit to the bay in 2016 as between 5.5-6.0m based on our shark diving cage which measure 4.5m and which she easily shadowed. Sharks of this size are rare to see and it was truly a privilege for our team and our guests to see such an animal, one that looked the epitome of a White shark, large in both length and girth, dark grey on the dorsal surface and stark white on the ventral surface, with slow determined, precise movements she dominated the water around our boat for the few days that she graced us with her presence. A highlight of this year for many and one we will be unlikely to repeat for years as she visits other places on her migration.
A truly impressive few months of White shark sightings from Marine Dynamics White shark caging boat, Slashfin.