Monthly Archives: June 2012

AMY SHARES RESULTS OF HER STUDY

What has been the most unexpected result of your study?

great white sharksThree weeks in, I now have over 9 hours of underwater footage of white sharks visiting Slashfin. Some no-sea days due to bad weather have given me the chance to start analysing my footage, which involves extracting stills from the video and cataloging the sharks by keywords. It is important to do this so I do not repeat shark observations by mistake, and I can add notes on parasite presence, sex, and wounding to the photos. I basically stare at hundreds of images of white sharks trying to decipher unique individual markings to use for identification. After a few hours, white and grey markings on sharks all start to look the same, but with sufficient tea breaks my mini-catalogue is taking shape.

What has surprised me is how many sharks I can see on the underwater footage which our biologists on the boat, and myself at the time, had no idea were present when taking data from the surface. Having worked with white sharks before, I was used to the frustrating aspect of not all of the sharks breaking the water for a nice dorsal fin identification photo, or even coming close enough to confirm they’re a new shark for that day, but fortunately some stunning visibility around Dyer Island and the Geldsteen recently has enabled optimum underwater surveillance. (Video also has that natty advantage of being replayable so you can double-check details to your heart’s content!) .) The seemingly relaxed behaviour of the sharks aggregating under the boat in such clear conditions was surprising. Perhaps if they are more aware of other individuals in their surroundings they are less easily spooked by one another? Two sharks even clashed heads as they both rush towards the bait line – clearly neither in a cautious mood. In the past 4 years (on and off) working with these animals, I have never seen them so tolerant of one another.

great white sharkAnother unexpected thing occurred at about 10pm one night as I continued to stare at my still image library before bed (and guaranteeing shark-filled dreams, nothing new there). I matched an individual on June 11th to the same shark on June 3rd, using the grey/white border pattern near the pelvic fin. What was surprising was that this animal on June 3rd had many copepod parasites on its pectoral fins and their egg cases looked like long hairs trailing from the fins. It was very distinctive, but 8 days later they had gone. Now, this isn’t exactly news; we know white shark ectoparasites appear and disappear and don’t stay attached permanently, but for a parasite-focused study it was certainly noteworthy. And again, new questions are raised: did the shark swim into colder or warmer water which may have caused the parasites to drop off? Were they physically dislodged? Or did they release their eggs of their own accord?

I shall be keeping my eyes peeled for any more novel observations that this project method may unveil. One thing is for sure, the white shark will always have the potential to surprise us.

THANK YOU TAMI

Tami and Alison Towner

Tami and Alison Towner

The best compliment of our volunteer programme are those that return year

after year. Tami Kaschke from Nebraska, US has been visiting us since 2009.

She has become part of the family and her expertise and value to the team

has grown. While here Tami assists with shark research and helps with

functions of the Trust. The team always enjoys her time with us.

This year Tami left us a really awesome gift – she has donated two Go Pro

cameras to assist with our shark research.

You can read more about our shark research here.

Thank you Tami. Come back soon!”

INTRODUCING OUR 2ND LEEDS UNI MASTERS CANDIDATE

great white shark intern

Lauren Duffield conducting studies on the Great White Shark

Lauren Duffield – University of Leeds

I am originally from Birmingham in the UK, and have spent the past four years at the University of Leeds, having completed my undergraduate degree (BSc Hons. Ecology and Environmental Biology) in July of 2011. I began my master’s degree (MRes Biodiversity and Conservation) the following September, also at the University of Leeds.

I have always been fascinated by carnivorous animals, the different strategies they have evolved in order to outwit their prey, as well as the power they display when they are bringing it down. As with many modern-day biologists, I have been greatly inspired by nature documentaries, which I used to watch avidly as a child, the fantastic scenes on the screen always led to questions of ‘why’ and ‘how’. I now feel privileged to be part of a global team of scientists striving to answer these questions, and really enjoy the whole process of biological research.

During the next two months, I will be collecting data on the white sharks’ behavioural responses to certain stimuli. This is to ascertain whether the sharks display distinct individual differences in their responses to these stimuli, and whether these responses are affected by the size and sex of the sharks. Studies of the ‘personality’ of animals is a relatively recent development in behavioural ecology, and the white shark will provide another behavioural model for scientists to explore the phenomenon of individual differences in behaviour.

So far at Marine Dynamics, I have enjoyed fantastic visibility in the water, which really helps with my research, and had some of the most memorable experiences of my life so far! The next two months will be absolutely amazing and I will be extremely sad to leave this beautiful place.

When I have finished my master’s degree, I hope to go on to do a PhD, and have my eye on one at the University of British Colombia, studying orca behaviour!

INTRODUCING OUR FIRST LEEDS UNI MASTERS CANDIDATE

Amy Blessington

Amy Blessington – Postgraduate: MRes candidate, University of Leeds. Undergraduate: MA (Hons), Natural Sciences (Zoology), University of Cambridge

I’ll have to go with the old cliché and say, “I’ve loved sharks since I can remember”. My parents are still trying to fathom where it started. I grew up in the city of Bradford, West Yorkshire, England; a city not particularly well known for producing marine biologists.

As a child I loved all animals, particularly the carnivorous type, and had the “dinosaur phase”. Something about sharks captured my imagination though, and I will fully admit that it was initially the negative portrayal and attack stories that I had a morbid fascination with. Early signs started when my plastic toy shark used to bite younger sister’s Barbie doll and red felt tip pen was used to add special effects. And (cliché again), I remember sitting riveted to the TV as my family all fell asleep around me the first time I watched Jaws, aged 9, and how loudly I screamed with joy when I unwrapped the VHS copy of it one Christmas.

A trip to South Africa for an internship with Great white sharks in Mossel Bay following my graduation in 2008 confirmed my passion and ambition to be a shark researcher. Since then, I have been fortunate to fly out to South Africa another four times where I have volunteered again with a white shark research program, learned to skipper a boat, tracked sharks, trained interns, designed surveys of Cape fur seals, assisted in filming documentaries, and presented at a shark conference. In 2011 a dream came true for me to act as a zoologist and guide for a season with Apex Shark Expeditions in False Bay, the home of “flying great white sharks”, where a lot of hunting behavior can be observed. Seeing 40+ predations in one morning did not disappoint. In this time I have met some amazing people and lifelong friends who share a strong passion for these animals.

Now I am commencing a two month study in collaboration with Dyer Island Conservation Trust and Marine Dynamics for my Masters thesis. It came about by pure coincidence as a project option from Leeds University but felt somewhat “meant-to-be”. I will be looking at external copepod parasite infection of the white sharks in Gansbaai and attempting to quantify general shark “health”, and whether the two are correlated. Parasites cause stress to their host as they commandeer energy resources and the host’s immune system attempts fight the infection. They may also facilitate transmission of other diseases. In Soay sheep, more inbred individuals have been shown to carry heavier loads of intestinal worm parasites. Honey bee declines due to a lethal virus are exacerbated by a parasitic mite. Despite extensive parasite research in other species, few studies have focused on this aspect of the white shark’s biology. If the white shark is indeed shown to be suffering from severe recent population declines and existing in low numbers, could parasites, with which is has coexisted for millions of years, start to pose more of a threat?

Body condition (here in terms of mid-body girth due to a distended stomach or liver), wounding, size or sex differences may have an effect on shark fitness. For example, are females significantly more scarred due to aggressive mating attempts from males (where they are assumed to bite during mating as in other shark species), and does this make them more susceptible to parasite infection? Are skinnier sharks (implying not being well-fed or lacking large energy stores in their liver) more infected by parasites? Are larger individuals more infected? I will be doing this by collecting footage from an underwater camera mounted on a pole. In addition, this camera is accompanied by a pair of parallel green lasers which will be used to project dots 50cm apart on to the shark, so I can attempt to estimate shark length as accurately as possible.