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Sharknotes
BY DR SARA ANDREOTTI AND HER OCEAN CONSERVATION TEAMS
World-renowned marine biologist Dr Sara Andreotti and her Stellenbosch University teams continue to make waves in the ocean conservation world with their ground-breaking work to monitor and protect great white sharks and other vulnerable shark populations around our coasts. Recently, Dr Andreotti’s unique SharkSafe barriers were installed in the Bahamas. This follows installation around Reunion Island. Slowly but surely, Sara and her teams are helping to change the traditional mindset about sharks as their invention creates safe and harmonious existence between sharks and people. Another branch of their research involves the caretaking of rare pyjama sharks, and the latest edition of SharkNotes takes us on a deep dive into this fascinating, rare and endangered species.
#9 SEPTEMBER 2024 PYJAMA SHARK SAMPLING
Pyjama sharks are found only in South Africa. Their name relates to the colour of their skin, which displays a set of distinctive horizontal dark stripes running from their nose to their tail. They are part of the shyshark family, due to their characteristic way of rolling up in a doughnut shape when feeling threatened. Pyjama sharks live mostly in the kelp forest, where they can find an abundance of their favourite food, such as squid and octopus.
They are primarily nocturnal hunters and have eyes very similar to those of cats (in fact, they are also called cat sharks). And just like cats – and all species of sharks – the pyjama sharks have a “light amplifier mirror” in their eyes, called tapetum lucidum, that allows them to see in very low light.
These sharks are absolutely harmless to humans. They grow to only one metre, and they can be found lying between rocks and inside little caves during the day, resting after the busy night. Together with Pretoria University and Stellenbosch University we are investigating how this species can adapt to changes in the climate. We are doing it by studying the position of their genes dedicated to the adaptation to different water temperature.
The first phase of studying shark DNA entails collecting a small piece of tissue from the animals, without harming them. We relied on a number of collaborators around the coastline, such as Oceans Research in Mossel Bay, the Shark & Marine Research Institute of Gansbaai, the Shark Conservancy in Hermanus, SeaSearch on the West Coast and Dive Team in Cape Town.
Of course, if sharks die of natural causes then we rush to the location to collect samples from the dead specimens. Recently we had an event where an algae bloom caused a red tide in the West Coast; this reduced the oxygen levels in the water and killed a large number of marine animals that were too small to swim away from it. That particular day was a very long day, with thousands of crayfishes and other marine life covering Elandsbaai beach for kilometres. The smell permeated the air and it stuck to our clothes, our hair and our boots for more than a week. There were fewer pyjama sharks on that beach compared with the numbers of puffadder shyshark (another shyshark species with a brownish pattern on their skin and the same cat-like eyes).
The job is understandably more pleasant when we can sample live sharks, directly from the Ocean. Thanks to the logistics support of Dive Team we set up an expedition to find 20 pyjama sharks in Cape Town, by deploying a custom-made trap with some sardines inside a tube, to attract the sharks inside it. Unfortunately, these animals didn’t seem too interested in climbing inside the trap, so we decided to move to a more straightforward approach. Given their harmless nature, these sharks are easy to catch by hand, by experienced scuba divers. The divers searched for them between crevices for few minutes and, once found, they were brought up to the boat.
Once on the boat, we needed to be as quick as possible, to minimise the stress. We positioned a towel on them to keep them in the dark, which helps calm them down. The sharks immediately went into their very cute doughnut position and lay very still. We then had the sharks measured from the nose to the end of the tail and then from the nose to the base of the tail, checked for gender (males have two visible claspers in their anal region) and proceeded to cut a small piece off their anal fin. When done correctly, the shark doesn’t bleed from the procedure, and the DNA contained in the skin is sufficient for several genetic analyses.
Speed is essential, because sharks feel pain, and we knew they could feel the procedure on their fins by the way they tensed their muscles. As soon as the samples were collected, the sharks were released back into the water. Tissue samples are stored in small tubes containing pure ethanol, then labelled and brought back to the lab for the DNA extraction.
We hope to get as much information as possible about the health status of this species. Although they not purposely caught by commercial fishery, their bycatch (or accidental capture) is all too common in the Western Cape. During the data collection we noticed the scarcity of these animals; so finding out how many of them are left, and knowing if they will be able to cope with ongoing climate change, will be key to efficiently protect this species. They are really incredible animals, and are crucially important for the continued balance of kelp forest ecosystems.
The field work equipment and logistics for this project were acquired thanks to the combined funds from the National Research Foundation, Italtile Retail, Italtile Foundation and Tivoli Taps.
As an Italtile customer, you can feel justifiably proud: every time you buy a Tivoli Tap, we donate R2 to our SharkWise Project – a fund that supports Dr Sara Andreotti and her vitally important shark conservation work.
Explore more about the extraordinary work of Dr Sarah Andreotti and her shark conservation teams here:
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