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A joint Sharklife/Sampla Zambezi shark discovery project By Fiona Ayerst
RESEARCHING
ZAMBEZIS
Sharklife is a relatively new conservation organisation having been formed in late 2005. Sharklife’s ultimate aim is to address the alarming exploitation (and we believe “over-exploitation”) of shark populations (and ocean fisheries) in South African waters. We are actively addressing the urgent need for education, research and protection of many marine species - foremost sharks. I am thrilled to be able to report back on the exciting start of the joint Sharklife/SAMPLA Zambezi Shark Discovery Project.
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AMPLA is the acronym for the South African Marine under any unnecessary stress, so Ryan undertook to tag Predator Lab. This is a research and exploration the shark underwater. The tag, Ryan would be using a institute working on uncovering the hidden lives continuous pinger, that would be inserted into the base of of sharks and other marine predators in Southern Africa. the dorsal fin where it would lodge and stay for a period SAMPLA is run by a quartet of marine scientists who are anywhere between nine months to a year before dislodgdedicated to increasing our understanding and inspiring ing. This would allow the shark to be tracked for a 9-12 our passion for the underwater world. month duration. Ryan has extensive experience in the tagIn 2007, SAMPLA and Sharklife realised they had a ging and tracking of Great white sharks but Zambezis were common goal and decided to embark on an extraordinarily tough adversary, much the first Zambezi Shark Discovery Project in tougher than we had expected. Ryan is a free diver Southern Africa. We decided to start the Ryan is a free diver and decided to initially and decided to initially exploration and research with the Zambezi try and tag the sharks whilst on breathold. try and tag the sharks shark population on Pinnacles reef in southThe team used biological attractant (bait) whilst on breathold. ern Mozambique. Some of the reasons for to assist Ryan with this task. This method this decision were: allowed the research team to get close - The close proximity of this area to South enough to study the animals without having Africa and the seemingly large population of Zambezi to use invasive capture techniques. Sharklife does not supsharks inhabiting the Pinnacles area. port the use of biological attractant (bait) to attract Zam- The warm waters, moderate currents and good visibility bezi sharks outside of research and education initiatives. also make Pinnacles an attractive and relatively stable This project aims to provide data to both the Mozambican study area. and South African governments for improved protection In January this year a team representing the two organiand management of the species. sations set out for an adventure in southern Mozambique This method of attraction would also assist the photo begin a long overdue and crucial study of the Zambezi tographers in capturing the images Ryan had asked for. or Bull shark, Carcharhinus leucas . On the team we had However, we still found it difficult to get close enough to a marine scientist, Ryan Johnson from SAMPLA, three the sharks. In particular I found that it is true that if you directors from Sharklife and a host of excited underwaswim after a Zambezi shark it will swim away from you ter photographers ready to capture the action. On this much faster. My specific problem was trying to make sure I first expedition we took acoustic transmitter tags and a had taken pictures of both sides of all the different sharks VEMCO VR-60 RF receiver. This is a frequency synthesised as this is what Ryan required for the photo identification. ultrasonic telemetry receiver that enables tagged sharks Underwater, these sharks all looked remarkably similar. I to be tracked. The plan was to tag and track a particular truly felt sorry for Ryan having to sift through all those ID shark’s movement and usage of the Pinnacles reef system. photos and to try and make some sense and structure out Ryan would then write a report on our findings to enable of it. Sharklife to present the information to prospective sponBut I needn’t have worried, as Ryan had his own parsors needed to continue the research. ticular brand of problems to deal with. He didn’t have any The photographers also played a crucial role in the success in tagging whilst on breathhold as the sharks were expedition. Individual sharks could be clearly identified in cautious of the divers and would move out of reach of the photographs taken. This allowed Ryan to approximate Ryan whilst he was descending on breathhold. Ryan then the size of the Zambezi shark population living in the area. switched to scuba, which proved more successful when he We also used a specially adapted underwater video camera was approaching the sharks. with parallel high intensity green laser beams to enable us Ryan was using a Hawaiian sling method to insert the to calculate the size of individual sharks. tag, i.e he had a tag on the end of a metal pole with a rubAs a group we had decided we did not want to “fish ber bungi attached. The bungie propelled the pole toward for” and hook a shark to the side of the boat in order to the shark, and theoretically would embed the transmittag it. We agreed that we preferred not to place the shark ter head into the cartilage base of the sharks dorsal fin.
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However, due to the water resistance and thickness of the shark’s skin this method proved unsuccessful. Ultimately and as a last resort, Ryan ended up placing the tag in a fish head and feeding it to our target specimen. The negative part of this method was that the tag would probably only remain in the shark’s system for a period of one week if we were lucky. Sharks have been known to regurgitate foreign objects from their stomachs with relative ease and we were concerned that this may happen. Unfortunately, we were unable to launch On the third day after our shark for the next two days due to had ingested the tag we found inclement weather. On the him at his usual spot near the Pinnacles and Ryan hauled out third day after our shark had the VR-60. Unfortunately our fears ingested the tag we found had manifested and our shark him at his usual spot near the had expelled the tag one way or Pinnacles and Ryan hauled out another. the VR-60. Unfortunately our fears had manifested and our shark had expelled the tag one way or another. No signal was being transmitted from the shark. We learned much for our next tagging attempt on Zambezis. Fortunately, the photographers saved the day as they were able to capture hundreds of images of sharks from every angle. Ryan got the identification pictures that he needed to complete the first part of his report to present to sponsors. Ryan found that there is a healthy population of nine different Zambezi sharks living around the Pinnacles and this is a viable population for further study. He was also able to study pictures that I had taken at exactly the same spot in January 2007 and to compare the two years.
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Three sharks were readily re-identified, giving a first hint that a resident population may inhabit the Pinnacles reef system. Currently the Zambezi shark is not given any protection in South Africa. Sharklife is of the view that the Zambezi requires protection due to its low reproductive capacity and the threats to its habitat, especially in river mouths where it is known to pup. Sharklife has been advised by government that there is insufficient information on this shark to warrant protection. The ultimate aim of this joint study is to gather sufficient evidence in as short a The ultimate aim of this joint time as is possible to advise and confirm our study is to gather sufficient concerns to government. These concerns evidence in as short a time as is all point to the ultimate conclusion that the possible to advise and confirm our concerns to government. Zambezi shark needs help. The dynamic combination of Sharklife and SAMPLA and their combined passion and energies are committed to changing this situation and to protecting this much maligned shark before it is too late. Another joint project coming up soon involving Sharklife and SAMPLA is the exploration and initial investigation of a population of Zambezis that have been sighted in the Breede River in the Cape. We are joining Meaghen McCord, the founder and director of the South African Shark Conservancy (SASC) on this adventure and will report back in a future edition of SUMBERGE. Thanks must go to all divers for their support of Sharklife. Your support is enabling us to achieve our goals. S
For information of projects please visit one of the following sites: www.sharklife.co.za www.sampla.org www.sharkconservancy.org April/May 2008 • SUBMERGE
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