The Science of Sharks

Many Shark Angels are respected scientists and marine biologists whose work has contributed much to the preservation of sharks and the oceans. In our fifth year, Shark Angels is thrilled to announce a more formal involvement with scientists spearheading important research projects geared towards the conservation of sharks. Their hard work is fundamental to understanding and protecting sharks and we are pleased to be a part of it.

Shark Angels have long contributed to the work of scientists around the world via the collection of data, the provision of logistics and supplies, volunteers, and funding. As an organization, we've also begun formalizing our relationships. Last year, the Shark Angels began sponsoring  scientist, Jéssica Escobar-Porras with her work on shark populations – using their DNA to determine range, origination and populations. See below for more details.

Shark Angels has also forged a formal partnership with the Watermen Project, the link between science and the sharks. Freedivers (and Shark Angels) Fred Buyle and William Winram employ their watermen skills to assist well-respected scientists in their critical studies. Using non-invasive and non-harmful methods, the Watermen can place tags on sharks and perform biopsies simply through freediving, rather than removing the shark from the water. The Shark Angels have formed a collaborative outreach, education and joint-campaign partnership with the Watermen.

Image by Sijmon deWaal

Shark population structure and reproduction, a step closer to their conservation

Meet Jéssica, a Shark Angel and marine biologist from Medellìn, Colombia. She currently lives in Durban, South Africa, where she is doing her PhD studies through the University of KwaZulu-Natal, on shark populations. Simultaneously, she is doing her PhD, on genetic population structure of sharks and its relation to their reproductive strategies; convinced that a live shark is better than a dead one, she is committed to conduct research using non-destructive, non-lethal research techniques. 

The Project: Sharks are apex predators that are currently being captured at high rates, and their low reproductive and slow growth rates make them vulnerable to overexploitation. The fished quantities are most likely exceeding their reproductive capacity. Although reproduction strategies and processes are an important factor for designing conservation and management initiatives, shark reproduction is still poorly understood.

As a result, the research project is looking at the relationship between genetic population structures and reproductive strategies present in shark species inhabiting South African waters - with an eye to applying this knowledge world-wide. This will lead to an improvement in the conservation strategies that are employed to protect these marine creatures both locally and globally.

The three species chosen for the study are Ragged-tooth (Carcharias taurus), Blacktip (Carcharhinus limbatus) and Catsharks (Holohalaelurus spp). Tissue samples, from these species, for genetic analysis are obtained from commercial prawn trawlers, Aliwal Shoal field trips and research cruises. Live sharks are sampled with a biopsy gun, which is used underwater, while free-diving. A small tissue plug from the surface epithelium is sampled from sized and sexed individuals, and fin clips are obtained from recreational fishers,trawlers and other scientists. Extraction of DNA from tissue is carried out using commercial kits or standards protocols. Different scales of genetic diversity is assessed by using mitochondrial DNA (mtDNA), which is only transferred from the mother, and nuclear DNA. 

While the study focuses primarily on the KZN coastal region, samples and information will also be drawn from Madagascar, Reunion, Mozambique and the Western Coast of South Africa.  

The results will have a direct bearing on South Africa’s shark populations and their relationship to sharks in the greater Indian Ocean region. Important information about basic biology, life history and population structure will be obtained through this study, which will contribute to the application of conservation and management strategies. We can’t wait for the results and will help promote them – using them to help protect the sharks of Southern Africa and beyond.

Image by Fred Buyle

The Angel collaborators: In addition to funding and donations in kind from the Shark Angels, an interesting element of this research project is the level of international involvement from various Shark Angel stakeholders in the exploration of an innovative conservation strategy. It truly is a collaborative effort between many different Shark Angels.

The Blacktip shark component of the genetic study is a unique international collaboration between Jéssica, and Shark Angels Mark and Gail Addison. Their company, Blue Wilderness, provides information, logistics, local shark expertise from Blue Wilderness, and aids the project by facilitating field trips and expertise.  Additionally, Watermen and Shark Angels, Fred Buyle and William Winram collaborate by offering their unique freediving skills to conduct non-lethal and non-destructive tissue sampling. Shark Angel Olivia Symcox is assisting with funding and press and Jess Vyvyan-Robinson is assisting with outreach.

Similarly, the Catshark component obtained tissues samples facilitated by South Western Indian Ocean Fisheries Program (SWIOFP), and thorough the Nansen research cruises. Partial funding was obtained from Mohamed bin Zayed Species Conservation Fund (Project number: 12253233). 

About Scientist and Shark Angel Jéssica Escobar-Porras 

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