Cabo Verde Elasmobranch Research and Conservation Project
Summary: The island nation of Cabo Verde holds one of the last remaining hotspots for elasmobranchs (sharks, skates and rays) in the North Atlantic Ocean and an important refuge for several highly threatened and endemic species of sharks, skates and rays. However, there is an increasing exploitation pressure on these species and adequate management structures to prevent further depletion are lacking.
Detailed scientific information on elasmobranchs in Cabo Verde is scarce, preventing any science-based management. Currently, there is no stock assessment available for any elasmobranch species and although marine reserves have been established, their benefit for elasmobranch conservation remains unclear. Hence, more detailed scientific information is needed to allow for sustainable use and a comprehensive and successful elasmobranch conservation strategy in Cabo Verde. Moreover, the characterization and conservation of Cabo Verde elasmobranch populations will contribute to both, the preservation of species diversity and support a sustainable resource for ecotourism and fisheries. The Cabo Verde Elasmobranch Research and Conservation Project aims to support the development of comprehensive, long-term and effective science based protections measures for Cabo Verde elasmobranchs, through scientific research, governmental, NGO and community based conservation projects. Therefore, an innovative coalition of researchers, industry, local communities, governmental and non-governmental organizations has been established. In 2015 a collaboration was formed between the Worm Lab at Dalhousie University (Halifax, Canada), the Ocean Tracking Network (OTN) (also at Dalhousie University), INDP, the NGO’s Biosfera I and FMB, Big Game Maio and local consultants, establishing the Cabo Verde Elasmobranch Research and Conservation Project. The primary goal of this project is to scientifically investigate and, based on scientific data, protect and aid sustainable use of elasmobranchs in Cabo Verde, in order to provide a scientific basis for comprehensive protection and management, aid the science of these species and to benefit local communities and Cabo Verde in terms of fisheries, education and maintenance of biodiversity. This project also aims to provide a sustained infrastructure, including the training of local high qualified personnel, to translate scientific information into on-the-water changes, and to improve our understanding of the biology, ecology, and conservation status of elasmobranchs in general. The project also strives to promote and utilize only non-lethal research methods and to be as minimally invasive as possible.
Investigating areas with high elasmobranch species density and localizing important habitat areas, such as nurseries, is a main objective of this project. Habitat protection is an important component of elasmobranch conservation, especially in areas where stock assessments are lacking and caches are not regulated. Pupping grounds, nursery areas and spawning grounds are critical for recruitment success and adequate protection of these sites could increase survival and resilience. Habitat protection is believed to be important for the weasel shark because of its limited distribution and potential high exploitation in most areas where it occurs. Likewise, species with limited movements such as the nurse shark will highly benefit from protecting important habitat areas.
Part of the project will focus on passive tagging where species are equipped with an external tag carrying a unique identification number and acoustic tagging where transmitters are implanted which send a unique acoustic signal over years that can be picked up by underwater listening stations (acoustic receivers). At this time, the main species of interests are the regionally endemic Atlantic weasel shark and the nurse shark. However, the project also focuses on investigating species diversity and localizing important habitat areas of all kind of shark, ray and skate species.
Acoustic tagging is ideal to provide information on site fidelity, a behavior where individuals return to key aggregation sites repeatedly over time. Site fidelity is a crucial factor in determining if a species will benefit from habitat protection.
Passive tagging can also provide general information on species movement and densities. It is a relatively cheap method and therefore allows to tag more species and individuals than acoustic tagging. In addition, tag and recapture studies can provide information on species’ specific mortality rates and important biological featues such as body growth. Furthermore, the data collected during the tagging events will allow for the investigation of further critical biological and ecological parameters, such as population connectivity and structure through genetic information.
Big Game Maio is helping with the acoustic tagging which is carried out by researchers from Dalhousie University and is also carrying out passive tagging by themselves around Maio island.