Case Study: Scientists Collaborate on Cabo Verde Shark, Ray and Skate Research

With more than 60 types of sharks, rays, and skates inhabiting its waters, Cabo Verde is a hotspot for several elasmobranch species. It’s also one of the last refuges for elasmobranchs in Western Africa. But detailed scientific information is scarce, no stock assessment has been conducted, and important habitats are basically unknown in this region.

According to the International Union for Conservation of Nature, one-third of all shark species around Cabo Verde are listed as threatened, and approximately 25 percent are considered data deficient. It is evident that more effective elasmobranch protection is required to safeguard important ecosystem services, including fisheries, an important economic sector in Cabo Verde.

In response to growing public and scientific concerns, Dalhousie University, the Ocean Tracking Network (OTN), the Instituto Nacional de Desenvolvimento das Pescas, Biosfera, Fundacao Maio Biodiversidade (FMB) and the local community have collaborated to establish the Cabo Verde Elasmobranch Research Project.

The project was initiated as part of Manuel Dureuil’s Ph.D. studies, which he pursued at Dalhousie University under the supervision of Boris Worm. As part of this project, a tagging program was launched in October 2015, the first of its kind in West Africa.

“We successfully installed the first Cabo Verde receiver array, which consists of three VR2W receiver lines covering bays on São Vicente, Santa Luzia and Maio,” said Dureuil. “This receiver array will support a larger network of arrays in the north Atlantic Ocean by linking, for example, to the OTN Angola Array in the south and the Azores Array in the north.”

In total, 13 sharks were tagged with Innovasea acoustic transmitters, including a presumably mature female lemon shark, a juvenile male nurse shark, and 11 sexually mature female nurse sharks.

The latter species are listed as data deficient on the IUCN Red List. Furthermore, the team discovered several multi-species nursery areas with high densities of various threatened or data deficient shark species, such as the Atlantic weasel shark and the smooth hammerhead.

“Among the various goals of this project, acoustic tags will help us to investigate the temporal and spatial use of important habitat areas such as nursery or mating sites, interactions among species within these areas and the connectivity of species among different islands,” added Dureuil.

For the next phase of the project, the research team will return with smaller acoustic tags that will allow them to track a variety of different shark species along the receiver lines.

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