It might sound odd, but to be able to improve the conservation of sharks and rays you often have to catch them. Scientific research is the basis of effective conservation of many species and in order to get enough data from a species or individual, we catch, tag and release them within the Bijagos Archipelago.
Although the environmental DNA (eDNA) can help us determine which shark and ray species are present within the Bijagos, we need confirm this and need to check the reliability of this novel technique. In addition, to be able to tell which age classes of certain elasmobranch species (sharks and rays) use the area, we need to measure them. To be able to study their role in the food web we need small tissue samples. So often, catching the animals is inevitable.
To get as much data from one individual as possible we have a strict protocol and sampling procedure. Within 5 minutes we do our length measurements, determine sex, take small tissue samples, give the animal a unique tag and release it and check its swim away. During this procedure the animals are placed upside down to induce “tonic immobility”, a natural trance-like state which reduces stress for the animal during the tagging procedure.