A BIRDSEYE VIEW: HOW CAN WE CAPTURE POTENTIAL SHARK NURSERY AREAS WITH UAV TECHNOLOGY? – SAN CRISTÓBAL, GALÁPAGOS

Mangrove forests and shallow nearshore environments are recognized as potential nursery zones for a variety of marine species. In particular, multiple species of elasmobranchs often inhabit a variety of nearshore environments during their juvenile life stage. Coastal mangroves surrounding San Cristobal Island in the Galapagos Archipelago are currently serving as nurseries or potential nurseries for juvenile Carcharhinus limbatus, the blacktip shark. Abundance studies are advanced via Unoccupied Aerial Vehicles (UAVs), more commonly known as drones. Shallow coastal habitat presence with oligotrophic waters around San Cristobal make these prime areas for preliminary UAV abundance studies of juvenile blacktip sharks. Seven sites were studied over 9 months to compare the efficacy of UAV footage compared to traditional gillnet catch for relative abundance values. An additional seven random sites were surveyed 1-2 times over the same period. UAV abundance across all sites was correlated with gillnet abundance, indicating that a UAV is capturing the similar relative abundance trends as the gillnet method. We identify consistently higher abundance with UAV footage across spatial and temporal scales. Our sites adhere to the first criterion of Heupel et al’s (2007) nursery definition, i.e., sharks must be more commonly encountered in the target area than other surrounding areas. On average, we observed 600 to 900% more juvenile black tip sharks using UAV video than using gillnets, indicating many of our study sites may be more important nursery habitats than previously understood. Five of our study sites are currently zoned by the Galapagos National Park for artisanal fishing and/or tourism. Delimiting these sites as nurseries or potential nurseries has significant implications for habitat and juvenile species conservation.