A new study at the University of Hawaii’s Institute of Marine Biology at Mānoa Hawaii successfully used drones to determine the age of endangered wild dolphins in Greece.
This work, carried out in collaboration with the Tethys Research Institute, helps to increase researchers’ knowledge of population density and demography, which can contribute to better management practices and ensure the survival of the species. The study was published in Animal welfare.
Researchers from the Marine Mammal Research Program (MMRP) are comparing the drone imagery results with long-term data and data from stable, non-threatened populations of bottlenose dolphins in Shark Bay, Australia, and Sarasota Bay, Florida.
“In (our new) study, we highlight the speed and accuracy of UAS photogrammetry (drone imagery) in assessing the age structure of wild dolphin populations and the implications for management and conservation,” said Fabien Vivier, MMRP researcher and lead author of the study. “We hope that this method will allow us to rapidly monitor the age structure of wild dolphin populations. This information can facilitate the detection of early signs of population changes, such as a decrease in the number of calves, and provide important insights for timely management decisions.”
Healthy dolphin populations have a consistent ratio of calves, juveniles and adults; deviations from this can indicate that the population is unstable. Using drones, researchers were able to quantify the age structure of the endangered dolphin population in Greece within a few days.
In a previous study, the MMRP team used specially calibrated drones to successfully measure the length of free-swimming dolphins and classify them by age.
“When dolphins come to the surface to breathe, they expose their blowhole and dorsal fin,” Vivier said. “By measuring the distance between the two, we can estimate their total body length. Since total length is related to age, we can estimate the age range of an individual dolphin.”
The marine mammals known as cetaceans, which include whales, dolphins and porpoises, face a multitude of threats: habitat destruction, climate change, fishing, and chemical and noise pollution. A quarter of the 92 known cetacean species are threatened with extinction and there is a clear and urgent need to implement effective conservation strategies.
The project was conducted in collaboration with the Shark Bay Dolphin Research Project and the Sarasota Dolphin Research Program. The work in Greece was funded by the Office of Naval Research (ONR), OceanCare, and the Costas M Lemos Foundation. The work in Hawaii is funded by ONR, NOAA Pacific Islands Fisheries Science Center, the Omidyar ʻOhana Fund of the Hawaiʻi Community Foundation, and Dolphin Quest.
