Recognising an individual within a study population is a key issue in many behavioural and ecological studies of animals. A good method for this is photo-identification (photo-ID), a technique that is based on the repeated identification of individuals through pictures. It is an important, non-invasive tool since marine mammals do not have to be physically captured, and it does not affect their behaviour.
With photo-ID, it is possible to obtain data regarding cetacean population dynamics that are essential for proper environmental management as well as migration. For example, if a cetacean is photographed in the same region over several months it provides valuable evidence that the individual is resident, or if the individual is recorded from year-to-year it reveals good information regarding the animal’s longevity. The more information that can be obtained over time and from several individuals, the more one can learn about populations of that species, their size, individual growth, associations, mortality, and reproductive rates. Most photo-identification studies of dolphins rely on nicks and cuts in the dorsal fin, that provide long-lasting, individually unique markings. Particular abrasions on the tail flukes are key identifying markers for whales.
Archipelagos Institute of Marine Conservation is using photo-ID methodology to monitor cetacean populations in the Greek Seas. The investigated species for this research are Common Bottlenose dolphin (Tursiops truncatus), Short-beaked Common dolphin (Delphinus delphis), Striped dolphin (Stenella coeruleoalba), Risso’s dolphin (Grampus griseus) and Sperm Whale (Physeter macrocephalus). D. delphis and T. truncatus are the most recorded species and in the last three years (2016-2018), 75 and 54 different individuals were photographed respectively. Our main aim is to study cetacean population dynamics and continue conservation strategies in such data-deficient area as the Aegean Sea is
Dennis van der Grift, Biology
MBO College Almere, Netherlands
