Abstract
Photographic identification is increasingly being used as a cost-effective and minimally invasive method to monitor species, which is of particular importance for endangered populations that are vulnerable to intrusive research methods. The purpose of our study was to collect photographs of an endangered population of beluga whales ( Delphinapterus leucas (Pallas, 1776)) in Cumberland Sound, Nunavut, Canada, for use in photographic identification. Rather than pursuing the whales with boats to collect photographs, drones were used to minimize disturbance. We analyzed drone photographs from 2017 to 2019 for distinctive markings on the whales, which were used to develop a photographic identification catalogue. In total, 93 individuals were identified, with 24 resightings of marked individuals over the survey period. Approximately 43.4% (standard error 3.3%) of the adult beluga population was uniquely marked. The beluga population has been harvested at a rate of 41 whales per year, not including struck and lost, since 2002. The markings were from unknown origins (61%), scars/wounds from gunshots (27%), anthropogenic or predatory given the size and severity (11%), or a satellite tag (1%). The continuation of the photographic identification program will allow for the estimation of important population demographics, such as abundance and calving interval, which are important parameters for population conservation and management.
Highlights
Photographic identification is a non-invasive and frequently used method of monitoring species, providing insight into reproductive history, estimating mortality and survival, collecting social and age structure data, and monitoring the health of individuals over time (Würsig and Jefferson 1990; Elliser et al 2018; Raoult et al 2020; McGuire et al 2021b)
Starting in 2018, the drone was operated by an experienced pilot who was trained by the former military pilot and at that time had over 2 years of experience as a local recreational drone operator and had worked in Cumberland Sound the previous 3 years on whale projects
Over the survey period from 2017 to 2019, 1651 drone photographs were taken of beluga whales in Cumberland Sound
Summary
Photographic identification (photo-ID) is a non-invasive and frequently used method of monitoring species, providing insight into reproductive history, estimating mortality and survival, collecting social and age structure data, and monitoring the health of individuals over time (Würsig and Jefferson 1990; Elliser et al 2018; Raoult et al 2020; McGuire et al 2021b). The individual identification of cetaceans using natural markings in research began in the early 1970s (Würsig and Würsig 1977; Würsig and Jefferson 1990), and photo-ID research conducted since typically utilizes similar methods including the use of unique markings and colouration, or notches in the dorsal fin or fluke (Gowans et al 2000; Matthews et al 2001; Young et al 2011; Bassos-Hull et al 2013). Identifying individual belugas posed a unique challenge because skin colour changes from dark gray to white over the lifetime of a whale and whales often lack unique or permanent pigmentation. They lack a dorsal fin, a feature that is common in other ice-inhabiting whales. Canada (Michaud 2014), and typically involve collecting boat- and shore-based photographs in areas where the whales are accessible
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