Population ecology and the management of whale watching operations on a data‐deficient dolphin population

Abstract

Whale watching is a popular commercial activity, producing socio‐ecological benefits but also potential long‐term effects on the targeted cetacean population. This industry is currently developing in data‐deficient contexts in a largely unregulated fashion. Management schemes should adopt precaution and be informed by the relevant literature, but would be more effective if the assessment of the target population vulnerability, biological impacts, and management implications was drawn from site‐specific data. This paper focuses on a reef‐associated, data‐deficient population of spinner dolphins in the Egyptian Red Sea. In Satayah Reef, new information on population size and dynamic parameters were documented using visual observation and photo‐identification‐based capture–recapture methods (Cormack–Jolly–Seber time‐since‐marking model). Dolphins occurred on 98% of the survey days. Average school size was 66 individuals (±42.1 SE), with most groups including calves. The population was equally divided into recurrent and transient individuals. An “emigration + mortality” model best described residence at the site. Five recurrent males (5% of the Satayah population) provided connectivity between this and the geographically close population of Samadai Reef. Average annual survival probability was 0.83 (±0.06 SE) in the year following first capture and 0.99 (±0.06 SE) for recurrent individuals. Mean yearly population sizes ranged 143–207 individuals. The study had the power to detect a 30% decline in the population, but not the rate of change in abundance estimated from the data (r = 0.018 ± 0.04), which would have required a 3‐ to 5‐times longer study. Synthesis and application: These findings advance the assessment of the Satayah population's intrinsic vulnerability and have three major management applications: (a) the delineation of management units; (b) the identification of key indicators for future impact monitoring and assessment; and (c) realistic estimates of the statistical power for trend detection. Based on our results, we recommend supporting future research, devising site‐specific time–area closure plans, and integrating them in a regional scheme. Approaches employed in this case study can inform the management of whale watching industries targeting other data‐deficient populations.

Effects of swim‐with‐dolphin tourism on the behaviour of spinner dolphins, at Samadai Reef in the Egyptian Red Sea

“…ment has yet to be completed. Similarly, Fumagalli et al (2019) have used photo-identification to monitor the numbers of spinner dolphins using Satayah Reef, 120 km to the south of Samadai. The population there ranged from 143 to 207 individuals and reduced during their study period, although not sufficiently for the decline to be statistically significant.…”

“…A comparable study on the effects of swim-with-dolphin tourism on Egyptian spinner dolphins, completed shortly after this study, has also investigated the effects of visitor presence on the dolphins making use of Sha'ab Samadai (Fumagalli et al, 2019). Fumagalli et al (2018) used a different approach, however, comparing dolphin behaviour at Samadai with that at two other offshore resting sites in the same region: Sha'ab Satayah, which is frequently visited by swim-with-dolphin tourist boats and where access is completely unregulated, and Qubbat'Isa, which is only rarely visited by tourist boats.…”

Machine Learning and Image Processing Methods for Cetacean Photo Identification: A Systematic Review

“…The applications of intelligent photo identification systems on vagrant species can be categorized into the following main topics: occurrence and migration patterns, site fidelity and residency patterns as well as population abundance and social dynamics. In particular, several studies have evaluated the site fidelity of cetaceans in the study area [26], [29]- [31], [43], [45], [48], [54] as the tendency of an individual to occupy or return to a previously known area. This concept is relevant because odontocetes are at the top of the food chain, and their presence indicates resilient ecosystems and highquality habitats.…”

“…Finally, photo identification can be efficiently applied to provide a baseline on species population abundance. A large part of these studies is related to animals ranked as data deficient, vulnerable or threatened by the International Union for Conservation of Nature (IUCN Red List) [25], [26], [48].…”

“…), and any combination of these attributes can be selected to sort the catalogue. FinBase helps analysts, during photo [26], [31], [33], [46], [48], [49], [53], [63] (*) [30] (**) - [25], [28], [29], [35], [42], [45], [59], [61], [ identification studies, sort the entire catalogue based on the similarity of each existing catalogue individuals' attributes to those of a newly sighted individual [51], [54], [55], [61]. This system, while created for a bottlenose dolphin research application, can be adapted to accommodate photo identification research on a variety of other species.…”