Large-scale movements of common bottlenose dolphins in the Atlantic: dolphins with an international courtyard

Abstract

Wide-ranging connectivity patterns of common bottlenose dolphins (Tursiops truncatus) are generally poorly known worldwide and more so within the oceanic archipelagos of Macaronesia in the North East (NE) Atlantic. This study aimed to identify long-range movements between the archipelagos of Macaronesia that lie between 500 and 1,500 km apart, and between Madeira archipelago and the Portuguese continental shelf, through the compilation and comparison of bottlenose dolphin’s photo-identification catalogues from different regions: one from Madeira (n = 363 individuals), two from different areas in the Azores (n = 495 and 176), and four from different islands of the Canary Islands (n = 182, 110, 142 and 281), summing up 1791 photographs. An additional comparison was made between the Madeira catalogue and one catalogue from Sagres, on the southwest tip of the Iberian Peninsula (n = 359). Results showed 26 individual matches, mostly between Madeira and the Canary Islands (n = 23), and between Azores and Madeira (n = 3). No matches were found between the Canary Islands and the Azores, nor between Madeira and Sagres. There were no individuals identified in all three archipelagos. The minimum time recorded between sightings in two different archipelagos (≈ 460 km apart) was 62 days. Association patterns revealed that the individuals moving between archipelagos were connected to resident, migrant and transient individuals in Madeira. The higher number of individuals that were re-sighted between Madeira and the Canary Islands can be explained by the relative proximity of these two archipelagos. This study shows the first inter-archipelago movements of bottlenose dolphins in the Macaronesia region, emphasizing the high mobility of this species and supporting the high gene flow described for oceanic dolphins inhabiting the North Atlantic. The dynamics of these long-range movements strongly denotes the need to review marine protected areas established for this species in each archipelago, calling for joint resolutions from three autonomous regions belonging to two EU countries.

Bryde's whales in the North‐East Atlantic: New insights on site fidelity and connectivity between oceanic archipelagos

“…These movements are also in accordance with what is observed for other species in the same area (e.g. Steiner et al, 2015; Alves et al, 2019; Dinis et al, 2021). Studies on Bryde's whales have demonstrated movements of individuals between closer areas (e.g.…”

“…Connectivity between the Azores, Madeira, and the Canaries has been recorded for three species of cetaceans through photo-id Dinis et al, 2021). Additionally, the lack of genetic differentiation between populations in Macaronesia has been shown for: shortfinned pilot whales (Alves et al, 2013;Miralles et al, 2016); bottlenose dolphins (Quérouil et al, 2007); Atlantic spotted dolphins,…”

“…Connectivity between the Azores, Madeira, and the Canaries has been recorded for three species of cetaceans through photo‐id comparison (for sperm whales, Physeter macrocephalus ; Steiner et al, 2015; for short‐finned pilot whales, Globicephala macrorhynchus ; Alves et al, 2019; and for bottlenose dolphins, Tursiops truncatus ; Dinis et al, 2021). Additionally, the lack of genetic differentiation between populations in Macaronesia has been shown for: short‐finned pilot whales (Alves et al, 2013; Miralles et al, 2016); bottlenose dolphins (Quérouil et al, 2007); Atlantic spotted dolphins, Stenella frontalis ; and short‐beaked common dolphins, Delphinus delphis (Quérouil et al, 2010).…”

Modeling Fine-Scale Cetaceans’ Distributions in Oceanic Islands: Madeira Archipelago as a Case Study

“…Moreover, baleen whales occur frequently in the archipelago, especially the Bryde's whale (Balaenoptera edeni), with a relatively high occurrence rate but with a very high interannual variation (Alves et al, 2018). Recent studies revealed cetacean interconnectivity among neighboring archipelagos, such as the Canaries and the Azores, with re-sightings of individuals from several species among the three archipelagos (e.g., Alves et al, 2019;Dinis et al, 2021). Additionally, Madeira constitutes an area of interest for several (at least ten) cetacean species due to being used for traveling, feeding, resting, socializing and calving (Alves et al, 2018).…”

Harnessing the Power of Social Media to Obtain Biodiversity Data About Cetaceans in a Poorly Monitored Area

“…One study registered the presence of six species along a ∼30 km coast stretch in the western Algarve during a little over 8 months (Castro, 2010), while the other study reported the presence of 11 species along the entire region during 6-month periods over 10 years (Laborde et al, 2019). Existing knowledge is mostly published as gray literature, while peer-reviewed publications are scarce and have focused on strandings (Silva and Sequeira, 2003;Sousa and Brito, 2012), aspects of population connectivity (Alves et al, 2019;Dinis et al, 2021) the population ecology of Delphinus delphis (Moura et al, 2012;Castro et al, 2020), and Orcinus orca (Esteban et al, 2013) description of opportunistic observations (Martin and Walker, 1997;Báez et al, 2007), interaction with fisheries (Goetz et al, 2015;Marçalo et al, 2015), diet (Marçalo et al, 2018(Marçalo et al, , 2021 or diet/trophic ecology (Giménez et al, 2017), behavioral responses to drones (Castro et al, 2021), and epidemiology (Bento et al, 2016).…”