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dc.contributor.authorLudwig, Kim E.
dc.contributor.authorDaly, Mags
dc.contributor.authorLevesque, Stephanie
dc.contributor.authorBerrow, Simon
dc.identifier.citationLudwig KE, Daly M, Levesque S and Berrow SD (2021) Survival Rates and Capture Heterogeneity of Bottlenose Dolphins (Tursiops truncatus) in the Shannon Estuary, Ireland. Front. Mar. Sci. 8:611219. doi: 10.3389/fmars.2021.611219en_US
dc.description.abstractAdult survival is arguably the most important demographic parameter for long-lived species as it has a large impact on population growth, and it can be estimated for cetacean populations using natural markings and mark-recapture (MR) modelling. Here we describe a 26-year study of a genetically discrete, resident population of bottlenose dolphins in the Shannon Estuary, Ireland, conducted by an NGO using multiple platforms. We estimated survival rates (SRs) using Cormack-Jolly-Seber models and explored the effects of variable survey effort, multiple researchers, and changes in camera equipment as well as capture heterogeneity induced by changes in marks and site fidelity variation, all common issues affecting longitudinal dolphin studies. The mean adult SR was 0.94 (±0.001 SD) and thus comparable to the estimates reported for other bottlenose dolphin populations. Capture heterogeneity through variation in mark severity was confirmed, with higher capture probabilities for well-marked individuals than for poorly marked individuals and a “transience” effect being detected for less well-marked individuals with 43% only recorded once. Likewise, both SR and capture probabilities were comparatively low for individuals with low site fidelity to the Shannon Estuary, and SR of these individuals additionally decreased even further toward the end of the study, reflecting a terminal bias. This bias was attributed to non-random temporal migration, and, together with high encounter rates in Brandon Bay, supported the hypothesis of range expansion. Our results highlight the importance of consistent and geographically homogenous survey effort and support the differentiation of individuals according to their distinctiveness to avoid biased survival estimates.en_US
dc.publisherFrontiers Media S.A.en_US
dc.relation.ispartofFrontiers in Marine Scienceen_US
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.subjectbottlenose dolphin (Tursiops truncatus)en_US
dc.subjectCormack-Jolly-Seber modelsen_US
dc.subjectsurvival rateen_US
dc.subjectcapture heterogeneityen_US
dc.subjectnon-random temporal migrationen_US
dc.subjectsite fidelityen_US
dc.titleSurvival Rates and Capture Heterogeneity of Bottlenose Dolphins (Tursiops truncatus) in the Shannon Estuary, Irelanden_US
dc.contributor.affiliationMarine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Irelanden_US
dc.contributor.affiliationBirdWatch Ireland, Kilcoole, Co. Wicklow, Irelanden_US
dc.subject.departmentMarine and Freshwater Research Centreen_US

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Attribution-NonCommercial-NoDerivatives 4.0 International
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International