Mirimin L.,University College Cork |
Mirimin L.,National University of Ireland |
Miller R.,University College Cork |
Dillane E.,University College Cork |
And 5 more authors.
Animal Conservation | Year: 2011
The identification of localized discrete populations is particularly important to the management and conservation of animal species, especially in the marine environment, where potential for dispersal is high but barriers to gene flow are often not clear. We investigated population genetic structuring of bottlenose dolphins Tursiops truncatus found along the west coast of Ireland, with particular attention to the Shannon Estuary, which is the only candidate Special Area of Conservation designated for this species in Irish waters. A genetic structure analysis using 62 biopsy samples from free ranging dolphins and 23 necropsies from stranded dolphins revealed fine-scale population structure among three distinct populations. The Shannon Estuary population appears to be genetically isolated from adjacent coastal areas, with the exception of four animals sampled from a small group of six dolphins that are now resident in Cork Harbour (south coast) indicating ongoing gene flow or recent dispersal between these two areas. A second genetically distinct aggregation was identified in the Connemara-Mayo region, where recent photo-identification studies have suggested that dolphins found in this area show a degree of site fidelity. We found moderate nuclear (15 microsatellites) and low mitochondrial (544bp of the control region) gene diversity in dolphins using the Shannon Estuary and the Connemara-Mayo region, while dolphins that stranded along the coast showed markedly higher levels of gene diversity at both classes of markers. Specifically, these stranded dolphins formed a third genetically distinct cluster, which may be part of a larger pelagic population, as also suggested by the high levels of gene diversity. These results provide new insights into population structure of bottlenose dolphins in Irish waters and will aid future management and conservation of the species in the eastern North Atlantic. © 2011 The Authors. Animal Conservation © 2011 The Zoological Society of London.
Hernandez-Milian G.,University College Cork |
Berrow S.,Kilrush Co. |
Santos M.B.,Spanish Institute of Oceanography |
Reid D.,Marine Institute of Ireland |
Rogan E.,University College Cork
Aquatic Mammals | Year: 2015
The stomach contents of 12 bottlenose dolphins were examined. Ten of the 11 samples origi-nated from dolphins that stranded on the west coast of Ireland between 1999 and 2011, while the remaining dolphin was bycaught. Ten of the stomachs contained food remains, mainly fish bones and otoliths; two stomachs were empty. A total of 37 prey taxa were identified, suggest-ing that they have a broad diet. The main prey items identified were five gadoid fish. Also, four species were only identified from non-otolith skeletal material, highlighting the importance of including all skeletal material in dietary studies. Three distinct populations of bottlenose dolphins have been identified in Irish waters using genetic markers. Differences in diet were found among these populations, where their stomach contents suggest that these animals might be foraging in different habitats. Significant differences were found between dolphins stranded alive and those that were found dead where the former appeared to have been feeding more on pelagic species. Significant differences were also found between male and female dolphin diet: males had eaten a wider variety of prey items than females. Annual consumption rates for the coastal bottlenose dol-phin population in Irish Atlantic coastal waters are estimated to be around 1,193.8 tonnes.
Fernandez R.,Copenhagen University |
Schubert M.,Copenhagen University |
Vargas-Velazquez A.M.,Copenhagen University |
Brownlow A.,United Road Services |
And 13 more authors.
Molecular Ecology Resources | Year: 2016
The field of population genetics is rapidly moving into population genomics as the quantity of data generated by high-throughput sequencing platforms increases. In this study, we used restriction-site-associated DNA sequencing (RADSeq) to recover genomewide genotypes from 70 white-beaked (Lagenorhynchus albirostris) and 43 Atlantic white-sided dolphins (L. acutus) gathered throughout their north-east Atlantic distribution range. Both species are at a high risk of being negatively affected by climate change. Here, we provide a resource of 38 240 RAD-tags and 52 981 nuclear SNPs shared between both species. We have estimated overall higher levels of nucleotide diversity in white-sided (π = 0.0492 ± 0.0006%) than in white-beaked dolphins (π = 0.0300 ± 0.0004%). White-sided dolphins sampled in the Faroe Islands, belonging to two pods (N = 7 and N = 11), showed similar levels of diversity (π = 0.0317 ± 0.0007% and 0.0267 ± 0.0006%, respectively) compared to unrelated individuals of the same species sampled elsewhere (e.g. π = 0.0285 ± 0.0007% for 11 Scottish individuals). No evidence of higher levels of kinship within pods can be derived from our analyses. When identifying the most likely number of genetic clusters among our sample set, we obtained an estimate of two to four clusters, corresponding to both species and possibly, two further clusters within each species. A higher diversity and lower population structuring was encountered in white-sided dolphins from the north-east Atlantic, in line with their preference for pelagic waters, as opposed to white-beaked dolphins that have a more patchy distribution, mainly across continental shelves. © 2016 John Wiley & Sons Ltd.
Ryan C.,Kilrush Co. |
Ryan C.,Mayo Institute of Technology, Galway |
Ryan C.,Marine Conservation Research International |
Craig D.,Kilrush Co. |
And 5 more authors.
Journal of Cetacean Research and Management | Year: 2014
The waters surrounding Cape Verde comprise one of two known breeding grounds for humpback whales in the North Atlantic. The population remains very small and has apparently failed to recover since the cessation of whaling there. During the breeding seasons of 2011 and 2012, sighting surveys were carried out for humpback whales off Boa Vista, the easternmost island of the Cape Verde Island archipelago. The distribution and relative abundance of humpback whales and mother-calf pairs was investigated by plotting effort-corrected sightings using a 2km2 grid-square. The study area, a 206km2region from the coastline up to 8km offshore, covered the western half of Boa Vista where whales have previously been regularly recorded. Following 1,954km of search effort, 117 sightings of humpback whales were made. An encounter rate of 0.11 whales per km was recorded for both years. It is hoped that these data may assist in implementing conservation measures to protect humpback whales and the habitat of Baia Sal Rei, which appears to be the single most important bay for winter breeding, calving and nursing humpback whales in the eastern North Atlantic.