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Abundance and demographic parameters of a bottlenose dolphin population in a highly impacted coastal ecosystem using a robust capture-recapture design
This study presents the first robust estimates of abundance and demographic parameters for a population of common bottlenose dolphins (Tursiops truncatus) in a highly impacted coastal ecosystem along the North Eastern Atlantic waters. Seasonal abundance, apparent survival and temporary emigration rates were estimated using Pollock’s robust design models. Photo-identification data were collected from 2014 to 2016 along the North Western Iberian Coast (Spain). Bottlenose dolphins were present year-round and with a high degree of occurrence in the study area, a highly human impacted area but also a highly-productive coastal ecosystem. Bottlenose dolphin population size ranged from 56 in Fall 2014 to 144 in Winter 2015. Apparent survival rate was high and constant indicating no mortality and no permanent emigration. Temporal emigration rates varied seasonally and were lower from fall to winter, suggesting that dolphins had a high probability to return during the winter period. The observed changes in abundance and emigration rates most likely reflect seasonal fluctuations in abundance of prey species in this area. These results provide important baseline information in an area subject to significant anthropogenic pressures and for future comparisons with other populations of similar characteristics under the pressure of human activities, as fisheries and aquaculture.
MF17346 Accepted 21 February 2018
© CSIRO 2018