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Advances in the aquatic sciences
RESEARCH ARTICLE

Abundance and demographic parameters of bottlenose dolphins in a highly affected coastal ecosystem

Séverine Methion A B C and Bruno Díaz López A
+ Author Affiliations
- Author Affiliations

A Bottlenose Dolphin Research Institute, Avenida Beiramar 192, E-36980 O Grove, Pontevedra, Spain.

B Université Bordeaux, UMR CNRS 5805 EPOC, Allee Geoffroy St Hilaire, F-33615 Pessac Cedex, France.

C Corresponding author. Email: severine@thebdri.com

Marine and Freshwater Research 69(9) 1355-1364 https://doi.org/10.1071/MF17346
Submitted: 15 November 2017  Accepted: 21 February 2018   Published: 4 June 2018

Abstract

This study presents the first robust estimates of abundance and demographic parameters of common bottlenose dolphins (Tursiops truncatus) in a highly affected coastal ecosystem along the north-eastern Atlantic. Seasonal abundance, apparent survival and temporary emigration rates were estimated using Pollock’s robust design models. Photographic 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, which is highly affected by human activity but is also a highly productive coastal ecosystem. Local abundance of bottlenose dolphins ranged from 56 in autumn 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 autumn to winter, suggesting that dolphins had a high probability of returning 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, such as fisheries and aquaculture.

Additional keywords: anthropogenic disturbances, Iberian Peninsula, marine top predator, photographic identification.


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