Decline in abundance and apparent survival rates of fin whales (Balaenoptera physalus) in the northern Gulf of St. Lawrence

A. Schleimer was supported by the Luxembourg National Research Fund (FNR; AFR/11256673). Estimates of abundance and survivorship provide quantifiable measures to monitor populations and to define and understand their conservation status. This study investigated changes in abundance and survival rate...

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Bibliographic Details
Published in:Ecology and Evolution
Main Authors: Schleimer, Anna, Ramp, Christian, Delarue, Julien, Carpentier, Alain, Bérubé, Martine, Palsbøl, Per J., Sears, Richard, Hammond, Philip S.
Other Authors: University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Centre for Research into Ecological & Environmental Modelling
Format: Article in Journal/Newspaper
Language:English
Published: 2019
Subjects:
Abundance
Capture heterogeneity
Capture-recapture
Fin whale
Site fidelity
Survival rate
Terminal bias
QH301 Biology
DAS
QH301
Balaenoptera physalus
Online Access:http://hdl.handle.net/10023/17305
https://doi.org/10.1002/ece3.5055
Description
Summary:A. Schleimer was supported by the Luxembourg National Research Fund (FNR; AFR/11256673). Estimates of abundance and survivorship provide quantifiable measures to monitor populations and to define and understand their conservation status. This study investigated changes in abundance and survival rates of fin whales (Balaenoptera physalus) in the northern Gulf of St. Lawrence in the context of anthropogenic pressures and changing environmental conditions. A long‐term data set, consisting of 35 years of photo‐identification surveys and comprising more than 5,000 identifications of 507 individuals, formed the basis of this mark–recapture study. Based on model selection using corrected Akaike Information Criterion, the most parsimonious Cormack–Jolly–Seber model included a linear temporal trend in noncalf apparent survival rates with a sharp decline in the last 5 years of the study and a median survival rate of 0.946 (95% confidence interval (CI) 0.910–0.967). To account for capture heterogeneity due to divergent patterns of site fidelity, agglomerative hierarchical cluster analysis was employed to categorize individuals based on their annual and survey site fidelity indices. However, the negative trend in survivorship remained and was corroborated by a significant decline in the estimated super‐population size from 335 (95% CI 321–348) individuals in 2004–2010 to 291 (95% CI 270–312) individuals in 2010–2016. Concurrently, a negative trend was estimated in recruitment to the population, supported by a sharp decrease in the number of observed calves. Ship strikes and changes in prey availability are potential drivers of the observed decline in fin whale abundance. The combination of clustering methods with mark–recapture represents a flexible way to investigate the effects of site fidelity on demographic variables and is broadly applicable to other individual‐based studies. Publisher PDF Peer reviewed

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