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Marine Ecology Progress Series

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MEPS 623:221-234 (2019)  -  DOI:

Spatio-temporal patterns in fin whale Balaenoptera physalus habitat use in the northern Gulf of St. Lawrence

Anna Schleimer1,2,3,*, Christian Ramp1,2, Stéphane Plourde4, Caroline Lehoux4, Richard Sears2, Philip S. Hammond1

1Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews, St Andrews KY16 8LB, UK
2Mingan Island Cetacean Study, St Lambert, Québec J4P 1T3, Canada
3Marine Evolution and Conservation, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen 9700 CC, The Netherlands
4Institut Maurice-Lamontagne, Fisheries and Oceans Canada, Mont-Joli, Québec G5H 3Z4, Canada
*Corresponding author:

ABSTRACT: Significant ecosystem changes in the Gulf of St. Lawrence (GSL), Canada, have had far-reaching effects at all trophic levels. The abundance of fin whales Balaenoptera physalus has declined significantly in the northern GSL over the past decade. This study aimed to test the hypothesis that the observed decline was correlated to changing environmental conditions. Cetacean sightings data from 292 surveys, resulting in 2986 fin whale encounters from 2007 to 2013, were used to fit 2 separate generalised additive models in terms of (1) bathymetric and oceanographic variables (the proxy model) and (2) modelled krill biomass (the prey model). The concept of ‘handling time’ was introduced to correct for time off search effort, applicable to other studies relying on opportunistically sampled data. While a positive correlation between krill biomass and fin whale numbers was found, the performance of the proxy model (24.2% deviance explained) was overall better than the prey model (11.8%). Annual predictive maps derived from the final proxy model highlighted 2 key areas with recurrently high relative fin whale abundance and a significant overlap with shipping lanes. While both models provided evidence for an annual decline in relative fin whale abundance, static bathymetric features were the most important predictors of habitat use, and no correlation between dynamic variables and the decline was found. High resolution prey data and a better understanding of the feeding ecology of fin whales are proposed to further investigate the predator-prey relationship and decline of fin whales in the GSL.

KEY WORDS: Habitat modelling · Effort quantification · Handling time · Proxy variables · Distribution · Predictive maps · Opportunistic surveys

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Cite this article as: Schleimer A, Ramp C, Plourde S, Lehoux C, Sears R, Hammond PS (2019) Spatio-temporal patterns in fin whale Balaenoptera physalus habitat use in the northern Gulf of St. Lawrence. Mar Ecol Prog Ser 623:221-234.

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