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Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season

BACKGROUND: Species distribution models have shown that blue whales (Balaenoptera musculus) occur seasonally in high densities in the most biologically productive regions of the California Current Ecosystem (CCE). Satellite telemetry studies have additionally shown that blue whales in the CCE regula...

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Autores principales: Palacios, Daniel M., Bailey, Helen, Becker, Elizabeth A., Bograd, Steven J., DeAngelis, Monica L., Forney, Karin A., Hazen, Elliott L., Irvine, Ladd M., Mate, Bruce R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637557/
https://www.ncbi.nlm.nih.gov/pubmed/31360521
http://dx.doi.org/10.1186/s40462-019-0164-6
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author Palacios, Daniel M.
Bailey, Helen
Becker, Elizabeth A.
Bograd, Steven J.
DeAngelis, Monica L.
Forney, Karin A.
Hazen, Elliott L.
Irvine, Ladd M.
Mate, Bruce R.
author_facet Palacios, Daniel M.
Bailey, Helen
Becker, Elizabeth A.
Bograd, Steven J.
DeAngelis, Monica L.
Forney, Karin A.
Hazen, Elliott L.
Irvine, Ladd M.
Mate, Bruce R.
author_sort Palacios, Daniel M.
collection PubMed
description BACKGROUND: Species distribution models have shown that blue whales (Balaenoptera musculus) occur seasonally in high densities in the most biologically productive regions of the California Current Ecosystem (CCE). Satellite telemetry studies have additionally shown that blue whales in the CCE regularly switch between behavioral states consistent with area-restricted searching (ARS) and transiting, indicative of foraging in and moving among prey patches, respectively. However, the relationship between the environmental correlates that serve as a proxy of prey relative to blue whale movement behavior has not been quantitatively assessed. METHODS: We investigated the association between blue whale behavioral state and environmental predictors in the coastal environments of the CCE using a long-term satellite tracking data set (72 tagged whales; summer-fall months 1998–2008), and predicted the likelihood of ARS behavior at tracked locations using nonparametric multiplicative regression models. The models were built using data from years of cool, productive conditions and validated against years of warm, low-productivity conditions. RESULTS: The best model contained four predictors: chlorophyll-a, sea surface temperature, and seafloor aspect and depth. This model estimated highest ARS likelihood (> 0.8) in areas with high chlorophyll-a levels (> 0.65 mg/m(3)), intermediate sea surface temperatures (11.6-17.5 °C), and shallow depths (< 850 m). Overall, the model correctly predicted behavioral state throughout the coastal environments of the CCE, while the validation indicated an ecosystem-wide reduction in ARS likelihood during warm years, especially in the southern portion. For comparison, a spatial coordinates model (longitude × latitude) performed slightly better than the environmental model during warm years, providing further evidence that blue whales exhibit strong foraging site fidelity, even when conditions are not conducive to successful foraging. CONCLUSIONS: We showed that blue whale behavioral state in the CCE was predictable from environmental correlates and that ARS behavior was most prevalent in regions of known high whale density, likely reflecting where large prey aggregations consistently develop in summer-fall. Our models of whale movement behavior enhanced our understanding of species distribution by further indicating where foraging was more likely, which could be of value in the identification of key regions of importance for endangered species in management considerations. The models also provided evidence that decadal-scale environmental fluctuations can drive shifts in the distribution and foraging success of this blue whale population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40462-019-0164-6) contains supplementary material, which is available to authorized users.
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spelling pubmed-66375572019-07-29 Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season Palacios, Daniel M. Bailey, Helen Becker, Elizabeth A. Bograd, Steven J. DeAngelis, Monica L. Forney, Karin A. Hazen, Elliott L. Irvine, Ladd M. Mate, Bruce R. Mov Ecol Research BACKGROUND: Species distribution models have shown that blue whales (Balaenoptera musculus) occur seasonally in high densities in the most biologically productive regions of the California Current Ecosystem (CCE). Satellite telemetry studies have additionally shown that blue whales in the CCE regularly switch between behavioral states consistent with area-restricted searching (ARS) and transiting, indicative of foraging in and moving among prey patches, respectively. However, the relationship between the environmental correlates that serve as a proxy of prey relative to blue whale movement behavior has not been quantitatively assessed. METHODS: We investigated the association between blue whale behavioral state and environmental predictors in the coastal environments of the CCE using a long-term satellite tracking data set (72 tagged whales; summer-fall months 1998–2008), and predicted the likelihood of ARS behavior at tracked locations using nonparametric multiplicative regression models. The models were built using data from years of cool, productive conditions and validated against years of warm, low-productivity conditions. RESULTS: The best model contained four predictors: chlorophyll-a, sea surface temperature, and seafloor aspect and depth. This model estimated highest ARS likelihood (> 0.8) in areas with high chlorophyll-a levels (> 0.65 mg/m(3)), intermediate sea surface temperatures (11.6-17.5 °C), and shallow depths (< 850 m). Overall, the model correctly predicted behavioral state throughout the coastal environments of the CCE, while the validation indicated an ecosystem-wide reduction in ARS likelihood during warm years, especially in the southern portion. For comparison, a spatial coordinates model (longitude × latitude) performed slightly better than the environmental model during warm years, providing further evidence that blue whales exhibit strong foraging site fidelity, even when conditions are not conducive to successful foraging. CONCLUSIONS: We showed that blue whale behavioral state in the CCE was predictable from environmental correlates and that ARS behavior was most prevalent in regions of known high whale density, likely reflecting where large prey aggregations consistently develop in summer-fall. Our models of whale movement behavior enhanced our understanding of species distribution by further indicating where foraging was more likely, which could be of value in the identification of key regions of importance for endangered species in management considerations. The models also provided evidence that decadal-scale environmental fluctuations can drive shifts in the distribution and foraging success of this blue whale population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40462-019-0164-6) contains supplementary material, which is available to authorized users. BioMed Central 2019-07-18 /pmc/articles/PMC6637557/ /pubmed/31360521 http://dx.doi.org/10.1186/s40462-019-0164-6 Text en © The Author(s). 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Palacios, Daniel M.
Bailey, Helen
Becker, Elizabeth A.
Bograd, Steven J.
DeAngelis, Monica L.
Forney, Karin A.
Hazen, Elliott L.
Irvine, Ladd M.
Mate, Bruce R.
Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title_full Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title_fullStr Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title_full_unstemmed Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title_short Ecological correlates of blue whale movement behavior and its predictability in the California Current Ecosystem during the summer-fall feeding season
title_sort ecological correlates of blue whale movement behavior and its predictability in the california current ecosystem during the summer-fall feeding season
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637557/
https://www.ncbi.nlm.nih.gov/pubmed/31360521
http://dx.doi.org/10.1186/s40462-019-0164-6
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