Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns

Helena Herr, Natalie Kelly, Boris Dorschel, Marcus Huntemann, K. Kock, Linn Sophia Lehnert, Ursula Siebert, Sacha Viquerat, Rob Williams, Meike Scheidat

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

This study investigates the distribution of Antarctic minke whales (AMW) in relation to sea ice concentration and variations therein. Information on AMW densities in the sea ice‐covered parts of the Southern Ocean is required to contextualize abundance estimates obtained from circumpolar shipboard surveys in open waters, suggesting a 30% decline in AMW abundance. Conventional line‐transect shipboard surveys for density estimation are impossible in ice‐covered regions, therefore we used icebreaker‐ supported helicopter surveys to obtain information on AMW densities along gradients of 0%–100% of ice concentration. We conducted five helicopter surveys in the Southern Ocean, between 2006 and 2013. Distance sampling data, satellite‐derived sea‐ice data, and bathymetric parameters were used in generalized additive models (GAMs) to produce predictions on how the density of AMWs varied over space and time, and with environmental covariates. Ice concentration, distance to the
ice edge and distance from the shelf break were found to describe the distribution of AMWs. Highest densities were predicted at the ice edge and through to medium ice concentrations. Medium densities were found up to 500 km into the ice edge in all concentrations of ice. Very low numbers of AMWs were found in the ice‐free waters of the West Antarctic Peninsula (WAP). A consistent relationship between AMW distribution and sea ice concentration weakens the support for the hypothesis that varying numbers of AMWs in ice‐covered waters were responsible for observed changes in estimated abundance. The potential decline in AMW abundance stresses the need for conservation measures and further studies into the AMW population status. Very low numbers of AMWs recorded in the ice‐free waters along the WAP support the hypothesis that this species is strongly dependent on sea ice and that forecasted sea ice changes have the potential of heavily impacting AMWs
LanguageEnglish
Pages5664-5682
Number of pages19
JournalEcology and Evolution
Volume9
Issue number10
Early online date30 Apr 2019
DOIs
Publication statusPublished - May 2019

Fingerprint

aerial survey
whale
sea ice
ice
helicopters
distribution
Balaenoptera bonaerensis
line transect
ocean
shelf break
open water
oceans
water
satellite data
space and time

Keywords

  • Antarctic minke whale distribution
  • density surface models
  • distance sampling
  • marginal ice zone
  • ship-based helicopter surveys
  • southern ocean

Cite this

Herr, Helena ; Kelly, Natalie ; Dorschel, Boris ; Huntemann, Marcus ; Kock, K. ; Lehnert, Linn Sophia ; Siebert, Ursula ; Viquerat, Sacha ; Williams, Rob ; Scheidat, Meike. / Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns. In: Ecology and Evolution. 2019 ; Vol. 9, No. 10. pp. 5664-5682.
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title = "Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns",
abstract = "This study investigates the distribution of Antarctic minke whales (AMW) in relation to sea ice concentration and variations therein. Information on AMW densities in the sea ice‐covered parts of the Southern Ocean is required to contextualize abundance estimates obtained from circumpolar shipboard surveys in open waters, suggesting a 30{\%} decline in AMW abundance. Conventional line‐transect shipboard surveys for density estimation are impossible in ice‐covered regions, therefore we used icebreaker‐ supported helicopter surveys to obtain information on AMW densities along gradients of 0{\%}–100{\%} of ice concentration. We conducted five helicopter surveys in the Southern Ocean, between 2006 and 2013. Distance sampling data, satellite‐derived sea‐ice data, and bathymetric parameters were used in generalized additive models (GAMs) to produce predictions on how the density of AMWs varied over space and time, and with environmental covariates. Ice concentration, distance to theice edge and distance from the shelf break were found to describe the distribution of AMWs. Highest densities were predicted at the ice edge and through to medium ice concentrations. Medium densities were found up to 500 km into the ice edge in all concentrations of ice. Very low numbers of AMWs were found in the ice‐free waters of the West Antarctic Peninsula (WAP). A consistent relationship between AMW distribution and sea ice concentration weakens the support for the hypothesis that varying numbers of AMWs in ice‐covered waters were responsible for observed changes in estimated abundance. The potential decline in AMW abundance stresses the need for conservation measures and further studies into the AMW population status. Very low numbers of AMWs recorded in the ice‐free waters along the WAP support the hypothesis that this species is strongly dependent on sea ice and that forecasted sea ice changes have the potential of heavily impacting AMWs",
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author = "Helena Herr and Natalie Kelly and Boris Dorschel and Marcus Huntemann and K. Kock and Lehnert, {Linn Sophia} and Ursula Siebert and Sacha Viquerat and Rob Williams and Meike Scheidat",
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Herr, H, Kelly, N, Dorschel, B, Huntemann, M, Kock, K, Lehnert, LS, Siebert, U, Viquerat, S, Williams, R & Scheidat, M 2019, 'Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns', Ecology and Evolution, vol. 9, no. 10, pp. 5664-5682. https://doi.org/10.1002/ece3.5149

Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns. / Herr, Helena; Kelly, Natalie; Dorschel, Boris; Huntemann, Marcus; Kock, K.; Lehnert, Linn Sophia; Siebert, Ursula; Viquerat, Sacha; Williams, Rob; Scheidat, Meike.

In: Ecology and Evolution, Vol. 9, No. 10, 05.2019, p. 5664-5682.

Research output: Contribution to journalArticleAcademicpeer-review

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AU - Herr, Helena

AU - Kelly, Natalie

AU - Dorschel, Boris

AU - Huntemann, Marcus

AU - Kock, K.

AU - Lehnert, Linn Sophia

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AU - Viquerat, Sacha

AU - Williams, Rob

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AB - This study investigates the distribution of Antarctic minke whales (AMW) in relation to sea ice concentration and variations therein. Information on AMW densities in the sea ice‐covered parts of the Southern Ocean is required to contextualize abundance estimates obtained from circumpolar shipboard surveys in open waters, suggesting a 30% decline in AMW abundance. Conventional line‐transect shipboard surveys for density estimation are impossible in ice‐covered regions, therefore we used icebreaker‐ supported helicopter surveys to obtain information on AMW densities along gradients of 0%–100% of ice concentration. We conducted five helicopter surveys in the Southern Ocean, between 2006 and 2013. Distance sampling data, satellite‐derived sea‐ice data, and bathymetric parameters were used in generalized additive models (GAMs) to produce predictions on how the density of AMWs varied over space and time, and with environmental covariates. Ice concentration, distance to theice edge and distance from the shelf break were found to describe the distribution of AMWs. Highest densities were predicted at the ice edge and through to medium ice concentrations. Medium densities were found up to 500 km into the ice edge in all concentrations of ice. Very low numbers of AMWs were found in the ice‐free waters of the West Antarctic Peninsula (WAP). A consistent relationship between AMW distribution and sea ice concentration weakens the support for the hypothesis that varying numbers of AMWs in ice‐covered waters were responsible for observed changes in estimated abundance. The potential decline in AMW abundance stresses the need for conservation measures and further studies into the AMW population status. Very low numbers of AMWs recorded in the ice‐free waters along the WAP support the hypothesis that this species is strongly dependent on sea ice and that forecasted sea ice changes have the potential of heavily impacting AMWs

KW - Antarctic minke whale distribution

KW - density surface models

KW - distance sampling

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