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Model-informed classification of broadband acoustic backscatter from zooplankton in an in situ mesocosm

Abstract

Classification of zooplankton to species with broadband echosounder data could increase the taxonomic resolution of acoustic surveys and reduce the dependence on net and trawl samples for ‘ground truthing’. Supervised classification with broadband echosounder data is limited by the acquisition of validated data required to train machine learning algorithms (‘classifiers’). We tested the hypothesis that acoustic scattering models could be used to train classifiers for remote classification of zooplankton. Three classifiers were trained with data from scattering models of four Arctic zooplankton groups (copepods, euphausiids, chaetognaths, and hydrozoans). We evaluated classifier predictions against observations of a mixed zooplankton community in a submerged purpose-built mesocosm (12 m3) insonified with broadband transmissions (185–255 kHz). The mesocosm was deployed from a wharf in Ny-Ålesund, Svalbard, during the Arctic polar night in January 2022. We detected 7722 tracked single targets, which were used to evaluate the classifier predictions of measured zooplankton targets. The classifiers could differentiate copepods from the other groups reasonably well, but they could not differentiate euphausiids, chaetognaths, and hydrozoans reliably due to the similarities in their modelled target spectra. We recommend that model-informed classification of zooplankton from broadband acoustic signals be used with caution until a better understanding of in situ target spectra variability is gained.
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Category

Academic article

Language

English

Author(s)

  • Muriel Dunn
  • Chelsey McGowan-Yallop
  • Geir Pedersen
  • Stig Falk-Petersen
  • Malin Daase
  • Kim Last
  • Tom J. Langbehn
  • Sophie Fielding
  • Andrew S. Brierley
  • Finlo Cottier
  • Sünnje L. Basedow
  • Lionel Camus
  • Maxime Geoffroy

Year

2023

Published in

ICES Journal of Marine Science

ISSN

1054-3139

Volume

81

Issue

7

Page(s)

1371 - 1384

View this publication at Norwegian Research Information Repository