Improving the accuracy of krill target strength using a shape catalog

Fiona Jay Bairstow, Sven Gastauer, Luke Finley, Tom Edwards, C Tom A Brown, So Kawaguchi, Martin Cox

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
2 Downloads (Pure)

Abstract

Antarctic krill are subject to precautionary catch limits, based on biomass estimates, to ensure human activities do not adversely impact their important ecological role. Accurate target strength models of individual krill underpin biomass estimates. These models are scaled using measured and estimated distributions of length and orientation. However, while the length distribution of a krill swarm is accessible from net samples, there is currently limited consensus on the method for estimating krill orientation distribution. This leads to a limiting factor in biomass calculations. In this work, we consider geometric shape as a variable in target strength calculations and describe a practical method for generating a catalog of krill shapes. A catalog of shapes produces a more variable target strength response than an equivalent population of a scaled generic shape. Furthermore, using a shape catalog has the greatest impact on backscattering cross-section (linearized target strength) where the dominant scattering mechanism is mie scattering, irrespective of orientation distribution weighting. We suggest that shape distributions should be used in addition to length and orientation distributions to improve the accuracy of krill biomass estimates.
Original languageEnglish
Article number658384
Number of pages14
JournalFrontiers in Marine Science
Volume8
DOIs
Publication statusPublished - 7 Apr 2021

Keywords

  • Antarctic krill
  • Euphasia superba
  • Morphometrics
  • Target strength
  • Acoustic scattering

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