Krill biomass estimation : sampling and measurement variability
Abstract
Krill are the subject of growing commercial fisheries and therefore fisheries management is necessary to ensure long-term sustainability. Krill catch limits, set by Commission for the Conservation of Antarctic Marine Living Resources, are based on absolute krill biomass, estimated from acoustic-trawl surveys. In this work, we develop a method for determining an error budget for acoustic-trawl surveys of krill which includes sampling and measurement variability. We use our error budget method to examine the sensitivity of biomass estimates to parameters in acoustic target strength (TS) models, length frequency distribution and length to wetmass relationships derived from net data. We determined that the average coefficient of variation (CV) of estimated biomass was 17.7% and the average CV due from scaling acoustic observations to biomass density was 5.3%. We found that a large proportion of the variability of biomass estimates is due to the krill orientation distribution, a parameter in the TS model. Orientation distributions with narrow standard deviations were found to emphasise the results of nulls in the TS to length relationship, which has to potential to lead to biologically implausible results.
Citation
Bairstow , F , Gastauer , S , Wotherspoon , S , Brown , C T A , Kawaguchi , S , Edwards , T & Cox , M J 2022 , ' Krill biomass estimation : sampling and measurement variability ' , Frontiers in Marine Science , vol. 9 , 903035 . https://doi.org/10.3389/fmars.2022.903035
Publication
Frontiers in Marine Science
Status
Peer reviewed
ISSN
2296-7745Type
Journal article
Rights
Copyright © 2022 Bairstow, Gastauer, Wotherspoon, Brown, Kawaguchi, Edwards and Cox. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Description
FB is funded by an EPSRC studentship (grant code: EP/R513337/1).Collections
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