Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al

Antarctic krill (Euphausia superba Dana, 1850) exemplifies the key role of marine crustaceans in fisheries, foodwebs, and biogeochemical cycles. Ecological understanding and policy decisions require information on population trends. We have therefore worked with international colleagues to publish K...

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Published in:Journal of Crustacean Biology
Main Authors: Hill, SL, Atkinson, A, Pakhomov, EA, Siegel, V
Format: Article in Journal/Newspaper
Language:English
Published: Oxford Academic 2019
Subjects:
Online Access:http://plymsea.ac.uk/id/eprint/8213/
http://plymsea.ac.uk/id/eprint/8213/1/Hill%20et%20al.pdf
https://doi.org/10.1093/jcbiol/ruz004
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spelling ftplymouthml:oai:plymsea.ac.uk:8213 2023-05-15T13:57:48+02:00 Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al Hill, SL Atkinson, A Pakhomov, EA Siegel, V 2019-05-01 text http://plymsea.ac.uk/id/eprint/8213/ http://plymsea.ac.uk/id/eprint/8213/1/Hill%20et%20al.pdf https://doi.org/10.1093/jcbiol/ruz004 en eng Oxford Academic http://plymsea.ac.uk/id/eprint/8213/1/Hill%20et%20al.pdf Hill, SL; Atkinson, A; Pakhomov, EA; Siegel, V. 2019 Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al. Journal of Crustacean Biology, 39 (3). 316-322. https://doi.org/10.1093/jcbiol/ruz004 <https://doi.org/10.1093/jcbiol/ruz004> cc_by_4 CC-BY Publication - Article NonPeerReviewed 2019 ftplymouthml https://doi.org/10.1093/jcbiol/ruz004 2022-09-13T05:49:19Z Antarctic krill (Euphausia superba Dana, 1850) exemplifies the key role of marine crustaceans in fisheries, foodwebs, and biogeochemical cycles. Ecological understanding and policy decisions require information on population trends. We have therefore worked with international colleagues to publish KRILLBASE, a database of fishery-independent krill population information for every decade since the 1970s. These data were used by Cox et al. (2018) who dispute the evidence for a late twentieth-century decline in krill density (number per unit area) in the Southwest Atlantic sector of the Southern Ocean and claim to overturn “much of recent thinking about climate-driven change in krill populations.” They support this claim with an analysis which reaffirms one non-significant result from an earlier paper but does not challenge the five significant results from that paper or those of other studies which support a decline. In this comment we examine the methods which led Cox and coauthors to conclude that krill density has been stable over the last 40 years. Although these authors provide a potentially useful approach, we show that their analysis was biased by the exclusion of usable net types, the inclusion of negatively biased data and down-weighting of high densities in the early part of the analysis period, the absence of recent data from the north of the sector, and a lack of statistical hypothesis testing. These factors maximise the chances of failure to detect a real decline. To aid future analyses we provide recommendations to supplement those which accompany KRILLBASE. We also suggest the need for consensus scientific advice on krill population dynamics based on agreed standards of evidence, evaluation of uncertainty, and a thorough understanding of the data. This will be more useful to policy makers and other stakeholders than polarised opinions. Meanwhile, the evidence for a decline in krill density still stands. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Euphausia superba Southern Ocean Plymouth Marine Science Electronic Archive (PlyMSEA - Plymouth Marine Laboratory, PML) Antarctic Southern Ocean Journal of Crustacean Biology 39 3 316 322
institution Open Polar
collection Plymouth Marine Science Electronic Archive (PlyMSEA - Plymouth Marine Laboratory, PML)
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language English
description Antarctic krill (Euphausia superba Dana, 1850) exemplifies the key role of marine crustaceans in fisheries, foodwebs, and biogeochemical cycles. Ecological understanding and policy decisions require information on population trends. We have therefore worked with international colleagues to publish KRILLBASE, a database of fishery-independent krill population information for every decade since the 1970s. These data were used by Cox et al. (2018) who dispute the evidence for a late twentieth-century decline in krill density (number per unit area) in the Southwest Atlantic sector of the Southern Ocean and claim to overturn “much of recent thinking about climate-driven change in krill populations.” They support this claim with an analysis which reaffirms one non-significant result from an earlier paper but does not challenge the five significant results from that paper or those of other studies which support a decline. In this comment we examine the methods which led Cox and coauthors to conclude that krill density has been stable over the last 40 years. Although these authors provide a potentially useful approach, we show that their analysis was biased by the exclusion of usable net types, the inclusion of negatively biased data and down-weighting of high densities in the early part of the analysis period, the absence of recent data from the north of the sector, and a lack of statistical hypothesis testing. These factors maximise the chances of failure to detect a real decline. To aid future analyses we provide recommendations to supplement those which accompany KRILLBASE. We also suggest the need for consensus scientific advice on krill population dynamics based on agreed standards of evidence, evaluation of uncertainty, and a thorough understanding of the data. This will be more useful to policy makers and other stakeholders than polarised opinions. Meanwhile, the evidence for a decline in krill density still stands.
format Article in Journal/Newspaper
author Hill, SL
Atkinson, A
Pakhomov, EA
Siegel, V
spellingShingle Hill, SL
Atkinson, A
Pakhomov, EA
Siegel, V
Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
author_facet Hill, SL
Atkinson, A
Pakhomov, EA
Siegel, V
author_sort Hill, SL
title Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
title_short Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
title_full Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
title_fullStr Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
title_full_unstemmed Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al
title_sort evidence for a decline in the population density of antarctic krill euphausia superba dana still stands. a comment on cox et al
publisher Oxford Academic
publishDate 2019
url http://plymsea.ac.uk/id/eprint/8213/
http://plymsea.ac.uk/id/eprint/8213/1/Hill%20et%20al.pdf
https://doi.org/10.1093/jcbiol/ruz004
geographic Antarctic
Southern Ocean
geographic_facet Antarctic
Southern Ocean
genre Antarc*
Antarctic
Antarctic Krill
Euphausia superba
Southern Ocean
genre_facet Antarc*
Antarctic
Antarctic Krill
Euphausia superba
Southern Ocean
op_relation http://plymsea.ac.uk/id/eprint/8213/1/Hill%20et%20al.pdf
Hill, SL; Atkinson, A; Pakhomov, EA; Siegel, V. 2019 Evidence for a decline in the population density of Antarctic krill Euphausia superba Dana still stands. A comment on Cox et al. Journal of Crustacean Biology, 39 (3). 316-322. https://doi.org/10.1093/jcbiol/ruz004 <https://doi.org/10.1093/jcbiol/ruz004>
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op_doi https://doi.org/10.1093/jcbiol/ruz004
container_title Journal of Crustacean Biology
container_volume 39
container_issue 3
container_start_page 316
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