Correcting density-dependent effects in abundance estimates from bottom-trawl surveys
Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that...
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2014
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Online Access: | http://dx.doi.org/10.1093/icesjms/fst208 http://academic.oup.com/icesjms/article-pdf/71/5/1107/29148397/fst208.pdf |
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croxfordunivpr:10.1093/icesjms/fst208 2024-04-28T08:14:41+00:00 Correcting density-dependent effects in abundance estimates from bottom-trawl surveys Kotwicki, Stan Ianelli, James N. Punt, André E. 2014 http://dx.doi.org/10.1093/icesjms/fst208 http://academic.oup.com/icesjms/article-pdf/71/5/1107/29148397/fst208.pdf en eng Oxford University Press (OUP) ICES Journal of Marine Science volume 71, issue 5, page 1107-1116 ISSN 1095-9289 1054-3139 Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography journal-article 2014 croxfordunivpr https://doi.org/10.1093/icesjms/fst208 2024-04-09T07:58:13Z Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that the efficiency of the survey bottom trawl (BT) for some species can be density-dependent, which could affect the reliability of survey-derived indices of abundance. A function qe∼f(u), where qe is the BT efficiency and u the catch rate, was derived using experimentally derived acoustic dead-zone correction and BT efficiency parameters obtained from combining a subset of BT catch data with synchronously collected acoustic data from walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS). We found that qe decreased with increasing BT catches resulting in hyperstability of the index of abundance derived from BT survey. Density-dependent qe resulted in spatially and temporarily variable bias in survey cpue and biased population age structure derived from survey data. We used the relationship qe∼f(u) to correct the EBS trawl survey index of abundance for density-dependence. We also obtained a variance–covariance matrix for a new index that accounted for sampling variability and the uncertainty associated with the qe. We found that incorporating estimates of the new index of abundance changed outputs from the walleye pollock stock assessment model. Although changes were minor, we advocate incorporating estimates of density-dependent qe into the walleye pollock stock assessment as a precautionary measure that should be undertaken to avoid negative consequences of the density-dependent qe. Article in Journal/Newspaper Bering Sea Theragra chalcogramma Oxford University Press ICES Journal of Marine Science 71 5 1107 1116 |
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Open Polar |
collection |
Oxford University Press |
op_collection_id |
croxfordunivpr |
language |
English |
topic |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
spellingShingle |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography Kotwicki, Stan Ianelli, James N. Punt, André E. Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
topic_facet |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
description |
Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that the efficiency of the survey bottom trawl (BT) for some species can be density-dependent, which could affect the reliability of survey-derived indices of abundance. A function qe∼f(u), where qe is the BT efficiency and u the catch rate, was derived using experimentally derived acoustic dead-zone correction and BT efficiency parameters obtained from combining a subset of BT catch data with synchronously collected acoustic data from walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS). We found that qe decreased with increasing BT catches resulting in hyperstability of the index of abundance derived from BT survey. Density-dependent qe resulted in spatially and temporarily variable bias in survey cpue and biased population age structure derived from survey data. We used the relationship qe∼f(u) to correct the EBS trawl survey index of abundance for density-dependence. We also obtained a variance–covariance matrix for a new index that accounted for sampling variability and the uncertainty associated with the qe. We found that incorporating estimates of the new index of abundance changed outputs from the walleye pollock stock assessment model. Although changes were minor, we advocate incorporating estimates of density-dependent qe into the walleye pollock stock assessment as a precautionary measure that should be undertaken to avoid negative consequences of the density-dependent qe. |
format |
Article in Journal/Newspaper |
author |
Kotwicki, Stan Ianelli, James N. Punt, André E. |
author_facet |
Kotwicki, Stan Ianelli, James N. Punt, André E. |
author_sort |
Kotwicki, Stan |
title |
Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
title_short |
Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
title_full |
Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
title_fullStr |
Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
title_full_unstemmed |
Correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
title_sort |
correcting density-dependent effects in abundance estimates from bottom-trawl surveys |
publisher |
Oxford University Press (OUP) |
publishDate |
2014 |
url |
http://dx.doi.org/10.1093/icesjms/fst208 http://academic.oup.com/icesjms/article-pdf/71/5/1107/29148397/fst208.pdf |
genre |
Bering Sea Theragra chalcogramma |
genre_facet |
Bering Sea Theragra chalcogramma |
op_source |
ICES Journal of Marine Science volume 71, issue 5, page 1107-1116 ISSN 1095-9289 1054-3139 |
op_doi |
https://doi.org/10.1093/icesjms/fst208 |
container_title |
ICES Journal of Marine Science |
container_volume |
71 |
container_issue |
5 |
container_start_page |
1107 |
op_container_end_page |
1116 |
_version_ |
1797580638581161984 |