Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves
To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easi...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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Online Access: | http://dx.doi.org/10.1139/f04-128 http://www.nrcresearchpress.com/doi/pdf/10.1139/f04-128 |
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crcansciencepubl:10.1139/f04-128 2024-09-09T19:17:18+00:00 Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves Marshall, C Tara Needle, Coby L Yaragina, Nathalia A Ajiad, Adnan M Gusev, Evgeny 2004 http://dx.doi.org/10.1139/f04-128 http://www.nrcresearchpress.com/doi/pdf/10.1139/f04-128 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Fisheries and Aquatic Sciences volume 61, issue 10, page 1900-1917 ISSN 0706-652X 1205-7533 journal-article 2004 crcansciencepubl https://doi.org/10.1139/f04-128 2024-06-20T04:11:55Z To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easily accessible. For each year in a 56-year time series (19462001) for Northeast Arctic cod (Gadus morhua), pseudo-observations of weight and length were generated by pairing the Norwegian and Russian values for weight-at-age provided annually to the assessment working group with estimates of length-at-age derived from the same databases. A weightlength relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30120 cm). This index was uncorrelated with both the liver condition index and the abundance of Barents Sea capelin (Mallotus villosus), suggesting that at the stock level, the girth of cod is not necessarily indicative of the magnitude of stored energy reserves. Partitioning body size into length-at-age and girth revealed long-term trends in body size. In particular, large/old cod showed substantially higher values of both length-at-age and girth that could be the result of long-term increases in fishing mortality. Article in Journal/Newspaper Arctic cod Arctic Barents Sea Gadus morhua Northeast Arctic cod Canadian Science Publishing Arctic Barents Sea Canadian Journal of Fisheries and Aquatic Sciences 61 10 1900 1917 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easily accessible. For each year in a 56-year time series (19462001) for Northeast Arctic cod (Gadus morhua), pseudo-observations of weight and length were generated by pairing the Norwegian and Russian values for weight-at-age provided annually to the assessment working group with estimates of length-at-age derived from the same databases. A weightlength relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30120 cm). This index was uncorrelated with both the liver condition index and the abundance of Barents Sea capelin (Mallotus villosus), suggesting that at the stock level, the girth of cod is not necessarily indicative of the magnitude of stored energy reserves. Partitioning body size into length-at-age and girth revealed long-term trends in body size. In particular, large/old cod showed substantially higher values of both length-at-age and girth that could be the result of long-term increases in fishing mortality. |
format |
Article in Journal/Newspaper |
author |
Marshall, C Tara Needle, Coby L Yaragina, Nathalia A Ajiad, Adnan M Gusev, Evgeny |
spellingShingle |
Marshall, C Tara Needle, Coby L Yaragina, Nathalia A Ajiad, Adnan M Gusev, Evgeny Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
author_facet |
Marshall, C Tara Needle, Coby L Yaragina, Nathalia A Ajiad, Adnan M Gusev, Evgeny |
author_sort |
Marshall, C Tara |
title |
Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
title_short |
Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
title_full |
Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
title_fullStr |
Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
title_full_unstemmed |
Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
title_sort |
deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
publisher |
Canadian Science Publishing |
publishDate |
2004 |
url |
http://dx.doi.org/10.1139/f04-128 http://www.nrcresearchpress.com/doi/pdf/10.1139/f04-128 |
geographic |
Arctic Barents Sea |
geographic_facet |
Arctic Barents Sea |
genre |
Arctic cod Arctic Barents Sea Gadus morhua Northeast Arctic cod |
genre_facet |
Arctic cod Arctic Barents Sea Gadus morhua Northeast Arctic cod |
op_source |
Canadian Journal of Fisheries and Aquatic Sciences volume 61, issue 10, page 1900-1917 ISSN 0706-652X 1205-7533 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f04-128 |
container_title |
Canadian Journal of Fisheries and Aquatic Sciences |
container_volume |
61 |
container_issue |
10 |
container_start_page |
1900 |
op_container_end_page |
1917 |
_version_ |
1809757307098103808 |