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://hdl.handle.net/11250/108492 https://doi.org/10.1139/F04-128 |
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ftimr:oai:imr.brage.unit.no:11250/108492 2024-09-15T17:52:27+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, Natalia A. Ajiad, Adnan Mosa Gusev, Evgeny 2004 895814 bytes application/pdf http://hdl.handle.net/11250/108492 https://doi.org/10.1139/F04-128 eng eng urn:issn:0706-652X http://hdl.handle.net/11250/108492 http://dx.doi.org/10.1139/F04-128 1900-1917 61 Canadian Journal of Fisheries and Aquatic Sciences 10 cod arctic cod torsk mortality herring sild dødelighet arktisk torsk Journal article Peer reviewed 2004 ftimr https://doi.org/10.1139/F04-128 2024-07-31T03:37:25Z 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 (1946-2001) 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 weight-length relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30-120 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 Arktis* Barents Sea Gadus morhua Northeast Arctic cod Institute for Marine Research: Brage IMR Canadian Journal of Fisheries and Aquatic Sciences 61 10 1900 1917 |
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Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
cod arctic cod torsk mortality herring sild dødelighet arktisk torsk |
spellingShingle |
cod arctic cod torsk mortality herring sild dødelighet arktisk torsk Marshall, C. Tara Needle, Coby L. Yaragina, Natalia A. Ajiad, Adnan Mosa Gusev, Evgeny Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves |
topic_facet |
cod arctic cod torsk mortality herring sild dødelighet arktisk torsk |
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 (1946-2001) 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 weight-length relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30-120 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, Natalia A. Ajiad, Adnan Mosa Gusev, Evgeny |
author_facet |
Marshall, C. Tara Needle, Coby L. Yaragina, Natalia A. Ajiad, Adnan Mosa 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 |
publishDate |
2004 |
url |
http://hdl.handle.net/11250/108492 https://doi.org/10.1139/F04-128 |
genre |
Arctic cod Arktis* Barents Sea Gadus morhua Northeast Arctic cod |
genre_facet |
Arctic cod Arktis* Barents Sea Gadus morhua Northeast Arctic cod |
op_source |
1900-1917 61 Canadian Journal of Fisheries and Aquatic Sciences 10 |
op_relation |
urn:issn:0706-652X http://hdl.handle.net/11250/108492 http://dx.doi.org/10.1139/F04-128 |
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_ |
1810294477380648960 |