Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence
For each year from 1971 to 1991 and age from 3 to 8+, we estimated catchability of Atlantic cod ( Gadus morchua ) to an otter-trawl fishery (q) and a research survey (k) using SPA-based abundance estimates (N) and catch rates to the fishery (U) or survey (R). q tended to be highest early in the time...
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Oxford University Press
1994
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fthighwire:oai:open-archive.highwire.org:icesjms:51/4/493 2023-05-15T15:27:22+02:00 Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence Swain, D. P. Nielsen, G. A. Sinclair, A. F. Chouinard, G. A. 1994-08-01 00:00:00.0 text/html http://icesjms.oxfordjournals.org/cgi/content/short/51/4/493 https://doi.org/10.1006/jmsc.1994.1050 en eng Oxford University Press http://icesjms.oxfordjournals.org/cgi/content/short/51/4/493 http://dx.doi.org/10.1006/jmsc.1994.1050 Copyright (C) 1994, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer Articles TEXT 1994 fthighwire https://doi.org/10.1006/jmsc.1994.1050 2013-05-26T14:08:25Z For each year from 1971 to 1991 and age from 3 to 8+, we estimated catchability of Atlantic cod ( Gadus morchua ) to an otter-trawl fishery (q) and a research survey (k) using SPA-based abundance estimates (N) and catch rates to the fishery (U) or survey (R). q tended to be highest early in the time series for young cod (ages 3 and 4), late in the time series for old cod (ages 7 and 8+), and at the two extremes of the time series for cod of intermediate ages (5 and 6). k tended to be higher later in the time series for all ages of cod. We tested for density dependence of q and k by comparing InU or InR to InN. The slope of the regression of InU versus InN was significantly less than 1.0 for ages 3 to 5 and greater than 1.0 for ages 8+, indicating an inverse relationship between q and N for the younger ages and a positive relationship for the older age. The slope of the regression of InR on InN was significantly greater than 1.0 for ages 5 to 7, indicating a positive relationship between k and N for these ages of cod. An SPA calibration model assuming a non-linear relationship between catch rate and abundance led to the same conclusions about the density dependence of q and k. We discuss possible causes of these apparent changes in q and k, and relate density-dependent changes in k to previous reports of density-depedent changes in spatial distribution for this population. Text atlantic cod Gadus morhua HighWire Press (Stanford University) ICES Journal of Marine Science 51 4 493 504 |
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English |
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Articles |
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Articles Swain, D. P. Nielsen, G. A. Sinclair, A. F. Chouinard, G. A. Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
topic_facet |
Articles |
description |
For each year from 1971 to 1991 and age from 3 to 8+, we estimated catchability of Atlantic cod ( Gadus morchua ) to an otter-trawl fishery (q) and a research survey (k) using SPA-based abundance estimates (N) and catch rates to the fishery (U) or survey (R). q tended to be highest early in the time series for young cod (ages 3 and 4), late in the time series for old cod (ages 7 and 8+), and at the two extremes of the time series for cod of intermediate ages (5 and 6). k tended to be higher later in the time series for all ages of cod. We tested for density dependence of q and k by comparing InU or InR to InN. The slope of the regression of InU versus InN was significantly less than 1.0 for ages 3 to 5 and greater than 1.0 for ages 8+, indicating an inverse relationship between q and N for the younger ages and a positive relationship for the older age. The slope of the regression of InR on InN was significantly greater than 1.0 for ages 5 to 7, indicating a positive relationship between k and N for these ages of cod. An SPA calibration model assuming a non-linear relationship between catch rate and abundance led to the same conclusions about the density dependence of q and k. We discuss possible causes of these apparent changes in q and k, and relate density-dependent changes in k to previous reports of density-depedent changes in spatial distribution for this population. |
format |
Text |
author |
Swain, D. P. Nielsen, G. A. Sinclair, A. F. Chouinard, G. A. |
author_facet |
Swain, D. P. Nielsen, G. A. Sinclair, A. F. Chouinard, G. A. |
author_sort |
Swain, D. P. |
title |
Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
title_short |
Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
title_full |
Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
title_fullStr |
Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
title_full_unstemmed |
Changes in catchability of Atlantic cod (Gadus morhua) to an otter-trawl fishery and research survey in the southern Gulf of St Lawrence |
title_sort |
changes in catchability of atlantic cod (gadus morhua) to an otter-trawl fishery and research survey in the southern gulf of st lawrence |
publisher |
Oxford University Press |
publishDate |
1994 |
url |
http://icesjms.oxfordjournals.org/cgi/content/short/51/4/493 https://doi.org/10.1006/jmsc.1994.1050 |
genre |
atlantic cod Gadus morhua |
genre_facet |
atlantic cod Gadus morhua |
op_relation |
http://icesjms.oxfordjournals.org/cgi/content/short/51/4/493 http://dx.doi.org/10.1006/jmsc.1994.1050 |
op_rights |
Copyright (C) 1994, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer |
op_doi |
https://doi.org/10.1006/jmsc.1994.1050 |
container_title |
ICES Journal of Marine Science |
container_volume |
51 |
container_issue |
4 |
container_start_page |
493 |
op_container_end_page |
504 |
_version_ |
1766357808516694016 |