Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation
We tested for density-dependent changes in growth and maturation of Northwest Atlantic porbeagle (Lamna nasus) after the population declined by 75%–80% from fishing. Vertebrae and reproductive data collected from the virgin (1961–1966) and exploited (1993–2004) populations were analysed to test for...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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2007
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Online Access: | http://dx.doi.org/10.1139/f06-167 http://www.nrcresearchpress.com/doi/pdf/10.1139/f06-167 |
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crcansciencepubl:10.1139/f06-167 2023-12-17T10:33:05+01:00 Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation Cassoff, Rachel M Campana, Steven E Myklevoll, Sigmund 2007 http://dx.doi.org/10.1139/f06-167 http://www.nrcresearchpress.com/doi/pdf/10.1139/f06-167 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Fisheries and Aquatic Sciences volume 64, issue 1, page 19-29 ISSN 0706-652X 1205-7533 Aquatic Science Ecology, Evolution, Behavior and Systematics journal-article 2007 crcansciencepubl https://doi.org/10.1139/f06-167 2023-11-19T13:38:41Z We tested for density-dependent changes in growth and maturation of Northwest Atlantic porbeagle (Lamna nasus) after the population declined by 75%–80% from fishing. Vertebrae and reproductive data collected from the virgin (1961–1966) and exploited (1993–2004) populations were analysed to test for differences in growth rate and age and length at maturity between the time periods. We detected significant differences between reparameterized von Bertalanffy growth models for each period, using likelihood ratio tests. Beyond an age of 7 years, mean length at age was greater during 1993–2004 than during 1961–1966. Between 1961–1963 and 1999–2001, length at maturity decreased in males (from 179 to 174 cm curved fork length (CFL)) and was invariant in females (216 cm CFL), whereas age at maturity declined in both males (from 8 to 7 years) and females (from 19 to 14 years). An analysis of porbeagle temperature associations indicated that sharks occupied comparable temperature conditions during the mid-1960s and 1990s, ruling out the possibility of temperature-induced growth changes. The observed increase in growth rate and decrease in age at maturity following exploitation support the hypothesis of a compensatory density-dependent growth response. Article in Journal/Newspaper Lamna nasus Northwest Atlantic Porbeagle Canadian Science Publishing (via Crossref) Canadian Journal of Fisheries and Aquatic Sciences 64 1 19 29 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
Aquatic Science Ecology, Evolution, Behavior and Systematics |
spellingShingle |
Aquatic Science Ecology, Evolution, Behavior and Systematics Cassoff, Rachel M Campana, Steven E Myklevoll, Sigmund Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
topic_facet |
Aquatic Science Ecology, Evolution, Behavior and Systematics |
description |
We tested for density-dependent changes in growth and maturation of Northwest Atlantic porbeagle (Lamna nasus) after the population declined by 75%–80% from fishing. Vertebrae and reproductive data collected from the virgin (1961–1966) and exploited (1993–2004) populations were analysed to test for differences in growth rate and age and length at maturity between the time periods. We detected significant differences between reparameterized von Bertalanffy growth models for each period, using likelihood ratio tests. Beyond an age of 7 years, mean length at age was greater during 1993–2004 than during 1961–1966. Between 1961–1963 and 1999–2001, length at maturity decreased in males (from 179 to 174 cm curved fork length (CFL)) and was invariant in females (216 cm CFL), whereas age at maturity declined in both males (from 8 to 7 years) and females (from 19 to 14 years). An analysis of porbeagle temperature associations indicated that sharks occupied comparable temperature conditions during the mid-1960s and 1990s, ruling out the possibility of temperature-induced growth changes. The observed increase in growth rate and decrease in age at maturity following exploitation support the hypothesis of a compensatory density-dependent growth response. |
format |
Article in Journal/Newspaper |
author |
Cassoff, Rachel M Campana, Steven E Myklevoll, Sigmund |
author_facet |
Cassoff, Rachel M Campana, Steven E Myklevoll, Sigmund |
author_sort |
Cassoff, Rachel M |
title |
Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
title_short |
Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
title_full |
Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
title_fullStr |
Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
title_full_unstemmed |
Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus , following heavy exploitation |
title_sort |
changes in baseline growth and maturation parameters of northwest atlantic porbeagle, lamna nasus , following heavy exploitation |
publisher |
Canadian Science Publishing |
publishDate |
2007 |
url |
http://dx.doi.org/10.1139/f06-167 http://www.nrcresearchpress.com/doi/pdf/10.1139/f06-167 |
genre |
Lamna nasus Northwest Atlantic Porbeagle |
genre_facet |
Lamna nasus Northwest Atlantic Porbeagle |
op_source |
Canadian Journal of Fisheries and Aquatic Sciences volume 64, issue 1, page 19-29 ISSN 0706-652X 1205-7533 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f06-167 |
container_title |
Canadian Journal of Fisheries and Aquatic Sciences |
container_volume |
64 |
container_issue |
1 |
container_start_page |
19 |
op_container_end_page |
29 |
_version_ |
1785586969327173632 |