Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass
In September after summer feeding has ceased, Northeast Atlantic mackerel (Scomber scombrus) tend to aggregate in ICES Area IVa before starting to migrate south towards the spawning grounds, between December and February. During this autumn period, the Norwegian purse-seine fleet catches mackerel in...
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Language: | English |
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Oxford University Press
2007
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Online Access: | http://hdl.handle.net/11250/108416 https://doi.org/10.1093/icesjms/fsm070 |
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ftimr:oai:imr.brage.unit.no:11250/108416 2024-09-15T18:25:28+00:00 Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass Slotte, Aril Skagen, Dankert W. Iversen, Svein A. 2007-04 application/pdf http://hdl.handle.net/11250/108416 https://doi.org/10.1093/icesjms/fsm070 eng eng Oxford University Press urn:issn:1054-3139 http://hdl.handle.net/11250/108416 http://dx.doi.org/10.1093/icesjms/fsm070 989-994 64 ICES Journal of Marine Science 5 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 Journal article Peer reviewed 2007 ftimr https://doi.org/10.1093/icesjms/fsm070 2024-07-31T03:37:25Z In September after summer feeding has ceased, Northeast Atlantic mackerel (Scomber scombrus) tend to aggregate in ICES Area IVa before starting to migrate south towards the spawning grounds, between December and February. During this autumn period, the Norwegian purse-seine fleet catches mackerel in the southern part of the Norwegian Sea and the northern part of the North Sea. Between 1999 and 2005, Norway’s Institute for Marine Research carried out annual acoustic surveys on a research vessel capable of trawling, to estimate the biomass concurrently with the fishery. During the surveys, mackerel were sampled with pelagic trawls (486 and 538 m circumference) at an average speed of 3.5–4 knots, and age, length, and weight was determined for use in biomass estimation. Mackerel age, length, weight, length-at-age, and weight-at-length (condition) in trawl catches were all significantly lower than observed in purse-seine catches from nearby commercial vessels, indicating that the research trawl selects younger, smaller, and perhaps weaker, fish. This finding has a significant influence on acoustic estimation of abundance of mackerel. Using data from purse-seine-caught mackerel instead of those caught in the trawl, the estimated total number of mackerel in the area of operation decreased by an average of 26.4%, and concurrent estimates of total biomass increased by an average of 32.2%. The results raise the importance of awareness of the differences in applying trawl samples to estimate year-class abundance and biomass and to study variations in growth and condition of fast-swimming species such as mackerel. Article in Journal/Newspaper Northeast Atlantic Norwegian Sea Institute for Marine Research: Brage IMR ICES Journal of Marine Science 64 5 989 994 |
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Open Polar |
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Institute for Marine Research: Brage IMR |
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language |
English |
topic |
VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 |
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VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 Slotte, Aril Skagen, Dankert W. Iversen, Svein A. Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
topic_facet |
VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 |
description |
In September after summer feeding has ceased, Northeast Atlantic mackerel (Scomber scombrus) tend to aggregate in ICES Area IVa before starting to migrate south towards the spawning grounds, between December and February. During this autumn period, the Norwegian purse-seine fleet catches mackerel in the southern part of the Norwegian Sea and the northern part of the North Sea. Between 1999 and 2005, Norway’s Institute for Marine Research carried out annual acoustic surveys on a research vessel capable of trawling, to estimate the biomass concurrently with the fishery. During the surveys, mackerel were sampled with pelagic trawls (486 and 538 m circumference) at an average speed of 3.5–4 knots, and age, length, and weight was determined for use in biomass estimation. Mackerel age, length, weight, length-at-age, and weight-at-length (condition) in trawl catches were all significantly lower than observed in purse-seine catches from nearby commercial vessels, indicating that the research trawl selects younger, smaller, and perhaps weaker, fish. This finding has a significant influence on acoustic estimation of abundance of mackerel. Using data from purse-seine-caught mackerel instead of those caught in the trawl, the estimated total number of mackerel in the area of operation decreased by an average of 26.4%, and concurrent estimates of total biomass increased by an average of 32.2%. The results raise the importance of awareness of the differences in applying trawl samples to estimate year-class abundance and biomass and to study variations in growth and condition of fast-swimming species such as mackerel. |
format |
Article in Journal/Newspaper |
author |
Slotte, Aril Skagen, Dankert W. Iversen, Svein A. |
author_facet |
Slotte, Aril Skagen, Dankert W. Iversen, Svein A. |
author_sort |
Slotte, Aril |
title |
Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
title_short |
Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
title_full |
Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
title_fullStr |
Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
title_full_unstemmed |
Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
title_sort |
size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass |
publisher |
Oxford University Press |
publishDate |
2007 |
url |
http://hdl.handle.net/11250/108416 https://doi.org/10.1093/icesjms/fsm070 |
genre |
Northeast Atlantic Norwegian Sea |
genre_facet |
Northeast Atlantic Norwegian Sea |
op_source |
989-994 64 ICES Journal of Marine Science 5 |
op_relation |
urn:issn:1054-3139 http://hdl.handle.net/11250/108416 http://dx.doi.org/10.1093/icesjms/fsm070 |
op_doi |
https://doi.org/10.1093/icesjms/fsm070 |
container_title |
ICES Journal of Marine Science |
container_volume |
64 |
container_issue |
5 |
container_start_page |
989 |
op_container_end_page |
994 |
_version_ |
1810465979023491072 |