Effect of foraging activity on the shoal structure of cod ( Gadus morhua )
Acoustic methods used to quantify the shoaling dynamics of Atlantic cod (Gadus morhua) during their shoreward migration across the northeast Newfoundland shelf (spring 1992) showed that shoal structure and horizontal displacement were associated with the density distribution of small pelagic scatter...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1995
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1139/f95-830 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-830 |
id |
crcansciencepubl:10.1139/f95-830 |
---|---|
record_format |
openpolar |
spelling |
crcansciencepubl:10.1139/f95-830 2023-12-17T10:27:04+01:00 Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) DeBlois, E. M. Rose, G. A. 1995 http://dx.doi.org/10.1139/f95-830 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-830 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Fisheries and Aquatic Sciences volume 52, issue 11, page 2377-2387 ISSN 0706-652X 1205-7533 Aquatic Science Ecology, Evolution, Behavior and Systematics journal-article 1995 crcansciencepubl https://doi.org/10.1139/f95-830 2023-11-19T13:38:56Z Acoustic methods used to quantify the shoaling dynamics of Atlantic cod (Gadus morhua) during their shoreward migration across the northeast Newfoundland shelf (spring 1992) showed that shoal structure and horizontal displacement were associated with the density distribution of small pelagic scatterers, for example, shrimp (Pandalus borealis). Cod speeds (to 20 km/d) were lower after encounters with shrimp (4–7 km/d). The relationship between several characteristics of the cod shoal (density, vertical spread, height off the bottom) and shrimp density was dome shaped. Internal shoal densities declined and shoal spread and height increased until shrimp densities surpassed a critical level. Above this threshold, these trends were reversed. The vertical spread of the cod shoal matched that of shrimp up to, but not beyond, a shrimp spread of 85 m. At this observed maximum in the expansion of the shoal, fish were eight body lengths apart. At all times during our survey, cod stayed within the warmer waters (> 2 °C) found at depths greater than 250 m. Our results are the first field verification of theoretical predictions and laboratory findings that shoals expand and contract in response to foraging activity and demonstrate the potential importance of cod aggregation dynamics to interpretations of trawl data. Article in Journal/Newspaper atlantic cod Gadus morhua Newfoundland Pandalus borealis Canadian Science Publishing (via Crossref) Northeast Newfoundland Shelf ENVELOPE(-52.500,-52.500,51.000,51.000) Canadian Journal of Fisheries and Aquatic Sciences 52 11 2377 2387 |
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 DeBlois, E. M. Rose, G. A. Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
topic_facet |
Aquatic Science Ecology, Evolution, Behavior and Systematics |
description |
Acoustic methods used to quantify the shoaling dynamics of Atlantic cod (Gadus morhua) during their shoreward migration across the northeast Newfoundland shelf (spring 1992) showed that shoal structure and horizontal displacement were associated with the density distribution of small pelagic scatterers, for example, shrimp (Pandalus borealis). Cod speeds (to 20 km/d) were lower after encounters with shrimp (4–7 km/d). The relationship between several characteristics of the cod shoal (density, vertical spread, height off the bottom) and shrimp density was dome shaped. Internal shoal densities declined and shoal spread and height increased until shrimp densities surpassed a critical level. Above this threshold, these trends were reversed. The vertical spread of the cod shoal matched that of shrimp up to, but not beyond, a shrimp spread of 85 m. At this observed maximum in the expansion of the shoal, fish were eight body lengths apart. At all times during our survey, cod stayed within the warmer waters (> 2 °C) found at depths greater than 250 m. Our results are the first field verification of theoretical predictions and laboratory findings that shoals expand and contract in response to foraging activity and demonstrate the potential importance of cod aggregation dynamics to interpretations of trawl data. |
format |
Article in Journal/Newspaper |
author |
DeBlois, E. M. Rose, G. A. |
author_facet |
DeBlois, E. M. Rose, G. A. |
author_sort |
DeBlois, E. M. |
title |
Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
title_short |
Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
title_full |
Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
title_fullStr |
Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
title_full_unstemmed |
Effect of foraging activity on the shoal structure of cod ( Gadus morhua ) |
title_sort |
effect of foraging activity on the shoal structure of cod ( gadus morhua ) |
publisher |
Canadian Science Publishing |
publishDate |
1995 |
url |
http://dx.doi.org/10.1139/f95-830 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-830 |
long_lat |
ENVELOPE(-52.500,-52.500,51.000,51.000) |
geographic |
Northeast Newfoundland Shelf |
geographic_facet |
Northeast Newfoundland Shelf |
genre |
atlantic cod Gadus morhua Newfoundland Pandalus borealis |
genre_facet |
atlantic cod Gadus morhua Newfoundland Pandalus borealis |
op_source |
Canadian Journal of Fisheries and Aquatic Sciences volume 52, issue 11, page 2377-2387 ISSN 0706-652X 1205-7533 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f95-830 |
container_title |
Canadian Journal of Fisheries and Aquatic Sciences |
container_volume |
52 |
container_issue |
11 |
container_start_page |
2377 |
op_container_end_page |
2387 |
_version_ |
1785578854141657088 |