Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls
Thesis (M. Sc.)--Memorial University of Newfoundland, 1998. Biopsychology Bibliography: leaves p. 71-84 Identifying and measuring the factors that affect the catchability of otter trawl fishing gear has been the subject of much research in recent years. Variation in catching efficiency is known to b...
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ftmemorialunivdc:oai:collections.mun.ca:theses3/181710 2023-05-15T15:27:18+02:00 Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls Winger, Paul D., 1972- Memorial University of Newfoundland. Biopsychology Programme 1998 89 leaves : ill. Image/jpeg; Application/pdf http://collections.mun.ca/cdm/ref/collection/theses3/id/181710 eng eng Electronic Theses and Dissertations (10.94 MB) -- http://collections.mun.ca/PDFs/theses/Winger_PaulD.pdf a1321221 http://collections.mun.ca/cdm/ref/collection/theses3/id/181710 The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries Plaice American--Locomotion Atlantic cod--Locomotion Trawls and trawling--Catch effort Text Electronic thesis or dissertation 1998 ftmemorialunivdc 2015-08-06T19:20:44Z Thesis (M. Sc.)--Memorial University of Newfoundland, 1998. Biopsychology Bibliography: leaves p. 71-84 Identifying and measuring the factors that affect the catchability of otter trawl fishing gear has been the subject of much research in recent years. Variation in catching efficiency is known to be associated with changes in the vulnerability offish to trawl capture. In particular, the swimming capability offish in response to an approaching trawl plays an important role in detennining the likelihood of successful capture. In order to quantify the efficiency of the capture process, knowledge of the swimming endurance of marine groundfish species is necessary. The purpose of this study was to investigate factors affecting the swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) under laboratory conditions. The effects offish length, water temperature and swimming speed were examined using a swimming flume. The data were analyzed using failure time (survival) analysis, a more robust statistical technique for endurance-type data when censored observations require consideration. -- Swimming trials for plaice were conducted across a range offish lengths (14 to 44 cm) and water temperatures (-0.2 to 9.7 C) at a swimming speed of 0.30 m/s. The probability of plaice achieving a given endurance was found to significantly improve with increasing fish length and water temperature. The findings indicate that the herding of plaice by otter trawl sweeps may be size- and temperature-dependent. At low temperatures, small plaice are expected to have a lower probability of sufficient endurance required to reach the path of an approaching trawl, thereby experience a greater likelihood of escaping capture. -- Swimming trials for cod were conducted across a range offish lengths (41 to 86 cm), water temperatures (0.0 to 9.8 C) and swimming speeds (0.60 to 1.30 m/s). Swimming speed was the only factor found to significantly affect the endurance of cod. The probability of achieving a given endurance was found to decrease rapidly with increasing swimming speed. The findings indicate that even small changes in the speed of a trawl through the water could dramatically affect the rate of exhaustion, i.e. turn-over rate, of cod swimming in the mouth of a trawl. Thesis atlantic cod Gadus morhua Newfoundland studies University of Newfoundland Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
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Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
op_collection_id |
ftmemorialunivdc |
language |
English |
topic |
Plaice American--Locomotion Atlantic cod--Locomotion Trawls and trawling--Catch effort |
spellingShingle |
Plaice American--Locomotion Atlantic cod--Locomotion Trawls and trawling--Catch effort Winger, Paul D., 1972- Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
topic_facet |
Plaice American--Locomotion Atlantic cod--Locomotion Trawls and trawling--Catch effort |
description |
Thesis (M. Sc.)--Memorial University of Newfoundland, 1998. Biopsychology Bibliography: leaves p. 71-84 Identifying and measuring the factors that affect the catchability of otter trawl fishing gear has been the subject of much research in recent years. Variation in catching efficiency is known to be associated with changes in the vulnerability offish to trawl capture. In particular, the swimming capability offish in response to an approaching trawl plays an important role in detennining the likelihood of successful capture. In order to quantify the efficiency of the capture process, knowledge of the swimming endurance of marine groundfish species is necessary. The purpose of this study was to investigate factors affecting the swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) under laboratory conditions. The effects offish length, water temperature and swimming speed were examined using a swimming flume. The data were analyzed using failure time (survival) analysis, a more robust statistical technique for endurance-type data when censored observations require consideration. -- Swimming trials for plaice were conducted across a range offish lengths (14 to 44 cm) and water temperatures (-0.2 to 9.7 C) at a swimming speed of 0.30 m/s. The probability of plaice achieving a given endurance was found to significantly improve with increasing fish length and water temperature. The findings indicate that the herding of plaice by otter trawl sweeps may be size- and temperature-dependent. At low temperatures, small plaice are expected to have a lower probability of sufficient endurance required to reach the path of an approaching trawl, thereby experience a greater likelihood of escaping capture. -- Swimming trials for cod were conducted across a range offish lengths (41 to 86 cm), water temperatures (0.0 to 9.8 C) and swimming speeds (0.60 to 1.30 m/s). Swimming speed was the only factor found to significantly affect the endurance of cod. The probability of achieving a given endurance was found to decrease rapidly with increasing swimming speed. The findings indicate that even small changes in the speed of a trawl through the water could dramatically affect the rate of exhaustion, i.e. turn-over rate, of cod swimming in the mouth of a trawl. |
author2 |
Memorial University of Newfoundland. Biopsychology Programme |
format |
Thesis |
author |
Winger, Paul D., 1972- |
author_facet |
Winger, Paul D., 1972- |
author_sort |
Winger, Paul D., 1972- |
title |
Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
title_short |
Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
title_full |
Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
title_fullStr |
Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
title_full_unstemmed |
Swimming endurance of American plaice (Hippoglossoides platessoides) and Atlantic cod (Gadus morhua) : implications for catchability by otter trawls |
title_sort |
swimming endurance of american plaice (hippoglossoides platessoides) and atlantic cod (gadus morhua) : implications for catchability by otter trawls |
publishDate |
1998 |
url |
http://collections.mun.ca/cdm/ref/collection/theses3/id/181710 |
genre |
atlantic cod Gadus morhua Newfoundland studies University of Newfoundland |
genre_facet |
atlantic cod Gadus morhua Newfoundland studies University of Newfoundland |
op_source |
Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries |
op_relation |
Electronic Theses and Dissertations (10.94 MB) -- http://collections.mun.ca/PDFs/theses/Winger_PaulD.pdf a1321221 http://collections.mun.ca/cdm/ref/collection/theses3/id/181710 |
op_rights |
The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. |
_version_ |
1766357742182727680 |