Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density
Background and aims: Early environmental conditions are known to influence the phenotypic development of animals, including behavioural alterations. The overall aim of this thesis is to investigate the effects of density, social stability and structural complexity on growth, behaviour, and survival...
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ftunivgoeteborg:oai:gupea.ub.gu.se:2077/21127 2023-10-29T02:35:05+01:00 Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density Brockmark, Sofia 2010-01-10T13:41:41Z application/pdf http://hdl.handle.net/2077/21127 eng eng Paper I. Griffiths SW, Brockmark S, Höjesjö J and Johnsson JI 2004. Coping with divided attention: the advantage of familiarity. Proceedings of the Royal Society of London B 271:695-699.::doi::10.1098/rspb.2003.2648 Paper II. Brockmark S and Johnsson JI, in press. Reduced hatchery rearing density increases social dominance, post-release growth and survival in brown trout (Salmo trutta). Canadian Journal of Fisheries and Aquatic Sciences. Paper III. Brockmark S, Adriaenssens B and Johnsson JI. Less is more: density influences the development of behavioural life skills in trout. Manuscript. Brockmark S, Neregård L, Bohlin T, Björnsson B Th and Johnsson JI 2007. Effects of rearing density and structural complexity on the pre- and post-release performance of Atlantic salmon. Transactions of the American Fisheries Society 136:1453-1462.::doi::10.1577/T06-245.1 978-91-628-7971-6 http://hdl.handle.net/2077/21127 rearing density structural complexity familiarity antipredator response limited attention social status growth rate smolt status fin erosion post-release performance hatchery supplementation brown trout Atlantic salmon Text Doctoral Theses Doctor of Philosophy 2010 ftunivgoeteborg 2023-10-04T21:08:37Z Background and aims: Early environmental conditions are known to influence the phenotypic development of animals, including behavioural alterations. The overall aim of this thesis is to investigate the effects of density, social stability and structural complexity on growth, behaviour, and survival in the wild, using juvenile brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) as model species. The result can add to the basic knowledge in this research area and can also be used to enhance the welfare and fitness of released hatchery-reared fish. Methods: In papers II-IV sea-ranched trout and salmon were reared from early life stage in conventional hatchery tanks with modified physical structure and/or density. Hatchery fish were measured for growth, studied for individual and social behaviours, and analysed for fin-erosions and smolt-status. In paper I wild-caught juvenile trout were used for behavioural studies. In papers II-IV fish from different treatment groups were also released in natural streams to investigate treatment effects on survival and growth in the wild. Results and conclusions: My results collectively show clear positive effects of reduced rearing density, whereas the effects of structure were unclear and harder to interpret. In papers II-IV reduction of conventional hatchery densities generally increased growth rate in the hatchery and post-release survival. Salmonids reared at reduced densities were more dominant in competition for food, consumed more novel prey, escaped faster to refuges after a predator attack and located more food in a maze, compared to fish from higher densities. At time of parr-smolt transformation, salmon reared at reduced densities had less fin erosions and were more fully smolted than salmon reared at higher densities. Taken together, the results presented in this thesis clearly show that reduced rearing densities facilitate the development of adaptive individual and social behaviour in salmonids, resulting in increased growth and survival after release in ... Doctoral or Postdoctoral Thesis Atlantic salmon Salmo salar University of Gothenburg: GUPEA (Gothenburg University Publications Electronic Archive) |
institution |
Open Polar |
collection |
University of Gothenburg: GUPEA (Gothenburg University Publications Electronic Archive) |
op_collection_id |
ftunivgoeteborg |
language |
English |
topic |
rearing density structural complexity familiarity antipredator response limited attention social status growth rate smolt status fin erosion post-release performance hatchery supplementation brown trout Atlantic salmon |
spellingShingle |
rearing density structural complexity familiarity antipredator response limited attention social status growth rate smolt status fin erosion post-release performance hatchery supplementation brown trout Atlantic salmon Brockmark, Sofia Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
topic_facet |
rearing density structural complexity familiarity antipredator response limited attention social status growth rate smolt status fin erosion post-release performance hatchery supplementation brown trout Atlantic salmon |
description |
Background and aims: Early environmental conditions are known to influence the phenotypic development of animals, including behavioural alterations. The overall aim of this thesis is to investigate the effects of density, social stability and structural complexity on growth, behaviour, and survival in the wild, using juvenile brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) as model species. The result can add to the basic knowledge in this research area and can also be used to enhance the welfare and fitness of released hatchery-reared fish. Methods: In papers II-IV sea-ranched trout and salmon were reared from early life stage in conventional hatchery tanks with modified physical structure and/or density. Hatchery fish were measured for growth, studied for individual and social behaviours, and analysed for fin-erosions and smolt-status. In paper I wild-caught juvenile trout were used for behavioural studies. In papers II-IV fish from different treatment groups were also released in natural streams to investigate treatment effects on survival and growth in the wild. Results and conclusions: My results collectively show clear positive effects of reduced rearing density, whereas the effects of structure were unclear and harder to interpret. In papers II-IV reduction of conventional hatchery densities generally increased growth rate in the hatchery and post-release survival. Salmonids reared at reduced densities were more dominant in competition for food, consumed more novel prey, escaped faster to refuges after a predator attack and located more food in a maze, compared to fish from higher densities. At time of parr-smolt transformation, salmon reared at reduced densities had less fin erosions and were more fully smolted than salmon reared at higher densities. Taken together, the results presented in this thesis clearly show that reduced rearing densities facilitate the development of adaptive individual and social behaviour in salmonids, resulting in increased growth and survival after release in ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Brockmark, Sofia |
author_facet |
Brockmark, Sofia |
author_sort |
Brockmark, Sofia |
title |
Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
title_short |
Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
title_full |
Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
title_fullStr |
Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
title_full_unstemmed |
Environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
title_sort |
environmental influences on the behavioural ecology of juvenile salmonids – the importance of rearing density |
publishDate |
2010 |
url |
http://hdl.handle.net/2077/21127 |
genre |
Atlantic salmon Salmo salar |
genre_facet |
Atlantic salmon Salmo salar |
op_relation |
Paper I. Griffiths SW, Brockmark S, Höjesjö J and Johnsson JI 2004. Coping with divided attention: the advantage of familiarity. Proceedings of the Royal Society of London B 271:695-699.::doi::10.1098/rspb.2003.2648 Paper II. Brockmark S and Johnsson JI, in press. Reduced hatchery rearing density increases social dominance, post-release growth and survival in brown trout (Salmo trutta). Canadian Journal of Fisheries and Aquatic Sciences. Paper III. Brockmark S, Adriaenssens B and Johnsson JI. Less is more: density influences the development of behavioural life skills in trout. Manuscript. Brockmark S, Neregård L, Bohlin T, Björnsson B Th and Johnsson JI 2007. Effects of rearing density and structural complexity on the pre- and post-release performance of Atlantic salmon. Transactions of the American Fisheries Society 136:1453-1462.::doi::10.1577/T06-245.1 978-91-628-7971-6 http://hdl.handle.net/2077/21127 |
_version_ |
1781058056415608832 |