Physiological Changes Associated with the Diadromous Migration of Salmonids

Table of Contents

• Cover page 1
• Publishing information 2
• Title page 3
• Copyright 4
• Contents 5
• Abstract 7
• Résumé 8
• Introduction 9
• 1. The river migration 11
• 1.1. Factors regulating onset of migration 11
• 1.1.1. Abiotic Factors 11
• 1.1.2. Biological factors 15
• 1.1.3. Relative significance of the different factors 18
• 1.2. Motor activity during migration 20
• 1.2.1. Swimming pattern 20
• 1.2.2. Swimming speed and physiological adjustments 22
• 1.3. Metabolic aspects of migration 25
• 1.3.1. Energy requirements 25
• 1.3.2. Energy mobilization 26
• 1.3.3. Selective significance 27
• 1.4. Orientation 28
• 1.4.1. Stream direction and velocity 29
• 1.4.2. Olfaction 29
• 1.4.3. Visual references 32
• 1.4.4. Magnetism 32
• 1.4.5. Temperature 33
• 1.4.6. Conclusions 33
• 2. The transfer between river and sea 35
• 2.1. The transfer from freshwater to seawater 35
• 2.1.1. Osmoregulatory changes 35
• 2.1.2. Acid-base status, respiratory, and circulatory variables 41
• 2.1.3. Metabolic changes 43
• 2.2. The transfer from seawater to freshwater 45
• 2.2.1. Osmoregulatory adaptations 46
• 2.2.2. Respiratory variables and acid-base status 48
• 3. Preadaptive changes 49
• 3.1. Preadaptation to seawater transfer 49
• 3.1.1. Common and differential features among salmonids 49
• 3.1.2. The interrelation between migration and smoltification 50
• 3.1.3. Hormones and smolting 52
• 3.2. Preadaptation to freshwater transfer 54
• 3.2.1. Experimental evidence 54
• 3.2.2. Putative relation with desmoltification 56
• 4. Endocrinological aspects 60
• 4.1. Thyroid hormones 60
• 4.1.1. General aspects of thyroid physiology in fish 60
• 4.1.2. Possible involvement of thyroid hormones in smoltification 64
• 4.1.3. Possible involvement of thyroid hormones in river migration 67
• 4.1.4. Possible involvement of thyroid horomones during salinity changes 69
• 4.2. Corticosteroids 71
• 4.2.1. General physiology of corticosteriods in fish 71
• 4.2.2. Possible involvement of corticosteroids in preparatory adaptations to salinity changes 75
• 4.2.3. Possible involvement of corticosteroids in upstream migration 78
• 4.2.4. Possible involvement of corticosteroids in downstream migration 80
• 4.2.5. Possible involvement of corticosteroids during salinity changes 82
• 4.3. Prolactin 85
• 4.3.1. General physiology of prolactin in fish 85
• 4.3.2. Possible involvement of prolactin in preparatory adaptations to salinity changes 90
• 4.3.3. Possible involvement of prolactin in river migration 92
• 4.3.4. Possible involvement of prolactin during salinity changes 93
• 4.4. Other hormones 95
• 4.4.1. Growth hormone 95
• 4.4.2. Sex steroids 98
• 4.4.3. Melatonin 101
• 4.4.4. ANP-like peptides 103
• 4.4.5. Insulin 105
• 4.4.6. Others 107
• Conclusions 108
• References 111