Arctic Charr Aquaculture

284 Pages·2002·4.39 MB·English

Arctic Charr Aquaculture
Gavin Johnston
Northern Biomes Ltd
British Columbia, Canada
© 2002 William Gavin Johnston First published 2002
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For my father, Pat Johnston, who believed it was possible, and to C.G., wherever she
may be.
Contents
Foreword by Dr Lionel Johnson xi
Preface xiii
Acknowledgments xiv
Section I The Basic Requirements for Culture 1
1 An Introduction to Arctic Charr 3
Use of Arctic charr by indigenous peoples 4
Commercial exploitation 6
The Canadian Arctic fi shery 6
The Labrador fi shery 7
Greenland, Ireland, Great Britain, and European fi sheries 9
Development of Arctic charr aquaculture 10
Production levels of cultured Arctic charr 13
2 Wild Arctic Charr: Basic Attributes Important to Culture 16
Geographic distribution 16
Taxonomy 17
Morphology: the outward appearance 19
Arctic charr forms and morphs 21
Anadromous form 21
Resident form 24
Morphs 25
Growth, size, and age at maturity 27
Matters of fecundity 31
Behavior: aggression, shoaling, and inter-species competition 33
Food habits 35
3 The Rearing Environment: Chemical, Physical and Biological 37
Water: the environment of Arctic charr 37
Incoming source water 38
Rearing water 39
Outfl ow water 40
Chemical parameters of water quality 41
vi Contents
Oxygen 41
Fish activity and oxygen consumption 43
Food intake and oxygen consumption 43
Water temperature and daily patterns of oxygen consumption 46
Fish size and oxygen consumption 48
Carbon dioxide 48
Total gas pressure and gas supersaturation 49
pH 49
Ammonia-N 50
Effect of pH and temperature on ammonia toxicity 51
Safe levels of ammonia 51
Nitrite and nitrate 53
Salinity, seawater tolerance, and smoltifi cation 53
Alkalinity and hardness 55
Suspended solids 56
Physical parameters of water quality 56
Temperature 56
Recommended temperatures 57
Light 58
Rearing densities 59
Biological aspects: stress and disease-causing organisms 60
Infectious disease and pathogens 63
Infectious pancreatic necrosis virus (IPNV) 64
Infectious hematopoietic necrosis virus (IHNV) 65
Viral hemorrhagic septicemia virus (VHSV) 65
Furunculosis 65
Bacterial kidney disease (BKD) 66
Vibriosis 67
Saprolegniasis 68
Proliferative kidney disease (PKD) 68
Metazoan parasites – tapeworms and roundworms 69
Gyrodactylid monogenean parasites –fl ukes 70
Sea lice 70
Other non-infectious disease agents 71
Toxicity of chemical compounds and construction materials 71
Swim bladder stress syndrome (SBSS) 71
Summary 72
4 Growth, Nutrition and Feeding 74
Growth in Arctic charr 74
Measuring growth performance 75
Growth rate (R) 75
Condition factor 78
Food conversion ratio (FCR) 79
Factors affecting patterns and rates of growth 81
Contents vii
Water temperature and its effect on growth 81
Body size and growth 82
Size variation, dominance, and growth 83
Seasonal and daily rhythms in growth 84
The effect of sexual maturation on growth and market size 88
Compensatory growth 91
Nutritional requirements 92
Protein requirements 92
Essential amino acids 93
Lipids and essential fatty acids 94
Lipid as an energy source 94
Essential fatty acids 95
Dietary carbohydrate 97
Vitamin requirements 97
Minerals and other trace elements 99
Carotenoid pigments 99
Levels of pigment required 102
Prepared diets and manufactured feeds 103
Investigations of Arctic charr diets 104
The ideal Arctic charr diet 106
Manufactured feeds for Arctic charr 107
Feeding Arctic charr 108
Setting daily ration levels 109
Feed sizes 110
Feeding strategies 111
Satiation, restricted, or compensatory feeding 111
Optimum feeding times 114
Spatial distribution and feeding frequency 114
Feed delivery methods 115
Feed monitoring 117
Section II Husbandry 119
5 The Standard Arctic Charr 123
The attributes for culture 123
Attributes of existing strains used for commercial culture 125
The Norwegian Hammerfest and Svalbard strains 125
The Swedish Hornavan strain 126
The Icelandic Grenlækur and Ölvesvatn strains 126
The Canadian Fraser strain 127
The Canadian Nauyuk strain 127
Potential for improving attributes of existing strains 128
Heritability of growth-related traits 130
Heritability of other traits 131
Breeding strategies for improving commercial stocks 132
The standard Arctic charr 133
viii Contents
6 Brood Operations: Keeping Brood, Egg Collection, and Incubation 136
Spawning 139
The spawning window 139
Ovulation and spermatogenesis 140
Methods for sexing and assessing ripeness 141
Sorting brood fi sh prior to spawning 142
Careful handling of spawning fi sh 144
Egg collection 145
Management and organization of the egg-take 146
Preparation of equipment for egg-take and incubation 148
Anesthetizing Arctic charr brood 149
Techniques for taking eggs 151
The dry fertilization method of egg taking 151
Removing eggs 151
Removing milt 153
Fertilizing eggs 154
Loading incubation trays 154
After spawning 156
Egg incubation 156
Effect of temperature on embryo development and mortality 158
Husbandry techniques in the egg room 159
Monitoring egg development and inventory control 159
Monitoring and controlling fungal growth 160
Egg shocking and picking techniques 160
Hatching 161
Methods for receiving and transporting eyed ova 162
7 Raising Alevin, Fry, and Fingerlings 164
From larval alevin to free-swimming fry 164
Preparing the ponding environment 167
Moving alevins to ponding tanks 170
First-feeding techniques 170
Types and sizes of starter diets 171
Methods for delivering starter diets 172
Ponding tank maintenance: good health or mortality 173
Into larger tanks: rearing fi ngerlings 174
Light levels and photoperiod control 175
Feeding fi ngerling Arctic charr 176
Size-grading, sorting, and splitting Arctic charr lots 178
Grading techniques 179
From the hatchery to grow-out facilities 181
Section III The Business of Production 185
8 Production of Arctic Charr for the Consumer 187
Different production strategies for on-growing 187
Contents ix
Holding structures 188
Stocking density for growing Arctic charr in lakes 189
Stocking density when growing Arctic charr in tanks 190
Production cycles 192
Light manipulation and growth 198
Feeding strategies 198
Ration size 199
Feed delivery 200
Diet 201
Sorting and other fi sh husbandry practices 202
Harvesting and processing 205
Harvesting 205
Pre-harvest preparation 206
Harvesting methods 207
Reaching sexual maturity before harvest 208
Processing 209
9 Marketing and Market Economics 210
Marketing Arctic charr 210
Quality in Arctic charr products 211
Product forms best suited for Arctic charr 212
Price of Arctic charr products 214
Marketing strategies 215
Distribution channels 216
Market economics of raising Arctic charr 219
Capital costs 219
Fixed operating costs 220
Variable operating costs 220
Profi tability and contribution margin 222
Harvest size and profi tability 224
Market price and profi tability 224
Other variables 226
10 Managing Culture Facilities 227
Business management of commercial culture facilities 227
Operations management 230
Environmental monitoring 230
Fish health management 231
Water-quality monitoring 233
Managing downstream water 234
Importance of good mechanical systems management 237
Emergency preparedness: alarms and back-up systems 239
Production management 241
The operations manual 243
A fi nal word 244
x Contents
Appendix: Protozoan and Metazoan Parasites of Wild and Cultured Arctic Charr 245
Bibliography 249
Index 265
Foreword
Nauyuk Lake was selected in the early 1970s as a suitable location for the establishment of a
research station devoted to the study of Arctic charr, certainly one of the most important na-
tive species for the inhabitants of Arctic Canada. Nauyuk Lake is situated at the southern tip
of the Kent Peninsula in the central Arctic, approximately 150 kilometres from Cambridge
Bay, Nunavut, Canada. The surrounding land is of great natural beauty with majestic cliffs
along the western and southern shorelines. It is connected to the Arctic Ocean by a short river,
some 150 metres long, that cuts between cliffs which turn red in the low August sun when the
charr are returning from their summer in the sea. Nauyuk is Inukituk for ‘sea gull’ and the lake
is so called because of a colony of Thayer’s gulls which nest on the cliffs overlooking the
lake. Close to the mouth of the river, there is a small summer encampment of Inuit composed,
at the time we were there, of Peter and Doris Aglegoetok, Charley and Mona Kioyok, their
children and their dogs.
Charley Kioyok was a great help in those early days in showing us poor Kabluna where the
spawning grounds were and how the pre-spawning charr passed up through a small stream
to a tributary lake, Willow Lake, where they spent the summer before spawning and then
the winter afterwards. As soon as the ice goes out, seaward migration out of Nauyuk Lake
begins, with the largest charr invariably leading the way. At Nauyuk Lake, these fi sh are
almost entirely non-spawners going to the sea to feed on the briefl y abundant small fi sh and
crustaceans. At the same time the spawners move up Willow Creek into Willow Lake and
the spawners of the previous year, now in a weakened condition having spent 22 months in
fresh water without feeding, move down Willow Creek, across Nauyuk Lake and so to the
sea. After fi ve to six weeks in the sea they return to Nauyuk Lake, having made a particularly
good recovery from their post-spawning emaciation. All the returning charr spend the winter
in Nauyuk Lake for they are prevented from enteringthe lakeby the very low stream fl ow at
this time of the year.
That Nauyuk Arctic charr would become the best strain for commercial culture came about
by chance. We decided to collect some eggs of the anadromous and resident forms, and their
respective crosses, for investigation in the laboratory of the Freshwater Institute in Winnipeg.
It was hoped that laboratory studies would help to elucidate the breeding pattern and deter-
mine whether the two forms were independent populations, although this seemed unlikely as
both stocks intermingle on the spawning grounds and ripen at the same time.
In 1978, after the summer crew had left at the end of August, Andy Dwilow, a fi sh health
specialist, and I stayed on in an attempt to collect fertilized eggs. Nauyuk Lake Arctic charr