Preface xi
List of Contributors xiii
Atlantic Cod: A Bio-Ecology 1
Introduction 1
1 Atlantic Cod: Origin and Evolution 7
Gudrun Marteinsdottir and George A. Rose
1.1 Introduction 7
1.2 Taxonomy and Morphology 9
1.3 Origin and Evolution 9
1.4 Cod: One of Few Endemic Atlantic Species 11
1.5 The Ancient North Atlantic: Dispersal and Early Population Structure 12
1.6 Rise of Cod and Current Population Structure 13
1.7 Is Diversity a Key to Cod's Success? 16
1.8 The Genetic Seascape 17
Bibliography 20
2 Ecophysiology 27
Denis Chabot and Guy Claireaux
2.1 Introduction 27
2.2 Temperature 31
2.2.1 Thermal Physiology 31
2.2.2 Thermal Niche of Cod 33
2.2.3 Temperature Range for Different Cod Stocks 33
2.2.4 Thermal Preferendum in the Laboratory 34
2.2.5 Temperature and Cod Growth 34
2.2.6 The OCLTT Hypothesis and Cod 36
2.2.7 Lethal Temperature for Cod: The Effect of Acclimation 37
2.2.8 Aerobic Metabolic Scope of Temperature-Acclimated Cod 38
2.2.9 Temperature and Cod Recruitment 40
2.2.10 Temperature Adaptation in Cod 41
2.3 Dissolved Oxygen 42
2.3.1 Hypoxia 42
2.3.2 Respiration 42
2.3.3 Responses of Fishes to Hypoxia 43
2.3.4 Hypoxia Exposure of Cod Populations 45
2.3.5 Survival of Cod in Hypoxia 48
2.3.6 Impact of Hypoxia on Cod Recruitment 48
2.3.7 Impact of Hypoxia on Cod Distribution 48
2.3.8 Cod Performance in Hypoxia 49
2.3.9 Hypoxia and Feeding of Cod 49
2.4 Salinity 50
2.4.1 Osmoregulation in Marine Fishes 50
2.4.2 Salinity Tolerance of Cod 51
2.4.3 Salinity and Growth Rate of Cod 51
2.4.4 Interactions Between Ambient Salinity, Temperature and Oxygen 52
2.4.5 Salinity Selection by Cod 53
2.4.6 Salinity and Cod Recruitment 53
2.5 Water pH 55
2.5.1 Causes of Ocean Acidification 55
2.5.2 Physiological Impacts of Ocean Acidification 55
2.5.3 Cod and Higher Carbonate Solubility 56
2.5.4 Cod Acid-Base Regulation 56
2.5.5 Acidification and Performance 56
2.5.6 Interaction Between pH and Hypoxia 57
2.6 Other Environmental Variables 57
2.6.1 Light 58
2.6.2 Contaminants 58
2.6.3 Trophic Interactions 60
2.6.4 Parasites and Diseases 61
2.7 Applications of Ecophysiological Understanding 62
2.8 Conclusions 64
Acknowledgements 64
Bibliography 65
3 Reproduction and Spawning 87
Peter J. Wright and Sherrylynn Rowe
3.1 Summary 87
3.2 Introduction 87
3.3 Variation in Maturation 89
3.4 Reproductive Investment 94
3.5 Spawning Location 100
3.6 Spawning Time 107
3.7 Spawning Behaviour 110
3.8 The Future 116
Acknowledgements 116
Further Reading 117
Bibliography 117
4 Early Life History 133
Timothy B. Grabowski and Jonathan H. Grabowski
4.1 Introduction 133
4.2 Early Development of Atlantic Cod 135
4.2.1 Life in the Plankton 137
4.2.2 'Bottoming out' - Settlement and Juvenile Habitat Use 149
4.3 Mortality 153
4.4 Feeding and Growth 155
4.5 Habitat Shifts, Dietary Shifts, and Growing Up 157
4.6 Conclusions 157
Acknowledgements 158
Bibliography 158
5 Migration 169
David Righton and Julian Metcalfe
5.1 Introduction 169
5.2 Why Migrate? 170
5.3 Studying Migration: What We Need to Know and How We Learn 173
5.3.1 Tagging and Marking Experiments 174
5.3.2 Natural Marks - Meristics, Parasites, and Chemical Composition 174
5.3.3 Artificial Marks - Simple Tags 175
5.3.4 Artificial Marks - Electronic Tags 177
5.4 Mechanisms of Migration 179
5.4.1 Swimming Behaviour 179
5.4.2 Use of Currents 180
5.4.3 Migration Pathways 181
5.4.4 Migrations and Populations 181
5.5 Cod in the Western Atlantic 182
5.5.1 Gulf of Maine and Georges Bank 186
5.5.2 Scotian Shelf and Southern Newfoundland 187
5.5.3 Gulf of St Lawrence 189
5.5.4 Grand Banks 190
5.5.5 Labrador Shelf and Eastern Newfoundland 190
5.6 Cod at Iceland and Greenland 192
5.6.1 Movements of Cod from Greenland to Labrador 195
5.7 Cod in the Eastern Atlantic 195
5.7.1 Barents Sea/ Norwegian Coast (Arcto-Norwegian Cod) 195
5.7.2 The North Sea 197
5.7.3 The Baltic 198
5.8 The Importance of Oceanographic, Physiological, and Evolutionary Influences on Cod Migration and Stock Structure 200
5.9 What of the Future? 203
Bibliography 204
6 Feeding, Growth, and Trophic Ecology 219
Jason S. Link and Graham D. Sherwood
6.1 Summary 219
6.2 Introduction 219
6.3 Feeding: What and How 222
6.3.1 Cod Feeding Behaviour and Energetic Consequences 224
6.3.2 Compared to Other Predators 226
6.3.3 Research Remaining and Further Work 226
6.4 Feeding: How Much? 227
6.4.1 Estimating How Much Cod Eat 227
6.4.2 Magnitude of How Much Cod Eats 230
6.4.3 Research Remaining and Further Work 231
6.5 What Happens to the Food Cod Eat: Losses and Metabolism 231
6.5.1 Egestion 232
6.5.2 Specific Dynamic Action 232
6.5.3 Excretion 233
6.5.4 Standard Metabolism (Respiration) 234
6.5.5 Activity 234
6.5.6 Summary of Metabolic Costs 235
6.5.7 Research Remaining and Further Work 237
6.6 What Happens to the Food Cod Eat: Individual Growth 237
6.6.1 How Is Growth Measured? 238
6.6.2 Reporting Growth and Variability in Growth 239
6.6.3 Condition Indices 242
6.6.4 Climate Change Effects on Growth 246
6.6.5 Summary 249
6.6.6 Research Remaining and Further Work 249
6.7 What Happens to the Food Cod Eat: Population Growth via Reproduction 250
6.7.1 Maturity 250
6.7.2 Fecundity 253
6.7.3 Realizing Reproductive Potential Through Feeding 254
6.7.4 Summary 255
6.7.5 Research Remaining and Further Work 256
6.8 What Happens to the Food Cod Eat: Population Dynamics of Cod Prey 257
6.8.1 Prey Population Dynamics 257
6.8.2 Cannibalism 258
6.8.3 Cod Prey and Other Fisheries 259
6.8.4 Research Remaining and Further Work 260
6.9 What Happens to the Food Cod Eat: Population Dynamics of Cod
Predators 260
6.9.1 Main Types and Responses of Cod Predators 260
6.9.2 Special Commentary on Marine Mammal Predators 261
6.9.3 Complex Food Web Dynamics: Cultivator Effects 262
6.9.4 Research Remaining and Further Work 263
6.10 Conclusions 263
Further Reading 263
Bibliography 264
7 Exploitation: Cod is Fish and Fish is Cod 287
George A. Rose, Gudrun Marteinsdottir, and Olav-Rune Godo
7.1 The Earliest Cod Fisheries (and the Gift of Viking 'Stockfish') 288
7.2 Cod and the 'Fish Event Horizon' 289
7.3 The Icelandic Fisheries 294
7.4 The Newfoundland and Grand Banks Fisheries 296
7.5 The North Atlantic Cod Trade 300
7.6 Technology in the Fisheries 300
7.7 Science and the Cod Fisheries 306
7.7.1 Landings 306
7.7.2 Fisheries-Independent Data (Surveys...) 311
7.7.3 Stock Assessment 316
7.7.4 Ageing 316
7.7.5 Stock Units and Tagging 317
7.7.6 Models 319
7.7.7 Stock-Recruitment 321
7.7.8 Productivity 323
7.8 Ecosystem-Based and Precautionary Management 328
Bibliography 329
8 Cod and Climate Change 337
Keith Brander
8.1 Summary 337
8.2 Introduction 337
8.3 Learning from the Past 340
8.4 The Greenland Story 340
8.5 Scales and Processes 342
8.6 Changing Climate of the North Atlantic 342
8.7 Impacts on Individuals and Populations 348
8.7.1 Growth 349
8.7.2 Survival 351
8.7.3 Recruitment 352
8.7.4 Surplus Production 353
8.8 Recent History of Cod Fisheries and the Role of Climate 355
8.9 Future Distribution and Abundance 358
8.10 Lessons for Fisheries Management 360
8.A Appendix 362
8.A.1 The ICES/GLOBEC Cod and Climate Change Programme 362
8.A.2 Aims, Organization, and Funding 363
8.A.3 What the Programme Achieved 367
8.A.3.1 Comparative Information on Spawning and Life History 367
8.A.3.2 Backward Facing Workshops 367
8.A.3.3 Growth 371
8.A.3.4 Applying Environmental Information in Stock Assessment 371
8.A.3.5 Decline and Recovery of Cod Stocks 371
8.A.3.6 Cod and Future Climate 372
8.A.3.7 Symposia and Individual Papers 372
Selected Papers: 374
Acknowledgements 375
Bibliography 375
9 The Future of Wild Cod and Their Fisheries 385
George A. Rose
9.1 The State of Stocks 385
9.2 Cod Economics 386
9.3 The Future 387
Acknowledgements 388
Bibliography 388
Index 391
