Sci. Report 41- PICES - North Pacific Marine Science Organization

Report 41 (August 2012)

PICES Advisory Report on the Decline of Fraser River Sockeye Salmon Oncorhynchus nerka (Steller, 1743) in Relation to Marine Ecology


Full report [pdf, 4 Mb] (Right-click and choose "Save Target As..." to save it on your computer)

Contents [pdf, < 1 Mb]				iii
List of Authors [pdf, < 1 Mb]				vii
Preface [pdf, < 1 Mb]				ix
Executive Summary [pdf, < 1 Mb]				xi

Fraser River Sockeye				1
1.	Introduction [pdf, < 1 Mb]			1
	1.1	Motivation		1
	1.2	Authorship – North Pacific Marine Science Organization		2
	1.3	Organization of the Report		2
	1.4	Research Directed at Salmon in the Ocean		3
	1.5	General Biology		4
		1.5.1	Life cycle of sockeye salmon	5
		1.5.2	Spawning behaviour	7
		1.5.3	Migrations and habitat changes	7
		1.5.4	Ecotypes	9
		1.5.5	Production cycles	9

2.	Postsmolt Year [pdf, < 1 Mb]			11
	2.1	Postsmolt Migration Route		11
	2.2	Postsmolt Migration Timing		16
	2.3	Postsmolt Migration Speed		19
	2.4	Factors Affecting Postsmolt Migration Behaviour		19
	2.5	Postsmolt Feeding		20
	2.6	Postsmolt Growth		22
		2.6.1	Strait of Georgia	22
		2.6.2	Continental shelf	24

3.	Beyond the Continental Margin [pdf, < 1 Mb]			27
	3.1	Distribution and Migration		27
	3.2	Behaviour		31
	3.3	Feeding		33
	3.4	Growth		35
		3.4.1.	Density-dependent growth (intra-specific)	35
	3.5	Thermal Limits to Oceanic Distribution		37
		3.5.1	Sockeye salmon in waters exceeding thermal limits	38
		3.5.2	Global climate model projections	41

4.	Maturation and Migration [pdf, < 1 Mb]			45
	4.1	Distribution of Maturing Fraser River Sockeye Salmon		45
	4.2	Diet and Feeding of Maturing Fraser River Sockeye Salmon		46
	4.3	Growth of Maturing Fraser River Sockeye Salmon		48
		4.3.1	Average size at age	48
		4.3.2	Trends	51
		4.3.3	Density-dependent growth (intra-specific)	53
		4.3.4	Density-dependent growth (inter-specific)	54
	4.4	Migration Behaviour and Timing		57
		4.4.1	Depth of migration	57
		4.4.2	Migration timing	58
	4.5	Landfall		61
	4.6	Northern Diversion		64

5.	Survival [pdf, < 1 Mb]			67
	5.1	Productivity and Survival		67
	5.2	Difficulties Estimating Salmon Abundance		68
	5.3	Smolt-to-Adult Survival		68
	5.4	Variability at Different Temporal Frequencies		71
		5.4.1	Interannual	71
		5.4.2	Decadal	72
		5.4.3	Evolutionary-scale	72
	5.5	Tag Recapture Rates as a Proxy for Survival		73
	5.6	Leading Indicators of Survival		73
		5.6.1	Comparisons with coho salmon survival	73
		5.6.2	Preliminary signs of 2010 abundance	75

6.	Oceanography and Climate [pdf, 1.5 Mb]			79
	6.1	Strait of Georgia		79
		6.1.1	Wind	79
		6.1.2	Fraser River discharge	80
		6.1.3	Surface water properties at lighthouses	82
		6.1.4	Hydrography at Nanoose station	86
		6.1.5	Nanoose Bay as an index of water properties in the Strait of Georgia	88
		6.1.6	Nutrients and chlorophyll	89
		6.1.7	Zooplankton	89
		6.1.8	Ichthyoplankton	89
		6.1.9	Temperatures in the Strait of Georgia in 2008	90
	6.2	Coastal Gulf of Alaska		91
		6.2.1	General description	91
		6.2.2	Queen Charlotte Sound	93
		6.2.3	Coastal biological oceanography beyond the Strait of Georgia	97
	6.3	Gulf of Alaska		101
		6.3.1	Large-scale climate processes	101
		6.3.2	Sea level pressure	102
		6.3.3	Ocean circulation	104
		6.3.4	Hydrography	104
		6.3.5	Physical spring in offshore Gulf of Alaska	107
		6.3.6	Nutrients	109
		6.3.7	Biological spring	110
	6.4	Extreme Sea Surface Temperatures		112
	6.5	Future of the Gulf of Alaska		113
		6.5.1	NEP ROMS model description	113
		6.5.2	Model sea surface temperature	114

7.	Discussion [pdf, < 1 Mb]			117
	7.1	Cause of Low Returns in 2009		117
		7.1.1	Data shortages	117
		7.1.2	Warm and cool in 2007	117
		7.1.3	Location of mortality	118
		7.1.4	The Harrison River anomaly	120
	7.2	Decline in Marine Productivity or Change in Distribution?		121
		7.2.1	Interpreting returns per spawner	121
		7.2.2	Gradual versus abrupt decline	123

Acknowledgments [pdf, < 1 Mb]				129
References [pdf, < 1 Mb]				131

Appendices [pdf, < 1 Mb]
Appendix 1			North Pacific Marine Science Organization (PICES)	141
Appendix 2			Terminology	143
Appendix 3			Average age composition based on brood year returns to 2004	144
Appendix 4			Comments on Pacific Salmon Commission workshop report	145
Appendix 5			State of the Science	148

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