Evaluation of growth, survival, and recruitment of chinook salmon in Southeast Alaska rivers Item Type Thesis Authors Graham, Cory J. Download date 06/10/2021 06:49:01 Link to Item http://hdl.handle.net/11122/7292 EVALUATION OF GROWTH, SURVIVAL, AND RECRUITMENT OF CHINOOK SALMON IN SOUTHEAST ALASKA RIVERS By Cory J. Graham, B.S., B.A. A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of M aster of Science in Fisheries University of Alaska Fairbanks December 2016 APPROVED: Dr. Trent Sutton, Committee Chair Dr. Milo Adkison, Committee Member Dr. Megan McPhee, Committee Member Dr. Gordon Kruse, Chair Department of Fisheries Dr. Bradley Moran, Dean College of Fisheries and Ocean Sciences Dr. Michael Castellini, Dean of the Graduate School Abstract Recent reductions in the run sizes of Chinook Salmon Oncorhynchus tshawytscha in Southeast Alaska have resulted in social and economic hardships within the region. Pacific salmon year- class strength may be determined by size-selective processes during the early marine phase of their life cycle; however, the relative importance of growth during freshwater and marine residence in determining recruitment success is unknown. A scale-based retrospective analysis was conducted to examine the effects of freshwater and annual marine growth and early marine conditions on survival to reproductive maturity for female Chinook Salmon by brood year (BY) in the Taku (BYs 1979 - 1985, 1990 - 1999, 2002 - 2004) and Unuk (BYs 1981 - 1983, 1986 - 1988, 1994 - 2003, 2005 - 2006) rivers. First-year marine growth was positively related to survival and total return for Chinook Salmon stocks from both systems. Growth during freshwater residence (i.e., size-at-ocean entry) was not related to survival or total return of either stock. In addition, there was a positive relationship between marine survival of Unuk River Chinook Salmon and sea-surface temperatures in Upper Chatham Strait, Icy Strait, and Auke Bay Monitor(P = 0.04) during early marine residence. The results of my research highlight the importance of growth and marine conditions during the first year at sea in determining the survival of Chinook Salmon in Southeast Alaska and suggest that current declines in run sizes and survival of stocks within this region may be the attributed to poor growth conditions or growth during early marine residence. iii iv Table of Contents Page Title P ag e.............................................................................................................................................................. i Abstract .............................................................................................................................................................. iii Table of Contents ............................................................................................................................................... v List of Figures....................................................................................................................................................ix List of Tables .....................................................................................................................................................xi Acknowledgements ........................................................................................................................................xiii General Introduction ......................................................................................................................................... 1 Literature Cited................................................................................................................................................... 8 Chapter 1: Evaluation of growth, survival, and recruitment of Chinook Salmon in Southeast Alaska rivers ......................................................................................................................................................17 Abstract ........................................................................................................................................................17 Introduction................................................................................................................................................. 18 M ethods........................................................................................................................................................22 Study sites................................................................................................................................................22 Scale samples..........................................................................................................................................23 Scale reading ...........................................................................................................................................25 Recruitment benchmarks .....................................................................................................................26 Relationship between annual growth zones and recruitment benchmarks .............................. 28 Relationship between growth zones...................................................................................................30 Size-selective mortality at ocean entry.............................................................................................31 R esults..........................................................................................................................................................32 v Relationship between brood year recruitment success and annual growth...............................33 Relationship between annual growth and marine survival .......................................................... 34 Relationship between growth zones...................................................................................................34 Size-selective mortality at ocean entry.............................................................................................35 Discussion ...................................................................................................................................................35 Influence of annual growth on survival .............................................................................................35 Growth dependency.............................................................................................................................. 40 Size-selective mortality at ocean entry.............................................................................................. 41 Literature Cited..........................................................................................................................................45 Chapter 2: Influence of abiotic and biotic factors on the freshwater overwinter survival of Unuk River Chinook Salmon .................................................................................................................................... 67 Abstract ........................................................................................................................................................67 Introduction.................................................................................................................................................68 M ethods........................................................................................................................................................72 Study site..................................................................................................................................................72 Biological data....................................................................................................................................... 73 Parr and smolt capture, tagging, and sampling................................................................................73 Smolt abundance and freshwater overwinter survival .................................................................. 73 Physical data...........................................................................................................................................74 Data analyses..........................................................................................................................................75 R esults..........................................................................................................................................................77 Discussion ...................................................................................................................................................78 Literature Cited..........................................................................................................................................84 vi Chapter 3: Influence of smolt biological attributes and early marine conditions on the marine survival of Unuk River Chinook Salmon ....................................................................................................95 Abstract ........................................................................................................................................................95 Introduction.................................................................................................................................................97 M ethods......................................................................................................................................................100