effects of climate and ocean conditions on the marine survival of irish salmon (salmo salar, l.)

EFFECTS OF CLIMATE AND OCEAN CONDITIONS ON THE MARINE SURVIVAL OF IRISH SALMON (SALMO SALAR, L.) A Dissertation Presented by ARNAUD J. PEYRONNET Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfilment of the requirements for the degree of DOCTOR OF PHILOSOPHY February 2006 Wildlife and Fisheries Conservation UMI Number: 3206206 3206206 2006 Copyright 2006 by Peyronnet, Arnaud J. UMI Microform Copyright All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 All rights reserved. by ProQuest Information and Learning Company. © Copyright by Arnaud J. Peyronnet 2006 All Rights Reserved EFFECTS OF CLIMATE AND OCEAN CONDITIONS ON THE MARINE SURVIVAL OF IRISH SALMON (SALMO SALAR, L.) A Dissertation Presented by ARNAUD J. PEYRONNET Approved as to style and content by: _________________________________________________ Kevin D. Friedland, Chair _________________________________________________ Robert DeConto, Member _________________________________________________ Francis Juanes, Member Niall O’Maoileidigh, Member _______________________________________ Matthew J. Kelty, Department Head Department of Natural Resources Conservation iv ACKNOWLEDGMENTS This work was funded by a Marine Institute grant, under the Marine Institute and NOAA Cooperation programme. I wish to express my gratitude to several people who have been instrumental in helping me complete this research. I thank my advisors, Kevin Friedland and Niall Ó Maoiléidigh, for helping me design this study and conducting this research, and for their patience in reviewing my writing. I also wish to thank the other members of my committee, Francis Juanes and Rob DeConto for always providing encouragement and assisting me. I thank both Phil McGinnity and Sam Cushman who were always available to discuss important aspects of this work and provided constructive comments and suggestions. I wish to thank our director in ACMS and President of NASCO, Ken Whelan, for his help and support throughout this fellowship and for his infecting enthusiasm about salmon angling. Many thanks also to the ACMS station manager, Russell Poole, and his staff, for providing me with a tremendous administrative and scientific support during my time in Furnace. Thanks to Ger Rogan, for his help tracking information on Burrishoole salmon, for his great sense of humour and his constant good spirit. Thanks also to all my other colleagues from the Marine Institute, particularly Kathleen Sweeney and the rest of the ACMS team; but also Glen Nolan in OSS for his support and advice on oceanographic data. v I am very grateful to all the individuals who provided data for this study: Jan-Even Nilsen for the MLD Data; David Johns and Darren Stevens (both in SAHFOS) for their help with CPR data; Rowan Fealy from NUI Maynooth; Aidan Murphy in Met Eirann; Walter Crozier, Lars-Petter Hansen, Gudni Gudbersson, Lars Karlsson, Julian McLean and Jacques Dumas for the time series of marine survival of European salmon. I would like to thank my parents, family and friends for their encouragements. Finally my greatest gratitude goes to my wife Joanne, for her tremendous support and wonderful patience during the last few years. This work is dedicated to her. vi ABSTRACT EFFECTS OF CLIMATE AND OCEAN CONDITIONS ON THE MARINE SURVIVAL OF IRISH SALMON (SALMO SALAR, L.) FEBRUARY 2006 ARNAUD J. PEYRONNET, Bsc., UNIVERSITE BORDEAUX I Msc., UNIVERSITY COLLEGE CORK Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Dr. Kevin D. Friedland This dissertation investigates the role of climate and ocean conditions on the marine survival of Atlantic salmon. The overall objective was to identify the relevant environmental variables controlling salmon marine survival, in order to establish predictive models of marine recruitment. These models are required to improve the management process of the Irish and European salmon resources. I first explored the levels of synchrony in the marine survival of European salmon, in order to assemble evidence on the spatial scale of the processes controlling survival. I demonstrate that these levels of synchrony are low and I conclude that large scale events are not directly exerting a control on the rates of salmon survival, perhaps indicating the presence of several intermediary processes. Using information from a scale analysis of a monitored Irish population, I then explore the hypothesis that marine survival is linked to marine growth. I present evidence that the level of marine recruitment of 1SW salmon is linked to growth during the marine residency, and that decreasing growth over the last 30 years explains the observed decrease in salmon recruitment. vii Finally, I explore the role of several environmental variables on salmon marine survival, by constructing semi-parametric models (GAMs) of marine survival for wild and hatchery Irish populations. These models explain an important part of the inter-annual variability in survival and provide a capability to forecast survival. These models also help to identify the role of specific variables, more specifically the North Atlantic Oscillation, sea surface temperatures, and the abundance of zooplankton, to explain the variations in survival. I conclude that the changes in climate in the northeast Atlantic have affected the salmon via bottom-up effect, by affecting the abundance, distribution and phenology of key zooplankton species in the northern North Sea and southern Norwegian Sea. Keywords: Atlantic salmon; Climate; GAM, Growth; Marine survival; NAO; Ocean; Synchrony; Zooplankton. viii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS…………………………………………………… iv ABSTRACT……………………………………………………… ……………vi LIST OF TABLES……………………………………………………………….ix LIST OF FIGURES…………………………………………………………… x CHAPTER 1. INTRODUCTION……………………………………….……………… ……1 2. IS THERE COHERENCE IN THE MARINE RECRUITMENT OF NORTHEAST ATLANTIC SALMON, SALMO SALAR, L.? IMPLICATIONS FOR THE SPATIAL SCALES OF THE PROCESSES CONTROLLING……………………………………………………… … 11 3. LINK BETWEEN MARINE GROWTH AND SURVIVAL OF IRISH ATLANTIC SALMON (SALMO SALAR, L.)…………………………….…52 4. EFFECTS OF CLIMATE CHANGE ON SALMON (SALMO SALAR, L.) MARINE RECRUITMENT IN THE NORTHEAST ATLANTIC………….76 5. CONCLUSION………………………………………………………………112 6. BIBLIOGRAPHY…………………………………… ………………… …117 ix LIST OF TABLES Table Page 2.1. Summary of the marine survival time series, the coordinates of the point of entrance to the Sea, the methods used to generate the data and information on the data holders and their affiliation…….… 44 2.2. Testing hypotheses on the structure of synchrony in Marine survival of European salmon stocks………………………… 45 2.3. Matrix of inter-stocks distances (km)…………………………………….….46 2.4. Summary of pairwise cross-correlation coefficients between aggregated stocks………….…………………………………… 47 2.5. Mantel tests results for synchrony versus distance and other hypothetical models of synchrony organization……… …… 51 3.1. Correlation between growth indices and salmon recruitment………… ….73 4.1. Final GAM for Wild salmon survival and nested models…………… … 101 4.2. Numerical output from the model (GAM) of wild salmon survival….……102 4.3. Final GAM for Hatchery salmon survival and nested models…………… 106 4.4. Numerical output for the model (GAM) of hatchery marine survival…… 107 [...]... in the climate and ocean conditions, with effects on the marine ecosystems of the north Atlantic (Beaugrand and Reid 2003; Jonsson and Jonsson 2004; Friedland et al 2005) Links between the environmental conditions and survival have been established, with a particular focus on the early marine residency (Friedland et al 2005) Rates of marine survival have been linked to the extent of a favourable thermal... in our knowledge of the ecology of salmon at sea From a management point of view, and in the context of dwindling stocks, it is important to understand the processes responsible for the regulation of salmon populations in the marine environment This requires the understanding of the spatio-temporal scale of the processes controlling salmon survival, in order to establish the role of potential predictor... understanding of the relationships between climate and marine conditions has not been strong enough to construct such a model (Crozier et al 2003) This study was designed to explore more explicitly the links between the marine conditions and the levels of recruitment for Irish populations The index of PFA is central to the delivery of the scientific advice for catches of Irish salmon A forecasting model of. .. synchrony in PFA across European regions was poor The overall synchrony in PFA for all regions (northern and southern) was less than 22% Similar results were found for the synchrony in the northern region (r < 0.120) and the synchrony between the northern and southern region (r < 0.140) The synchrony inside the southern region was more pronounced This is also the only region for which the method of first-differencing... synchrony increased with distance between stocks Taken together the results from the levels of cross-correlation and the Mantel tests present a wide-ranging analysis of the scales and patterns of the synchrony of salmon stocks in the north Atlantic Firstly, there is no evidence of global basinscale drivers of synchrony (tests 1, 2 and 3) The Mantel test for the hypothesis of regulation at the scale of the. .. specifically, the 9 variability in survival seems to result from the synergetic effects of climate change on the pelagic ecosystem of the northeast Atlantic 10 CHAPTER 2 IS THERE COHERENCE IN THE MARINE RECRUITMENT OF NORTHEAST ATLANTIC SALMON, SALMO SALAR L.? IMPLICATIONS FOR THE SPATIAL SCALES OF THE PROCESSES CONTROLLING SURVIVAL Abstract The levels of inter-annual synchrony in marine recruitment of 18... of synchrony could be linked to the lack of synchrony between northern Iceland and the European stocks Tests 9 and 10 confirmed that marine survival for south Iceland was more synchronous with marine survival for Scandinavia and Europe respectively, rather than survival with northern Iceland The test for the Irish region only (test 11), produced a positive test coefficient (r = 0.327; p = 0.055), therefore... demonstrate that there is little synchrony in marine survival, and that similar results also arise from the analysis of coherence of the longer time-series of PFA Several potential interpretations are provided as well as their consequences for the study of the factors controlling survival In the second chapter, I investigate the nature of the link between marine growth and marine recruitment for a monitored... Norway) and then the hatchery stocks from the Corrib and the Screebe rivers (both in Ireland) The survival of hatchery stocks was significantly lower than the survival of wild stocks (t test; p ≤ 0.01), with the exception of the wild stocks from the northern coast of Iceland The highest mean survival was recorded for the wild stock from the river Bush, the two stocks (wild and hatchery) from the Burrishoole... semi-parametric models of marine survival for Hatchery and Wild Irish salmon, based on the selection of both linear and nonlinear predictors, using Generalized Additive Models (GAM) The most relevant and parsimonious GAM explain a large amount of the variability in survival of Irish Hatchery and Wild populations These models provide an insight into the role of particular predictors, and their relevance is . EFFECTS OF CLIMATE AND OCEAN CONDITIONS ON THE MARINE SURVIVAL OF IRISH SALMON (SALMO SALAR, L. ) A Dissertation Presented by ARNAUD J. PEYRONNET Submitted to the Graduate School of the University. recruitment. vii Finally, I explore the role of several environmental variables on salmon marine survival, by constructing semi-parametric models (GAMs) of marine survival for wild and hatchery Irish populations ATLANTIC SALMON, SALMO SALAR, L. ? IMPLICATIONS FOR THE SPATIAL SCALES OF THE PROCESSES CONTROLLING……………………………………………………… … 11 3. LINK BETWEEN MARINE GROWTH AND SURVIVAL OF IRISH ATLANTIC SALMON