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The Ecology of Arctic Cod (Boreogadus Saida) and Interactions with Seabirds, Seals, and Whales in the Canadian Arctic

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The Ecology of Arctic Cod (Boreogadus Saida) and Interactions with Seabirds, Seals, and Whales in the Canadian Arctic The Ecology of Arctic Cod (Boreogadus saida) and Interactions with Seabirds, Seals, and Whales in the Canadian Arctic by Jordan K. Matley A Thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfilment of the requirements of the degree of MASTER OF SCIENCE Department of Biological Sciences University of Manitoba Winnipeg, Manitoba Copyright © 2012 by Jordan K. Matley i Abstract This thesis investigates the foraging behaviour of Arctic cod (Boreogadus saida) and its predators during the summer in Allen Bay and Resolute Bay, Cornwallis Island, Nunavut, Canada. Major findings included the identification of Arctic cod, ringed seal (Pusa hispida), beluga (Delphinapterus leucas), and narwhal (Monodon monoceros) diet shifts in response to seasonal prey availability; calculation of isotopic diet-tissue discrimination factors for Arctic cod, ringed seals, and whales based on local tissue and stomach content sampling; and determination of cues that predators use to optimize foraging, such as the presence of schools. Additionally, I quantified seabird feeding and interspecific interactions such kleptoparasitism and found that black-legged kittiwakes (Rissa tridactyla) and northern fulmars (Fulmarus glacialis) captured cod directly but lost many to parasitic jaegers (Stercorarius parasiticus) and glaucous gulls (Larus hyperboreus). Finally, I determined that schools of cod were important prey sources for northern fulmars, glaucous gulls, and whales however non-schooling cod were a significant source for black-legged kittiwakes and ringed seals. ii Acknowledgements Numerous people and funding sources are responsible for the completion of this thesis. First, I thank my parents for being supportive of all my endeavours. Second, I thank staff, professors, and students in the Department of Biological Sciences at the University of Manitoba. In particular I am very grateful to M. Foster, J. Stringer, and S. Lapointe for administrative assistance; J. Roth for sharing lab space; and K. Gardiner, O. Friesen, M. Martens, C. Szumski, R. MacDonald, and M. Guzzo for editing, analytical assistance, as well as intellectual discussion. Third, I thank G. Lescord and G. Lipkey for further assistance writing and analyzing data. Fourth, I thank the Hunters and Trappers Association in Resolute, the staff at Polar Continental Shelf, as well as B. Iqaluk and S. Simeone for assistance in the field. Fifth, I thank laboratory personnel including R. ii Wastle, W. Walkusz, A. Hussey, X. Wang, A. Sett, L. Postma, D. Tenkula, and B. Stewart. Sixth, I thank external researchers for sample collection and analysis including D. Muir, L. Loseto, M. Mallory, and R. Crawford. Seventh, I thank my committee for being supportive and approachable, including A. Fisk and R. Baydack. Eighth, I thank funding sources including the Canadian Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council (NSERC), the Ocean Tracking Network (OTN), the Kenneth M. Molson Foundation, and the Faculty of Science at the University of Manitoba. Finally, I thank my advisor T. Dick. I would like to convey my appreciation for the opportunity to study and learn at such a high and demanding academic level. iii TABLE OF CONTENTS Abstract ............................................................................................................................... i Acknowledgements ........................................................................................................... ii List of Tables ................................................................................................................... vii List of Figures ................................................................................................................. viii Thesis Format and Manuscript Claims ........................................................................... x General Introduction ......................................................................................................... 1 Importance of Arctic cod ..................................................................................... 1 Studying predator-prey interactions in the Arctic ............................................... 2 Rationale .............................................................................................................. 8 Research topics .................................................................................................... 9 Chapter 1: Literature Review ........................................................................................... 16 1.1. Arctic cod ................................................................................................... 16 iii 1.1.1. General biology ....................................................................... 16 1.1.2. Diet .......................................................................................... 17 1.1.3. Distribution, habitat, and schooling behaviour ....................... 19 1.2. Beluga and narwhal .................................................................................... 22 1.2.1. General biology ....................................................................... 22 1.2.2. Diet .......................................................................................... 24 1.2.3. Interactions with prey ............................................................. 25 1.3. Ringed seal ................................................................................................. 27 1.3.1. General biology ....................................................................... 27 1.3.2. Diet .......................................................................................... 27 1.3.3. Interactions with prey ............................................................. 28 1.4. Seabirds ...................................................................................................... 29 1.4.1. General biology in Arctic........................................................ 29 1.4.2. Diet .......................................................................................... 30 1.4.3. Interactions with prey ............................................................. 31 1.4.4. Distribution of seabirds in relation to prey ............................. 34 1.5. Stable isotopes ............................................................................................ 36 iv 1.5.1. Introduction ............................................................................. 36 1.5.2. What is a stable isotope? ......................................................... 36 1.5.3. Measuring stable isotopes ....................................................... 37 1.5.4. Application of nitrogen stable isotopes ................................... 39 1.5.5. Application of carbon stable isotopes ..................................... 40 1.5.6. Application of trophic level .................................................... 41 1.5.7. Selecting the tissue to sample ................................................. 42 1.5.8. Isotopic baselines and variation .............................................. 43 1.5.9. Discrimination values and turnover rates ............................... 44 1.5.10. Uncertainty quantifying carbon stable isotopes due to lipids .................................................................................................. 47 1.5.11. Uncertainty caused by fasting ............................................... 48 1.5.12. Applications in the Canadian Arctic - Introduction .............. 49 1.5.13. Applications in the Canadian Arctic - marine mammals ...... 50 iv 1.5.14. Applications in the Canadian Arctic - seabirds..................... 51 1.5.15. Applications in the Canadian Arctic - fish ............................ 52 1.5.16. Critique of food web studies ................................................. 54 1.5.17. Critique#1 ............................................................................. 54 1.5.18. Critique#2 ............................................................................. 56 1.5.19. Summary of uses of stable isotopes ...................................... 58 1.5.20. Summary of advantages of stable isotopes ........................... 59 1.5.21. Summary of limitations of stable isotopes ............................ 60 1.6. Hydroacoustics ........................................................................................... 61 1.6.1. Introduction ............................................................................. 61 1.6.2. Hydroacoustic system ............................................................. 62 1.6.3. Acoustic transducers ............................................................... 64 1.6.4. Target strength ........................................................................ 64 1.6.5. Frequency ................................................................................ 66 1.6.6. Beam width ............................................................................. 66 1.6.7. Transducer configuration ........................................................ 67 1.6.8. Transducer deployment ........................................................... 68 v 1.6.9. Calibration............................................................................... 69 1.6.10. Design of survey ................................................................... 69 1.6.11. Quantitative estimation ......................................................... 70 1.6.12.
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