ISSN 1198-6727 Fisheries Centre Research Reports 2009 Volume 17 Number 2 Modelling the trophic role of marine mammals in tropical areas: data requirements, uncertainty, and validation Fisheries Centre, University of British Columbia, Canada Modelling the trophic role of marine mammals in tropical areas: data requirements, uncertainty, and validation by Lyne Morissette, Jenny Lynn Melgo, Kristin Kaschner and Leah Gerber Fisheries Centre Research Reports 17(2) 120 pages © published 2009 by The Fisheries Centre, University of British Columbia 2202 Main Mall Vancouver, B.C., Canada, V6T 1Z4 ISSN 1198-6727 Fisheries Centre Research Reports 17(2) 2009 MODELLING THE TROPHIC ROLE OF MARINE MAMMALS IN TROPICAL AREAS: DATA REQUIREMENTS, UNCERTAINTY, AND VALIDATION by Lyne Morissette, Jenny Lynn Melgo, Kristin Kaschner and Leah Gerber CONTENTS Page DIRECTOR’S FOREWORD ..........................................................................................................................................1 ABSTRACT...............................................................................................................................................................2 GENERAL INTRODUCTION ....................................................................................................................................... 3 An Ecosystem Approach to the ‘whales eat fish’ Issue.................................................................................. 3 References ................................................................................................................................................... 4 FOOD WEB MODEL AND DATA FOR STUDYING THE INTERACTIONS BETWEEN MARINE MAMMALS AND FISHERIES IN THE NORTHWEST AFRICAN ECOSYSTEM .................................................................................................................. 6 Abstract........................................................................................................................................................6 Introduction ................................................................................................................................................ 6 Materials and methods ............................................................................................................................... 7 Study area .................................................................................................................................................... 7 Harvesting on the ecosystem......................................................................................................................8 Whaling ...................................................................................................................................................8 Fishery.....................................................................................................................................................8 Model description ..................................................................................................................................... 13 Groups 1 - 10. Marine mammals.......................................................................................................... 16 11. Seabirds............................................................................................................................................ 27 12. Large pelagics.................................................................................................................................. 27 13. Mesopelagic predators....................................................................................................................28 14. Bathydemersal predators ...............................................................................................................28 15. Sharks ..............................................................................................................................................29 16. Rays..................................................................................................................................................29 17. Coastal tunas ...................................................................................................................................30 18. Coastal demersals ...........................................................................................................................30 19. Clupeids........................................................................................................................................... 31 20. Other coastal pelagics ....................................................................................................................32 21. Cephalopods....................................................................................................................................32 22. Crustaceans.....................................................................................................................................33 23. Benthos ...........................................................................................................................................33 24. Benthic producers ..........................................................................................................................34 25. Zooplankton....................................................................................................................................34 26. Phytoplankton ................................................................................................................................34 27. Detritus............................................................................................................................................34 Balancing the model.................................................................................................................................. 35 Time series data ........................................................................................................................................40 Biomass .................................................................................................................................................40 Effort .....................................................................................................................................................43 Uncertainty analyses.................................................................................................................................44 Sensitivity analysis ...............................................................................................................................45 ‘Ecoranger’ analysis ..............................................................................................................................45 Fitting the model to time series data................................................................................................... 46 Simulating the removal of great whales in the ecosystem ................................................................. 46 Discussion ................................................................................................................................................. 46 A new dataset built for Northwest Africa............................................................................................ 46 Strengths and weaknesses of these modelling efforts ........................................................................ 47 Acknowledgements ................................................................................................................................... 47 References ................................................................................................................................................. 47 FOOD WEB MODEL AND DATA FOR STUDYING THE INTERACTIONS BETWEEN MARINE MAMMALS AND FISHERIES IN THE CARIBBEAN ECOSYSTEM................................................................................................................................. 53 Abstract ..................................................................................................................................................... 53 Introduction .............................................................................................................................................. 53 Materials and methods ............................................................................................................................. 55 Study area ............................................................................................................................................. 55 Model description ..................................................................................................................................... 56 Resource exploitation of the ecosystem ...............................................................................................61 Balanced ecosystem model for the Caribbean region............................................................................. 70 Groups 1 - 10. Marine mammals ......................................................................................................... 70 11. Seabirds ........................................................................................................................................... 79 12. Seaturtles.........................................................................................................................................80