FCRR
Mass-Balance Models of North-eastern Pacific Ecosystems
Editors
Publication
Fisheries Centre Research Reports, Vol. 4 No. 1 Pages: 131pp
1996 | PDF
1996 | PDF
Edited by Pauly, D., Christensen, V. and Haggan, N.
ABSTRACT
A one-week workshop was held at the Fisheries Centre, UBC, from November 6-10, 1996, during which ten invited participants, mainly from the scientific community in British Columbia, Alaska and Washington, and Fisheries Centre faculty and graduate students assembled the elements required for preliminary mass-balance models of trophic fluxes in the Alaska Gyre, on the shelf off southern British Columbia, and in the Strait of Georgia.
Such mass-balance models were urgently required, as no systematic attempt had been made to verify that commonly-cited biomass, production and consumption rate estimates published for various critical marine groups in these three systems (e.g. salmon, marine mammals), were mutually compatible. The construction of these mass-balance models not only allowed verification (or correction) of previously published flux and biomass estimates, but also identification of major gaps in knowledge, and cost-effective estimation of some of the previously unknown rates and biomasses required for assessment of marine carrying capacity in the Northeastern Pacific.
Each workshop participant covered a functional group and its associated fluxes: phytoplankton and primary production, zooplankton and secondary production, major fish species and their fisheries, marine mammals and birds and their food consumption.
Model construction was performed using the well-documented Ecopath approach and software, previously applied to over eighty aquatic ecosystems throughout the world, and of which a pre-release Windows-based version was applied during the workshop.
This report documents the parametrization of the three above-mentioned models through short contributions authored by the participants, the construction and validation of these (still) preliminary models, then presents suggestions for their future development and uses.
TABLE OF CONTENTS
ABSTRACT | 1 |
Directors Foreword (T. Pitcher) | 4 |
FOREWORD (P.A. Larkin) | 6 |
Preface and Acknowledgments (D. Pauly and V. Christensen) | 7 |
Table of Contents | 8 |
List of exhibits | 10 |
INTRODUCTION | 12 |
Rationale For Mass-Balance (Trophic) Models (D.Pauly and V. Christensen) | 12 |
Alaska Gyre model | |
The Marine Ecosystem of the Gulf of Alaska (J.J. Polovina) | 16 |
Lower trophic levels (J. Purcell) | 16 |
Carnivorous Zooplankton, Jellies and Velella (M. Arai) | 17 |
Initial Estimates on Krill (A. Jarre-Teichmann) | 20 |
Salmon in the Ocean (L. Huato) | 21 |
Mesopelagics (J. Purcell) | 23 |
Sharks (J. Polovina) | 23 |
Miscellaneous fishes (P. Livingston) | 24 |
Marine Mammals (A. Trites and K. Heise)25 | 25 |
Seabirds in the Alaskan Gyre (J. Kelson,. Y. Wada and S. Speckmann) | 31 |
Balancing the Alaska gyre Model (V. Christensen) | 32 |
SOUTHERN B.C. SHELF MODEL | |
The area covered (D.Pauly) | 37 |
Euphausiids, Chaetognaths and Herbivores (J. Purcell) | 37 |
Invertebrate Benthos (A. Jarre-Teichmann and S. Guenette) | 38 |
Carnivorous Jellies (M. Arai) | 39 |
Krill (A. Jarre-Teichmann) | 40 |
Small pelagics (R. Buckwsworth) | 40 |
Pacific Cod and Sablefish (P. Livingston) | 41 |
Pacific Halibut (J. Venier) | 43 |
Spiny Dogfish (J. Polovina) | 45 |
Hake (T. Pitcher) | 45 |
Marine Mammals (A. Trites and K. Heise) | 51 |
Seabirds of the southern B.C. shelf (Y. Wada and J. Kelson) | 55 |
Fisheries catches (E.A. Buchary) | 57 |
Balancing the model (J.Venier) | 59 |
STRAIT OF GEORGIA MODEL | |
System Definition and primary production (S. Mackinson) | 63 |
Zooplankton, incl. Jellies (J. Venier) | 65 |
The Demersal Fish "Box" (J. Venier and J. Kelson) | 65 |
The Pelagic "Box" (R. Buckworth) | 67 |
Marine Mammals and Birds (Y. Wada) | 69 |
Fisheries harvest in the Strait of Georgia (E.A. Buchary) | 73 |
Balancing the Strait of Georgia Model (J. Venier) | 74 |
GENERAL DISCUSSION | |
A Road Test of Ecopath (R. Buckworth) | 81 |
Suggested Improvements for Ecopath Modeling (C. Walters) | 81 |
Exploring ecosystem responses to environmental variation (J.J. Polovina) | 82 |
Integration of local environmental knowledge (N. Haggan) | 88 |
Updates on Ecopath development and applications (D. Pauly and V. Christensen) | 89 |
References | 92 |
Appendix 1: Tables A-O | 116 |
Appendix 2: Workshop schedule | 128 |
Appendix 3: List of participants | 130 |
