Preliminary Mass-Balance Food Web Model of the Eastern Chukchi Sea
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NOAA Technical Memorandum NMFS-AFSC-262 Preliminary Mass-balance Food Web Model of the Eastern Chukchi Sea by G. A. Whitehouse U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Alaska Fisheries Science Center December 2013 NOAA Technical Memorandum NMFS The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center. This document should be cited as follows: Whitehouse, G. A. 2013. A preliminary mass-balance food web model of the eastern Chukchi Sea. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-262, 162 p. Reference in this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. NOAA Technical Memorandum NMFS-AFSC-262 Preliminary Mass-balance Food Web Model of the Eastern Chukchi Sea by G. A. Whitehouse1,2 1Alaska Fisheries Science Center 7600 Sand Point Way N.E. Seattle WA 98115 2Joint Institute for the Study of the Atmosphere and Ocean University of Washington Box 354925 Seattle WA 98195 www.afsc.noaa.gov U.S. DEPARTMENT OF COMMERCE Penny. S. Pritzker, Secretary National Oceanic and Atmospheric Administration Kathryn D. Sullivan, Under Secretary and Administrator National Marine Fisheries Service Samuel D. Rauch III, Acting Assistant Administrator for Fisheries December 2013 This document is available to the public through: National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 www.ntis.gov ABSTRACT A preliminary mass-balance food web model was developed for the eastern Chukchi Sea continental shelf, describing the trophic structure and function of this ecosystem. The model was developed with the Ecopath framework and provides an annual snapshot of the food web structure in the eastern Chukchi Sea. Species were represented individually where data permitted or were aggregated into functional groups with species of similar diet, life history, and habitat requirements where data were sparse. The model consists of 52 living functional groups, two detrital compartments, and nine subsistence harvest groups. The purpose of this report is to document the construction of this trophic model and the development of model input parameters for all functional groups; including literature and data sources, data quality, model assumptions and limitations, any parameter adjustments, and parameter estimation methods. iii CONTENTS INTRODUCTION ........................................................................................................................................ 1 METHODS ................................................................................................................................................... 4 RESULTS and DISCUSSION ...................................................................................................................... 6 ACKNOWLEDGMENTS .......................................................................................................................... 10 CITATIONS ............................................................................................................................................... 11 Appendix A Functional Group Descriptions and Data Sources ......................................................... 51 Cetaceans ............................................................................................................................. 51 Caniformia ........................................................................................................................... 57 Seabirds ............................................................................................................................... 88 Fish ...................................................................................................................................... 93 Benthic Invertebrates ......................................................................................................... 110 Pelagic Invertebrates and Microbes ................................................................................... 133 Primary Production ............................................................................................................ 139 Model Parameters .............................................................................................................. 143 Diet Matrix ........................................................................................................................ 144 Appendix B Detailed Parameter Estimation Methods ..................................................................... 151 Benthic-Pelagic Flows to Detritus ..................................................................................... 151 Marine Mammal Production Rates .................................................................................... 152 Marine Mammal Consumption Rates ................................................................................ 153 Seabird Biomass ................................................................................................................ 155 Seabird Production Rates .................................................................................................. 156 Fish and Selected Invertebrate Biomass ............................................................................ 157 Fish Diets ........................................................................................................................... 158 Other Benthic Invertebrate Biomass.................................................................................. 160 Appendix C Data quality grading .................................................................................................... 161 v TABLES Table A1. -- Ecopath model inputs (bolded) and balanced outputs for the eastern Chukchi Sea. TL = trophic level, B = biomass, P/B = production/biomass, Q/B = consumption/biomass, EE = ecotrophic efficiency, P/Q = production/consumption (or growth efficiency), catch = fishery or harvest take. Biomass and catch is in t km-2; P/B, Q/B, and P/Q are in yr-1; and EE is dimensionless. ................. 143 Table A2. -- Eastern Chukchi Sea diet matrix, where rows represent prey groups and the columns are predators. The predator column numbers correspond to the prey group numbers and names. Each column represents a single predator’s diet and the values sum to 1 (some columns may not sum to 1 due to rounding). Values of 0.0000 are prey items in trace amounts. ................. 144 Table B1. -- Estimated model parameters for surrogate mammal life histories from Barlow and Boveng (1991). ..................................................................................................... 152 Table B2. -- The Q/B ratios, daily energy requirements, average body mass, and estimated prey caloric density for marine mammals. The coefficient (a) is a taxonomic specific parameter from Perez et al. (1990) used to calculate energy requirements from equation B5. There is no coefficient (a) for polar bears. ........................................................................................................... 154 Table B3. -- Summary of the average individual weights, abundance estimates, and estimated total biomass for all seabird groups represented in the eastern Chukchi Sea model. Average weights are from Hunt et al. (2000) and abundance estimates from the Beringian Seabird Colony Catalog (USFWS 2003). ................................................................................................................................. 155 Table B4. -- Seabird functional group P/B values along with the literature values of annual mortality or survival they were derived from . (Table recreated from Aydin et al. (2007)). ........... 156 Table C1. -- Criteria for data quality pedigree (or grade) based on the data pedigree originally described for Ecopath with Ecosim (EwE) by Christensen et al. (2005). B = biomass, P/B = production/biomass ratio, Q/B = consumption/biomass ratio, DC = diet composition, and C = fishery catch or subsistence harvest (Table recreated from Aydin et al. 2007). ..................................................... 161 Table C2. -- Confidence intervals taken from Aydin et al. (2003) with their corresponding data pedigree (or grade) for the different model parameters. B = biomass, P/B = production/biomass ratio, Q/B = consumption/biomass ratio, DC = diet composition, and C = fishery catch or subsistence harvest. ....................................................................................................................... 161 Table C3. -- Data pedigree (grade) and corresponding confidence intervals (C.I.) for eastern Chukchi Sea model parameters. Colors highlight the range of data quality based on the confidence interval from good (green, ~0.1), to acceptable (yellow, ~0.5), to poor (red, ~0.8). *The Chukchi Sea stock of polar bears has two separate subsistence harvests (U.S. and Russian) that