Science Series Technical Report no.142 An ecosystem model of the North Sea to support an ecosystem approach to fisheries management: description and parameterisation S. Mackinson and G. Daskalov Science Series Technical Report no.142 An ecosystem model of the North Sea to support an ecosystem approach to fisheries management: description and parameterisation S. Mackinson and G. Daskalov This report should be cited as: Mackinson, S. and Daskalov, G., 2007. An ecosystem model of the North Sea to support an ecosystem approach to fisheries management: description and parameterisation. Sci. Ser. Tech Rep., Cefas Lowestoft, 142: 196pp. This report represents the views and findings of the authors and not necessarily those of the funders. © Crown copyright, 2008 This publication (excluding the logos) may be re-used free of charge in any format or medium for research for non-commercial purposes, private study or for internal circulation within an organisation. This is subject to it being re-used accurately and not used in a misleading context. The material must be acknowledged as Crown copyright and the title of the publication specified. This publication is also available at www.Cefas.co.uk For any other use of this material please apply for a Click-Use Licence for core material at www.hmso.gov.uk/copyright/licences/ core/core_licence.htm, or by writing to: HMSO’s Licensing Division St Clements House 2–16 Colegate Norwich NR3 1BQ Fax: 01603 723000 E-mail: [email protected] List of contributors and reviewers Name Affiliation Contribution Steven Mackinson Cefas All – with focus on lower trophic levels Georgi Daskalov Cefas All – with focus on higher trophic levels Paul Mickleburgh Kings College London Fisheries groupings and analysis Tom Howden Kings College London Ecospace methods Bill Mulligan Kings College London Economic and social analysis Paul Eastwood Cefas Spatial data methods Andrew South Cefas Spatial data preparation Peter Robinson Cefas Data extraction Ewen Bell Cefas Nephrops data Simon Jennings Cefas Benthos conversions, fleet effort data Melanie Sapp Cefas Micoflora Michaela Schratzberger Cefas Meiofauna Tom Moens University of Ghent Meiofauna Hubert Rees Cefas Benthos Stefan Bolam Cefas Benthos Brian Rackham Cefas IBTS and diet data Morten Vinter DIFRES Fisheries data Grant Course Cefas Discard data Ruth Calloway Bangor University Benthos data Jan Hiddink Bangor University Benthos data Vliz www.Vliz.he/vmdcdata.nsbs Benthos data Tom Brey Alfred-Wegner Instiutute Conversion factors for benthos and production model Steve Milligan Cefas Phytoplankton Jim Aitkin Plymouth Marine Laboratory Phytoplankton Chris Lynam University of St. Andrews Jellyfish Villy Christensen University of British Columbia Ecosim and Ecospace parameterisation Carl Walters University of British Columbia Ecosim parameterisation ICES secretariat Fisheries data, IBTS Survey, 1991 Year of the Stomach Richard Mitchell Cefas Data manipulation Sophie Pitois Cefas Zooplankton data Derek Eaton Cefas Crabs Graham Pierce University of Aberdeen Squid Jon Elson Cefas Nephrops Axel Temming University of Hamburg Shrimp Neils Dann IMARES Fish diets Hans-Georg Happe IFM-GEOMAR Microflora Jim Ellis Cefas Benthos, fish Contents Forword 6 4. Testing model stability using Ecosim 60 4.1 Ecosim parameterisation – stage 1: List of contributors 7 Adult-juveniles groups and stability testing 60 4.2 Ecosim parameterisation – stage 2: Section A. A Model Representation Of The North Estimating vulnerabilities by time-series Sea Ecosystem fitting 68 1. Introduction 9 5. Ecospace parameterisation 83 1.1 Purpose and approach to modelling the North Sea 9 5.1 Basemap and species habitat assignments 83 1.2 Drivers behind ecosystem modelling 5.2 Dispersion from assigned habitat 87 research 9 5.3 Spatial distribution of fishing fleets 89 1.3 Single and multi-species/ecosystem 5.4 Equilibrium distribution of species and fishing approaches 10 activity 90 1.4 The Ecopath with Ecosim approach to 5.5 Investigating MPA’s 92 ecosystem modelling 12 1.5 Ecosystem modelling of the UK shelf seas 13 1.6 Disclaimer 14 6. Notes on limitations and usefulness 93 Section B.Description of data sources, methods, 2. Characteristics of the North Sea and assumptions used in estimating ecosystem 14 parameters 2.1 The physical and ecological setting 14 2.2 Fisheries and fish stocks in the North Sea 16 7. Primary producers 95 3. The Ecopath model 19 8. Detritus 97 3.1 Structure of the model 19 3.2 Data pedigree assessment 19 9. Microbial heterotrophs 98 3.3 Balancing the North Sea model 19 3.3.1 The meaning of 'model balancing' and 9.1 What the model needs to represent 98 general strategies 19 9.2 How the ecology of microflora is 3.3.2 Changes made during balancing 20 represented in the model 98 3.3.3 Warning! - key sensitive species 20 3.4 System analysis and characterization 43 3.4.1 Ecosystem structure and biomass flows 43 10. Zooplankton 103 3.4.2 Food web interactions 46 3.4.3 Whole system indicators 53 10.1 Herbivorous zooplankton (mainly copepods) 3.5 Sensitivity 58 and Omnivorous zooplnkton (Microplankton) 103 10.2 Carnivorous zooplankton (Euphasiids, chaetognaths (arrow worms, eg sagitta), amphipods, mysiids, ichthyoplankton 107 10.3 Gelatinous zooplankton 108 continued Contents 11. Benthic invertebrates 13.26 Juvenile herring and Adult herring 140 (infauna and epifauna) 109 13.27 Sprat 140 13.28 Mackerel 140 11.1 Data sources, treatment and approach 109 13.29 Horse mackerel 141 11.2 Estimating biomass from survey data 109 13.30 Sandeels 141 11.2.1 Deriving mean weights for benthos 110 13.31 Plaice 142 11.2.2 Biomass calculations 111 13.32 Dab 142 11.3 Estimating P/B 112 13.33 long-rough dab 142 11.4 Infaunal macrobenthos, Small infauna 13.34 Flounder 142 (polychaetes), Epifaunal macrobenthos (mobile 13.35 Sole 143 grazers), Small mobile epifauna (swarming 13.36 Lemon sole 143 crustaceans), Sessile epifauna 113 13.37 Witch 143 11.5 Nephrops 119 13.38 Turbot and brill 143 11.6 Shrimp 121 13.39 Megrim 144 11.7 Large crabs 126 13.40 Halibut 144 11.8 Meiofauna 128 13.41 Dragonets 144 13.42 Catfish (wolf-fish) 144 13.43 Large demersal fish 144 12. Squids 132 13.44 Small demersal fish 145 13.45 Miscellaneous filter feeding pelagic fish 145 13. Fishes 134 14. Fisheries landings, discards, economics 13.1 Functional groups (FGs) 134 and social metrics 146 13.2 Bimass estimates 134 13.3 Production 134 14.1 Database descriptions 146 13.4 Consumption 135 14.2 Matching fleet and species definitions used in 13.5 Diet 135 databases 148 13.6 Elasmobranchs 135 14.3 Manipulation of data and assumptions used 149 13.7 Juvenile sharks 135 13.8 Spurdog 135 13.9 Large piscivorous sharks 136 15. Mammals and Birds 173 13.10 Small sharks 136 13.11 Juvenile skates and rays 136 15.1 Baleen whales 173 13.12 Starry ray and others 136 15.2 Toothed whales 173 13.13 Thornback and Spotted ray 136 15.3 Seals 174 13.14 Common skate and cuckoo ray 137 15.4 Birds 174 13.15 Juvenile cod and Adult cod 137 13.16 Juvenile whiting and Adult whiting 137 13.17 Juvenile haddock and Adult haddock 138 16. References 175 13.18 Juvenile saithe and Adult saithe 138 13.19 Hake 138 13.20 Blue whiting 138 17. Appendices 191 13.21 Norway pout 139 13.22 Other gadoids (large) 139 1. Ecopath with Ecosim formulation 191 13.23 Other gadoids (small) 139 2. Conversion factors 192 13.24 Anglerfish monkfish 139 13.25 Gurnards 140 continued 6 Foreword FOREWORD I am delighted to introduce this technical report that is an important product for a number of scientists and technicians both within, and outside of, Cefas. It represents the distillation of knowledge and ideas pertaining to the North Sea marine ecosystem contributed over the past six years from work undertaken both nationally and internationally. This report describes the data sources, assumptions and analyses used in developing representational models of the North Sea ecosystem (defined by ICES area IV) for the years 1973 and 1991, and the simulations of changes over space and time. In doing so, it brings together in one source a vast range of data and scientific knowledge that will become a valuable resource to ecologists and modellers alike. The contributions of experts, reflected in the authorship of the individual sections, have been central to ensuring the relevance and high quality of this synthesis. The models presented are just one of the tools needed to support the implementation of an ecosystem approach to fisheries management in the North Sea. While the reviews of biological knowledge for each functional group stand alone as useful contributions to knowledge on the North Sea, the added-value comes from the effort to render this information mutually compatible in the framework of an ecosystem model. The need to develop methods and approaches for exploring alternative hypotheses about ecosystem function and response to natural and human-induced change necessitates that such approaches be developed. The models capture and quantify the trophic structure and energy flows in 68 functional groups including marine mammals, birds, fish, benthos, primary producers and categories of detritus. They also include the landings, discards, and economic and social data for appropriately defined fishing fleets. Hind caste predictions of changes in the North Sea during the recent past are ‘calibrated’ against time series data from assessments and scientific survey data. Based on strong foundations, the models are useful tools for exploring dynamic change in ecosystems and macro- ecological patterns. The models may be further developed in their application to specific problems such as evaluating the relative influence of climate and fishing on ecosystem change, evaluating the effects of Marine Protected Areas (MPAs), predicting fish stock recovery and evaluating harvesting strategies.