Advanced course: Ecosim

6 November 2014, Room P31 at ICM-CSIC

This advanced once day course explored the deeper workings of Ecosim, the temporal module of EwE. Participants learned how to use the advanced options of the Ecosim model, how to fit models to time series, and how to interpret Ecosim outputs.

Teachers: Villy Christensen (UBC, Canada), Steve Mackinson (CEFAS, UK), with assistance from Sheila Heymans (SAMS, UK)

In order to address wide-ranging policy questions, such as the relative impact of climate and fisheries, tracing effects of bioaccumulation, and the evaluation of social and economic consequences of management interactions, it is imperative that we can describe the historic changes that occurred in the ecosystem. Although there are more than 6,000 registered Ecopath users in 155 countries, not all of these users have undertaken the temporal analysis Ecosim. Ecosim allows for time dynamic simulations of fluxes in the ecosystem driven by forcing data of either fishing or environmental change. It incorporates the effects of micro-scale behaviour on macro-scale rates and includes biomass and size dynamics for key groups. Ecosim enables you to recreate changes in the ecosystem using either the foraging arena theory and/or other functional responses between predators and prey.

The students’ time was split between lectures and tutorials, with a focus on hands-on examples of how to fit models to time series using a formal fitting procedure, and how to interpret the Ecosim outputs, how to run policy trade-off analyses, etc.

Agenda

Tuesday 4 November
Time Topic Resources
09:00-10:15 Introduction: Ecosim – time dynamic modelling of predator-prey interactions, foraging arena theory, density-dependence and carrying capacity.practical Lecture: Ecosim and FAT(see Ahrens et al. 2012)
10:15-10:30 Break
10:30-12:30 Ecosim practical, how the foraging arena impacts outcomes of your simulations

Time series fitting, mediation, and environmental forcing. Modeling environmental impact. Primary production anomalies. Using climate drivers.
Lecture: Time Series Fitting
Tutorial 1: Fitting ecosystem models to time series data
12:30-14:00 Break
14:00-15:15 More time series fitting
Model fitting and performance testing: ‘Key runs’ – for models used in advice
Tutorial 2 Introduction: Pretty and plausible model fits – lessons from fitting the North Sea (on importance of SR fitting and consequences of vulnerabilities)
Tutorial 1 continued
Tutorial 2 Fitting the North Sea models using fisheries and environmental data (as needed)
(see Mackinson 2014)
15:15-15:30 Break
15:30-16:15 Fitting continued
16:15-17:00 Lecture: Policy trade-off analysis, optimisation tools, MSE and value chain tools
Recap and Q&A – common pitfalls and good practice

Recommended reading

  • Ahrens, R. N. M., C. J. Walters, and V. Christensen. 2012. Foraging arena theory. Fish and Fisheries 13:41-59
  • Christensen V, Walters CJ, Pauly D, Forrest R 2008. Ecopath with Ecosim version 6. User Guide. Vancouver, Canada: Fisheries Centre, University of British Columbia. 235 p. (can be downloaded from www.ecopath.org)
  • Walters C, Christensen V. 2007. Adding realism to foraging arena predictions of trophic flow rates in Ecosim ecosystem models: Shared foraging arenas and bout feeding. Ecological Modelling 209:342-350
  • Walters C, Pauly D, Christensen V, Kitchell JF. 2000. Representing Density Dependent Consequences of Life History Strategies in Aquatic Ecosystems: EcoSim II. Ecosystems 3:70-83>/li>