Introducing Space and Spatial Interactions in DISPAS: Demersal Fish Probabilistic Agent-based Simulator

DISPAS [3] is an individual-based, probabilistic, agent-based simulator developed as a support for fish stock assessment, in particular for the species of common sole (Solea solea L.) in the Adriatic Sea. DISPAS has been developed by the University of Camerino in collaboration with the Institute of Marine Sciences (CNR - ISMAR) of Ancona. The simulator is implemented on the Repast Symphony suite [2] and can be used to reproduce the biomass and the abundance of the common sole observed along the period 2005-2011 by scientific surveys. Data for the estimation of the probabilities and for the validation come from the SoleMon project [1]. In order to specify and simulate more detailed scenarios, spatial interactions among the agents and the environment are introduced. In particular, each agent - representing an individual of the modeled species - can perform a Random Walk within the simulation space, which is divided in a grid of cells. Each cell is also associated with a value representing Food Availability. Such amount can be consumed by the agents and is continuously generated using a given rate. The rate can be influenced by geographical or environmental available data. Another improvement is the introduction - besides the current micro scale, where the simulated space is an average square kilometer - of a macro scale in which the entire Adriatic Sea can be represented and simulated. In the latter case, an agent does not represent an individual of the species anymore; instead, it represents a group of individuals that can possibly move from an area of the sea to another according to known biological information.