Influence of variable catch factors on sardine population level in eastern Adriatic tested by System Dynamics

System perspective can be applied to the fishery management. Therefore investigation of sardine population behaviour dynamics by system dynamics methodology is presented in this paper. The model is based on Schaefer production model and available biological data was used for sardine in the Adriatic Sea. The Schaefer production model is often applied in order to submit behavior dynamics of fish population and particularly to manage marine natural resources efficiently. Alegria-Hernandez (1983) used Schaefer and Fox production models for sardine population in Eastern Adriatic. Initial value for catchability coefficient of 3,99E-5 is taken from Alegria-Hernandez (1983). According to the same author value of the optimal fishing effort is between 4115 and 5292 effective fishing days in one year for the sardine in the Eastern Adriatic. Those values are tested using developed model. Simulation scenarios were made in Powersim and DYNAMO. Although model can be applied for all other species and many of different regions, sardine population was chosen due to its great importance to Croatian fishing.