Abstract
Fish Populations in small streams are affected by construction of water management facilities that block movement among various habitat patches. Some methods to improve those passage blockages (networking) have been applied but the benefit has not been evaluated preliminarily. We proposed a fish population dynamics model designed for stream networks. In the model, a canal system is depicted using numerous mesh elements which contain habitats separated by passage barriers. The difficulty of movement over the boundary between adjacent mesh elements is given as an attribute value for each element. Accordingly, the points separating habitat areas and the degree of improvement at those points can be depicted using the assigned boundary attributes. Movement distance for each individual is calculated using normal random numbers. Success and failure of movements over each boundary are determined by comparing the boundary's attribute value with a uniform random number. Within each mesh element, reproduction (number of new individuals) is calculated using the logistic growth model. We simulated population dynamics before and after networking of habitat areas in a hypothetical canal system and suggested methods to predict and evaluate the effect of networking of water areas.
