Model of fish population dynamics with calculation of individual growth rate and hydrological situation scenarios

Abstract

Introduction: Populations of commercially valuable fish species develop in aquatic ecosystems according to internal mechanisms of their evolutionary adaptations, which do not always suit the environmental conditions which can change due to anthropogenic pressure. Often the factors of reservoir eutrophication or introduction of new species into the ecosystem aggravate the competitive confrontation of the populations. The changes spread by domino effect and complicate the development of a strategy for rational exploitation of biological resources. Species under non-optimal anthropogenic conditions are vulnerable. Purpose: Developing a model for introduced population dynamics, implemented as a group of scenarios for a volatile environment. Results: We developed a computational model of a population to describe the scenarios for its adaptation to environmental conditions. The scenarios include the pace of dimensional development and nutrition of fish. The model includes a unit for calculating diets, taking into account the hydrological situation factors: the oxygen content and the activity of hydrogen ions. The model is capable of operating in two modes: under standard environmental conditions (without specifying the hydrological situation) and with preset conditions for anthropogenic changes. Our approach allowed us to predict changes in the population structure with variability in abiotic factors. The model demonstrate the risk of taking out the fish which make the greatest contribution to the biomass growth rate. Practical relevance: The model was identified using the data on whitefish population in the Lake Sevan. It is suitable for computer simulation experiments, which made it possible to describe specific features of scenarios of population dynamics for the cases of increased fishing, limited feeding and changes in the hydrological conditions of the lake.