ANALISIS KESTABILAN DAN KONTROL OPTIMAL MODEL LESLIE-GOWER FUNGSI RESPON HOLLING III DENGAN PEMANENAN PADA POPULASI PREDATOR DAN PREY

This article modified the leslie-gower model on harvesting with predator and prey population. This study aims at construct a modification of leslie-gower model with holing III response function. In addition, there is an effort harvesting in predator and prey population, analyzing an equilibrium point, finding bionomic equilibrium and the condition where the present value is maximum from net income by controlling harvesting in both populations. In the modified leslie-gower model there is an equilibrium point which is asymptotically stable and when there have harvesting, the equilibrium point is also asymptotically stable. Bionomic equilibrium from harvesting on the modified leslie-gower model is maximizing the profit function π of harvesting on a model with the maximum pontryagin principle resulting an optimal equilibrium) affected by instantaneous rate of discount δ.

Dynamics of a Harvested Prey–Predator Model with Prey Refuge Dependent on Both Species

The present paper deals with a prey–predator model with prey refuge in proportion to both species, and the independent harvesting of each species. Our study shows that using refuge as control, it can break the limit cycle of the system and reach the required state of equilibrium level. We have established the optimal harvesting policy. The boundedness, feasibility of interior equilibria and bionomic equilibrium have been determined. The main observation is that the coefficient of refuge plays an important role in regulating the dynamics of the present system. Moreover, the variation of the coefficient of refuge changes the system from stable to unstable and vice-versa. Some numerical illustrations are given in order to support our analytical and theoretical findings.

Analysis of a Prey-Predator Fishing Model for Harvesting with The Limited Effect of Density and Toxicity

We proposed a model of prey-predator fishing by considering proportion of prey density and toxicity in ecosystem. The model is analysed to study about biological equilibrium, bionomic equilibrium and its stability. The aim of the model is to determine the optimal sustainable harvesting for each species. The optimal harvesting is resulted from Pontryagin’s maximal principle. The global stability of coexistence equilibrium is analyzed from Lyapunov function. The effect of toxicity leads to the decreasing of sustainable harvesting.

Optimal harvest of an interval model of carbon sink fisheries with multi-trophic levels

Considering the uncertainty of kelp–abalone–sea cucumber population, an interval model of carbon sink fisheries with multi-trophic levels is proposed. The equilibria of the model are identified and the corresponding stabilities are discussed. And the existence of bionomic equilibrium of the model is investigated. Next the optimal controller is designed to obtain the optimal harvest using Pontryagin’s maximum principle. Numerical simulations are carried to prove the results.

MODELING PREY-PREDATOR TYPE FISHERY WITH RESERVE AREA

This paper presents a prey-predator type fishery model in two patch environment. We assume that one patch is accessible to both prey and predator while other is a refuge for prey. The prey refuge constitutes a reserve zone where fishing is not allowed. In the unreserved area there are both prey and predators and harvesting of only predators is permitted. The equilibria of the model and their stability are discussed. Also we investigate various possibilities of bionomic equilibrium. Finally, the model is simulated for varied set of parameters and sensitivity of the parameters and effect of the size of reserve on maximum yield are studied. We found that it is the best to keep the size of reserve small and increase the harvesting effort upto optimal harvesting effort to get the higher maximum yield.

Harvesting of a Single-Species System Incorporating Stage Structure and Toxicity

A single species stage-structured model incorporating both toxicant and harvesting is proposed and studied. It is shown that toxicant has no influence on the persistent property of the system. The existence of the bionomic equilibrium is also studied. After that, we consider the system with variable harvest effect; sufficient conditions are obtained for the global stability of bionomic equilibrium by constructing a suitable Lyapunov function. The optimal policy is also investigated by using Pontryagin's maximal principle. Some numeric simulations are carried out to illustrate the feasibility of the main results. We end this paper by a brief discussion.