Global stability in the Ricker model with delay and stocking

TL;DR

This paper analyzes the global stability of the Ricker model with delay and stocking, showing high stocking density can neutralize delay effects and establishing conditions for stability and bifurcations.

Contribution

It introduces new conditions for global stability in delayed Ricker models with constant or periodic stocking using embedding techniques.

Findings

High stocking density neutralizes delay effects on stability.

Conditions for global stability of equilibrium and 2-periodic solutions are established.

The model can undergo Neimark-Sacker bifurcation leading to invariant curves.

Abstract

We consider the Ricker model with delay and constant or periodic stocking. We found that the high stocking density tends to neutralize the delay effect on stability. Conditions are established on the parameters to ensure the global stability of the equilibrium solution in the case of constant stocking, as well as the global stability of the $2$-periodic solution in the case of $2$-periodic stocking. Our approach extensively relies on the utilization of the embedding technique. Whether constant stocking or periodic stocking, the model has the potential to undergo a Neimark-Sacker bifurcation in both cases. However, the Neimark-Sacker bifurcation in the $2$-periodic case results in the emergence of two invariant curves that collectively function as a single attractor. Finally, we pose open questions in the form of conjectures about global stability for certain choices of the parameters.