Sensitivity analysis of marine reserves and its implications as a fishery management tool was examined. A fishing free zone was established analytically which led to stability of the fishing free zone by employing linearization, first order differential equation and Jacobian matrix and unstable fishing free zone was obtained. We then apply some protection in the fishing zone and obtain a stable environment with the same techniques. Finally, the use of MATLAB helps us to discover that fishing effort has significant influence on fish biomass. The result reveals that as fishing effort increases, both the fraction of fish stock in the fishing zone and fraction in the reserves zone approaches their respectful extinction limits. It was equally examined that when the biomass in the open zone is heavily fished then there is a significant disparity in stock density between the two zones. An increased flow of transfer from the reserved zone to the fishing zone result in the catch reaching its maximum level as the transfer reaches its peak. Finally, there is predator interference which may lead to extinction of the prey, meanwhile, the protected zone does not allow predator and thus the fishing environment has no implications.