We consider a fishery described by two state variables, namely, the stock of fi sh and its marine environmental quality, operationalized as an index of habitat extent and quality, which influences the growth rate and the carrying capacity (MEQ). Assuming that myopic fishing agents exploit the fishery, we characterize and contrast the steady-state values in two scenarios: (i) a scenario where the agents (correctly) perceive that the MEQ is non-constant and (ii) a scenario where they behave as if the MEQ is a given constant. Not unexpectedly, the harvest rates diff er across the two scenarios and consequently lead to di fferent steady states. Interestingly, for some parameter values, we obtain that assuming a constant MEQ has a conservation flavor, that is, it results in a larger stock of fish and higher MEQ in the steady state. We show that there exists a steady-state solution to the planner's problem, and that it can be supported by a large number of appropriately designed tax schemes, while the approach path to the steady state depends on the implemented tax scheme. We also discuss the implications for optimal regulation under open access when habitat matters.