FISHING IN A SHALLOW LAKE: A CASE FOR EFFORT CONTROLS?

摘要

In many situation, fishing activity adversely impacts the state of the marine ecosystem, impacts which feed back to affect fish stocks. Some ecosystems appear to have multiple equilibria and exhibit hysteresis, whereby they can become stuck in low productivity states. We show how adding ecosystem dynamics to a classic fisheries model can introduce hysteresis impacts, impacts that affect both the evolution of the fish stock and the fishery harvesting it. We demonstrate that harvest and effort taxes are not equivalent instruments for controlling this externality. We also show that if the fishery is sufficiently degraded, it may not be optimal to move the system back to a healthy environment.