A simple bioeconomic model of a marine reserve

We model the effect of a no-take reserve in a marine fishery management area, such as on a coral reef. Implicitly, eggs and larvae are mobile but adults are not; and there is open access fishing outside the reserve. A reserve is found to increase equilibrium catch if the prior ratio of stock to carrying capacity is less than a half, and the catch-maximising reserve proportion rises towards a half as this ratio falls towards zero. After initial adjustment, long-run stability is improved by a reserve. We estimate that coral reef reserves could increase world wide annual catches by about a billion dollars.