This note deals with a harvesting model for a single stock fishery. In the case of small pelagic fish it seems reasonable to consider harvest functions depending nonlinearly on fishing effort and on fish stock. Empirical evidence about these fish species suggests that marginal catch does not...

Pelagic species are one of the fish stocks which are most vulnerable to unrestrained fishing. Their initial abundance has been a source for substantial profits in the past, with several fishing collapses resulting from it. This paper analyses the case of