Formulation of management strategies for two exploited West African prawn populations

Abstract

The life histories of the estuarine prawn, Nematopalaemon hastatus Aurivillius, and the brackish river prawn, Macrobrachium macrobrachion Herklots, were compared in relation to their seasonal exploitation patterns in the Cross River estuary, Nigeria. The period of intensive exploitation of N. hastatus (March to June) was outside the main spawning season (July to October), because these prawns migrate from the main fishing area in the estuary and near shore coastal waters into the deeper continental shelf waters to spawn. This probably contributes to their reproductive success and conservation of the stock. With M. macrobrachion, the peak spawning period and the major fishing season converge between July and September. These prawns also migrate from the fresh water into the major fishing zone within the estuary during the spawning season. This exposes the spawning population to intense human exploitation. On the basis of their spawning dynamics, M. macrobrachion requires more urgent management attention. An option would be a closed season for M. macrobrachion within the estuary during the spawning period.