VARIATION IN SHRIMP ABUNDANCE ON THE SOFALA BANK, MOZAMBIQUE, AND ITS RELATION TO THE ZAMBEZI RIVER RUNOFF

Variations in the catch of shallow water shrimp at the Sofala Bank, central Mozambique, are considered using abundance indices of Penaeus indicus by length groups. Both monthly, seasonal and year to year fluctuations are presented and related to Zambezi River runoff and rainfall. The influence of varying fishing effort is also investigated. Correlation analyses show that catch rate is positively related to river runoff and negatively related to effort, but no significant correlations with rainfall were found. Descriptive and predictive models are also developed. Annual abundance may be predicted based on wet season river runoff. During years with a well defined dry season and a late onset of the wet season, there seems to be a shift in the size distribution towards larger shrimp. The Cahora Bassa Dam regulation may be used to enhance shrimp production, by providing well-planned water releases. © 1992 Academic Press Limited.