Influence of Rainfall on Optimal Spawner Catch for the Shrimp Fishery in Iran

Abstract

Penaeid shrimp culture in Iran depends on a supply of spawners from the sea for seed production. The inadequate stock of wild Indian white shrimp Penaeus indicus spawners for hatcheries is a bottleneck to the development of Iran's shrimp culture. The aim of this paper is to test the influence of rainfall on the spawner population and to determine the maximum sustainable and economic yields for the harvest of spawners. Surplus production bioeconomic models (Schaefer 1954 and Fox 1970) with and without rainfall effects were used and the parameters estimated from pooled time series and cross-sectional data on catch per unit effort (CPUE; spawners per day). It was found that the models with rainfall effects provided better fits to the data than those without that variable. Rainfall had significant and positive effects on CPUE and optimum catch. Based on econometric criteria, the Schaefer model with rainfall was preferred. With that model, the estimated maximum economic yield of wild Indian white shrimp spawners was 25,449 with rainfall and 15,963 without rainfall. These results mean that the allowable catch of such spawners may be adjusted annually based on the rainfall prior to the shrimping season.