Factors Affecting Penaeus monodon Yield in Extensive Farming System in Southwest Bangladesh

摘要

An investigation of the factors affecting Penaeus monodon yields was carried out from extensive shrimp farming system in southwest Bangladesh. Data were collected from 82 shrimp farms between January and August 2002. A questionnaire survey along with PRA tools were conducted in gathering information. It was found that the surveyed shrimp farms accured economic losses. Penaeus monodon yielded 146.39 kg ha 1 to 153.12 kg ha 1 against expected 250 kg ha 1 to 400 kg ha 1. The return to the total cost was US$ 0.012-0.015. According to the results, the factors affecting the shrimp yield are old aged farms, inadequate water exchange, shallow water, accessing bad water, salinity fluctuation, unstable soil and water parameters, variable stocking density, absence of quality post larva and competition by non-target species in the shrimp farm. The results also indicated that shrimp farmers accured consequences as a result of disease outbreak in 2001-2002. Farmers responded to combat diseases in the areas through pre-harvesting (83%), sun-drying of ponds (43%), increasing use of pesticides (15%) and conversion of land into paddy (12.19%). Employment loss, repayment of loan default, break up of group farms (60%), revenue loss and flee of farmers (6%) to the neighbouring country were encountered as a result of socio-economic consequences. Widespread disease outbreaks and consequent heavy losses to farmers are thus challenging the sustainability of shrimp aquaculture in Bangladesh.