Description

Abstract: The Mekong River flows through southern Vietnam in two major branches, encompassing a 39,550- km2 delta with 14.2 million inhabitants. With open access to vast estuaries, extensively interconnected rivers and canals constitute most of the aquatic environment in the Mekong Delta: an ideal habitat for the native freshwater prawn (Macrobrachium rosenbergii) (Fig. 1). The prawns are harvested primarily by a common small-scale method using shelter traps. The shelter traps installed along the edges of rivers and canals are square or rectangular enclosures surrounded with bamboo or wooden frames, within which piles of tree branches and aquatic vegetation (water hyacinth) are placed to attract prawns from the open water. Periodically, fishers surround the shelters with seine nets and remove prawns from within them. Prawns are harvested all year-round and the larger ones are sold at more than US$4/kg, either to local markets or government processing plants. Smaller prawns and juveniles are kept alive and sold to prawn farmers at around US$1.5/kg, which comprises 200 to 300 individuals.

The total annual freshwater prawn production in Vietnam during 1985-90 was reported to vary from 5,000 to 8,000 t, most of it from natural fisheries. Unless the harvest of wild juveniles is managed, it may undermine the sustainability of the natural fisheries.

There have been few efforts to estimate the standing stock of prawns in any given river or habitat. Nor is there information on catch/effort and rate of natural recruitment for the prawn population. Without such data, it will be difficult, if not impossible, to assess their present status and predict the future trend of the prawn fisheries