(05) The rapid expansion of shrimp culture in the past five years is one of the most remarkable developments in the country's fisheries sector. From less than 20 000 ha of brackishwater shrimp ponds in 1980 the area expanded to over 70 000 ha in 1985. Over the same period, cultured shrimp production has grown from less than 1 000 mt per year to over 6 000 mt in 1985.
(6) Though the exact magnitude of areas suitable for shrimp culture is yet to be surveyed and identified, some agencies feel that approximately 2.5 million ha of coastal tidal lands have good potential for brackishwater pond culture of shrimp and fish. Most of the shrimp ponds constructed during recent years have been in areas originally developed for paddy or for salt pans. Because such areas were already cleared within polders, conversion to shrimp culture required relatively low capital investment and returns from operations have been high. While some areas continue to seasonally alternate between paddy and shrimp culture or salt and shrimp production, in other areas culture of shrimps alone has proven to be profitable.
(07) Present pond management practices are generally simple, involve few inputs and have low operational costs. Ponds tend to be large in size (upto 40 ha or more), have poorly constructed dikes and rely on tidal flushing. Most farmers stock 10 000 – 20 000 wild caught shrimp postlarvae per ha, along with other shrimp and fish that inadvertently enter the ponds upon filling. More progressive farmers prepare their ponds prior to stocking, maintain well-constructed gates with screens, and fertilize. On the well-managed farms, yields of upto 500 kg/ha per year are reached with little or no supplemental feeding. However, average production approximates to 250 kg/ha per year at present.
(08) As farmers have recognized the benefits of increased stocking of their ponds, the wild fry collection and distribution industry has developed. In 1985 it is estimated that about 1 – 3 billion shrimp postlarvae were collected from the rivers and bay, and that about 50 % of these survived to be stocked into shrimp ponds. A major constraint in the shrimp culture industry is seed stock. The seed stock shortage arises in part from poor collection and handling techniques that lead to high mortality prior to stocking. Additional mortality also occurs at the time of stocking because of inadequate attention to acclimatization. Artificial reproduction of shrimps did not yet develop.
