Investigation of two crop culture of western white shrimp

Two crop culture of western white shrimp with 2 treatments and 2 replicates in each treatments in earthen ponds with area 0.4 hectares at a density of 20 pl 18 in each square meter were done. For the culture of shrimp in the second stage, the post larvae cultured in nursery pond with area of 0.25 hectare, and density of 96 post larvae in each square meter, and then transfer to the rearing ponds. In each pond, 2 aerators with potency of 3 horsepower fixed. Every day horsepower clarified at 21p.m. to 23 p.m and out at 6 a.m to 7 a.m. The first stage of culture begun in 19 April with pl 18. The yield pick-up after 96 days. The stocking of pl in the nursery ponds was done in 25 July with pl16 and after 38 days hunted and transferred to second stage culture. The second culture was done in 1 September and pick-up after 65 days. For feeding of shrimps we used commercial food numbers 4001 until 4006. In the first mount the feeding of shrimps were done as blind feed and then with the shrimps biomass and with research of feeding trays. Water temperature, dissolved oxygen and pH daily in 2 times at the morning (6 a.m) and evening (at 15 p.m) and the salinity, transparency and water depth 1 time daily measured. In the first culture period (96 days), the mean weight, length, daily weight gain, FCR, survival percent shrimp production were 14.03 gr, 12.08 cm, 0.15 gr, 1.02 gr, 92 percent and 2132 kilograms and in the second culture period (65 days) 14.55 gr, 12.48 cm, 0.22 gr, 0.84, 73 percent and 2675 kilogarms measuered respectively. Totally, in the second period culture the initial weight of shrimps was higher than the first period culture 1.95 gr and 0.008 gr respectively, therefore growth indexes in the second period were better than the first culture period. Coefficient of determination of weight and lenth of shrimps with increase of cultue days, in the first and second culture periods, in the total cases the number were higher than 0.97. This shown that the role of increase of days on the increase of weight and lenth is higher than 97 percent. Also, determination of product moment, showed that there is very strong correlation between increase of days and increase of weight and lenth and between weight and lenth (0.97 to 0.99).

Iranian Fisheries Science Research Institute

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