000			nam a22 7a 4500
999			_c9412 _d9412
003			OSt
005			20181226133610.0
008			181214b xxu||||| |||| 00| 0 eng d
040			_cNARA
100			_917534 _aCorea, A.S.L.E.
245			_aRecent Disease incidence observed in shrimp Aquaculture in the Dutch Canal Area
260			_c2004, _bNARA, _aSri Lanka,
300			_a1p.
440			_917546 _aProceeding of the Tenth Annual Scientific Sessions of the Sri Lanka Association for Fisheries and Aquatic Resources, 2004
520			_aShrimp aquaculture in the North western Province is strained by the While spot disease since 1996. Several precautionary methods taken to prevent the outbreaks of this disease have not been very successful. Prior (a lh© outbreak of the disease several symptoms related to water quality and pond environment deterioration could be observed. These symptoms unused by bacteria, fungi, protozoans, or toxic effects of deteriorating aiwlronmental conditions receive very little attention at present. Therefore, (hi present study was carried out to study the disease incidences other than lh® white spot disease in shrimp farms situated along the Dutch canal. About 100 shrimp farms were used for the study. The soft shell, black gills, fouling organisms on body, broken ®PP©ndages and growth retardation were observed in 60 % of the farms. Mortality due to any of these reasons is considered as due to white spot cilisase by the farmers and immediate harvesting takes place. During the survey, alkalinity levels in the ponds were found to vary between 34 mg/l tnd 102 mg/l. Soft shell was recorded from 26 % of the farms where Alkalinity levels were below 60 mg/l. Forty two percent of the.farms reported growth retardation, 18 % reported algal crashes, 12 % reported black gills, ind 7 % reported the occurrence of fouling organisms. Mortality due to high ffiffimonia concentrations was recorded from 3 % of the farms and 45 % of th§ farms reported dead shrimp during early mornings. Although samples did not show any external symptoms of white spot disease, some samples Indicated symptoms of low oxygen conditions. All these ponds were harvested immediately and reported as those affected by the white spot disease. During these disease incidences, ammonia level in the Dutch Qliial varied between 0.42 mg/l and 1.96 mg/l. these results indicate that there is a need to pay more attention to lh© cause of mortality and environmental management in shrimp farms. It is taleo necessary to maintain correct records of data in order to revive the Industry to its former levels.
700			_917545 _aJayasinghe, J.M.P.K.
942			_cRP _2ddc