FT Vol.46(1)
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- ItemWhite Tail Disease: A Viral Disease of Giant Freshwater Prawn, Macrobrachium rosenbergii (deMan)(Society of Fisheries Technologists (India)Cochin, 2009)Virus borne diseases are extremely difficult to control and constitute one of the major problems of prawn farming. Till recently, the giant freshwater prawn, Macrobrachium rosenbergii was regarded as disease resistant. But there have been recent reports on white tail disease (WTD), a virus borne disease of M.rosenbergii affecting the aquaculture industry of India. In this review, clinical signs, causative agents, mode of transmission and various diagnostic methods of white tail disease are discussed.
- ItemEffect of tow duration on the capture efficiency and catch characteristics of bottom trawl(Society of Fisheries Technologists (India), Cochin, 2009)The catching performance of a 34 m High opening bottom trawl (HOBT) was studied with tow durations of 15, 60 and 120 min each and with two towing speeds (0.87± 0.03 and 1.36 ± 0.03 ms-1) to find out changes in the species retention and escapement in terms of weight and number from the codend. Variations in the retention and escapement catch per unit effort (CPUE) in terms of weight and number for the different tow durations were compared. Although, the mean catch rate expressed as mean CPUE was found to be consistently higher in·the 15-min haul, the difference was not statistically significant from that of 60 and 120-min hauls. Within and between hauls variation in catch rate of six species (as determined by SIMPER analysis) was studied using univariate GLM with tow duration and speed· as categorical predictors. The catch rates of three species Trichiurus lepturus, Lactarius lactarius and Uroteuthis (Photololigo) duvauceli were found to be significantly different due to tow duration effect, but neither speed nor the interaction effect had any significant effect on the catch rates for these species. The mean diversity, dominance and evenness indices showed no significant difference among the hauls of different tow durations. Based on the results of the study, it is concluded that the short duration tows of 15-min are as effective as the 60 and 120- min tows Jr estimating catch per unit effort in terms of total weight, number and diversity indices.
- ItemEffect of hydrocolloids on the functional properties of batter mix used for the preparation of coated shrimps(Society of Fisheries Technologists (India), Cochin, 2009)n the present study, the effect of the addition of three different hydrocolloids viz. Guar Gum (GG), Carboxy Methyl Cellulose (CMC) and Carboxy Methyl Chitosan (CMT) on the functional properties of batter mix used for the preparation of coated shrimps was investigated. The maximum viscosity was noticed in batter containing GG at 1:2 dilution followed by batters containing CMC and CMT. Among the three batter systems, GG based batter showed highest shear thinning behavior and indicated maximum viscosity at lower dilutions and lower shear rates. Compared to the other two batters, GG based batter indicated maximum water retention capacity irrespective of temperatures and dilutions. In coated shrimps, the highest pick up was observed with GG-based batter, followed by CMC and CMT based batters. Thus, in terms of functional properties and batter consistency, GG based batter mix was found to be superior to the other two batter mixes.
- ItemAntidumping investigations on shrimp exports from India to US - a case study(Society of Fisheries Technologists (India), Cochin, 2009)The anti-dumping investigation against India and five other major shrimp exporting countries by the US was initiated in December 2003. This paper examines the impact on the quantity and value of shrimp imports from these countries in general and India in particular, during the period of investigation and after. It was observed that there has been a negative impact on Indian shrimp exporters and the number of exporters has decreased considerably. The effect on the price in the US market has been negligible with the unit value of imports actually falling. Only a short-term rise in price index was observed during the initial phase of the investigation period as well as the period when the affirmative decision was announced.
- ItemAdoption of good management practices by aquafarmers(Society of Fisheries Technologists (India), Cochin, 2009)The study was conducted among the aquafarmers in four selected districts viz., Trichur, Alleppey, Ernakulam and Kannur in Kerala. Data were collected on the extent of adoption of good management practices among the sample respondents. Of the 10 practices evaluated, the adoption scores were higher for six practices viz., preparation of ponds (93.15%), eradication of predators and weeds (85.39%), use of PCR tested seeds (84.47%), use of recommended feeding schedule (77.63%), water exchange and quality monitoring (71.69%) and harvesting after prescribed days of culture (70.32%). The extent of adoption of each practice varied significantly (p < 0.01) among the aquafarmers with the overall mean adoption score of 70.09% (n=73). The variables viz., number of training programmes undergone, number of information sources utilized and expert services availed, were found to have positive relationship with the extent of adoption. Regression analysis revealed that of the seven variables, only one variable viz., number of training programmes undergone had contributed significantly (p < 0.05) towards the extent of adoption of improved practices.