FT Vol.33(1)
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- ItemUptake and Depuration of Phenol by Rohu (Labeo rohita) during a Chronic Sublethal Bioassay(Society of Fisheries Technologists (India)Cochin, 1996) Sherief, P.M; Nair, J.R. Rajasekharan; Mrithyunjayan, P.SStudies on the body residue levels in surivors of bioassay tests can provide valuable information on bioaccumulation and organism tolerance, while residue in survivors allowed to depurate in clear water could furnish data on detoxification and elimination of pollutants. Early juveniles of rohu (Labeo rohita) were exposed to five sublethal concentrations of phenol (0.1,0.5,2.0,5.0 and 10.0 mg I"1) and a control under a static-with 48 h replacement procedure with nominal concentrations for a period of 28 days. The phenol body residue concentration increased from 8.17 to 24.85 mg kg"' whereas the bioaccumulation factor decreased from 81.7 to 2.5 as the phenol concentration in water increased from 0.1 to 10.0 mg I"1. The 72 h percentage depuration of the accumulated body phenol residues ranged from 58.5 to 71.2% on exposure to clear water. The study reveals that phenol as a pollutant has a low bioaccumulation potency and a high rate of depuration in fishes.
- ItemObservations on the Growth Performance of Labeo dussumieri (Val.) in Mono and Mixed Culture Experiments(Society of Fisheries Technologists (India)Cochin, 1996) Kurup, B. MadhusoodanaGrowth performance and production potential of an indigenous carp of Kerala, Labeo dussumieri (Val.) has been studied by culturing it alone and also in combination with Indian major carps. In monoculture trials, L. dussumieri attained a mean weight of 392 and 356 g at stocking densities of 3000 and 4000 ha'1, respectively within a period of 10 months. In composite culture trials when L. dussumieri (Thooli) was reared along with Catla, Rohu and Mrigal in the ratio 1:1:1:0.5, and the average weight attained by Catla, Rohu, Mrigal and Thooli within a period of ten months were 671, 602, 474 and 322 g, respectively at a stocking density of 6000 ha"1 whereas at a higher density of 8000 ha"1, the average weights registered were in the order of 557, 506, 397 and 283 g, respectively. These would work out to a gross production of 2698 and 3043 kg ha"1 at stocking densities of 6000 and 8000 ha"1, respectively. The growth attained by L. dussumieri was apparently poor in the experiments when ratio of the above four species was maintained at 1:1:1:1. Physicochemical and biotic parameters of the ponds were also studied.
- ItemEffect of Hormones on Growth and Food Utilization of the Indian Major Carp, Cirrhinus mrigala(Society of Fisheries Technologists (India)Cochin, 1996) Jayaprakas, V; Sindhu, B.SThe influence of human chorionic gonadotropin (HCG) and testosterone propionate (TP) at the dosages of 10 ppm and 3 ppm respectively, and their combination (HCG+TP) of 8 ppm and 1.5 ppm on the growth, food conversion, digestibility, enzyme activity, nucleic acid content. Oxygen consumption and ammonia excretion of the Indian Major Carp, Cirrhinus mrigala was assessed. The experiments were conducted in cement tanks (5x4x1 m) for 98 days by feeding hormones through fish meal based prepared diet having 35% protein. Growth of C. mrigala was high in hormone fed fishes than the control with the maximum growth recorded in the HCG treatment followed by HCG+TP, TP and control. Specific growth rate (SGR), food conversion efficiency (FCE), apparent protein and lipid digestibility were high in hormone fed fishes (p < 0.01) than the control. The enzyme activity in the foregut, midgut and hindgut showed marked variation with the highest activity noticed in the foregut followed by midgut and hindgut. The rates of oxygen consumption and ammonia excretion of hormone fed fishes were found to be not significantly different from control (P > 0.05). The hormones stimulate growth through increasing the appetite and enhancing food utilization and protein synthesis.
- ItemRing Seines of South Kerala Coast(Society of Fisheries Technologists (India)Cochin, 1996) Edwin, Leela; Hridayanathan, CRing seine or mini-purse seine is currently one of the prominent fishing gears in the artisanal fishery sector of Kerala. Since its introduction in mid-eighties, the ring seine has caused displacement of gears such as Thangu vala, operated from the traditional boat seine craft, Thangu Vallam. The design and operational features of the ring seine prevalent in the Alleppey - Cochin coast have been described in this paper alongwith a review of the important changes that have taken place in the design and operation of the gear, since its introduction.