FT Vol.20(2)
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- ItemOBSERVATION ON THE DURABILITY OF FIFTEEN SPECIES OF CCA TREATED TIMBER IN THE COCHIN HARBOUR(Society of Fisheries Technologists (India) Cochin, 1983)Observations on the durability of fifteen species of common Indian timber treated with CCA at two absorption levels, for eight years are presented. CCA tteatment has improved the durability of these timber to a great extent. T. grandis, D. indicus and X. xylocarpa give maximum durability on treatment with CCA. Less durable A. kurzi, T. nudiflora and P. longifolia when treated with CCA showed results comparable to the best species
- ItemMERCURY TOXICITY IN TWO INTERTIDAL TROPICAL MARINE MOLLUSCS(Society of Fisheries Technologists (India) Cochin, 1983)Lethal and sub-lethal effects of mercury have been studied in Perna viridis and Modiolus carvalhoi. For P. viridis LC30 is 1.0 p.p.m. at 48 hand 0.23 p.p.m. at 96 h. Recorded LC50 values forM. carvalhoi are 0.5 p.p.m. and 0.19 p.p.m. at 48 hand 96 h respectively. The results document that these two species, although inhabiting the same area in the tidal belt, exhibit clear differences in mercury resistance. It is further shown that the duration of exposure affects mortality rates. In sub-lethal concentration, between 0.01 and 0.10 p.p.m. decrease in pedal-gland activity is conspicuous in P. viridis. At concentrations•much below LC50 values (at 96 h), although some animals are alive, pedal-gland activity is totally suspended, supporting the assumption that shellclosure ability plays a minor role in byssus thread production. In M. carvalhoi total cessation of p~dal gland activity occurred at 0.09 p.p.m. of mercury.
- ItemINFLUENCE OF MUSCLE FATS ON THE QUALITY OF INTERMEDIATE MOISTURE FISH(Society of Fisheries Technologists (India) Cochin, 1983)Chrysicthys nigrodigitatus with 12.95~~ fat having an iodine value of74.8 and a saponification number o( 198.48 and Citharinus citherus containing only 3.25% fat with iodine value of 67.8 and a saponification number of 145.86 were studied as examples of fatty and lean fishes respectively. The intermediate moisture (IM) products of both fish types compared with normal cooked samples, were evaluated as of acceptable colour, odour, texure and juiciness but of inferior taste due to the glycerol impact. However, during storage at 30°C the IM products became increasingly less acceptable with the deterioration being greater in the fatty fish than in the lean fish, although the fatty IM fish was superior to the IM lean fish with regard to water retention and juiciness. Overall quality differences were most apparent in colour and odour with the fatty IM fish being worse. The fatty fish had also greater evolution of TEA-reactive carbonyl breakdown products of lipid oxidation which were subsequently used up in non-enzymic browning producing the correspondingly darker fish colour and greater off odour
- ItemCROTON TIGLIUM (LINN) SEED AS AN IDEAL ERADICANT OF PESTS AND PREDATORS IN FISH FARM(Society of Fisheries Technologists (India) Cochin, 1983)The toxicity of Croton tiglium seed is very effective in the eradication of most of the aquatic fauna except a few species of hard shelled crustaceans such as crabs and prawns which are resistant to even very high concentrations of it. Its toxicity ranged between 0.4 and 2.2 p.p.m. for different species of fishes. Application of homogenised C. tiglium seed at the rate of 10 kg/ha (0.5 m depth) is found effective for the eradication of aquatic pests and predators of fish farms. While its toxicity lasts for 5-8 days in still water ponds, it is only for 1-3 days in tidal ponds with frequent replenishment of water. This method is thus most useful for the initial preparation of the ponds for pisciculture.
- ItemA BACTERIOLOGICAL STUDY OF THE NATURAL FLORA OF EDIBLE OYSTER, CRASSOSTREA MADRASENSIS(Society of Fisheries Technologists (India) Cochin, 1983)The total viable bacterial populations in the oysters and the sea water from the edible oyster farm at Tuticorin were · in the range of 103 to 104 per ml and 102 to 103 per ml respectively. The maximum most probable number of faecal coliform recorded during the one year period of study of both the oysters and seawater were 33 per 100 ml. Pathogenic bacteia (Salmonella sp., Vibrio cholerae, coagulase positive staphylococci and faecal streptococci were absent in oysters and farm water. Study of 197 (98 taken from oyster liquid and 99 from oyster farm water) randomly isolated cultures indicated that gram negative asporogenus rod-like bacteria of the Vibrio, Flavobacterium, Achromobacter and Pseudomonas gcoups were the dominant flora of the oyster liquid as well as seawater.