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1991 - 19922
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Subject: Fisheries × Author: KAU × End date: 1999 × Start date: 1991 × Type: Thesis × Thesis Type: M.F.Sc ×
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    ThesisItemOpen Access
    Studies on certain aspect of the biology of the barracuda of Cochin region
    (Department of Fishery Biology, College of Fisheries, Panangad, 1992) Krishnadas, K J; KAU; Rajasekharan Nair, J
    A systematic redescription of the three species viz. SphyraenajelloCuv.,S.obtusata (Cuv. & Val.) andS. barracuda (Walbaum), available in the Cochin region has been done. The food and feeding habits, breeding biology, length – weight relationship and condition cycles of S. jello, the commercially most important species of the region, have been studied in detail. A total of 141 males (270 – 943 mm TL) and 64 females (322 – 770 mm TL) collected during Nov. ’88 to Oct. ’90 were subjected to various investigations like qualitative and quantitative assessment of stomach content, feeding intensity, prey – predator length relationship, feeding habits, quantification of maturity stages, size at first maturity, spawning season and spawning frequency, sex ratio, spawning potential, length – weight relationship and condition and relative condition cycles using standard methods. S. jello is found to be a typical predator and a predominant piscivore. The species mostly feeds on small pelagic and mid – water shoaling fishes like clupeids, anchovies, scads and silverbellies, occasionally consuming cephalopods. The total length of the prey rangfed from 18.68 to 31.43% of the predator length. The size at first maturity is found to be 360 mm for males and 370 mm for females (350 – 400 mm length class). The species exhibits a prolonged spawning season in the Cochin region, spanning from April – September/October with increased activity during June to September. Individuals of S.jello spawn more than once during this prolonged spawning season. Female dominance in the population was noticed during May to July coinciding with spawning activity. The absolute fecundity of recruit spawners of S. jello ranged between 82, 431 and 1, 63,533 9400 – 501 mm TL). The intensity of feeding was lower during the period of increased spawning activity and higher during post – spawning period. The length – weight relationship worked out for the species is log W = -4.2751 + 2.5848 log L, the relationship showing no significant difference between the sexes. The relative condition cycle closely followed the spawning cycle, the values being close to ‘1’. Condition factor calculated using eviscerated weight of fish provided an index of true well being of the fish.
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    ThesisItemOpen Access
    Growth response of penaeus monodon fabricus to pelleted feeds of different protein sources
    (Department of Aquaculture, College of Fisheries, Panangad, 1991) Josekkutty, P A; KAU; Susheela, Jose
    The efficiency and keeping quality of the five pelleted feeds formulated from different protein sources viz. clarm meal, prawn meal, slaughter house waste meal, soybean meal, single protein (marine yeast) were tested with a view to develop a suitable supplementary feed for Penaeus monodon The feeds were isonitrogeneous , crude protein content ranged from 39.76 to 40.3%) and isocaloric (Caloric value between 3.34-3.72 K.cal/g). The quality of the feeds over a period of four months of storage remained good, eventhough a slight reduction in nutritive value has occurred. P. monodon juvenile were reared for 6 weeks in experimental tanks with different artificial feeds the highest growth and survival were recorded in those fed with diet based on animal protein sources. Among the feeds tested, the clam meal based diet was found to be superior followed by diet based on slaughter house waste meal. The diet based on marine yeast was found to give better performance than those based on prawn meal or soybean meal. The food conversion ratios obtained with different feeds ranged from 2.18 to 3.26. The lowest FCR was recorded in diet based on clam meal (2.18) and the highest (3.26) in diet based on marine yeast. Protein efficiency ratios and protein digestability values were found to be higher in prawns fed with diet based on clam meal followed by diet based on slaughter house waste meal. Significant variations in the biochemical composition of prawns fed with diet based on different protein sources were recorded. Significant variation in oxygen consumption, ammonia, excretion and O:N ratios were recorded in prawns reared on different protein based diets. Highest oxygen consumption rate and lowest ammonia excretion rate were observed for diets based on animal protein sources than plant or single cell protein source. Among the different diets tested, diet based on clam meal recorded highest oxygen consumption, lowest ammonia excretion and highest O:N ratio values. The optimum food ration for P.mondon juveniles was found to be at 6% of the body weight while maintenance and maximum rations were 1.8% and 15% respectively for clam meal based diet. Food consumption, growth and survival of P.monodon increased, as feeding frequency was raised, however these parameters increased only upto an increase of 3 meal/day and there after they showed a declining trend.