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Theses

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1992 - 19966
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Subject: Fisheries × End date: 1996 × Start date: 1992 × Type: Thesis ×
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Now showing 1 - 6 of 6
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    ThesisItemOpen Access
    Comparative study on certain aspects of the biology of Macrobrachium Equidens Equidens (Dana, 1852) and M. Equidens Pillaii Jayachandran, 1989
    (Department of Fishery Biology, College of Fisheries, Panangad, 1993) Anitta Sebastian, KAU; Jayachandran, K V
    The aim of the present study has been to establish the taxonomic status of Macrobrachium equidens equidens (Dana, 1852) (spotted variety) and M. equidens pillaii Jayachandran, 1989 (striped variety) which co-exist in Cochin backwaters, by undertaking investigations on certain aspects of their biology. The two populations differ in colouration, length and arrangement of teeth in the rostrum, nature of carapace, telson, proportions of different podomeres and nature of pubescence of fingers of 2nd cheliped. Considerable differences in the growth patterns of the two populations also have been noticed in the characters, such as, rostrum, cephalothorax, carapace, width of carapace and ischium, merus, carpus, propodus, palm and fingers of 2nd cheliped. The meristic studies revealed that the arrangement of rostral teeth is specific for each population. Similarly these two populations differ in the length-weight relationships also. The SDS polyacrylamide gel electrophorogram showed clear difference in the number and position of bands in the two populations. Though the early part of oogenesis of the two populations showed similarity, considerable differences have been observed in the yolk deposition. The present investigation revealed that the two populations differ drastically in respect of all the characters studied and therefore are to be considered as two distinct species. The striped variety had been described as new species twice before of which the name "sulcatus” preoccupies any other name. Therefore the present investigation proposes the names for the two species as M. equidens (Dana, 1852) and M. sulcatus (Henderson & Matthai, 1910).
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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
    Studies on depuration of edible oyster Crassostrea madrasensis (Preston)
    (Department of processing technology, College of fisheries, Panangad, 1993) Usha, P T; KAU; Damodaran, Namboodiri
    Oysters crassostrea madrasensis harvested from cochin back waters are commonly contaminated with low levels of food poisoning organisms such as E.coli, Salmonella, Shigella, Vibrio cholera, V-parahaemolyticus etc, heavy metals like cadmium, lead, copper, zinc, mercury etc and sand content. Depuration studies were conducted to find out any changes in the biochemical constituents such as total Nitrogen, salt soluble Nitrogen, Non protein Nitrogen, Ash and sand content. The studies revealed that there were no significant changes in the biochemical constituents during the 48th depuration period. Oysters were laboratory contaminated to levels in excess of 10000 cells /g with E.coli and it was cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light and chlorination for sterilizing the depuration water. Depuration in sterilized water using ultra violet light treatment was found to be more efficient in cleansing the oyster of pathogen, E.Coli than using chlorination. Of the two salinity tested depuration of oyster in seawater at 35 ppt salinity gave better results compared t that in 30ppt salinity sea water both sterilised with uv light. Depuration of oyster in unsterile seawater and in seawater sterilised 10 ppm chlorination was found to be least effective in cleansing the oyster to the acceptable international standard of less than 2.3 E.Coli/g oyster meat within 48h depuration. There was no appreciated change in the sensory characteristics of oysters such as aroma, taste, and flavor. However there was significant change in the grittiness characteristics of oyster after 48h depuration. Depuration was not effective in removing heavy metals such as cadmium, lead, zinc, Tin and Mercury from the oyster within the depuration period of 48h.
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    ThesisItemOpen Access
    Investigations on head drooping In head-on processed prawns
    (Department of Processing Technology, College of Fisheries, Panangad, 1994) Jose, V T; KAU; Sherief, P M
    Head drooping is the major quality problem associated with processing of headon prawns. The head drooping in head on prawns refers to the condition of oozing out of hepatopancreatic juice resulting from the breakage of the arthrodial membrane, which connects cephalothoraz of prawn to abdomen dorsally. The susceptibility of prawns to head drooping depends on the stability of the arthrodial membrane which in turn is determined by its biochemical composition. In this connection various biochemical constituents of the arthrodial membrane such as protein, phospholipid, moisture, calcium and cholesterol were analysed for two specied of prawn, Penaeus indicus and Penaeus monodon under three size groups (30/40, 50/60, and 70/80 pieces /kg). The activities of various hydrolytic enzymes of the hepatopancreas were also studied. The various biochemical constituets showed significant difference between species. Within the same species a size wise variation in the constituents of the arthrodial membrane and enzyme activity of hepatopancreas was observed. The various unit process such as hauling time, ice storage durations, freezing methods, cold storage durations and thawing methods were studied individually for their influence on head drooping. The study shows that the major determinants of head drooping in prawns are the biochemical composition of the arthrodial membrane and the easiness with which the hydrolytic enzymes of the hepatopancreas are released on postmortem handling and processing.
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    ThesisItemOpen Access
    Vitamin C requirement and its deficiency syndromes in Macrobrachium Rosenberg II juveniles
    (Department of Aquaculture, College of Fisheries, Panangad, 1996) Gijo Ittoop; KAU; Sebastain, M J
    An experiment was conducted to study the influence of dietary vitamin e on growth, survival, food conversion ratio, moulting rate and whole body ascorbic acid content of juvenile Macrobrachium rosenbergii, to determine the optimum dietary requirement of vitamin e and to characterise the deficiency syndromes, if any. Juvenile prawns kept under defined environmental conditions were fed casein based semipurified diets containing eight levels of vitamin C. CVC - F 90, a hydrogenated vegetable oil coated form of vitamin C with 90% available ascorbic acid was used as the vitamin source. Growth, survival, food conversion ratio, moulting rate and whole body ascorbic acid content were found to be significantly affected by dietary vitamin C (P≤ 0.01). Below a level of 75 mg CVC - F 90 per kg of dry diet, deficiency syndromes like poor growth, survival and food conversion, incomplete moulting and black lesions at the tip of walking legs were noticed. The maximum weight gain of 194.92% was obtained with a dietary level of 150 mg eve - F 90 per kg dry diet. Non-linear regression estimate based on percentage weight gain showed the optimum requirement to be 200.3 mg CVC - F 90 per kg dry diet which is equivalent to 182.97 mg AAE / kg dry diet. The tissue ascorbic acid level seemed to reflect dietary levels of Vitamin C. About 15 µ gm tissue ascorbic acid / g was required for maximum growth and survival.
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    ThesisItemOpen Access
    Studies on the effect of purging the freshwater prawn Macrobrahium rosenbergii in extending its iced storage life
    (Department of Processing Technology, College of Fisheries, Panangad, 1995) Sudhir, B; KAU; Krishnakumar, S
    In this study the effect of purging the prawn Macrobrachiumrosenbergiito improve its quality during iced storage was studied. Various biochemical and sensory changes that occurred during iced storage was observed. Experiments were done both for headless and headon prawns. For the headless prawns the treatments were (1) freshwater purged, and (2) purged and further chlorine dipped and the purging time was 5 hrs in a 500 litre tank. For the headon prawns purging in running water in a 5000 litre tank for 18 hrs was done. Both experiments were done with a control of unpurged prawns. The headless prawns kept longer than the head on product style more so perhaps due to the effect of beheading. Analysis of variance for alpha amino nitrogen, TVB, NPN, pH and sensory evaluation showed significant difference between purged and unpurged samples in the headon product sytle, the purged sample being of better quality. Similar results were not evident in the case of headless scampi. Longer duration of purging for 18 hrs or longer seems to have an influence on quality. For the headon prawns the acid insoluble ash showed a significant difference between treatments indicating the success in flushing the gut contents by purging. Sensory evaluation showed that headless and headon prawns were acceptable for more than 10 and 7 days respectively. Mushiness was not observed in the headless prawns but started from the third day for the headon control and the fifth day for the purged prawn. In headon prawn presence of black vein was reduced considerably by purging. Thus it was seen that there was an improvement in the general quality of the prawn due to purging.