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ThesisItem Open 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, JA 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.ThesisItem Open Access Extent of adoption of scientific practices in prawn farming(Department of Management Studies, College of Fisheries, Panangad, 1990) Sasikumar, P K; KAU; Pushkaran, P SThis study was undertaken to probe into the present situation of prawn farming in Kerala. The study aimed at assessing the communication media used for the dissemination of scientific prawn farming practices, the communication media utilized by prawn farmers at awareness and adoption stages, extent of adoption of scientific practices, correlates of adoption behaviour and the reasons for non-adoption or partial adoption of scientific practices. The study was conducted in Ernakulam district among 100 prawn farmers randomly selected. The data were collected through personal interview using a structured and pre-tested interview schedule. Appropriate standard statistical tools were used for analysis and interpretation. The extent of adoption was measured using the adoption quotient formula. Twenty four characteristics of prawn farmers were tested to find their association with adoption behaviour. The socio-economic variables studied were age, education, experience , land possession training participation, institutional credit utilization and income from prawn farming. The situational characteristics included total farming area, area under selective stocking , salinity, distance from bar mouth, average depth at high tide, average depth at low tide and number of crops raised. Scientific orientation, economic motivation risk preference, marketing orientation, extent of awareness of scientific practices in prawn farming and rationality in decision making were the socio-psychological variables tested. The communication variables studied were utilization of personal localite sources, utilization of personal cosmopolite sources and utilization of mass media sources. The study revealed that the extension communication media were very extensively used for the dissemination of scientific prawn farming technology. The most important individual method employed was farm and home visits. Other methods frequently employed were lectures, film shows, group discussions, training programmes and demonstrations. The farmers utilized more of personal localite sources, followed by personal cosmopolite and mass media sources for awareness as well as adoption. The mean awareness index of prawn farmers was 64.00 with majority of the farmers falling under the category of medium awareness. The mean extent of adoption of scientific practices was worked out , and majority of the farmers came in the medium category based on extent of adoption. Of the 19 scientific practices selected for study, all the practices except ‘acclimation of seeds’, ‘maintenance of dissolved oxygen level in the pond’ ‘monitoring and control of PH, control of algal blooms and ‘need based control of disease and parasites’ were heard by over 50 percent of the respondents. Only three practices viz. strengthening of buds and deepening of channels, fixing or repairing of sluice gate, and stocking the pond with selected prawn seeds were heard by all the respondents. Only two practices namely ‘strengthening of bunds and deepening of channels’ and ‘fixing or repairing of sluice gate’ were found fully adopted by 50 or above 50 percent of respondents. Highest full adoption was observed for the practices ‘fixing or repairing of sluice gate’. There was no full adoptes for the practices ‘maintenance of dissolved oxygen level in the pond’ ‘need based water exchange’ and ‘need based control of disease and parasites’. Highest partial adoption was observed for the practice ‘need based water exchange’ followed by ‘removal of aquatic weeds’, supplementary feeding based on biomass’ and ‘strengthening of bunds’ and ‘deepening of channels’. The partial adopters of these practices were 99 percent , 92 percent, 57 percent and 49 percent respectively. Important reasons for non-adoption and partial adoption of the practices were lack of awareness, lack of knowledge and non-adoption of the practice ‘stocking the ponds with selected prawn seeds’. Among the 24 variables tested to find out association with extent of adoption, only nine showed significant influence on adoption behaviour. The characteristics of prawn farmers which were found significantly contributing to extent of adoption were training participation, land possession, institutional credit utilization, area under selective stocking, number of crops raised, extent of awareness of scientific practices in prawn farming, rationality in decision making, utilization of personal cosmopolite sources and utilization of mass media sources. Multiple regression model fitted with the above nine variables illustrated that these nine variables together explained 86.82 percent of variations in extent of adoption. Further, the step-wise regression analysis revealed that the best subset of variables in predicting the dependent variables were utilization of personal cosmopolite sources, utilization of mass media sources and area under selective stocking. These three variables together explained 86.48 percent of variations in adoptive behaviour. Of the nine variables subjected to path – analysis all the variables except awareness of scientific practices in prawn farming and rationality in decision making had positive path coefficients. The indirect influence of the variables on extent of adoption were mainly channeled through utilization of personal cosmopolite sources and area under selective stocking.ThesisItem Open 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, JoseThe 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.ThesisItem Open Access Utilization of prawn waste as pig feed(Department of Animal Nutrition, College of Veterinary and Animal Sciences, Mannuthy, 1991) Syam, Mohan K M; KAU; Sivaraman, EAn investigation was carried out to assess the feeding value of prawn waste as a partial or complete replacement of unsalted dried fish in the rations for growing – finishing pigs. Thirty – two Large White Yorkshire weanling pigs with an average body weight of 9.1 kg were distributed randomly and uniformly as far as possible to four groups (Groups 1, 11, 111 and IV) of eight animals each, with regard to age, sex and body weight and housed in pairs of the same sex. The four dietary treatments A, B, C and D were allotted to the pigs in the groups 1, 11, 111 and IV respectively. Of the total protein, 25 per cent in the diets A, B and C and 12.5 per cent in the diet D were provided as animal protein. Unsalted dried fish was used as animal protein source in the diets C and D. Diet C formed the control diet. In the diets A and B, 50 per cent and 100 per cent replacements respectively of animal protein from unsalted dried fish were made using dried prawn waste. All the animals were maintained on the respective diets with 18 per cent total protein upto an average live weight of 50 kg and with 14 per cent protein till they attained a body weight of 70 kg or 8 months of age, whichever was earlier, when they were slaughtered to study carcass characteristics.ThesisItem Open Access High density rearing of Labeo Rohita (Hamilton) spown indoors using different feeds(Department of Aquaculture, College of Fisheries, Panangad, 1998) Dinesh, K; KAU; Mohankumaran, Nair CThree day old rohu spawn was reared in indoor tanks with eight different feeds The diets tried were newly hatched Artemia nauplii, size graded Moina micrura, formulated feed, Artemia nauplii + formulated feed, Moina micura+ formulated feed, first 3 days Artemia nauplii and formulated feed later on, first 3 days Moina micrura and formulated feed later on and mixed zooplankton + ricebran and GOC in I: I ratio (conventional method).ThesisItem Open Access Studies on depuration of edible oyster Crassostrea madrasensis (Preston)(Department of processing technology, College of fisheries, Panangad, 1993) Usha, P T; KAU; Damodaran, NamboodiriOysters 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.ThesisItem Open Access Breeding biology of Villorita cyprinoides (Gray) in relation to salinity gradients(Department of Fishery Biology, College of Fisheries, Panangad, 1991) Sudha, B Nair; KAU; Jose, T MThe present study was undertaken to investigate the influence of salinity variations on the breeding biology of populations of black clam Villorita cyprinoides (Gray), inhibiting two different cological zones of the Vembanad Lake. Two stations with perennial clam beds, but differing greatly in salinity conditions were selected for the study. Station I, in the northern side of Thanneermukkam barrier, has more influx of sea water and Station II, in the southern side has low saline influx. Monthly collections of black clams and bottom and surface waters were made from May 1989 to June 1990. Major environmental parameters such as salinity, temperature, dissolved oxygen and pH of bottom and surface waters were estimated with a view to understand the circannual variations within and between the stations. Among these, salinity was found to be the most important parameter showing prominent variations. At Station I, the bottom salinity values ranged from 0.0 to 18.12%0 and in Station II from 0.0 to 2.12%0. Histological studies of the clams collected from the two stations revealed that animals inhabiting Station I, a predominantly brackish water zone, have a protracted, almost year round breeding season extending from September to June with peak spawning during March to June and coinciding with the peak salinity levels and temperature. At Station II, a predominantly freshwater zone, the clams have a short duration spawning season extending from March to June with peak spawning during Apirl and May, again coinciding with the peak salinity levels and temperature. It is also observed that there exists a positive correlation between the bottom salinity and gondal maturation and spawning. Size – frequency studies of the calms collected from the two stations revealed that at Station I, the clam fishery was dominated by small sized animals, when compared to Station II. This may be related to the differences observed in the extend of spawning activity between the population of the two stations, resulting in the divergent apportionment of energy resource for somatic growth versus reproduction.ThesisItem Open 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 MHead 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.ThesisItem Open Access Ensiling cuttlefish wastes for use as fish feed ingredient(Department of Processing Technology, College of Fisheries, Panangad, 1999) Santhosh Kumar, C; KAU; George, M CThe disposal of cuttle fish processing waste is becoming a major problem for the seafood processing industries in India. Formic acid fish silages and fermented fish silages were prepared using the waste. The silage preparations were stored for 90 days. Samples were drawn on 0,2,3,5,7,14,30,60 and 90th days of storage. The pH and various biochemical parameters like, total nitrogen (TN), non protein nitrogen (NPN), total volatile base nitrogen (TVBN), tri methyl amine (TMA) and peroxide value (PV) were carried out. Microbial analyses, viz., total plate count (TPC) and most probable number (M.P.N) of coliforms were carried out for formic acid fish silage preparations, whereas for fermented fish silage preparations, acid producing bacterial count (APBC) and M.P.N of coliforms were determined. All the combinations of fermented fish silage preparations studied, preserved well. A pH of not more than 3.8 was necessary for the formic acid fish silage to be preserved for 90 days. All the silages, which preserved well, were used for making fish feed. The pelletised feeds were fed to common carp tCyprinus carpio) fingerlings. The feeds were consumed by the fishes within 15 minutes of feeding.
