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ThesisItem Open Access Reproductive biology of macrobrachium canarae ( tiwari, 1958 ) (decapoda, palaemonidae)(Department of Fishery Biology, College of Fisheries, Panangad, 2008) Sreedevi, K H; KAU; Jayachandran, K VThe aim of this project is to introduce the freshwater prawn Macrobrachium canarae (Tiwari, 1958) as a candidate species in a community aquarium. The orange red shining spot on the second cheliped where the movable finger joins with palm makes it appealing in the aesthetic sense. This species is found to breed in captivity also. For the effective management of the prawn in the aquarium, a thorough knowledge on the various aspects of its reproductive biology is a prerequisite. The various aspects of reproductive biology dealt with are 1. Taxonomy 2. Sexual dimorphism 3. Breeding dress 4. Maturity stages and ovarian development 5. Fecundity 6. Moulting Since the species do not exhibit sexual dimorphism in size, it is difficult to identify male and female. The difference in colour of antennular flagellum between sexes becomes useful especially when they are bred in captivity. The data on maturity stages and also the time of ovarian development finds its use especially in the aquarium rearing. The fecundity studies gives an idea of the number of offsprings which could be produced from a single brood .ThesisItem Open Access Ovararian maturation, breeding and early embryonic development of an indigenous ornamental cyprinid of the western ghats - chela fasciata silas(Department of Fishery Biology, College of Fisheries, Panangad, 2008) Indira, Divipala; KAU; Anna Mercy, T VChela fasciata is an indigenous ornamental cyprinid endemic to the Western Ghats of Kerala. It inhabits the riffle zones of River Bharathapuzha at Thootha. A total of 144 fishes (94 females and 50 males) ranging in size from 26.0 to 82.0 mm were collected from the wild and used for the study of reproductive biology. The gonads were quantified into six maturity stages based on external morphology as immature virgin, maturing virgin, early ripening, late ripening, ripe and partially spent. Studies on oocyte distribution of the six stages of maturity were done to understand the maturation of ova in the ovary. The ovaries of Chela fasciata showed asynchronous oocyte development. The oocyte development was classified into nine different oogenic stages namely, chromatin nucleolus stage, early perinucleolus stage, late perinucleolus stage, yolk vesicle stage, primary yolk stage, secondary yolk stage, tertiary yolk stage, migratory nucleus stage and mature oocyte). The first mature females appeared in the length group of 40 – 45 mm and males in the group of 25 – 30 mm. The size at first maturity for female was found to be at 45.75 mm TL (45 – 50 mm) and for males at 36.25 mm TL (35 – 40 mm). All the females were mature by 60.00 mm TL and the males by 45.00 mm TL. Based on the ova diameter frequency study of the ripe ovary, Chela fasciata was found to be a multiple spawner, with a protracted spawning season, the individuals spawning intermittently. Absolute fecundity of the fishes ranged from 2669 to 4437 in fishes of size range 49.5 mm to 82 mm TL. The number and size of eggs were found to be directly proportional to the size and age of the fish. Fecundity showed a positive linear relationship (5% level of significance) with the length and weight of both the fish and ovary. The embryonic development studies showed that the cleavage stage of the egg lasted for about 2 hrs 10 min., post fertilization. The inside egg embryo stage had lasted for 21 hrs, post fertilization. The eggs hatched at the end of 21 hrs, and the embryos emerged tail first. Pigmented eye was seen in one-day-old free embryo. Free embryo stage lasted for three days post fertilization. By the end of third day, the mouth developed, the yolk sac was empty and the exogenous feeding started, the free embryo entering the larval period. A complete understanding of basic reproductive biology of this fish will definitely help in the commercial production under captivity for the domestic and export market of this indigenous ornamental fish.ThesisItem Open Access Temporal variation in the hydrography and biodiversity of the Cochin backwaters of Puduveypu region.(Department of Fishery Hydrography, College of Fisheries, Panangad, 2011) Trinayan Deb, Sarmah; KAU; Raman, N NThe study was carried out to find out the temporal variation in the hydrography of the Cochin backwaterS of Puduveypu region and to find out the richness of the biodiversity of the area. The study was conducted from April, 2010 to Apil, 2011. The present study was carried out to find out the temporal variation in the hydrography of the Cochin backwater of Puduveypu region and to find out the richness of the biodiversity of the area. The value of salinity in the backwaters of Puduveypu showed a wide fluctuation. The maximum value was recorded in the second half of January. The salinity showed considerable reduction during the period of March-April, 2011 due to Premonsoon showers. . Water temperature showed peak values during pre-monsoon period and with the onset of monsoon the value decreased. High pH was observed during the monsoon season while low values were observed during N.E. monsoon and pre-monsoon period. Alkalinity showed an increasing trend during the pre-monsoon, post monsoon and N.E. monsoon seasons but a decreasing trend was observed during monsoon season. Total hardness ranged between 22.22 mg CaCO3/l and 710.01 mg CaCO3/l. Dissolved oxygen showed high values during monsoon and post monsoon period. During the N.E. monsoon period the dissolved oxygen showed a decreasing pattern and reached a minimum of 2.1mg/l in the second half of February. The higher values of nitrate-N were observed during post monsoon and monsoon season. Seasonal variation of nitrite 133 was not that much pronounced. The phosphate value ranged between 2.2 μg at/l and 5.8 μg at/l during the study period. The maximum value of silicate-Si was recorded during the last phase of the monsoon. Turbidity ranged between 11.11 NTU and 40.4 NTU. It showed a negative correlation with transparency. Transparency value of the study region falls within a range of 30 cm. to 47 cm. Primary productions showed a wide range from 32 mgC/m3/day to 3707 mgC/m3/day. The highest value of chlorophyll was observed during the second half of July and the minimum value was observed during the second half of October. The sediment pH value ranged between 7.02 and 8.3 with an average of 7.78. The analysis revealed that sediment of the Puduveypu region contains maximum sand followed by silt and clay. Mangrove species like Rhizophora mucronata, Rhizophora apiculata, Rhizophora conjugate, Brugiuera cylindrical, Brugiuera gymnorhiza, Sonerasia caseolaris, Sonerasia alba, Avicennia officianalis, Exocearia agallocha, Acanthus ilicifolius, Clerodenterum innerme, Premma latifolia, and Acrostichum aureum were found in the study area. , Avicennia officianalis contribute 70% of the total population of mangrove. Penaeus monodon, P. indicus, Metapenaeus dobsonii, M. monoceros, Feneropenaeus indicus, Penaeus semisulcatus, Macrobrachium equidens, M. idella have been identified from the study area. Crabs in the study area include Scylla serrata, Scylla tranquebarica, Thalamita creneta, Charybdis annulata, Sesarma quadratum, Uca vocans. Bivalves includes Lamellidens 134 sp., Villorita Sp. and Cirriped in the study region include Balanus. 36 species of finfishes were collected during the study period. The fishes can be categorized into 10 order and 26 families.ThesisItem Open Access Studies on drying of fish using a BARC - TYPE solar dryer.(Department of Processing Technology,College of Fisheries, Panangad, 2011) Vimaladevi, S; KAU; Sajan, GeorgeA study was conducted with the aim of evaluating the drying efficiency of a newly designed solar dryer (modified BARC type) in comparison with conventional sun drying. The materials used for drying were beheaded prawn (Metapenaeus dobsoni) and salted fish (Cynoglossus macrostomus). Rate of drying was found to be influenced by the atmospheric temperature and humidity, either using dryer (test or by sun drying (control). In the case of prawn, the drying period was 7h by dryer compared to control which took about 10h whereas in the case of fish it was only 7h compared to control which took about 9h. Various parameters such as moisture content, water activity, TPC, TFC, TVBN content and PV, during drying were monitored. The quality variations in prawn or fish were significantly lower when dried using the solar dryer compared to direct sun drying. Sensory evaluation based on colour, odour, texture and taste, also proved that the solar dried samples were of superior quality compared to control. Sorption isotherm for test and control did not vary much in shape for both prawn and fish. This indicates that the effect of the type of drying on the bound water of the products. For conducting storage studies the dried prawn and dry salted fish, both test and control, were packed in low permeable polypropylene- polyamide bags and stored at room temperature for about 80 days. Quality parameters, viz., moisture content and water activity, TPC, TFC, TVBN content, PV and sensory evaluation based on colour, odour, taste and texture were evaluated during storage. Both test and control samples remained acceptable throughout the storage period. However, the quality of prawn or fish dried in solar dryer was found to be superior compared to their respective sun dried control samples. The additional cost was only Rs 2.40/ kg for dried prawn and Rs 2.00/ kg for dry salted fish. The equipment is recommended for small scale production of dried products.ThesisItem Open Access Microbial risk assessment and process standardization for cook-chill fish and partially processed value added fish(Department of processing technology, College of fisheries, Panangad, 2007) Anju; KAU; Namboodiri, D DA study was undertaken for the preparation of cook-chill fish from Selar crumenophthalmus and partially processed value added fish from Oreochromis mossambicus and their microbial risk analysis. Standardization of processing technique for both products was done. Parameters standardized were brining conditions and blanching conditions for cook-chill fish. Standardization of brining condition was carried out for partially processed value added fish. Various brining conditions studied were brine concentrations of 3%, 5%, 6% for 5min, 10min, 15min and blanching at 75oC for 60sec, 90sec, and 120sec for cook-chill fish. In the case of partially processed value added fish brining concentrations of 1%, 2%, 3% for 5min, 10min, and 15min. Salt content and sensory evaluation were carried out, in case of cook-chill fish to select best blanching time. TPC values were determined. Based on the results the following treatments were selected. In the case of cook-chill fish brine concentration of 5% for 10min and blanching at 75oC for 90sec were selected. For partially processed value added fish the brine concentration of 2% for 10min was selected. Both products were packed and chill stored using ice at 4oC. Cook-chill fish was packed in polyethylene and heat sealed. Partially processed value added fish was vacuum packed in 12 polyester laminated with polyethylene 200 gauge. Control was used for comparative study. Control in the case of cook-chill fish (Selar crumenophthalmus) was fish fillets stored without any brining, cooking treatments. For partially processed value added fish (Oreochromis mossambicus), control was not given any brine treatment, was packed in polyethylene and heat sealed using electric heat sealer. During storage TMA, TVB-N, TPC and test for specific microorganisms were carried out. Results of quality parameters showed a greater shelf life of five days for test samples compared to the control in both the products.ThesisItem Open Access Influence of cryoprotectant levels on storage stability of surimi from a tropical fish, Nemipterus japonicus (Bloch) and quality of surimi-based products(Department of Processing Technology, College of Fisheries, Panangad, 2009) Parvathy, U; KAU; Sajan, GeorgeA study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting stability of the material during frozen storage. The concentration of sugar in commercially produced surimi is generally about 8% which may result in high sweetness in the products prepared. A tropical fish, Nemipterus japonicus (Bloch) was used as the raw material. Minced fish meat was strained, water leached, mixed with different levels (0%, 2%, 4%, 6% and 8%) of sucrose-sorbitol mixture in 1:1 ratio, quick frozen at -35 oC and frozen stored at -20 oC. Water leaching resulted in a slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have a moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sucrose-sorbitol mixture. Sugar content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared to those prepared using surimi with 6% and 8% sugar mixture. A slight sweetness in the product (2% to 4% sugar in surimi) was more preferred by the panelists than their respective controls prepared using surimi containing no sugar. Frozen storage studies were carried out at -20oC on surimi treated with various concentrations of sugar mixture as mentioned above for a period of five months. pH and total plate count remained nearly steady for all sugar concentrations and throughout the storage period indicating insignificant microbial activity. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration probably on account of addition of the sugar mixture. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar concentration, while expressible water content of the sausage showed an increasing trend with storage period and a decreasing trend with cryoprotectant concentration. These indicate a greater extent of protein denaturation occurring at low concentration of surimi samples. Sensory evaluation parameters - elasticity, sweetness and preference - remained more or less steady during storage. However, elasticity of sausage prepared from surimi with no cryoprotectant (control) and with 2% sugar level showed a decreasing trend with storage. Elasticity and sweetness increased while preference decreased with cryoprotectant concentration. Elasticity and gel strength seemed to be much lower for control (1.7 and 783.71 g.cm, respectively) compared to even the lowest concentration of sugar (2%) used (2.6 and 886.9 g.cm, respectively). From the study it may be concluded that a concentration of 2 to 4% sucrose-sorbitol mixture is well accepted by the consumers in products such as surimi sausage, patty and cake. At this range of concentration, surimi can be well-preserved in frozen condition at -20oC for at least five months.ThesisItem Open Access Ecology of mangrove patches in the Vembanad lake at Panangad(Department of Fishery Hydrography, College of Fisheries, Panangad, 2009) Sukam, Monalisha devi; KAU; Raman, N NThe present study was carried out in mangrove area and backwater connected to the backwater through a sluice gate where mangrove patches are present. The study was undertaken in order to identify the floral composition, fishes, prawns, crabs and molluscs found in the area. The seasonal changes of hydrographical parameters like DO, pH, water temperature, alkalinity, salinity, primary productivity, silicate-silicon, phosphate-phosphorus, nitrite-nitrogen and nitrate-nitrogen and the sediment characteristics like sediment pH, total organic carbon, sediment texture were also studied. The mangrove species found in the study area were identified. Water temperature was minimum during south-west monsoon and maximum was during pre-monsoon. Average water temperature was lesser in mangrove area. Negative correlation was found between dissolved oxygen and all the nutrients. Through out the study period pH was alkaline. pH increased with increase in salinity and alkalinity. Dissolved oxygen was high during monsoon when compared with pre-monsoon period. It decreased with increased in salinity. Maximum salinity recorded during pre-monsoon when there was less freshwater intrusion. Average salinity was higher in backwater. Salinity showed negative correlation with all the nutrients. Alkalinity minimum value was observed during south-west monsoon it increases in post-monsoon and attained maximum during pre-monsoon. Alkalinity is higher in mangrove area. Primary productivity was maximum when light intensity was maximum. Average concentration of nutrients was higher in mangrove area. Maximum concentration was seen when inflow of freshwater was more. Sediment pH was minimum during pre-monsoon. Average sediment pH was lower in mangrove area than to backwater. Average Total organic carbon was maximum during post-monsoon in mangrove area and backwater. Sediment texture showed that substratum was silty sand in both the stations. When sand percentage increased total organic carbon was lowered. t-Test was done to compare significant difference between mangrove area and backwater. It showed that there was no significant difference with any of the hydrographical parameters between the two stations except primary productivity. ANOVA was conducted separately for two stations to compare significant difference between three seasons- monsoon, post-monsoon and pre-monsoon. In mangrove area pH and dissolved oxygen did not showed significant seasonal difference. In backwater water temperature, phosphate and nitrite did not show any seasonal difference. Dominant mangrove plants include Rhizophora mucronata, Brugiuera gymnorhiza, Brugiuera cylindrica, Avicennia officinalis, Acrostichum aureum, Acanthus ilicifolius. Prawns and crabs were abundant. Among prawns Fenneropenaeus indicus was caught through out the study period. Among crabs Scylla serrata and Uca spp. were commonly found. Balanus, Lamellidens sp., Villorita sp. were also seen in the study area. 30 species of fishes were identified from the study area and major contribution was by fishes belonging to the Order Perciformes. Mostly juveniles contributed to the fish catch.ThesisItem Open Access Quantification of ammonia excretion by selected five varieties of freshwater ornamental fishes(Department of Aquaculture, College of Fisheries, Panangad., 2006) Senthamilselvi, A; KAU; Mohan, M VAmmonia excretion of five species of freshwater ornamental fishes, platy (Xiphophorus maculatus), swordtail (Xiphophorus helleri), angelfish (Pterophyllum scalare), goldfish (Carassius auratus) and blue gourami (Trichogaster trichopterus). Fishes acclimated for two weeks were incubated for a specific period in closed containers and the ammonia excretion rates were determined. Ammonia was determined using phenol hypochlorite method. Regression analysis of ammonia excretion rate and weight showed that ammonia excretion rate increased with body weight. The regression coefficient of the relationship was 0.4320 in platy, 0.7534 in swordtail, 0.4851 in angelfish, 0.6309 in goldfish and 0.6518 in blue gourami. The weight specific ammonia excretion rate decreased with bodyweight and the slope of the weight specific ammonia excretion rate – weight relationship was - 0.5680 in platy, - 0.2466 in swordtail, - 0.5149 in angelfish, - 0.3691 in goldfish and - 0.3482 in blue gourami. The regression coefficient of total length- weight and standard length- weight relationship are 3.1031 and 3.0565 for platy, 3.1512 and 3.1454 in swordtail, 3.0331 and 2.9656 in angelfish, 2.6191 and 3.0328 in goldfish and 2.9721 and 3.0011 for blue gourami, respectively. The regression coefficients were significantly different from 3 in both the relationships. The weight specific ammonia excretion rate ranged from 0.0032 to 0.0640 g NH3-N/mg/h for platy, 0.0028 to 0.0140 g NH3-N/mg/h for swordtail, 0.0033 to 0.1309 g NH3-N/mg/h for angelfish, 0.0043 to 0.0525 g NH3-N/mg/h for goldfish and 0.0091 to 0.0394 g NH3-N/mg/h for blue gourami. Ammonia excretion rate and weight specific ammonia excretion rate were highest for blue gourami, followed by goldfish, angelfish, swordtail and platy but the weight specific ammonia excretion rate was highest in platy than swordtail for the smaller size group. Quantification of ammonia excretion for standard weight and length facilitates prediction of ammonia build up in a freshwater aquariumThesisItem Open Access Structure & functions of the accessory nidamental gland in the indian squid,loligo duvanuceli orbigny(mollusca:cephalopoda)(Department of Fishery Biology, College of Fisheries,Panangad, 2008) Gomathi, P; KAU; Rjashekaran Nair, JFemales of the Indian squid, Loligo duvauceli in different stages of sexual maturity were collected during September-November, 2007. Mantle length of the ripe females was 16.22 ± 0.487 cm and body weight was 125.3 ± 8.628 g. Accessory nidamental glands (ANG) were conspicuous only in sexually maturing females. These paired glands were located at the anterior end of the nidamental glands (NG) and were closely associated with the ventral surface of the ink sac. The colour of ANG was orange red in mature specimens. The colour has been attributed to pigments of symbiotic bacteria. The ANG-somatic index of ripe females of L. duvauceli was 0.154 ± 0.024 %. Based on the morphological changes like gross size, coloration of the gland and also histological changes like formation, distribution, size and shape of the pigment granules during the course of maturation, the accessory nidamental glands were quantified into four stages namely immature, ripening, ripe and spent. Antibacterial activity of ANG-butanol extracts (2.5 g in 5.0 ml butanol) from different stages of maturity was studied. The extracts from ripe stage ANG showed antibacterial activity against gram negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa, and gram positive bacteria, Staphylococcus aureus. Immature and spent gland extracts did not show any antibacterial activity. The ANG-butanol extract of ripe ANG showed an absorbance maximum at 498.5 nm, followed by shoulders at 528.0, 290.5 and 315.5 nm. In the case of immature stage an absorbance maximum at 285.0 nm was obtained, followed by shoulders at 340.5, 358.0 and 400.5 nm. For the spent stage the absorbance spectrum was very similar to the immature stage. The peak at 498.5 nm (2.597A) obtained for the ripe stage could be attributed to the presence of carotenoid pigments. The peak obtained at 286 nm for the different stages indicated the presence of peptides/ proteins. Thin layer chromatography of the ANG- butanol extract did not show the presence of polyphenols/flavonoids or quinones, whereas neutral lipid components such as phospholipids, cholesterol, free fatty acids, triglycerides, fatty acid esters, and cholesteryl esters were detected. The total free fatty acid (FFA) content in the ripe ANG was 16.0 ± 0.143 mg oleic acid/g tissue, whereas in immature ANG, it was 10.3 ± 0.114 mg oleic acid/g tissue. The FFA content was significantly higher in the ripe stage. Gas chromatographic studies of immature and ripe stages revealed the presence of a mixture of fatty acids. The total fatty acid content was 3.925 mg/g tissue in ripe stage and 0.704 mg/g tissue in immature stage showing the high gross value in the ripe stage. The quantum of the major four fatty acid (Palmitic acid, Oleic acid, Docosahexaenoic acid and Eicosapentaenoic acid) components was clearly found to be much more in the ripe stage than in the immature stage, especially the unsaturated fatty acids and may be the factors responsible for the antibacterial activity.