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Open Access
Genetic characterization, controlled breeding and development of transgenic varieties of puntius denisonii (day, 1865).
(Department of Aquaculture, College of Fisheries, Panangad, 2010) Manoj, C K; KAU; Mohanakumaran Nair, C
Puntius denisonii, a beautiful ornamental fish indigenous to the Western Ghats, which has been indiscriminately exploited from the different rivers of Kerala has been recently declared to be vulnerable by the IUCN. The population structure and genetic diversity of P. denisonii has not yet been studied and documented. Many previous attempts to breed this fish in captivity have yielded negative results. The increasing demand for this fish to decorate aquariums worldwide could be satisfied only by developing controlled breeding techniques and larval rearing of its fry. In the present study, the present population structure of P. denisonii has been studied combining both phenotypic and genotypic techniques. Fishes were collected from Irrity, Chaliyar and Periyar rivers of Kerala. Truss network analysis was conducted and the size adjusted morphometric variables were subjected to Principal Component Analysis and Canonical Variance Analysis. Scatter diagram and Dendrogram was plotted using PCA and CVA loadings. The Irrity and the Chaliyar populations were grouped on the positive sector of the PC and CV component showing morphological similarities between the two populations while the Periyar population was placed in the negative sector of the component separated far from the other two. The PC scores were used to find out the variables showing maximum variation between fishes collected from different rivers. RAPD PCR was conducted after isolating DNA from the fins of different populations of P. denisonii. Universal random primers were screened and the primers that produced reproducible bands were selected. Popgene analysis of the binary data yielded the genetic structure of different populations of P. denisonii. Number and percentage of polymorphic loci, Nei's (1973) gene diversity, Shannon's Information index Lewontin (1972), Nei's Unbiased Measures of Genetic Identity and Genetic distance and Dendrogram Based Nei's (1978) Genetic distance using UPGMA --Modified from NEIGHBOR procedure of PHYLIP Version 3.5 were studied. The results obtained supports the truss analysis in that the Irrity and Chaliyar populations in Northern Kerala are genetically more similar while that of Periyar population in Central Kerala are distinct. P. denisonii was successfully induced bred under controlled conditions with synthetic hormone preparations Ovaprim and WOVA-FH. Stress during transport and handling was minimized and live feed was supplemented to enhance maturation of the broodstock. The whole developmental sequence starting from fertilized eggs to hatching was photographed and documented. It took 29-30 hours for the eggs to hatch at 280C. Rearing of fry was successfully accomplished under laboratory conditions. In an attempt to develop transgenic varieties of P. denisonii, pCMV-GFP was electroporated into newly fertilized eggs, maintained in hypoosmolar electroporation buffer. The electroporation parameters that yielded best results were 20V, 3 bursts at 1 second interval. Fin clips were taken from the transgenic individuals reared for a period of 6 weeks. Dot blot test was positive showing integration of the GFP gene in P. denisonii, eventhough expression was not detected under blue or UV light. The genetic and phenotypic data of P. denisonii populations in the present study will aid as a base line for formulating conservation procedures to protect the genetic diversity of wild ones. Stock identification studies are recommended for more concise information on each population. Moreover, the larval rearing and controlled breeding techniques along with the genetic diversity studies will help to design captive breeding programs and enhance the production of hatchery bred ones to meet increasing demand. Further research is recommended for generating transgenic lines with uniform GFP expression.
Open Access
Growth and survival of penaeus monodon in monosex and mixed sex culture under laboratory condition
(Department of Aquaculture, College of Fisheries, Panangad, 2008) Bajaniya Viralkumar, Chhaganlal; KAU; Mohanakumaran Nair, c
Sexual dimorphism is apparent in the black tiger shrimp, Penaeus monodon with females achieve larger size than the males. This character may be attributed to behavioral and/or physiological differences between the sexes. An experiment was developed to determine if there were advantages in rearing all female or all male P. monodon as opposed to mixed-sex populations. Juvenile shrimps (4.46±0.54 g) were collected from earthen pond and individually hand sexed and stocked in the circular cement tanks. Treatments all male, all female and mixed-sex were stocked @ 8 nos./tank. Each treatment had five replicates. The shrimps were offered commercial shrimp feed. The experiment was conducted for a period of 50 days. At harvest, all female shrimps had shown significantly higher growth than all male and mixed-sex treatment. Survival was not significantly different among treatments. FCR of all female was significantly lower than the all male and mixed-sex treatment. Result of the present study demonstrates a benefit to all female culture of P.monodon against the all male or mixed-sex culture. Thus culture of all female may be commercially more attractive to entrepreneurs. Although additional research is required to find a reliable and quick procedure for separation of the sexes or techniques for the production of all female populations.
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 V
The 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 .
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 V
Chela 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.
Open Access
Molecular taxonomy of selected species of macrobrachium bate, 1868 (DECAPODA, PALAEMONIDAE) of Kerala waters
(Department of Fishery Biology, College of Fisheries, Panangad, 2011) Jayaraj, G; KAU; Jayachandran, K V
Freshwater prawns of the genus Macrobrachium are a conspicuous and important prawn constitute one of the most diverse, abundant and widespread crustacean genera. They are distributed in different water bodies of the tropical and subtropical regions of the world and comprises over 200 described species (Jayachandran, 2001). The palaenonids have taxonomically difficult groups because they appear to be morphologically higher conservative and also greater confusion among the evolutionary status. The present study was carried out both on morphological and molecular data to investigate the confirmation of species status and finding phylogenetic relationship of selected species of Macrobrachium in kerala waters. The species of M. canarae, M. idella, M. latimanus and M. scabriculum were collected from different water bodies of kerala, such as hill streams, rivers and brackish water. The four species inhabit varied habitats: M. latimanus is a hill stream prawn; M. canarae inhabits valleys without migration; M. idella and M. scabriculum inhabits lower stretches of river with estuarine migrations. These species were accurately identified based on morphology of earlier literature done by Jayachandran, 2001 and it shows variations within the individuals of M. idella. The use of DNA based methods to infer phylogenetic relationship can potentially overcome some of the difficulties encountered through the use of morphological characters. In molecular part, 16S rRNA and COI genes of mitochondrial DNA were analysed. Sequences of 16S rRNA and COI were obtained and submitted to NCBI. Based on sequence information, M. canarae shows few minor variations within the individuals. M. idella is shows significant variations within the two types of individuals. M. latimanus is shows separate clades of other country species. M. scabriculum is also shows significant variation with NCBI sequence of M. scabriculum. Phylogenetic relationship is clearly shows two types of M. idella based on NJ and MP tree. Hence, both morphological and molecular data is very effective for finding species variants and phylogeny.
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 N
The 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.
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, George
A 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.
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, George
A 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.
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 N
The 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.

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