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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
Standardisation of thermal processing of cuttle fish nidamental glant
(Department of Processing Technology, College of Fisheries, Panangad, 2007) Bikash kumar Pati; KAU; Sherief, P M
Cuttlefish nidamental gland is a pair of flattened glands associated with the female reproductive system in cuttlefish. The glands are exported as a frozen product under the name cuttlefish roe. The procedure for thermal processing of cuttlefish nidamental gland in brine packed in tin plate can is standardised to produce a ready- to- eat product. The standardisation process essentially involved determination of optimum blanching conditions, retorting temperature, process time, processing parameters, optimum solid- liquid ratio and process levels to produce a safe product and assessment of quality changes during storage at room temperature. Cuttlefish nidamental gland in brine was packed in tin plate cans in 65 : 35 ratio (gland : brine) and thermal processed in an overpressure retort. The optimum blanching condition was found to be 5 % brine for 5 min. The retorting temperature and process time were selected as 121.10C and 25 min, respectively. The F0 value attained by the process was found to be 11.25 min with total process time of 30.54 min. The cook value meant to achieve tenderness of product was 81.54 min. The processed product was found to be commercially sterile. The product was acceptable even after 3 months of storage at room temperature with regard to all sensory attributes like appearance, colour, odour, taste, texture and overall acceptability. There were significant variation in the salt, pH and TBA values (P<0.05). The cut- out test showed a marginal increase in solid weight. The study showed that the cuttlefish nidamental gland can be used for processing ready to eat product, which can be stored at room temperature for long periods.
Open Access
Effect of phosphatic fertilizer compounds on aquatic primary production in saline water
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2005) Rajkumar, K R; KAU; Mrithunjayan, P S
Fish production in farms largely depends on the primary productivity In the water bodies. Among many factors, plant nutrient levels and their availability in absorbable forms for the plankton is the most important one contributing to primary production. The plant nutrient element, phosphorus often found to limit the production, mainly due to the behavior of phosphorus compounds to remain in unavailable form in aquatic environment. Hence it becomes imperative to supplement phosphorus in suitable chemical form to achieve better production. While the dosage is also important, the salinity of water bodies has an interactive effect. Thus species of compounds in phosphatic fertilizer is vital. In the present study, two types of phosphatic fertilizers and combination of these fertilizers with additives were tested for their effect on aquatic primary production. Synthetic fertilizer namely single superphosphate and natural phosphatic fertilizer namely rock phosphate were selected for study. Commercial grade trisodium phosphate was used as additive in combination with single superphosphate and rockphosphate in 1: 1 ratio with respect to phosphate- P. All the above four fertilizer materials were tested in brackishwater having two salinity levels, a low salinity level of approximately 10 ppt and a high salinity level of approximately 20 ppt. Each fertilizer was added in three different doses, ie, O.lppm, 0.2 ppm and 0.4 ppm of phosphate-P. A set of control with two salinity level of water and without adding fertilizer were also run. All the experiments were done in duplicate, in accordance with statistically designed 2x4x4 Factorial Completely Randomized Design. The experiments were conducted in wide mouth polythene drums having 25 litre capacity using 20 liters of water. The experiment was set up in a protected, undisturbed, elevated place and kept exposed to sun light for 30 days. Volume loss due to evaporation was compensated by adding appropriate amount of water having corresponding salinity. 140 Water samples were drawn on l " day (before the addition of fertilizer), i\ 14th and so" days and analysed for available phosphate, total phosphate, silicate, nitrite, nitrate, iron, water pH, dissolved oxygen, carbon dioxide, total alkalinity, total hardness and calcium. Productivity was assessed on 1 st day and so" day by estimating chlorophyll. The results were statistically analysed with ANOV A technique. In the experiment, maxrmum productivity in terms of chlorophyll (14.6mg/m3) was found under the treatment with single super phosphate along with additive trisodium phosphate when applied at a dose of 0.4 ppm of phosphate-P in the high saline media. For the same type of treatment in low salinity level, a little reduced value of productivity was observed (chloropyll =13.9 mg/rrr'), The next effective treatment was rock phosphate with trisodium phosphate at a concentration of 0.4 ppm of phosphate-P, here a chlorophyll concentration of 13.6mg/m3 and 12.6 mg/rrr' were obtained in high and low salinities respectively. The minimum productivity levels were observed in treatments with rock phosphate alone in all concentrations, compared to other treatments. It could be concluded from the experiments the following i) single super phosphate with a combination of trisodium phosphate was most effective compared to rock phosphate with trisodium phosphate, which could be due to the greater solubility of single super ph~sphate ii) single super phosphate was found to be more effective than rock phosphate, which could be due to the grater solubility as already explained. iii) the concentration level of 0.4 ppm of phosphate-P was found to be the most effective in enhancing the primary production compared to the lower doses tried ie, 0.1 and 0.2 ppm. iv) along with an increase in the available phosphate from the added fertilizers there was an increase in the primary production also v) salinity was found to have some effect on production, higher the salinity grater the production. This can be due to the availability of other minerals and intrinsic factors required for the synthesis of chlorophyll and biomass.
Open Access
Studies on the maturation and reproduction of pristolepis marginata jerdon under captive conditions
(Department of Fishery Biology, College of Fisheries, Panangad, 2005) Nisha, Raj; KAU; Anna Mercy, T V
Pristolepis marginata Jerdon commonly called “Malabar catopra” or “Malabar sunfish” or “Chutichi” in the vernacular is an attractive ornamental fish belonging to the family Nandidae. This species, which is endemic to the Kerala part of Western Ghats inhabits clear and rapid streams. The species has been enlisted as vulnerable by – the Conservation Assessment and Mangement Plan Workshop (CAMP, 1998) for fresh water fishes of India held at NBFGR, Lucknow. Conservation of the endangered/vulnerable fishes cannot become successful without protection to the resources, which support the diversity and abundance. Hence Pristolepis marginata was one of the prioritized species for the development of captive breeding technology under NBFGR – NATP programme entitled “Germplasm inventory evaluation and gene banking of fresh water fishes of India”. Anna Mercy et al., (2003) developed the captive breeding technology for Pristolepis marginata. In the present study, an attempt was made to understand the maturation and reproduction of P. marginata in captivity. Captively reared fishes from the NATP project of College of Fisheries were utilized for the present study. A total of 209 fishes (12 to 149 mm) were used for the study of reproductive biology. A six-stage key was used for the classification of the maturity stages. The size at first maturity for females and females were found to be 54 mm and 72 mm SL respectively. Gross picture of distribution of ova stocks in the anterior, middle and posterior regions of the ovary remained almost the same except for the slight variation in the percentage composition of the mode. Based on the ova diameter frequency studies, P. marginata was found to be a multiple spawner, which release eggs in two or three batches. Absolute fecundity of the fishes ranged from 1102 (first time spawner) to 4965 (repeat spawner) in fishes of size range 66 to 80 mm SL. Number and size of eggs was found to be directly proportional to the size and age of the fish. Fecundity showed a positive linear relationship with the length and weight of the fish as well as to length and weight of the ovary. The reproductive organs of P. marginata were built on the usual percoid plan with paired ovaries and testis. The ovaries of P. marginata showed asynchronous development, in which oocytes at all the stages of development were present in the same ovary at the same time. During the spermatogenesis, there is a gradual decrease in size of different stages from spermatogonia to spermatozoans. Length – weight relationship values showed that the juveniles are exhibiting allometric growth pattern with ‘ b’ value equal to 2.83. Males also showed allometric growth pattern with ‘b’ value equal to 2.68. Females have shown isometric growth pattern with ‘b’ value equal to 2.94. Average relative condition factor values were higher in juvenile (1.43) due to the higher growth rate encountered during this stage of the life cycle. Males showed higher average relative condition value than females.
Open 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).
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, 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.
Open Access
Studies on temporal and spatial variations of circulation and hydrographic characteristics of Panangad region of the Vembanad Lake
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2003) Vijayakumar, C T; KAU; Varna, K K
The objective of the study was to find the seasonal and spatial variations of different hydrographical factors of the Vcmbanad Lake around Panangad region and compare the situation with that of the other parts of the lake. Salinity, temperature, current velocity and direction, dissolved oxygen, primary production and nutrients like phosphate, nitrite and nitrate were the parameters studied. For this monthly observations of these factors were made from nine stations located in and around Panangad region of Vembanad Lake. Beside this tidal cycle observations were carried out from two stations to study the tidal variation of the factors. S.T.D. meter was used to measure salinity, and temperature and a current meter for the current measurements. Water samples from surface and sub surfaces were collected with a clean bucket and a Van Dorn bottle. The estimation of dissolved oxygen, primary production and nutrients were done by standard methods. Marked seasonal fluctuation was noticed in the temperature of different stations. Annual variation showed two maxima. The temperature was minimum during southwest monsoon and maximum during pre monsoon months. In general, the vertical thermal stratification was small. The salinity exhibited marked seasonal fluctuation and generally the monsoon months recorded very low salinity values. After that there was an increase, reaching the maximum in pre monsoon months. Some vertical stratification was noticed during certain months. The Dissolved oxygen values were low during pre monsoon months and the content was more at surface than at the bottom layers. There was high seasonal fluctuation In the phosphate concentration. It showed high concentration during pre monsoon period. Generally bottom layers showed higher phosphate concentration than the surface layers. In the case of nitrite high values were observed durin 118 the monsoon and low values during dry season. Nitrate concentration also showed seasonal variation and high values were observed during the monsoon and low values during pre monsoon. The nutrient concentration was more in the inner smaller arms of the study area, in general. These inner arms were vertically homogenous also possibly due to higher mixing generated by the friction of the sides. In the tidal cycle observations it is found that salinity showed an increase during flood tide and decrease during ebb tide. At both stations considerable reduction in flood current speed was observed during post monsoon, compared to pre monsoon. During pre-rnonsoon a comparatively well mixed condition was prevailed. Post monsoon observations indicated very clear salinity stratification. This was due to the effect of freshwater discharge, which continued during this season though at reduced rate compared to monsoon season. It is found that the tidal effect on temperature was not well marked. It can be seen that different hydrographic factors of Panangad region of the Vembanad Lake exhibited much seasonal and spatial variations and the trend was in general, same to that shown by other parts of the lake.
Open Access
Community changes in zooplankton and macrobenthos of a prawn culture field in relation to hydrographical conditions
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2003) Shreeram Sudheer, Gubba; KAU; Cherian, C J
The present study was carried out in the prawn filtration field of the College of Fisheries at Panangad adjacent to the Cochin backwater system to find out the faunal variations of zooplankton and macrobenthos and to correlate them with the variations in hydro graphic conditions and compare the results with those obtained from the observations in the adjacent lake. Monthly samples for hydro graphical and biological studies were collected during the period from November 2002 to July 2003 from the culture field and adjacent backwater. Hydrographical features like temperature, salinity, transparency, pH, total alkalinity, dissolved oxygen, nitrate-N, phosphate-P, silicate-Si were observed. Crustacean larvae, copepods, tintinnids, nematodes, rotifers and veliger larvae of molluscs were the zooplankton groups obtained in the present study. Crustacean larvae and copepods were the dominant groups in both places and were found during all the months whereas tintinnids and nematodes were observed during saline period and their number decreased with decreasing salinity. Rotifers were recorded during low saline period only. Veliger larvae were recorded during December and February in the culture field, whereas, they were not present in the samples form the adjacent backwater. Statistical analysis for the influence of hydrographical parameters on the zooplankton showed that none of these had significant influence independently and the variations in the zooplankton abundance may be due to the combined effect of all these factors. Even though the seasonal changes in the total zooplankton were not pronounced the per cent composition of different groups showed fluctuation. Tanaidaceans, gastropods, polychaetes, amphipods, bivalves, isopods and chironomid larvae were the benthic groups obtained. Among these 112250 124 gastropods, tanaidaceans and polychaetes were the dominant forms. In the culture field benthic populations were maximum during the post-monsoon months and a showed a decreasing trend during pre-monsoon. With the onset of the monsoon they showed an increasing trend. In the backwater high benthic abundance was observed during January and February when high salinity prevailed and gradually decreased from March onwards reaching the minimum in July. In the culture field benthic abundance was mainly influenced by substratum characteristics and pH, whereas in the adjacent backwater salinity also played a role. The area of the present study is away from the barmouth and the nutrient levels especially phosphate is low in the culture field. This may be limiting the primary productivity of the area leading to low secondary production in terms of zooplankton and macrobenthos in the culture field. The high pH noticed in the culture field may be another reason for the low productivity.
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.

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