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  • ThesisItemOpen Access
    Evaluation of different protein sources in the formulated feed for macrobrachium Rosenbergii (De Man) Juveniles
    (Department of Aquaculture, College of Fisheries,Panangad, 1989) Anilkumar, P; KAU; Thampy, D M
    The nutritional quality of five locally available sources of protein such as clam meat, squid waste, squilla shrimp head waste and silkworm pupae was evaluated in the feed for the giant freshwater prawn, macrobrachium rosenbergii, with a view to develop a feed which is cost effective. The feeds were prepared using these locally available ingredients along with groundnut oil cake, wheat bran,tapioca flour, supplevite (a commercially available vitamin- mineral mixture) and sardine oil and maize oil mixture. The protein sources tested were not found to be grossly deficient in their nutritional quality as good survival rates of over 90% were obtained when they were used as the main protein sources in the feed of juvenile prawn. Highest growth rate was obtained for clam and squid based diets, intermediate growth response with squilla and shrimp head based diets and the lowest growth among the various sources was given by silkworm pupae diet. Feed conversion efficiency was higher for clam and squid based diets, while intermediate feed efficiency was noted for squilla and shrimp head meal diets. Lowest feed efficiency was observed for silkworm pupae diet. Protein efficiency ratio showed a similar pattern. In the second experiment, substitution with carbohydrate for protein was found to be promising from an economic point of view. It was found that lowering of protein level from 35 to 30% could be achieved by increasing the carbohydrate level from 20 to 30% without affecting the growth , survival and feed efficiency. Similarly, protein level could be lowered from 30 to 25% by increasing carbohydrate by 10% from 20% level. This suggest that a 5% reduction of costly protein could be achieved by including 10% more of carbohydrate which will be able to reduce the cost of the feed with out sacrificing the nutritional quality of the formulated feed.
  • ThesisItemOpen 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.
  • ThesisItemOpen 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.
  • ThesisItemOpen Access
    Studies on certain aspect of the biology of the barracuda of Cochin region
    (Department of Fishery Biology, College of Fisheries, Panangad, 1992) Krishnadas, K J; KAU; Rajasekharan Nair, J
    A systematic redescription of the three species viz. SphyraenajelloCuv.,S.obtusata (Cuv. & Val.) andS. barracuda (Walbaum), available in the Cochin region has been done. The food and feeding habits, breeding biology, length – weight relationship and condition cycles of S. jello, the commercially most important species of the region, have been studied in detail. A total of 141 males (270 – 943 mm TL) and 64 females (322 – 770 mm TL) collected during Nov. ’88 to Oct. ’90 were subjected to various investigations like qualitative and quantitative assessment of stomach content, feeding intensity, prey – predator length relationship, feeding habits, quantification of maturity stages, size at first maturity, spawning season and spawning frequency, sex ratio, spawning potential, length – weight relationship and condition and relative condition cycles using standard methods. S. jello is found to be a typical predator and a predominant piscivore. The species mostly feeds on small pelagic and mid – water shoaling fishes like clupeids, anchovies, scads and silverbellies, occasionally consuming cephalopods. The total length of the prey rangfed from 18.68 to 31.43% of the predator length. The size at first maturity is found to be 360 mm for males and 370 mm for females (350 – 400 mm length class). The species exhibits a prolonged spawning season in the Cochin region, spanning from April – September/October with increased activity during June to September. Individuals of S.jello spawn more than once during this prolonged spawning season. Female dominance in the population was noticed during May to July coinciding with spawning activity. The absolute fecundity of recruit spawners of S. jello ranged between 82, 431 and 1, 63,533 9400 – 501 mm TL). The intensity of feeding was lower during the period of increased spawning activity and higher during post – spawning period. The length – weight relationship worked out for the species is log W = -4.2751 + 2.5848 log L, the relationship showing no significant difference between the sexes. The relative condition cycle closely followed the spawning cycle, the values being close to ‘1’. Condition factor calculated using eviscerated weight of fish provided an index of true well being of the fish.
  • ThesisItemOpen Access
    Effect of eyestalk ablation on androgenic gland and male secondary sexual characters in Macrobrachium Idella (Hilgendorf)
    (Department of Aquaculture, College of Fisheries,Panangad, 1998) Sherine Sonia, Cubelio; KAU; Thampy, D M
    The present study in the prawn, Macrobrachium idella was taken up to find out morphotypic variation among the males, the endocrine basis for these variations and also to know the role if any, the eyestalk endocrines have, on the control of androgenic gland, which in turn is controlling the development of male primary and secondary sex characters. The study conducted to find the relationship between development of sex characters with that of androgenic gland conducted using 30 male prawns of different sizes has ShO\\-l1 that these sex characters are under the control of androgenic gland and have no relationship with that of the body size. Of the 30, 22 individuals were found to have a bodylength to cheliped length ratio below 1: 1.5, their androgenic gland and appendix masculina, not fully developed indicating that they are reproductively inactive. Remaining 8 individuals have a body length to cheliped length ratio above I: 1.5. They have well developed androgenic gland and appendix masculina showing that there is positive correlation between the biomass of androgenic gland and the cheliped length. An experiment conducted to find out the effect of unilateral eyestalk ablation on growth and development of primary and seconadry sexual characters as well as on the androgenic gland, had shown that destalking brings about a positive change in the development of androgenic gland and sex characters. The increase in the size of the androgenic gland and consequent hypertrophy of primary and secondary sexual characters brought about as a result of unilateral eyestalk ablation do indicate that the GlH, a hormone produced in the eyestalk has got an inhibitory effect on androgenic gland as well as on the growth of the prawn, which when removed by " destalking" , results in the enlargement of the androgenic gland and other sexual characters.
  • ThesisItemOpen 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.
  • ThesisItemOpen 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.
  • ThesisItemOpen Access
    Development of a ready to consume sweetened fish powder for children
    (Department of Processing Technology, College of Fisheries,Panangad, 2004) Varghese John; KAU; Sherief, P M
    A sweetened snack food was developed from a lean and cheap fish (Priacanthus hamrur Forskal, 1775) for children, to meet their increased requirements for protein and energy, corresponding to their higher growth rate and physical activities. The food was planned to be attractive & palatable to children; without any fish flavour and bones; and that could be stored at room temperature. The product was developed from surimi, since the latter was devoid of all the undesirable characteristics of fish flesh but retained its nutritive qualities. Surimi was solubilized with salt, into a protein-sol and sweetened it with sucrose, which also had a protective effect on protein from heat-denaturation. The sol was dried, ground and flavoured with cocoa- powder. The most preferred levels of sucrose and cocoa-powder were standardized by sensory evaluation of samples prepared with different levels of sucrose and cocoa powder. The final product was prepared by the standardized procedure, packed in polyester-LDPE laminated pouches and stored. Children's response to [he product was also tested. A 90day's storage study was conducted and the quality changes during storage were monitored periodically. There were no significant variations in the pH and TVBN values (P>O.05). The moisture and TBARS values showed a statistically significant increase. A decreasing trend was observed in the aerobic plate counts. The sensory quality parameters like odour, texture, taste and overall acceptability, did not decrease significantly. The product was acceptable throughout the storage period.
  • ThesisItemOpen Access
    Effect of eyestalk ablation on growth and reproduction of macrobrachium equidens (Dana)
    (Department of Aquaculture, College of Fisheries, Panangad, 1994) Bijulal, P S; KAU; Thampy, D M
    The objective of the present study is to evaluate the effect of eyestalk ablation on survival, growth, food conversion and reproduction of adult Macrobrachiumequidens. In the first experiment conducted for 35 days, unilateral eyestalk ablation, bilateral ablation and control treatments were employed at four level of salinities viz 5, 10, 15 and 20 ppt. Complete mortality in bilateral ablation and survival rates of 40.625 % and 68.75% for unilateral and control treatments were recorded at the end of the experiment, the values ranging significantly. The four salinity levels applied did not significantly affect survival. The difference in growth between ablated and unablatedtreatments was insignificant in terms of percentage gain, specific growth rate and average daily percentage gain in terms of length and weight. Salinity levels also showed insignificant difference in growth. Food conversion rate was significantly better in ablated treatment. The different salinity levels tried showed significant difference with regard to food conversion, being better at 20 ppt. In the second experiment conducted for 60 days on females, eyestalk ablation was found to enhance ovarian. In the second experiment conducted for 60 days on females, eyestalk ablation was found to enhance ovarian development in terms of the number of spawns per female. Fecundity, absolute fecundity, and incubation period were not significantly affected although a marginal increase in absolute fecundity could be observed . In the experiments conducted on males it was found that growth rate and cheliped development were significantly better in ablated ones. The number of spines in the appendix masculine, length and biomass of the androgenic gland and width of vas deference, did not show significant variation, although a marginal increase in the biomass of the androgenic gland and the number of spines in appendix masculine was observed in ablated treatment. The different eyestalk ablation experiments have shown that in females destalking does not stimulate growth but there is better response for reproduction, whereas in males there is better growth and only marginal response to reproduction.