Estimating the population density of prawns by the use of catch per effort data from prawn trawlers at Chilaw

The penaeid prawns of Sri Lanka from estuaries and sea are an important commercial fishery resource. This resource has been exploited over the last century or more by local fishermen using indigenous fishing gear from locally sail-driven or oar-driven fishing crafts. In more recent times, the Fisheries Research Division of the Department of Fisheries undertook surveys of the seas and lagoons of Sri Lanka with a view to ascertain whether any unexploited resources of prawns existed. These publications deal with the species composition, biology, distribution and abundance in the lagoons and inshore waters of Sri Lanka.

High-density comparative BAC mapping in the black muntjac (Muntiacus crinifrons): Molecular cytogenetic dissection of the origin of MCR 1p+4 in the X1X2Y1Y2Y3 sex chromosome system

The black muntjac (Muntiacus crinifrons, 2n = 8 female/9 male) is a critically endangered mammalian species that is confined to a narrow region of southeastern China. Male black muntjacs have an astonishing X1X2Y1Y2Y3 sex chromosome system, unparalleled i

CpG island density and its correlations with genomic features in mammalian genomes

Background: CpG islands, which are clusters of CpG dinucleotides in GC-rich regions, are considered gene markers and represent an important feature of mammalian genomes. Previous studies of CpG islands have largely been on specific loci or within one geno

A record of Probopyrus bithynis (Richardson, 1904) in Macrobrachium rosenbergii (De Man) from coastal Andhra Pradesh, India, with special reference to host-parasite relationship

An incidence of bopyrid isopod infestation was observed in giant freshwater prawn, Macrobrachium rosenbergii (de Man) juveniles (40-60 mm/0.9-1.5 g) in a scampi culture farm in East Godavari district of Andhra Pradesh. The presence of parasite was observed by conspicuous boil like swelling of the branchial chamber where the parasite was found lodged on the gills. The infested gill was highly compressed and necrosed. Only one branchial chamber was infested by the parasite while the other gill was normal. The infested prawns were thin and emaciated and showed retarded growth. The parasite was identified as Probopyrus bithynis (Richardson, 1904) which caused inhibition of ventilation due to its permanent lodging in the branchial chamber and impaired the gaseous exchange by gills. It was also observed that this parasite caused parasitic castration in the infested prawns.

Optimisation of stocking density of Thai silver barb (Barbodes gonionotus Bleeker) in the duckweed-fed four species polyculture system

The optimisation of stocking density of Thai silver barb (Barbodes gonionotus) in the polyculture with Labeo rohita, Catla cat/a and Cyprinus cmpio was investigated in seasonal ponds. Three different stocking densities of Thai silver barb i.e., 5,000, 6,000 and 7,000 fingerlings ha-1 were tested with stocking density of carps fixed at the rate of 10,000 fingerlings ha-1 Duckweed was applied to all ponds supplemented with rice bran and oil cake. There were no significant variations on either water quality parameters or abundance of planktonic organisms due to the different stocking densities of silver barb. A significantly higher fish production (pdensity of Thai silver barb was maintained.

Heliconema savala n.sp. (Nematoda:Physalopteridae) from marine fish Lepturacanthus savala (Cuvier) (Trichiuridae) and Psettodes erumei (Schneider) new host (Pisces:Pettodidae) of Physalopterid Nematode, Bulbocephalus inglisi Rasheed, 1966 in Pakistan

Helicnonema savala, n.sp. obtained from the marine fish, Lepturacanthus savala in Sindh coast is distinguished from members of the genus processing in the male 10 tessellated longtitudinal ridges and a spicule ratio 1:15. Females have vulvular flap. Heliconema savala is a morphologically most closely related to Heliconema heliconema. The marine fish, Psettodes erumei is recorded as a new host of Bulbocephalus inglisi.

Influence of stocking density on the culture potential of freshwater catfish Pangasius pangasius in pond

Influence of stocking density on the production of freshwater catfish Pangasius pangasius with formulated feed in ponds was studied. The fish fry were collected from the Meghna river near Chandpur which is a natural breeding ground of this fish. Three stocking densities chosen during this experiment were 5000, 8000 and 11000 fry/ha with an initial weight of 42.57 ±2.51 g. The formulated feed was prepared in the laboratory which contained 45% fish meal, 30% mustard oil cake, 15% wheat bran and 10% rice bran to supply 40.48% protein in feed. The growth of P. pangasius in terms of net weight gain was 409.49, 266.49 and 236.37 g at the 5000/ha, 8000/ha and 11000/ha stocking densities respectively, which was statistically significant (p<0.05). High food conversion ratio (FCR) was also observed during this research study which ranged between 7.06 to 7.72. A production of 2.6 tons/ha at the stocking density of 11000/ha; 2.13 tons/ha at the stocking density of 8000/ha and 2.04 tons/ha at the stocking density of 5000/ha was obtained, while the growth of individual fish at the end of experiment was in opposite order. The result of this experiment indicates that stocking density has significant influence on the culture potential of freshwater catfish P.pangasius.

Polyculture of freshwater prawn, Macrobrachium rosenbergii, de Man with carps: effects of prawn stocking density

Effects of three stocking densities, viz., 35, 50 and 65/decimal (1 decimal = 40.48 m2) of juvenile freshwater prawn (Macrobrachium rosenbergii) on prawn and fish production were tested in a polycuture system with silver carp (Hypophthalmichthys molitrix), catla (Catla catla), Grass carp (Ctenophmyngodon idella) and silver barb (Barbodes gonionotus). The fish stocking density was 19/decimal with the species combination of silver carp-10, catlac-6, grass carp-1 and silver barb-2. In a 8-month culture period, the prawn yield 423 ± 144 kg/ha was significantly lower (P< 0.5) with the prawn stocking density of 35/decimal than that of 548 ± 178 kg/ha and 662 ± 243 kg/ha with 50 and 65/decimal respectively. The fish production (1844-1891 kg/ha) did not differ significantly (p <0.05) among the three treatments indicating that prawn stocking densities had no influence on fish yield. The lower mean harvest weight (62 g) and survival rate (67 g) and higher yield (2.67 kg/decimal) with the highest stocking rate of prawn reveals that as density was increased, prawn survival and individual weight at harvest decreased but total yield increased.

Effect of stocking density on the production of common carp (Cyprinus carpio Lin.) in cages at Kaptai lake, Bangladesh

Growth, survival and food conversion ratio (FCR) of Cyprinus carpio in cages at different stocking density were studied in Kaptai lake. Fingerlings of common carp (12.47 ± 4.29 g) were stocked at 25/m2 , 50/m2 and 75/m2 each with replication in six floating net cages each of Sm x Sm x 4m and reared for 240 days. The growth rate was inversely related to the stocking density with the mean weights of 325.5 ± 11.74 g, 268.99± 8.44 g and 167.0 ± 11.66 g at low, medium and high densities, respectively. At harvest, standing crop biomass averaged 7 .82, 12.83 and 11.58 kg with the survival of 98.9%, 97.6% and 94.4% and food conversion ratios of 4.51, 3.82 and 4.21 for the above three densities, respectively. Weight gain and production at density 25 fish/m 2 were significantly different (p< 0.01) from other two densities. Water quality was not affected in the cages having different stocking densities.

Dynamics of parasite population and its histopathological and histophysiological effects in the stomach of a freshwater fish

The caryophyllaeid cestode Lytocestoides fossilis infects the freshwater catfish Heteropneustes fossilis. The study was conducted for two consecutive years (2004-06) to record the bio-statistical data of the parasite. The incidence, intensity, density and index of infection of the parasite have been recorded. The infection was more during June to September, moderate during February to May and low during October to January. The parasite brought about severe histopathological changes in the stomach of infected fish. The changes observed in the stomach of fish included structural damage of the villi, inflammation, and fibrosis associated with hyperplasia and metaplasia. The hypertrophy of mucous layer led to vacuolation and necrosis. Histochemical changes were noticed with enhanced carbohydrate, protein and lipid contents. The enhanced substrate content in the infected organ might be due to the disfunctioning of the digestive tract, which results in the accumulation of various metabolites. Mucus secretion was triggered as a protective interaction against parasitic invasion. The parasitic infection affects the general metabolic state of the host and as the result, the fish becomes sluggish and moribund.

Perylene-based fluorescent liquid crystal dye guest-host mixtures

We present a study on a series of dye guest-host mixtures using fluorescent perylene-based molecules as the guest dye in an organosiloxane host. These hosts have temperature-independent switching, at room temperature, through 90° for fields of the order of 10 Vrms/μm. Perylene molecules have been grafted onto the organosiloxane moiety via an alkyl spacer producing novel and rugged fluorescent dyes that are readily miscible in the host. Micro-separation of the low molar mass siloxane groups in the mesophases tend to form smectic phases. These planes produce an effective two-dimensional polymer backbonethat engenders the rugged mechanical properties of polymeric liquid crystals onto these low molar mass ferroelectric liquid crystals. In this study we show how the introduction of the dye molecules affects the electro-optic properties of the organosiloxane host. © 2001 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint, a member of the Taylor & Francis Group,.

A PCR-based RFLP analysis of Sarcocystis cruzi (Protozoa : Sarcocystidae) in Yunnan province, PR china, reveals the water buffalo (Bubalus bubalis) as a natural intermediate host

A polymerase chain reaction-based restriction fragment length polymorphism (RFLP) approach is used to examine Sarcocystis cruzi-like taxa from the atypical intermediate host, water buffalo, in Yunnan, People's Republic of China. The loci examined lie with

A paradigm for virus-host coevolution: Sequential counter-adaptations between endogenous and exogenous retroviruses

Endogenous retroviruses ( ERVs) are remnants of ancient retroviral infections of the host germline transmitted vertically from generation to generation. It is hypothesized that some ERVs are used by the host as restriction factors to block the infection o

Use of linear low density polythene film for frozen fish packaging

Physical properties of linear low density polythene film of 60 gauge thickness and its suitability as packaging material in frozen fish industry was studied in comparison with conventional 100 gauge low density polythene film. Both were comparable in water vapor transmission rate both at 38°C and -20°C, overall migration test and :flexibility at low temperatures. ·Even though the tearing strength was inferior to the conventional one, it is of no significance in its use in frozen fish industry. The new film worked out to be more economical than the other one.