Seasonal variation in the occurrence of some zooplankton in a fish pond

Observations were made on the seasonal variation in the occurrence of some zooplankton in a fish pond. A total of 31 genera were recorded, out of these, 8 belongs to Rotifera, 5 to Copepoda, 112 to Cladocera, 3 to Protozoa, 2 to Nematoda and 1 to Oligochaeta. The role of temperature, dissolved oxygen, free Co2, pH, turbidity and alkalinity in the occurrence of different genera is discussed.

Seasonal variation of alginic acid content in Sargassum cervicone Greville from Hikkaduwa

Sargassum cervicone Greville is one of the species of Sargassum occuring in abundance along the South Western Coast of Ceylon. Durairatnam 1966 carried out a survey from Ambalangoda to Hambantota, and estimated that approximately 130 tons of dried Sargassum can be harvested manually. The bulk of the Sargassum found in this area was Sargassum cervicone Greville.

Seasonal variation in the distribution and availability of Carangids ("Paraw" and "Parati") in the Wadge Bank

The Wadge Bank has been exploited regularly by Ceylon based trawlers since 1955 (Sivalingam & Medcof 1957). The bank is about 4,000 sq. miles in extent (Malpas 1926) and is located south of Cape Comorin within the Continental Shelf of India (Fig. 1). Carangids are taken in large numbers during the months of the south west monsoon (Sivalingam 1966). The quantity, in which the Carangids are captured as shown by the fishing records, is large enough to influence the total catch from the bank during these months (Fig. 2). Carangids are held in high esteem as excellent quality food fishes and accordingly constitute a commercially important group. This paper records the results of a detailed examination of the past fishing records in respect of this group, based on the analysis of the catch and fishing effort for the years 1957 to 1962. The distribution pattern of this group of fish in the Wadge Bank is discussed.

Fish fauna of a coastal lagoon in Sri Lanka: distribution and seasonal variation

In this paper results of investigations carried out over the period of September 1977 to August 1978 are presented. These data were collected in the course of a detailed investigation into the biology and the eco-physiology of the young grey mullet and the grey mullet fishery of the Negombo Lagoon. In this paper the distribution and seasonal variation of fin fish species within the Negombo Lagoon are presented.

Studies on the fish ponds at Pitipana, Negombo 1: seasonal and diurnal variation of some hydrobiological factors

The present paper is a part of a detailed investigation on the biology of grey mullet, Mugli cephalus L., and the feasibility of its culture in the brackish waters of Sri Lanka. The authors present the results of investigation on the water quality of five experimental ponds at the Pitipana Brackishwater Fisheries Station, Negombo, carried out over a period of one year, December 1976 to November 1977, together with studies on the primary productivity are presented.

Allozyme variation in four hatchery populations of Thai pangas, Pangasius hypophthalmus in Bogra, Bangladesh

Genetic variation of four hatchery stocks of Thai pangas, Pangasius hypophthalmu [sic] of Bogra region, Bangladesh was studied from 1 January 2002 to 31 December 2003. Muscle samples were collected for allozyme analysis from four (Bhai-Bhai, Jahangir, Belal and Bhai-Bon) different hatchery populations. For allozyme electrophoresis, eight enzymes were used and 11 loci viz. Adh-1*, Est-1*, GJpdh-1*, Gpi-1*, Gpi-2*, Jdhp-1*, Ldh-1*, Ldh-2*, Mdh-1*, Mdh-2*and Pgm* were identified, of which three loci (Est-1*, Gpi-2*, G3pdh-1 and Pgm*) were polymorphic in all the four populations. The mean proportion of polymorphic loci per population and the mean proportion of heterozygous loci per individual was 36.36% and 13.33, respectively for all the population studied. The highest variability measured by the mean number of alleles per locus was 1.545 in Bhai-Bon hatchery population. Based on Nei's (1972) genetic distance, the dendrogram (UPGMA) shows that four populations have made two clusters by D-value (D=0.043). Bhai-Bhai and Jahangir hatchery populations have made cluster-I, and Belal Uddin and Bhai-Bon hatchery populations formed cluster-II. Among the four populations, BhaiBhai and Jahangir hatchery populations were differentiated from each other by the D-value of 0.013, and Belal Uddin and Bhai-Bon populations were differentiated from each other by the D-value of 0.002, which suggests that the four populations may be fallen into the local population or race.

Allozyme and morphological variation in four hatchery stocks of Thai pangas, Pangasius hypophthalmus in Mymensingh, Bangladesh

Genetic and morphological characters of four hatchery population (Shambhuganj, Brahmaputra, Anudan and Bhai-Bhai) of Thai pangas, Pangasius hypophthalmus in Mymensingh region of Bangladesh was studied using morphological characters and allozyme markers from 29 November 2001 to 29 November 2002. A total of 14 morphometric and 6 meristic characters were verified, among which 3 morphometric (BDA, PELFL and HW) and 2 meristic characters (AFR, CFR) of Anudan hatchery population were found to be significantly higher (p>0.001) than those of the other three hatchery populations. Brahmaputra hatchery population was also significantly higher in two meristic characters (PCFR and CFR). For allozyme electrophoresis nine enzyme markers were used viz.: Esr-1*, G3pdh-2*, Gpi-1*, Gpi-2*, Ldh-1*, Ldh-2*, Mdh-1*, Mdh-2* and Pgm* where three loci (Esr-1*, Gpi-2* and Pgm*) were polymorphic (p>0.95) in Anudan and Brahmaputra hatchery populations. The mean proportion of polymorphic loci per population was higher (33.3%) in Brahmaputra and Anudan hatchery populations. Also the expected heterozygosity levels were 0.149 and 0.177 in Brahmaputra and Anudan hatchery populations, respectively. Based on Nei's (1972) genetic distances, the UPGMA dendrogram grouped the populations into two clusters. The Brahmaputra and Anudan populations are in one group; Shambhuganj, and Bhai-Bhai populations are in the second group. High genetic variation in Thai pangas was observed in the Brahmaputra and Anudan hatchery populations and less variation in the other two hatchery populations.

Determination of length-weight relationship in Sepia pharaonis and test for sex specific variation

The parameters a and b of the length-weight relationship of Sepia pharaonis of the form of W=a.L was determined. Sex separated size fequency data collected from Karachi fish Harbour was analysed the length-weight equations, separable by male, female and sex combined. The apparent difference in paired values of exponents b1, b2 for any combination i.e. male versus female and male, female versus sex combined was tested for their significant difference. No significant difference was observed for any combination, this indicated no sex specific variation in length-weigh relationship of Sepia pharaonis.

Production and economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds

The production of fish and net economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds were assessed. The experiment was arranged in three treatments each with three replications. The ponds were stocked with 30,000 fishes per hectare. In treatment 1 (T1) pangasiid catfish only, in treatment 2 (T2) pangasiid catfish and silver carp at the ratio of 1:1, and in treatment 3 (T3) pangasiid catfish and silver carp at the ratio of 2:1 were stocked. At harvest, production of fish was found significantly (p<0.05) different among the treatments, highest in T1 and lowest in T2. Though the total biomass production and total economic return was significantly highest in T1 than in T2 and T3, the net economic return was lowest because of the required highest input costs especially for supplemental feed and fingerlings, resulted the highest cost per unit yield (CPY in Tk/kg) in T1. Highest cost for supplemental feed required in T1 was due to highest quantity of feed required for the highest number of pangasiid catfish stocked in that treatment. The findings of the present study suggest that though monoculture of pangasiid catfish give higher fish biomass production but polyculture with silver carp is environmentally good and economically profitable.

The triglyceride fatty acids from heart lipids of Puntius sarana and their variation with different sizes

The triglyceride fatty acid components from the heart lipid of Puntius sarana of different sizes have been characterized by thin-layer and gas liquid chromatography. Csub(10) to Csub(24) acids including both odd-numbered and branched chain acids were detected. The major constituents were ante-iso Csub(10), Csub(10), Csub(12:2), Csub(14), Csub(16), Csub(16:1),Csub(17), Csub(18) , Csub(18:1), Csub(18:2), Csub(18:3) and Csub(20:4) while twenty other acids were detected in lower proportion. The composition of these acids and their variation with size of fish have been investigated and discussed.

Prices on Indian frozen shrimp in U.S. market: a note on seasonal variation

The supply and consumption of shrimp follow a more or less regular seasonal pattern. Like agricultural products, fishery products have also their period of heavy and less productions on which depend their price movements. The prices of shrimp in any particular market reflect this seasonal behaviour quite often.

Seasonal variation in the chemical composition of pomfret - 2. Silver Pomfret (Pampus argenteus)

Seasonal variation in the proximate composition of different body regions of Pampus argenteus is reported. The fat content of the fish is high during winter whereas during summer the fish becomes lean. A comparison of average values of proximate composition and energy values of silver pomfret and black pomfret (Parastromateus niger) is given.

Effect of variation in mesh size on trawl efficiency

Result of comparative fishing trials with a bulged belly design with three different mesh ranges in the body and wing to study the effect of mesh size difference on the performance of gear is discussed. While there is no significant difference in catch rate, predictably the 40 mm mesh size trawl fared wen when small sized fish like anchovies formed the major catch. The trawls with 60 and 80 mm mesh size gave better horizontal spread at a lower resistance showing savings in fuel.

Histoarchitecture, seasonal variation and reproductive function of the neuroendocrine organ, brain of freshwater prawn, Macrobrachium gangeticum

Histoarchitecture, seasonal variation and reproductive function of the neuroendocrine structure, brain of freshwater prawn Macrobrachium gangeticum were studied. Three types of NSCs - 'B', 'C' and 'D' were found to be concentrated in four groups in brain. These cells showed larger diameters and higher activity during breeding season. In case of females, the 'C' cells were more active during vitellogenic period. Brain extracts were found to induce gonadal maturation of both males and females.

Genetic variation survey of intra-specific (Sepia pharaonis) in the Persian Gulf and the Oman Sea using PCR-RFLP

This research was conducted to identify Cuttlefish population (Sepia pharaonis) in The Persian Gulf and the Oman Sea using PCR-RFLP. Specimens were collected from )0 different stations. Bottom trawling method was used for sampling from different zones of the Persian Gulf and the Oman Sea, and finally specimens from S. Pharaonis were collected at each station . DNA was extracted by phenol—Coloroform method. One pair primer was designed based on 1As rRNA gene nucleotide sequences. The results obtained from 1 As rRNA gene RFLP, which was reproduced by PCR technique, were analyzed and utilized for study of diversity of the Cuttlefish population. PCR product with o pair base in length achieved for all specimens, which was subjected to enzymatic digestion by A restriction action enzymes: Alu I-Taq I-Mnl I-Rsa I-Hind III-Dra I-vu II and Hae II DNA bands patterns in all specimens digested by those enzymen showed similarity with no any polymorphism. From this result, it can be concluded that there is not any possibility to isolate different populations in the studied Cuttlefish species under exploitation of rRNA gene.