37 resultados para differential association


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Fluctuations in the K values of Nemipterus japonicus (Bloch) off Bombay coast were interpreted regarding sex, month and females maturity stage. These indicate differential growth rates in males and females. Males and females attain first maturity at 145 mm and 115 mm respectively, second maturity is attained by both the sexes at 195 mm. First spawning occurs when both are of 155 mm length and at second spawning males and females attain 215 and 205 mm of length respectively. The fish mature and breed at "O" year; the main spawning period is from August to November with peak spawning activities in October. It grows about 155 mm in first year at 12.91mm per month and about 215 mm in the second year at 5.0 mm per month on an average. Length-weight relationships for males and females are given. The rate of growth of females by weight was found to be slower below 150 mm, but faster than that of males above 150 mm specimens.

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The bacteria from a variety of fresh-water fish, Cyprinus carpio. var. communis, showed the presence of micrococci, Gram positive and Gram negative rods. These have been characterized as far as was possible. Of thirty-eight strains of bacteria used, only six strains were considered as causing spoilage of fish flesh in experiments where flesh was incubated with individual cultures of the bacteria. These six strains had been found on the surface and/or intestine of the fish and support the suggestions that, after death, invasion of flesh by bacteria from the surface and intestine could be the cause of bacterial spoilage of fish.

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Some aspects of association and development of the caryophyllid cestode Lytocestus indicus Moghe, 1925 infecting the catfish Clarias batrachus (Linn.) from the Kailla Beel of Mymensingh, Bangladesh were studied. About 33.14% of Clarias batrachus were infected with a mean intensity of 3.75, mean density 1.25. The infection was not found throughout the year. Two seasonal occurrence of this cestode were observed, one in April-May and the other in August-September. However, maturation period of the worm coincided with the maturation of the host. The worm was found attached to the wall of the intestine of the host. At the site of attachment tissue layers were compressed due to mechanical injuries. Prevalence and mean intensity of infection increased with length groups. No variation in infection was significantly observed in different sexes of the host examined.

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Pond culture trials of Lates calcarifer (Bloch) were initiated in the ponds of Kharland Research Station, Panvel, from 1985 up to 1989 by adopting varying methods of inputs of commonly available organic substances comprising de-oiled cake of groundnut, rice bran and raw cattle dung. Although provision of zooplankton generated under phased fertilisation technique resulted in considerable yield level, subsequent trials in combination with direct feed methods gave higher yield. Trials during 1990-91 adopting similar feed input techniques were continued but by stocking the seed of both Lates and Oreochromis mossambicus with yield percentage around 72.23 for Lates and 27.73 for Oreochromis. Trials were further continued during next three years. In relation to the organic input levels the yields rate for seven months period was in the range of 119.4 kg/ha to 250.4 kg/ha for Lates. In case of Oreochromis the yield rate varied between 28.5 to 153.32 kg/ha indicating the influence of differential stocking rates and size of the seed of two species.

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Attached to hard substrata on our shores occur the branching colonies of gorgonian corals of the genus Muricella (Fig. 1A, Pl. 1B, C, D). Since there is no report on this genus from Pakistan this report be taken as the first record from here. The family Ovulidae comprises several hundred species of marine gastropods, all of which appear to be obligate associates of cnidarians as stated by Robertson (1970) and Hadfield (1976); the present ovulid gastropod genus Crenovolva lives exclusively on the gorgonians (Morton, 1989). Tirmizi and Zehra (1984) recorded thirty-two families of gastropods from Pakistan, but not any representative of the Ovulidae, so the material at hand may be the first record from Pakistan. Since we are unable to reach to specific level the material is being reported as unspecified.