A comparative study on the hatching of common carp eggs in hapa and hatchery (model CIFE D-80)

Common carp (Cyprinus carpio) eggs were incubated to study the efficiency of hatching in hapa and hatchery. During incubation the recorded temperature was 21-28 degree C and 20-31 degree C, dissolved oxygen 6-9 ppm. and 3-5 ppm., total alkalinity 180-250 ppm. and 28-62 ppm. respectively in the hatchery (model C.I.F.E. D-80) and hapa. CO sub(2) was totally absent in the hatchery, but recorded 3-10 ppm. in the hapa. The flow of water was maintained at 1.25 l/minute/jar in the hatchery. Under the above environmental conditions the eggs hatched in 42-51 hrs. in the hatchery and 61-81 hrs. in the hapa from egg to spawn thereby establishing the hatchery to be a better hatching system for carp eggs.

Antibacterial effect of the Indian squid, Loligo duvauceli (d'Orbigny), ink

The ink of the Indian squid Loligo duvauceli (d'Orbigny) was tested for antibacterial activity. The antibacterial effect of bacteria present in the ink gland was also tested. Only one type of bacteria was found to be present in the ink gland of squid and was identified as Photobacterium leiognathi. Among the various forms of ink extracts, the precipitated and freeze-dried ink showed more pronounced antibacterial effect against Gram-negative bacteria, Salmonella, spp. Escherichia coli, Vibrio cholerae, V. parahaemolyticus and Pseudoinonas spp., and a less pronounced effect against Gram-positive bacteria, Staphylococcus spp. and Micrococcus spp., P. leiognathi did not inhibit any of the above bacteria. The antibacterial activity was associated with the compounds of the ink.

Effects of physiological doses of vitamin D sub(3) (Cholecalciferol) on induced molting and growth in giant freshwater prawn, Macrobrachium rosenbergii (de Man)

Effects of three different doses of vitamin D sub(3) on molting, growth, and calcium and phosphate composition of tissue and molt during the grow-out of the giant freshwater prawn Macrobrachium rosenbergii (average weight 10.56 ± 0.20 g), obtained from a grow-out pond, were studied. Intramuscular doses of vitamin D sub(3) (100, 500 and 2000 IU/kg body weight) were given on the 1st, 3rd, 5th, 7th, 9th, 11th, 13th, 15th, 20th, 25th and 30th days. All the experimental animals were fed with a basal diet containing fish meal, shrimp meal, wheat flour, groundnut de-oiled cake, soybean meal and wheat bran at 3% of the body weight. The numbers of molts were recorded as 20±0.50, 29±1.16, 51±1.87, and 30±1.60 in control, 100, 500 and 2000 IU/kg body weight physiological doses, respectively. Maximum growth was recorded in prawns given 500 IU/ kg dose. Survival was between 58.33 ± 9.13 and 77.77 ± 8.61%. The ash content and calcium level increased significantly (p<0.05) and recorded the highest values in 500 IU/kg physiological dose. However, the inorganic phosphate (P sub(i)) content recorded the highest values in tissue in 2000 IU/kg dose (p<0.05, F = 50.60613). There is no significant difference in calcium contents (p>0.05) in both tissue and molt at 500 and 2000 IU/kg doses. It was found that a higher physiological dose (2000 IU/kg) of vitamin D sub(3) increased the rate of mortality. Results have shown that vitamin D sub(3) has a positive impact on the growth and survival of M. rosenbergii and it interferes with the metabolism of Ca and P sub(i), in tissue, and alters molting frequency. Results on physiological dose suggest an alternative and effective dietary supplementation method of vitamin D sub(3) in the grow-out phase of M. rosenbergii.

Investigation of the losses in the stator duct spacers of large A.C. motors using the A -ip 3-D eddy current formulation

This paper describes how the A -if) formulation may be applied to determine the losses in the stator duct spacers of large a.c. motors. The model is described in terms of its geometry and boundary conditions. The novel aspects of the application of the formulation to this problem are explained. These include the modelling of fixed currents sources (the stator windings), the location of the necessary cut surfaces and the determination of their magnetic scalar potential differences, and the implementation of periodic boundary conditions for vector variables. Results are presented showing how the duct spacer losses vary with load, and with the relative permeability of the spacer material. The effects of modelling iron nonlinearity, of both the spacer and the steel laminations, are also illustrated. © 1996 IEEE.

Apparent abundance of yellowfin and bigeye tuna in the inshore, off shore and near oceanic ranges around Ceylon

Sri Lanka entered oceanic longline fishery in 1967 and have limited the areas of operation to the central equatorial belt, thus limiting their fishery to the yellowfin and bigeye tunas. Sri Lanka while developing her coastal fishery took a leap into oceanic longlining and in view of her programme for accelerated development of the fishing industry, has to fill the gap between the two fisheries by exploiting the intermediate range (off shore and near oceanic) which would chiefly be for tunas and sharks. The present paper has been prepared in this context, utilizing available data and information on the tuna longline fishery in the inshore (approximately 6-15 miles), off shore (approximately 15-100 miles) and near oceanic (approximately 100-300 miles) ranges (Fig, 1).