The effects of brood stock size on the economy of catfish (Clarias anguillaris) fry production using the hormone induced natural breeding technique

89 ripe female brooders of the catfish, Clarias anguillaris (Body wt. Range 150g-1, 200g) were induced to spawn by hormone (Ovaprim) induced natural spawning technique over a period of 10 weeks. Matching ripe males were used for pairing the females at the ratio of two males to a female. Six ranges of brood stock body weights were considered as follows; <200g; 200g-399g; 400g-599g; 600-799g; 800g-999g; > 1000g and the number of fry produced by each female brooder was scored/recorded against the corresponding body weight range. The number of fry per unit quantity of hormone and the cost of production a fry based on the current price of Ovaprim (hormon) were determined so as to ascertain most economic size range. The best and most economic size range was between 400g-599g body weight with about 20,000 fry per ml of hormone and N0.028 per fry, while the females above 1000g gave the poorest results of 9,519 fry per ml of hormone and N0.059 per fry. For optimum production of Clarias anguillaris fry and maximum return on investment female brooders of body weights ranging between 400g-599g are recommended for hormone induced natural breeding exercises

Quantitative data on the feeding of Cyclops strenuus Fischer and Cyclops viridis Jurine. [Translation from: Trudy saratov.Otd.vses.nauchno-issled.Inst.ozer.rech.ryb.Khoz. 1, 163-176, 1951.]

Cyclopids, exactly in the same way as daphnids, significant component in the nutrition of plankton-f and the young of the majority of fishes. It is established that the food spectrum of cyclopids is extremely broad: daphnids, planarians, Copepodite stages of copepods (cannibalism), rotifers, protists, bacteria, phytoplankton and so on. It is clear that the problem of studying these or other components of feeding in the general food spectrum can be definitely resolved only after obtaining exact quantitative data on the feeding of cyclopids. This article attempts to fill the gap in the study of the quantitative side of the feeding of cyclopias; in it is investigated the size of the 24-hour ration of cyclopids feeding on protists, the dependence of the ration on some factors of the external medium, and the difference of 24-hour consumption per unit weight of tody with two species of cyclopids (Cyclops strenuus and Cyclops viridis).

Geometrical effects on the resonance absorption of neutrons

An investigation was conducted to estimate the error when the flat-flux approximation is used to compute the resonance integral for a single absorber element embedded in a neutron source.

The investigation was initiated by assuming a parabolic flux distribution in computing the flux-averaged escape probability which occurs in the collision density equation. Furthermore, also assumed were both wide resonance and narrow resonance expressions for the resonance integral. The fact that this simple model demonstrated a decrease in the resonance integral motivated the more detailed investigation of the thesis.

An integral equation describing the collision density as a function of energy, position and angle is constructed and is subsequently specialized to the case of energy and spatial dependence. This equation is further simplified by expanding the spatial dependence in a series of Legendre polynomials (since a one-dimensional case is considered). In this form, the effects of slowing-down and flux depression may be accounted for to any degree of accuracy desired. The resulting integral equation for the energy dependence is thus solved numerically, considering the slowing down model and the infinite mass model as separate cases.

From the solution obtained by the above method, the error ascribable to the flat-flux approximation is obtained. In addition to this, the error introduced in the resonance integral in assuming no slowing down in the absorber is deduced. Results by Chernick for bismuth rods, and by Corngold for uranium slabs, are compared to the latter case, and these agree to within the approximations made.

Effect of Fe impurity on the optical loss of Nd-doped phosphate laser glass

The optical loss coefficient at 1053-nm wavelength, influenced by Fe ions in N31-type Nd-doped phosphate laser glass, was determined precisely and analyzed in detail. It is found that the optical loss coefficient per unit of Fe concentration (cm^(-1)/ppmw) increases with Fe concentration in the range of 0---300 ppmw, but it approaches a constant as the Fe concentration is larger than 300 ppmw. Such a concentration effect is due to a shift in the redox equilibrium between Fe3+ and Fe2+ ions in the glass. The effect of oxygen pressure, temperature, and variable valence states of other metal ions in glass samples on the optical loss is also discussed.

Contributions to High-Throughput Computing Based on the Peer-to-Peer Paradigm

XII, 116 p.

An evaluation of the effects of blue crab (Callinectes sapidus) behavior on the efficacy of crab pots as a tool for estimating population abundance

Crab traps have been used extensively in studies on the population dynamics of blue crabs to provide estimates of catch per unit of effort; however, these estimates have been determined without adequate consideration of escape rates. We examined the ability of the blue crab (Callinectes sapidus) to escape crab pots and the possibility that intraspecific crab interactions have an effect on catch rates. Approximately 85% of crabs that entered a pot escaped, and 83% of crabs escaped from the bait chamber (kitchen). Blue crabs exhibited few aggressive behavioral interactions in and around the crab pot and were documented to move freely in and out of the pot. Both the mean number and size of crabs caught were significantly smaller at deeper depths. Results from this study show that current estimates of catch per unit of effort may be biased given the high escape rate of blue crabs documented in this study. The results of this paper provide a mechanistic view of trap efficacy, and reveal crab behavior in and around commercial crab pots.

Spatial and temporal patterns in the demersal fish community on the shelf and upper slope regions of the Gulf of Alaska

We analyzed data from National Marine Fisheries Service bottom trawl surveys carried out triennially from 1984 to 1996 in the Gulf of Alaska (GOA). The continental shelf and upper slope (0–500 m) of the GOA support a rich demersal fish fauna dominated by arrowtooth flounder (Atheresthes stomias), walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and Pacific Ocean perch (Sebastes alutus). Average catch per unit of effort (CPUE) of all groundfish species combined increased with depth and had a significant peak near the shelf break at 150–200 m. Species richness and diversity had significant peaks at 200–300 m. The western GOA was characterized by higher CPUEs and lower species richness and diversity than the eastern GOA. Highest CPUEs were observed in Shelikof Strait, along the shelf break and upper slope south of Kodiak Island, and on the banks and in the gullies northeast of Kodiak Island. Significant differences in total CPUE among surveys suggest a 40% increase in total groundfish biomass between 1984 and 1996. A multivariate analysis of the CPUE of 72 groundfish taxa revealed strong gradients in species composition with depth and from east to west, and a weak but significant trend in species composition over time. The trend over time was associated with increases in the frequency of occurrence and CPUE of at least eight taxa, including skates (Rajidae), capelin (Mallotus villosus), three flatfish species, and Pacific Ocean perch, and decreases in frequency of occurrence and CPUE of several sculpin (Myoxocephalus spp.) species. Results are discussed in terms of spatial and temporal patterns in productivity and in the context of their ecological and management implications.

Some perspectives on the late Quaternary paleoclimate of Beringia

EXTRACT (SEE PDF FOR FULL ABSTRACT): Analyses of the modern summer synoptic climatology of Beringia illustrate that the region cannot be treated as a homogenous climatic unit as a result of different circulation controls that operate over the region. GCM (general circulation model) simulations and information from the modern synoptic climatology were used to infer the summer paleosynoptic climatology of the region since the last glacial maximum. ... Variations in these climatic controls offer important implications in assessing the vegetation histories of western Beringia versus eastern Beringia.

A note on the production trend of marine shrimps in India

The paper reviews the production statistics of marine shrimps in the different maritime states of India from 1950 to 1962. It is pointed out that for a correct appraisal of the status of any fishery, it is necessary to have data on effort E and catch per unit effort in addition to the conventional data on catch C. A relationship between U and E has been developed and the status of the fishery of Metapenaeus dobsoni has been discussed in this connection with reference to the data on catch and effort obtained from trawler operations off Cochin.

On the relative catch efficiency of different shaped otter boards in bottom trawling

Three different types of otter boards varying in shape were tried to find out their relative catch efficiency. They were operated with two types of nets. The results indicated that the curved otter boards gave more catch per unit effort with all the combinations of nets and riggings tried.

Investigations on the number of trials required for statistical comparison of fishing gears

The number of fishing trials required for comparing the efficiency of fishing gears was investigated. A unique solution to this problem did not appear to exist because of the heterogeneity of the experimental material. Sequential experimentation and analysis have been found to be a practical approach to this problem. By this, the experiment can be terminated almost after 35 days fishing for catches with standard error per unit as per cent of the mean about 30% or less (after logarithmic transformation). For data with mean catches less than 1.5 kg analysis of variance approach does not appear to be meaningful.

Annual report to the PSC on the year 2012

Progress and Outputs: summary of 2012, progress of project logframe targets in year 4, events diary,activities within each sub-component. Risk assessment. Project finances. List of documents.

Studies on the growth and production of six major and exotic carps in Nasti baor, Jhenaidah, Bangladesh

An investigation on growth, production and fishery of three Indian major carps: rohu, Labeo rohita, catla, Catla catla and mrigal, Cirrhinus mrigala and three exotic carps: silver carp, Hypophthalmichthys molitrix, grass carp, Ctenopharyngodon idella, and common carp, Cyprinus carpio was carried out in Nasti baor during February to April months. In catch per unit effort (CPUE) study the highest catch/day/person (3.13 kg) and catch/day/gear (40.65 kg) was recorded in the month of March for kochal fishing. In komar fishing catch/day/person (15.08 kg) and catch/day/gear (1206 kg) was also found higher in March. Komar fishing was done only in March and April and its CPUE was greater in both the months than that of kochal. The average recovery rate (combination of all six species) was 37.80 considering the stocking from July month of the previous year. The recovery rate of common carp (54.1) was the highest and lowest (13.90) in case of silver carp. When the recovery was calculated on the basis of one year data and stocking, it was 55.6%. Analysis of production model revealed that the present production (54,806 kg/year) is less than both theoretical production (model I- 85,285 kg/year and model II -75,952 kg/year) estimated. Therefore, it may be concluded that the fish production from Nasti baor could still be increased from the present level of production.

On the fishes and fisheries of Lake Baringo

Six fish species are known to occur in Lake Baringo. Tilapia nilotica Linnaeus 1757, Barbus gregorii Boulenger 1902, Clarias mossambicus Peters 1852 and Labeo cylindricus Peters 1852 were recorded in 1930-31. In 1969, two more fish species were identified: Aplocheilichthys sp. and Barbus lineomaculatus Boulenger 1903. T. nilotica is the only fish species commercially exploited. But the catches, catch per unit effort and the mean size of fish caught in commercial gillnets have declined since 1968. B. gregorii is important in the subsistence rod-and-line fishery. L. cylindricus, C. mossambicus, B. lineomaculatus and Aplochelichthys sp. are not commercially exploited.

Boundary effects on the vibration statistics of a random plate

This paper considers the estimation of statistics of displacement of a vibrating rectangular plate with random wave scatterers. The influence of uncertainty is investigated using point impedance theory. Coherent boundary effects are seen, which decrease when the number of scatterers increases. The boundary effect is investigated using images and the first side and corner reflections are found to be a minimum requirement to estimate the spatial correlation. Statistics for point driven response are investigated under the assumption that the statistics of the natural frequencies follow those of the Gaussian Orthogonal Ensemble (GOE). The estimates are compared with Monte Carlo simulation results, and they show good agreement. © 2012 Elsevier Ltd. All rights reserved.