The Lake Trout of Lac la Ronge, Saskatchewan

1961 ◽  
Vol 18 (3) ◽  
pp. 423-462 ◽  
Author(s):  
D. S. Rawson
Keyword(s):  
Lake Trout ◽  
Average Rate ◽  
Fork Length ◽  
Commercial Catch ◽  
Average Growth ◽  
Main Lake ◽  
Spawning Run ◽  
C 50 ◽  
Average Size ◽  
Creel Census

The lake trout, Salvelinus namaycush, of Lac la Ronge was studied in the years 1948 to 1959 using gill netting, tagging, creel census and sampling of the spawning run. The trout spawned on shallow rocky reefs in the first week of October, when water temperatures were about 10 °C (50°F). Of the spawning run, 82% were from 7 to 12 years old. Possibly 10% of the mature trout failed to spawn in any single year.Growth rate varied widely in individuals and the average rate produced, at 10 years, a trout of 26 inches (66 cm) fork length and weighing 8 lb (3.6 0kg). No difference was found between growth rates of males and females and there was no change in average growth rate during the 10-year study. However, trout in the main lake grew considerably faster during their first 5 years than those in the deeper, colder Hunter Bay. Thirty-three trout weighing from 30 to 43 lb were examined.Ciscoes, whitefish, ninespine sticklebacks and other fish made up 90% of the food of adult trout. The crustaceans Mysis and Pontoporeia were eaten in moderate quantities, especially by trout in their third and fourth years. Two cestode parasites were found in the intestine and the larvae of a third in the muscle of trout.The trout were widely scattered from break-up of ice in mid-May to late June. As the upper water warmed above 10 °C (50°F) they moved down and were concentrated in areas deeper than 20 m (65 ft) during July and August. As the water cooled they again spread into shallow water about mid-September. Of 429 tagged, 60 or 14% were recovered during the first, second and third years after tagging. Recoveries showed extensive movement throughout the lake and a moderate exchange between the main lake and Hunter Bay.In standard gill-net catches plankton-feeding and bottom-feeding fish outweighed piscivores by 3 to 1 in the main lake and 1.8 to 1 in Hunter Bay. Catch data suggest that the trout population was greater in 1958–59 than in 1948–49. The average size of trout caught and the year-class composition were unchanged after 10 years.By diverting commercial fishing from trout to whitefish the average commercial catch in the 10-year period has been maintained at 250,000 lb per year, as compared to 316,000 lb in the previous 30 years. The anglers' catch of trout now averages 30,000 lb per year and this could be doubled without exceeding the known capacity of the lake for trout production. The creel census shows no decrease in average size of trout caught, average catch per angler, and number of very large trout taken.

Lake Ontario: Effects of Exploitation, Introductions, and Eutrophication on the Salmonid Community

1972 ◽  
Vol 29 (6) ◽  
pp. 913-929 ◽  
Author(s):  
W. J. Christie
Keyword(s):  
Yellow Perch ◽  
Lake Trout ◽  
White Perch ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Commercial Catch ◽  
Sequence Of Events ◽  
Catch Statistics ◽  
Average Size

Commercial catch statistics were analyzed to follow the sequence of events in the deterioration of the major fish stocks of Lake Ontario. Atlantic salmon (Salmo salas), lake trout (Salvelinus namaycush), burbot (Lota lota), deepwater ciscoes (Coregonus sp.), and whitefish (Coregonus clupeaformis) have all disappeared or declined seriously in abundance. Only the colonists alewife (Alosa pseudoharengus), smelt (Osmerus mordax) and white perch (Morone americana) are currently abundant. Abundance of deepwater ciscoes is thought to have been controlled originally by the piscivores lake trout and burbot. Three deepwater cisco species are inferred to have been progressively eliminated by overfishing, leaving only the smallest and least valuable present when the fishery collapsed. The effects of the sea lamprey (Petromyzon marinus) on the Lake Ontario fishes are held to have increased with the reduction of the number of dams in the watershed, and as fishing reduced numerical abundance and average size of the prey fishes. The early colonists alewife and carp (Cyprinus carpio) were thought to have stabilized early. It was suggested smelt were suppressed for many years by trout and burbot predation, and after the release of this constraint, the smelt in turn caused the collapse of the deepwater ciscoes and other species through predation. The white perch invasion of the Bay of Quinte was thought particularly swift and successful because of the absence of predators. Yellow perch (Perca flavescens) abundance may have increased because of eutrophication effects in the nearshore areas. Recent deterioration of water quality appears so extreme as to ensure that the last premium species which used the inshore areas cannot return. Overfishing is thought to have been the major destabilizing influence. The role of the open lake predators in the vectoring of energy and materials through the system is discussed.

Effects of Artificial Propagation and the Weather on Recruitment in the Lake Ontario Whitefish Fishery

1963 ◽  
Vol 20 (3) ◽  
pp. 597-646 ◽  
Author(s):  
W. J. Christie
Keyword(s):  
Lake Trout ◽  
Lake Ontario ◽  
Climatic Conditions ◽  
Commercial Catch ◽  
Air Temperatures ◽  
Spawning Stock ◽  
Catch Statistics ◽  
The Times ◽  
One Year ◽  
Over Exploitation

No significant relationship could be found between variations in the level of fry planting and ensuing variations in the level of catch in the long-term statistics of the Lake Ontario whitefish gill-net fishery. An alternate-year planting experiment in which fry were planted in the even-numbered years 1944 through 1954, similarly failed to show a detectable level of contribution of the hatchery fish to the fishery. The supported year-classes averaged larger than those not given hatchery support but this was judged coincidental because of a phasing with an alternate-year periodicity which characterized the catch statistics over the whole series examined, and was present in the six years prior to the start of the alternate-year plantings. Estimates of spawning stock were calculated and it was not found that the progeny-per-parent ratios were significantly affected by the fry plantings.A possible explanation for the periodicity was suggested by a significant correlation between air temperatures at the times of spawning and hatching, and the strengths of the produced year-classes. Cold Novembers followed by warm Aprils appeared to provide conditions associated with the production of larger year-classes, with the opposite combinations relating to the weaker broods.The disappearance of lake trout and ciscoes from the commercial catch resulted in increased fishing pressure directed towards the capture of the whitefish. Increases in the efficiency and intensity of the fishing were observed during the period of the study and these were likely responsible for the reduction of the average age of the fish in the catch by almost one year, and the resultant restriction of the annual catch to one year-class in recent years. Probably because most of the fish are currently caught before first spawning, a decline in spawning stock was almost continuous during the study period. The year-to-year fluctuations in the level of the catch increased both because of the reduced average age, and because of a greater variation in year-class strength. The year-classes produced in favourable years tended to increase, down to quite low levels of stock. This gave a configuration similar to Ricker's Type C reproduction curve, and which differed chiefly in that the limiting diagonal representing minimum reproduction fell below the replacement diagonal. It was suggested that the whitefish may require more than one spawning, to achieve stock replacement. The present instability of the catch, and the potentially serious effect of any sustained break in the rhythm of the climatic conditions suggest a condition of over-exploitation in this case.

Preparation of Copper-Doped ZnS/HFBA-Co-MAA Fiber Composites and its Photocatalytic H2 Evolution from Splitting of Water under Ultraviolet Irradiation

2013 ◽  
Vol 781-784 ◽  
pp. 202-206
Author(s):  
Hui Chang ◽  
Hong Xiang Ge ◽  
Wei Liang ◽  
Wen Juan Fan
Keyword(s):  
Copper Ions ◽  
Average Rate ◽  
Fiber Surface ◽  
Electrospun Nanofibers ◽  
Average Diameter ◽  
Fiber Composites ◽  
Bulk Polymerization ◽  
The Third ◽  
Sulfide Ions ◽  
Average Size

The copper-doped ZnS particles were immobilized on the surface of Hexafluorobutyl acrylate-co-methacrylic acid (poly (HFBA-co-MAA)) which synthesized by bulk polymerization electrospun nanofibers. The fluoropolymer fibers, which have around 200 nm in average diameter, of poly (HFBA-co-MAA) and are obtained by electrospinning. Zinc and copper ions are introduced onto the fiber surface by coordinating with carboxyls of MAA. After that, sulfide ions are incorporated to react with zinc and copper ions by a hydrothermal synthesis. Thus, copper-doped ZnS particles of around 100 nm in average size, are obtained and well loaded on the fiber surface. The absorption of copper-doped ZnS/HFBA-co-MAA fiber composites is at 262 nm and 326 within the ultraviolet light region. It was found that the average rate of H2 evolution of copper-doped ZnS powders slightly decreased, while the average rate of H2 evolution of copper-doped ZnS/HFBA-co-MAA fiber composites increased from the first to the third run. The average rate of H2 evolution using the copper-doped ZnS/HFBA-co-MAA fiber composites as the catalyst achieved 49.04 mL/h in the third run.

Age, growth and mortality of redfish Centroberyx affinis

2001 ◽  
Vol 52 (4) ◽  
pp. 637 ◽  
Author(s):  
A. K. Morison ◽  
K. R. Rowling
Keyword(s):  
Growth Rate ◽  
Significant Variation ◽  
Fork Length ◽  
Age And Growth ◽  
Average Error ◽  
Natural Mortality ◽  
Commercial Catch ◽  
Thin Sections ◽  
The Mean ◽  
Age Estimates

Age and growth of 5678 redfish, collected during 1991–98 from Australia’s South East Fishery, were estimated from thin sections of otoliths. A maximum age of 44 years was recorded for a 30 cm (fork length) female, but 80%of females in the commercial catch were <10 years, and 80%of males were <13 years. The largest was a 34 cm female estimated to be 36 years old. Repeated age estimates of a subsample revealed an average error of 3.79%. There was significant variation in the mean length-at-age among years, and there were significant effects for age*year, age*sex, age*region, region*year, and sex*region*year interactions. Assessments of the fishery have assumed a single stock, because tagging results from the 1980s indicate movement of redfish along the coast. This study found consistent differences in sex ratio and growth rate between regions, which indicate some structuring within the population. However, the differences in growth rates are not consistent among years and could not be explained by differences in depths fished, suggesting a more dynamic situation than spatially segregated stocks. Estimates of natural mortality ranged from 0.07 to 0.11 year–1 and differed between regions.

scholarly journals Volatility behavior of virtual currencies

2019 ◽  
Vol 10 (2) ◽  
pp. 537
Author(s):  
Jéssica Gonçalves Andrade ◽  
Nilson Brandalise
Keyword(s):  
Growth Rate ◽  
Data Analysis ◽  
Average Rate ◽  
Rate Of Return ◽  
Average Risk ◽  
Average Growth Rate ◽  
Average Growth ◽  
Volatility Analysis ◽  
One Year ◽  
Made In

In order to do a volatility analysis, since the exchange rate is higher than the average risk, the higher the average rate of return, the higher the average growth rate of the year. applied the method of data analysis. An attempt to volatility analysis can be made in one year, in the middle of the end of 2016.

scholarly journals THE MEDIC-STATISTICAL CHARACTERISTIC INCIDENCE OF PNEUMONIA IN THE UDMURT REPUBLIC

2018 ◽  
Vol 8 (6) ◽  
pp. 438-443
Author(s):  
E. S. Bobyleva ◽  
A. Yu. Gorbunov ◽  
O. I. Starodubtsevа ◽  
Ya. M. Vakhrushev
Keyword(s):  
Growth Rate ◽  
Russian Federation ◽  
Medical Information ◽  
Average Rate ◽  
Chronic Obstructive ◽  
Average Growth Rate ◽  
Average Growth ◽  
Incidence And Mortality ◽  
Udmurt Republic ◽  
The Russian Federation

The Community-acquired Pneumonia (CAP) is an urgent problem of modern medicine owing to its high prevalence, gravity of a current, the increasing resistance of a microflora to antibacterial therapy, a large number of complications and a high lethality. Udmurt republic is one of leaders among the regions of Russian Federation on morbidity by diseases of the respiratory system, include CAP. It is therefore necessary to take analysis and prognosis incidence for the future improving quality administer. Research objective. The analysis of incidence and mortality from diseases of respiratory organs in the Udmurt Republic for 2009-2016. Materials and methods. The retrospective and prospection clinical-epidemiological research of prevalence and primary incidence of diseases of respiratory organs among the adult population of the Udmurt Republic living in 4 cities is conducted (Izhevsk, Sarapul, Glazov, Votkinsk) and 25 rural areas for the 8-summer period (2009-2016). The analysis is carried out on the basis of data of the state statistical registration and reporting documentation of Budgetary institution of health care of the Udmurt Republic «Republican medical information and analysis center of the Ministry of Health of the Udmurt Republic». Results of a research. The prevalence of diseases of respiratory organs in the Udmurt Republic was 49871,39±1,33 on 100 thousand population. The average growth rate was 2,3%, and the average rate o f a gain was — 0,25%. In comparison with data for the same period to the Russian Federation, average growth rate the average rate of a gain — 5,48% was 1,7%, and that demonstrates some decrease in incidence. In the analysis of structure of incidence of diseases of respiratory organs of the population of the Udmurt Republic it is established that she throughout the entire period of observation significantly hasn’t changed. At the same time annually, leading places are taken by pneumonia and the chronic obstructive pulmonary disease (COPD). Estimating the level of primary incidence of diseases of respiratory organs, it is noted that on UR the average growth rate is 105,42%, the average rate of a gain of 5,42%, in comparison across the Russian Federation average growth rate of 87,07%, and the average rate of a gain — 12,93%. Conclusion. Thus, to UR, as well as in general across the Russian Federation steadily high incidence of pneumonia is noted. At the same time the tendency to increase in incidence and this pathology mortality is noted. This circumstance demands further studying of a problem of pneumonia, including improvement of methods of medical correction.

scholarly journals Sub-Saharan Africa Is Lighting Up: Uneven Progress on Electrification

2018 ◽  
Author(s):  
Ofei D. Mante
Keyword(s):  
Renewable Energy ◽  
Electricity Generation ◽  
Average Rate ◽  
Universal Access ◽  
Sub Saharan Africa ◽  
Energy Access ◽  
Average Growth ◽  
Financial Flows ◽  
Sub Saharan ◽  
Electricity Access

This research paper provides a regional review of the state of electricity access in Sub-Saharan Africa (SSA), focusing on installed capacity, electricity generation, the growth of renewable energy, electricity consumption, government investment, public financial flows, and several major initiatives. The study contrasts electrification between 1990 and 2010 with recent efforts and identifies countries that are consistently making progress and those that lag. The analyses show signs of progress on scaling up SSA power infrastructure and increasing electricity access, particularly in the Eastern and Western sub-regions. The installed generation capacity expanded at an average rate of 2.43 GW/year between 2005 and 2015. Renewable energy is growing, particularly solar, wind, and geothermal; about 9.7 GW of renewable energy capacity was installed between 2010 and 2016. Over this period, the net electricity generation in SSA increased at 9.1 TWh/year, more than double the historical average growth of 4.02 TWh/year (1990–2010). In general, the study found that rates of electrification across the entire region are more than twice the historical rates, and an average of at least 26 million people are now gaining access to electricity yearly. Nevertheless, progress is uneven across SSA. As of 2016, almost half of the population without electricity access live in Nigeria, DR Congo, Ethiopia, Tanzania, and Uganda. Quantitative analysis suggests that about 70 million people in SSA would have to gain access every year from 2017 to achieve universal access by 2030. Overall, SSA countries with national programs on energy access supported by policy/regulatory framework and infrastructure investment are making progress.

scholarly journals Land susceptibility to soil erosion in Orashi Catchment, Nnewi South, Anambra State, Nigeria

2018 ◽  
Vol 376 ◽  
pp. 87-95 ◽  
Author(s):  
Shakirudeen Odunuga ◽  
Abiodun Ajijola ◽  
Nkechi Igwetu ◽  
Olubunmi Adegun
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Growth Rate ◽  
Soil Erosion ◽  
Land Cover ◽  
Average Rate ◽  
Control Measures ◽  
High Susceptibility ◽  
Average Growth ◽  
Light Forest

Abstract. Soil erosion is one of the most critical environmental hazards that causes land degradation and water quality challenges. Specifically, this phenomenon has been linked, among other problems, to river sedimentation, groundwater pollution and flooding. This paper assesses the susceptibility of Orashi River Basin (ORB) to soil erosion for the purpose of erosion control measures. Located in the South Eastern part of Nigeria, the ORB which covers approximately 413.61 km2 is currently experiencing one of the fastest population growth rate in the region. Analysis of the soil erosion susceptibility of the basin was based on four factors including; rainfall, Land use/Land cover change (LULC), slope and soil erodibility factor (k). The rainfall was assumed to be a constant and independent variable, slope and soil types were categorised into ten (10) classes each while the landuse was categorised into five classes. Weight was assigned to the classes based on the degree of susceptibility to erosion. An overlay of the four variables in a GIS environment was used to produce the basin susceptibility to soil erosion. This was based on the weight index of each factors. The LULC analysis revealed that built-up land use increased from 26.49 km2 (6.4 %) in year 1980 to 79.24 km2 (19.16 %) in 2015 at an average growth rate of 1.51 km2 per annum while the light forest decreased from 336.41 km2 (81.33 %) in 1980 to 280.82 km2 (67.89 %) in 2015 at an average rate 1.59 km2 per annum. The light forest was adjudged to have the highest land cover soil erosion susceptibility. The steepest slope ranges between 70 and 82∘ (14.34 % of the total land area) and was adjudged to have the highest soil susceptibility to erosion. The total area covered of the loamy soil is 112.37 km2 (27.07 %) with erodibility of 0.7. In all, the overlay of all the variables revealed that 106.66 km2 (25.70 %) and 164.80 km2 (39.7 %) of the basin has a high and very high susceptibility to soil erosion. The over 50 % high susceptibility of catchment has serious negative implications on the surface water in terms of water quality and downstream siltation with great consequences on biodiversity and ecosystem services including domestic and industrial usage.

scholarly journals Age and growth of the dog snapper Lutjanus jocu (Bloch & Schneider, 1801) in Abrolhos Bank, Northeastern Brazil

2011 ◽  
Vol 9 (2) ◽  
pp. 393-401 ◽  
Author(s):  
Marília Previero ◽  
Carolina V. Minte-Vera ◽  
Matheus Oliveira Freitas ◽  
Rodrigo Leão de Moura ◽  
Claudenice Dei Tos
Keyword(s):  
Growth Parameters ◽  
Growth Models ◽  
Fork Length ◽  
Age And Growth ◽  
Northeastern Brazil ◽  
Constant Variance ◽  
Males And Females ◽  
Average Size ◽  
Constant Coefficient Of Variation ◽  
Estuarine Region

We determined the age and growth of the dog snapper (Lutjanus jocu), caught in the region of Abrolhos Bank, Bahia State, by the fishermen from coastal communities of Prado, Alcobaça, Caravelas, and Nova Viçosa. We examined 205 sectioned otoliths of fish caught by harpoon, longline, hand line, and gill nets (14.5 to 79.5 cm fork length). The formation of each ring was considered annual. The sectioned otoliths showed between 0 and 29 rings. Nearly half of the analyzed specimens had between 0 and 7 rings (88 of 205). Fish caught with nets in the estuarine region were the juvenile, while fish caught with lines and harpoons were the oldest. Two von Bertalanffy growth models were fitted to length-at-age data: one assuming constant variance of length-at-age (SVB) and another assuming constant coefficient of variation, i.e. variance increasing as a function of average size (CVVB). The SVB estimates were Loo = 87.82 cm, K = 0.10, and t0 = -1.486 and the CVVB estimates were Loo = 117.60 cm, K = 0.06, and t0 = -2.470. The largest Loo values estimated by the CVVB model are supported by reports from the literature of larger animals occurring in the deeper outer shelf of Abrolhos Bank. Growth parameters were also estimated for males and females separately (SVB model) (Loo = 92.80 cm, K = 0.099, and t0 = -1.680 for males, and Loo = 82.10 cm, K = 0.105, and t0 = -1.570 for females).

Mercury content of edible flesh from snapper, Chrysophrys auratus (Bloch & Schneider), in the Victorian commercial catch

1981 ◽  
Vol 32 (1) ◽  
pp. 75 ◽  
Author(s):  
TI Walker
Keyword(s):  
Mercury Concentration ◽  
Fork Length ◽  
Mercury Content ◽  
Total Weight ◽  
Commercial Fishing ◽  
Management Options ◽  
Commercial Catch ◽  
Wet Weight ◽  
The Mean ◽  
Statutory Limit

The concentrations of total mercury (range 0.1-1.5 �g /g) in 40 individual snapper, C. auratus, caught in two commercial fishing areas in Victorian waters were adequately correlated with fork length by a power-law relationship. From further relationships established between length and total weight, and between filleted weight and total weight, the mean mercury concentration in the edible flesh of this species was estimated for each of the six years (1973-78) for which information on the length-frequency distribution was available for the Victorian commercial catch. The annual estimates ranged from 0.47 to 0.52 �g/g wet weight, and 45-52% of the edible flesh had values exceeding the Victorian statutory limit of 0.5 �g/g. Various management options available to health and fisheries agencies are discussed, and the methods of calculating the important parameters corresponding to these options are described. For example, graphs are presented from which can be read a legal maximum length of landed snapper, designed to reduce the mean mercury concentration of the catch to below a nominated level.

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