Growth, Maturity and Mortality in the Relatively Unexploited Lake Trout, Cristivomer namaycush, of Great Slave Lake

1954 ◽  
Vol 11 (6) ◽  
pp. 827-852 ◽  
Author(s):  
W. A. Kennedy
Keyword(s):  
Significant Variation ◽  
Lake Trout ◽  
The Other ◽  
Commercial Fishing ◽  
Bear Lake ◽  
Great Slave Lake ◽  
Class Strength ◽  
Mature Size ◽  
Commercial Size ◽  
Annual Mortality

Ages of 9,215 lake trout were determined. Length-weight and time-maturity relationships are shown. Sex ratio is 1:1. Only half the females of mature size spawn each year. There is no growth except during June to September, inclusive. There is a tremendous difference in size at a given age. Growth is much faster in one half of the lake than in the other, it is the same as or slightly slower than in lakes farther south and considerably faster than in Great Bear Lake. Seven years of commercial fishing did not increase total annual mortality by much. Mortality rate increases with age among all fish of catchable size. A given year-class probably attains maximum biomass well before most of its members reach commercial size. No significant variation in year-class strength was found.

Observations on the Lake Trout of Great Bear Lake

1948 ◽  
Vol 7b (4) ◽  
pp. 176-189 ◽  
Author(s):  
R. B. Miller ◽  
W. A. Kennedy
Keyword(s):  
Shallow Water ◽  
Detailed Analysis ◽  
Lake Trout ◽  
The Other ◽  
Food Sources ◽  
Bear Lake ◽  
Near Shore ◽  
Mature Fish ◽  
Terrestrial Insects ◽  
River Mouths

The lake trout (Cristivomer namaycush) is the principal fish of Great Bear lake. The largest populations were found in semi-isolated bays, with smaller populations in the open lake on one hand and in river mouths and marshy areas on the other. The trout grow very slowly; by three years they are just over three inches (7.6 cm.) long and weigh one ounce (28 g.). A weight of one pound (0.45 kg.) is achieved in their ninth year and two pounds in their fourteenth year. Maturity is reached in from 13 to 17 years; the rate of growth in weight increases after maturity. Mature fish appear to spawn only every second or third year. Spawning begins about the middle of August. The young trout spend their first four summers in shallow water near shore. The adults feed on all food sources in the lake,—plankton, bottom organisms, fish and terrestrial insects. Fish preparing to spawn have pale flesh; others have orange to red flesh. There is some evidence of two morphologically distinct groups, probably resulting from environmental differences. A list of the parasites of the trout is given. A detailed analysis of the incidence of cysts of Triaenophorus crassus indicates that adult trout remain in one locality throughout life.

Growth, Maturity, Fecundity and Mortality in the Relatively Unexploited Whitefish, Coregonus clupeaformis, of Great Slave Lake

1953 ◽  
Vol 10 (7) ◽  
pp. 413-441 ◽  
Author(s):  
W. A. Kennedy
Keyword(s):  
Mortality Rate ◽  
Sex Ratio ◽  
Commercial Fishing ◽  
Coregonus Clupeaformis ◽  
Gill Nets ◽  
Weight Relationship ◽  
Great Slave Lake ◽  
Obvious Change ◽  
The Relationship ◽  
Annual Mortality

Ages were determined of 6,571 whitefish for which sizes were recorded. A length-weight relationship, the percentage of both sexes mature at each age, the sex ratio, the proportion of mature females that spawn annually and the relationship between size of fish and number of eggs were determined from smaller samples.Growth rate is difficult to assess because of net selection, but it seems to be slower than in more southerly lakes. Growth appears to be limited to the period June to September inclusive.The total annual mortality rate of 61 per cent represents the unexploited condition—four years of commercial fishing with 51/2-inch mesh gill-nets produced no obvious change. A moderate mortality rate acting at all ages will easily account for thousands of eggs being produced for every whitefish that survives to maturity—it is unnecessary to assume a low percentage of eggs fertilized or excessive mortality among fertilized eggs or among young fish.A more intensive fishery would probably increase sustained yield.

Studies of the Fish of Great Slave Lake

1951 ◽  
Vol 8b (4) ◽  
pp. 207-240 ◽  
Author(s):  
D. S. Rawson
Keyword(s):  
Lake Trout ◽  
Mesh Size ◽  
Fish Population ◽  
Commercial Fishing ◽  
Small Fish ◽  
Fish Food ◽  
Important Species ◽  
The North ◽  
Great Slave Lake ◽  
Gill Net

A four-year study of the fish of Great Slave Lake was initiated one year before the lake was opened for commercial fishing. Information has been obtained about the composition, distribution and general ecology of the major species. Twenty-one species are listed and the ciscoes, probably of three species, await identification. Lake trout, common whitefish and ciscoes dominate the population and the former two species support an extensive gill-net fishery. The inconnu Stenodus, and the deepwater sculpin, Triglopsis, are of special zoogeographic interest.Sampling was mainly with standardized 300-yard gangs of gill net. In these, some 12,000 fish weighing about 20,000 pounds were taken. Some data were obtained on the selective effect of mesh size. Young and small fish were collected by seining.Great Slave Lake's area of 10,500 square miles includes a large open portion and two great arms, one to the north, the other extending eastward. Part of the north arm is shallow and its fish population is much like that of the main lake. Goldeyes, white suckers and pikeperch are found in the shallow warmer parts of these areas. None of these species are found in the deep and cold east arm, but in it grayling and round whitefish are numerous. The common whitefish is virtually absent from McLeod Bay at the extremity of the east arm.Data concerning growth in length and weight are provided for round whitefish, white sucker, longnose sucker, burbot and pikeperch. Most of these species grow a little slower in Great Slave Lake than in lakes farther south. Growth studies of five other important species have been undertaken by other workers.Analysis of the food of all the larger species shows that the main food chains are plankton→ cisco→ lake trout and plankton→ detritus→ bottom organisms→ whitefish. Pontoporeia, Mysis and cottids are important fish food in the deep water.Twenty-one species of parasites are recorded from ten species of fish.

scholarly journals Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3500
Author(s):  
Michael Sayers ◽  
Karl Bosse ◽  
Gary Fahnenstiel ◽  
Robert Shuchman
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Great Lakes ◽  
Satellite Remote Sensing ◽  
Carbon Fixation ◽  
African Great Lakes ◽  
Wind Speeds ◽  
Bear Lake ◽  
Great Slave Lake ◽  
Significant Production

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m2/day to over 1100 mgC/m2/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends.

Descriptions of the larvae of four species of Procladius from Great Slave Lake (Chironomidae:Diptera)

1978 ◽  
Vol 56 (9) ◽  
pp. 2055-2057 ◽  
Author(s):  
J. W. Moore ◽  
I. A. Moore
Keyword(s):  
Antennal Segment ◽  
The Other ◽  
Large Size ◽  
Great Slave Lake ◽  
Palpal Segment ◽  
Almost All

Descriptions of larvae of Procladius denticulatus, Procladius culiciformis, Procladius freemani, and Procladius bellus collected from Yellowknife Bay (lat., 62°25′; long., 114°20′) are given. Procladius denticulatus was separated from the other species by its large size, a character which always proved distinctive. Procladius culiciformis and P. freemani were separated from one another through several measurements including those of the basal antennal segment and the basal palpal segment. Almost all characters of the head were useful in distinguishing the much smaller P. bellus from the other species.

Variability in ice phenology on Great Bear Lake and Great Slave Lake, Northwest Territories, Canada, from SeaWinds/QuikSCAT: 2000–2006

2009 ◽  
Vol 113 (4) ◽  
pp. 816-834 ◽  
Author(s):  
Stephen E.L. Howell ◽  
Laura C. Brown ◽  
Kyung-Kuk Kang ◽  
Claude R. Duguay
Keyword(s):  
Northwest Territories ◽  
Bear Lake ◽  
Great Slave Lake ◽  
Ice Phenology

The Thermal Regime of South Bay, Manitoulin Island

1967 ◽  
Vol 24 (1) ◽  
pp. 101-125 ◽  
Author(s):  
A. M. McCombie
Keyword(s):  
Thermal Regime ◽  
Thermal Stratification ◽  
Yellow Perch ◽  
Lake Trout ◽  
Smallmouth Bass ◽  
Lake Huron ◽  
Vertical Temperature ◽  
Class Strength ◽  
Influence Of Temperature On ◽  
History Of

The thermal regime of South Bay is described from records collected from 1953 to 1962 with thermometers, thermographs, and bathythermographs, the last being cast at 11 stations along the bay and one in Lake Huron. Warming begins in April and thermal stratification is established in June. Shallow areas warm more rapidly than deep in the spring and cool more quickly in autumn. The boundary between the epilimnion and the thermocline becomes sharper as summer advances but the transition from thermocline to hypolimnion remains gradual. The average seasonal trend of surface temperatures is a sine function with a maximum of 66 F in mid August and a minimum of 34 F in late March, though values outside this range occur frequently. At 180 ft the maximum of 47 F is attained in November. At the lake and outermost bay stations there is a temperature slump in June and July which may be due to an upwelling in the lake. Evidence of an exchange of water between the lake and bay is seen in vertical temperature sections and water movements Variations in epilimnial temperatures are correlated with those of the air temperature, but variations in epilimnial and hypolimnial temperatures appear to be unrelated. Finally, literature describing the influence of temperature on the year class strength of smallmouth bass, the distribution of lake trout, the growth of yellow perch, and the life history of Pontoporeia in South Bay is reviewed.

Policy analysis in Canada: an introduction

2018 ◽  
pp. 1-24
Author(s):  
Laurent Dobuzinskis ◽  
Michael Howlett
Keyword(s):  
Decision Making ◽  
Policy Analysis ◽  
Significant Variation ◽  
Program Planning ◽  
Past Research ◽  
Policy Advice ◽  
The Other ◽  
Policy Debates ◽  
Research Questions

The ILPA series of country studies displays some significant variation between jurisdictions in terms of the timing and purview of analysis and also shows how the movement towards the application of scientific precepts to policy questions continues to be moderated by adherence to older, more partisan political modes of decision-making and program planning. Despite a discernible trend toward the professionalization of policy advice in most countries, a variety of actors continue to contribute diverse ideas to policy debates, with policy advice systems, and their analytical components, taking diverse forms across nations, sectors and levels of government. In this volume, we present a more systematic and comparative up-to-date understanding of policy analysis practices in Canada than has hitherto been available. This introduction provides an overview of past research into the area and outlines a series of topics and research questions which are addressed in the other contributions to the book.

scholarly journals Range extension for Pygmy Whitefish (Prosopium coulterii) in the Northwest Territories, Canada

2015 ◽  
Vol 129 (1) ◽  
pp. 70 ◽  
Author(s):  
Paul Vecsei ◽  
Damian Panayi
Keyword(s):  
Northwest Territories ◽  
Range Extension ◽  
Bear Lake ◽  
Great Slave Lake ◽  
First Occurrence

We document the first occurrence of Pygmy Whitefish (Prosopium coulterii) in the Northwest Territories outside of Great Bear Lake. Six specimens were captured in Bluefish Lake in September 2012. Bluefish Lake is on the Yellowknife River, approximately 25 km upstream from Great Slave Lake.

scholarly journals Profiling of Individual Desulfo-Glucosinolate Content in Cabbage Head (Brassica oleracea var. capitata) Germplasm

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1860 ◽  
Author(s):  
Shiva Ram Bhandari ◽  
Juhee Rhee ◽  
Chang Sun Choi ◽  
Jung Su Jo ◽  
Yu Kyeong Shin ◽  
...  
Keyword(s):  
Significant Variation ◽  
The Other ◽  
Glucosinolate Content ◽  
Breeding Programs ◽  
Average Value ◽  
Hydrolysis Products ◽  
Coefficients Of Variation ◽  
Anti Cancer ◽  
The Individual ◽  
Different Origins

Individual glucosinolates (GSLs) were assessed to select cabbage genotypes for a potential breeding program. One hundred forty-six cabbage genotypes from different origins were grown in an open field from March to June 2019; the cabbage heads were used for GSL analyses. Seven aliphatics [glucoiberin (GIB), progoitrin (PRO), epi-progoitrin (EPI), sinigrin (SIN), glucoraphanin (GRA), glucoerucin (GER) and gluconapin (GNA)], one aromatic [gluconasturtiin (GNS)] and four indolyl GSLs [glucobrassicin (GBS), 4-hydroxyglucobrassicin (4HGBS), 4-methoxyglucobrassicin (4MGBS), neoglucobrassicin (NGBS)] were found this study. Significant variation was observed in the individual GSL content and in each class of GSLs among the cabbage genotypes. Aliphatic GSLs were predominant (58.5%) among the total GSLs, followed by indolyl GSL (40.7%) and aromatic GSLs (0.8%), showing 46.4, 51.2 and 137.8% coefficients of variation, respectively. GIB, GBS and NGBS were the most common GSLs found in all genotypes. GBS was the most dominant GSL, with an average value of 3.91 µmol g−1 (0.79 to 13.14 µmol g−1). SIN, GIB, PRO and GRA were the other major GSLs, showing average values of 3.45, 1.50, 0.77 and 0.62 µmol g−1, respectively. The genotypes with relatively high contents of GBS, SIN, GIB and GRA warrant detailed studies for future breeding programs since the hydrolysis products of these GSLs have several anti-cancer properties.

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