Divergent Growth in Two Lake Whiteflsh (Coregonus clupeaformis) Populations

1973 ◽  
Vol 30 (11) ◽  
pp. 1683-1696 ◽  
Author(s):  
B. F. Bidgood
Keyword(s):  
Growth Rate ◽  
Growth Pattern ◽  
Fish Population ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Predator Prey ◽  
The Past ◽  
Population Reduction ◽  
Young Of The Year ◽  
Stable Growth

Divergence in the growth pattern of Pigeon Lake and Buck Lake whiteflsh (Coregonus clupeaformis) began during the winter months in young-of-the-year fish. The growth rate of individuals in the Pigeon Lake whitefish population has declined over the past 12 years whereas individuals in the Buck Lake population have maintained a relatively stable growth pattern. These differences did not appear to be genetically controlled. Increased interspecific and intraspecific competition for the available food supply likely suppressed the growth rate of the Pigeon Lake whitefish population. Reduction of predator numbers in Pigeon Lake by the removal of habitat and increased angling pressure accelerated recruitment to both the white-fish population and other competitive feeding forage fish. A predator–prey relationship conducive to the maintenance of a faster growing lake whitefish population has been maintained in Buck Lake over the same period of time.

Lake Whitefish (Coregonus clupeaformis) Stocks of the Ontario Waters of Lake Huron

1981 ◽  
Vol 38 (12) ◽  
pp. 1772-1789 ◽  
Author(s):  
J. M. Casselman ◽  
J. J. Collins ◽  
E. J. Grossman ◽  
P. E. Ihssen ◽  
G. R. Spangler
Keyword(s):  
Growth Rate ◽  
Genetic Distances ◽  
Lake Huron ◽  
Starch Gel Electrophoresis ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Meristic Characters ◽  
Hardy Weinberg Equilibrium ◽  
Starch Gel ◽  
South Shore

Historical and contemporary data on lake whitefish (Coregonus clupeaformis) from the Ontario waters of Lake Huron were examined for evidence of stocks with the objective of defining population boundaries. We delineated the spatial distribution of five stocks from tag–recapture data and the general location of six additional stocks on the basis of population parameters such as growth rate, age structure, and abundance trends.Samples of fish collected (summer and fall) from 5 of the 11 potential stocks were evaluated on the basis of 11 morphometric and 7 meristic characters. We also examined osseometric features such as shape of scales and otoliths, and electrophoretic characteristics at 32 loci associated with 12 enzyme systems.The summer and fall samples for each group were generally not significantly different. For the phenotypes examined electrophoretically, each stock was in Hardy–Weinberg equilibrium; 12 of the 32 loci considered were polymorphic and 4 of the 10 possible genetic distances differed significantly from zero.The Inner Basin stock was distinctly different from all other stocks. The Blind River stock was also found to be different by osseometrics, but not by morphometrics or electrophoresis. Osseometrics separated the stocks by basin of origin. Two stocks, Outer Basin and Burnt Island, appeared to be the most similar and could be separated from each other only on the basis of growth rate and tagging data. These two stocks are adjacent to each other in the main basin of Lake Huron, along the south shore of Manitoulin Island.Whitefish stocks of Lake Huron represent groups of fish that differ phenotypically and genotypically in varying degrees, are spatially separated, and behave as cohesive units. We conclude that they should be regarded as functional units for management purposes.Key words: lake whitefish, Coregonus clupeaformis, Lake Huron, stocks, tag–recapture data, population structure, morphometrics, meristics, osseometrics, scale and otolith shape, starch gel electrophoresis, biochemical genetic variation

scholarly journals A review of population-based management of Southern mountain caribou in BC

2016 ◽  
Author(s):  
Stan Boutin ◽  
Evelyn Merrill
Keyword(s):  
Population Based ◽  
Management Tool ◽  
Predator Control ◽  
Single Population ◽  
Predator Prey ◽  
The Past ◽  
Population Reduction ◽  
High Predation ◽  
Source Populations ◽  
Basic And Applied Research

The decline in Mountain caribou in BC over the past decades has resulted in extensive basic and applied research to guide caribou management by understanding the proximate and ultimate causes of the decline. At the top of the list is high predation rates brought about by human alteration of habitat and the subsequent alteration of predator-prey dynamics. We reviewed population-based management experiments undertaken in BC to recover caribou populations. These included primary prey (moose) reduction, lethal predator control, maternal penning, translocations, and supplemental feeding. Moose reduction by liberalized harvests has led to wolf population reduction and stabilization of treated caribou herds. Translocations have had limited success and finding source populations for future attempts will be a challenge. Maternity pens are producing promising results but their efficacy is strongest in relatively small populations and best results appear to occur when combined with predator control in areas surrounding the pens. Predator control experiments have just begun and results are forthcoming. Overall, no single population-based management tool has increased caribou populations. It is recommended that multiple levers need to be applied in combination on an experimental basis going forward.

Annulus Formation on Scales of Four Species of Coregonids Reared Under Artificial Conditions

1968 ◽  
Vol 25 (10) ◽  
pp. 2111-2122 ◽  
Author(s):  
Walter J. Hogman
Keyword(s):  
Growth Rate ◽  
Metabolic Activity ◽  
Day Length ◽  
Lake Whitefish ◽  
Annulus Formation ◽  
Young Of The Year ◽  
Almost All ◽  
Coregonus Hoyi

Scales from known-age coregonids reared in the laboratory were examined to determine when annuli formed and to learn possible factors of their formation. Scales were taken monthly from marked fish for periods up to 21 months. Scales were also examined from fish that died and from preserved specimens of young-of-the-year for each species. Two marks formed on almost all scales each calender year. The stronger formed during March–April and the weaker in October–November. Both marks had all the usual characteristics of an annulus but the spring mark was considered the annulus and the fall mark an accessory check. The annulus formed during a period of constant temperatures and of little change in growth or increasing growth. The accessory check formed during a period of declining temperatures (1–5 degrees F, or 0.6–2.8 degrees C, per month) and of little change in growth or declining growth. Most fish grew throughout the winter; the only exceptions were one bloater (Coregonus hoyi) and several of the largest lake whitefish (C. clupeaformis). Fish were always given all the food they would eat to eliminate availability of food as a factor of mark formation. The temperature of the water during the winter (50 ± 0.3 F; 10.0 ± 0.2 C) did not arrest metabolic activity. The growth rate was related more closely to day length than to other variables examined.

Growth and Recruitment in Experimentally Exploited Lake Whitefish (Coregonus clupeaformis) Populations

1980 ◽  
Vol 37 (2) ◽  
pp. 255-267 ◽  
Author(s):  
M. C. Healey
Keyword(s):  
Natural Variation ◽  
Population Regulation ◽  
Logical Consequence ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Young Fish ◽  
The Past ◽  
Class Strength ◽  
Size At Age ◽  
Established Population

From 1971 to 1978 I conducted an exploitation experiment on lake whitefish (Coregonus clupeaformis) in four Northwest Territories lakes. The objective was to test the hypotheses that, when exploited, growth and recruitment would increase in the populations, and that the degree of increase would be proportional to the intensity of exploitation. Significant increases in size-at-age were recorded in the exploited lakes, and the degree and persistence of the increase were proportional to the intensity of exploitation. Good recruitment was stimulated in the heavily exploited lake, and to a lesser degree in the moderately exploited lake. The hypotheses were, therefore, corroborated. Analyses of growth and year-class strength in the unexploited control lake and the lightly exploited lake indicated that natural variation in growth and recruitment, on a similar scale to that stimulated by exploitation, had occurred in the past. The compensatory responses of lake whitefish populations to exploitation appear to be a logical consequence of the natural population regulating mechanisms for the species. The results of my experiment indicate that in unexploited lakes, recruitment and growth of young fish is regulated by the established population of mature fish.Key words: lake whitefish, growth, recruitment, exploitation, population regulation

Temperature Tolerance of Young-of-the-Year Lake Whitefish, Coregonus clupeaformis

1976 ◽  
Vol 33 (1) ◽  
pp. 177-180 ◽  
Author(s):  
Thomas A. Edsall ◽  
Donald V. Rottiers
Keyword(s):  
Temperature Tolerance ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Lethal Temperature ◽  
Young Of The Year ◽  
Coregonus Artedii ◽  
Coregonus Hoyi ◽  
Lake Herring

The ultimate upper lethal temperature of young-of-the-year lake whitefish, Coregonus clupeaformis, was 26.65 C; this value is closely similar to that reported for yearling bloaters, Coregonus hoyi (26.75 C) and young-of-the-year lake herring, Coregonus artedii (26.0 C).

A Hermaphroditic Lake Whitefish, Coregonus clupeaformis, from Lake Huron

1974 ◽  
Vol 31 (12) ◽  
pp. 1944-1945 ◽  
Author(s):  
T. R. Porter ◽  
S. Corey
Keyword(s):  
Growth Rate ◽  
Normal Growth ◽  
Lake Huron ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
External Characteristics

A hermaphroditic lake whitefish, Coregonus clupeaformis, caught in Lake Huron is described. The specimen had a normal growth rate and had no apparent abnormal external characteristics. Both gonads were ovotestes. The ovarian and testicular portions appeared to be functional and developing normally.

scholarly journals A review of population-based management of Southern mountain caribou in BC

2016 ◽  
Author(s):  
Stan Boutin ◽  
Evelyn Merrill
Keyword(s):  
Population Based ◽  
Management Tool ◽  
Predator Control ◽  
Single Population ◽  
Predator Prey ◽  
The Past ◽  
Population Reduction ◽  
High Predation ◽  
Source Populations ◽  
Basic And Applied Research

The decline in Mountain caribou in BC over the past decades has resulted in extensive basic and applied research to guide caribou management by understanding the proximate and ultimate causes of the decline. At the top of the list is high predation rates brought about by human alteration of habitat and the subsequent alteration of predator-prey dynamics. We reviewed population-based management experiments undertaken in BC to recover caribou populations. These included primary prey (moose) reduction, lethal predator control, maternal penning, translocations, and supplemental feeding. Moose reduction by liberalized harvests has led to wolf population reduction and stabilization of treated caribou herds. Translocations have had limited success and finding source populations for future attempts will be a challenge. Maternity pens are producing promising results but their efficacy is strongest in relatively small populations and best results appear to occur when combined with predator control in areas surrounding the pens. Predator control experiments have just begun and results are forthcoming. Overall, no single population-based management tool has increased caribou populations. It is recommended that multiple levers need to be applied in combination on an experimental basis going forward.

scholarly journals Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting

2021 ◽  
Vol 7 (6) ◽  
pp. eabb7118
Author(s):  
E. Harris ◽  
E. Diaz-Pines ◽  
E. Stoll ◽  
M. Schloter ◽  
S. Schulz ◽  
...  
Keyword(s):  
Growth Rate ◽  
Nitrous Oxide ◽  
N Fertilization ◽  
High Variability ◽  
Nitrous Oxide Emissions ◽  
Severe Drought ◽  
Total N ◽  
The Past ◽  
Precipitation Changes ◽  
Isotopic Measurements

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N2O emissions result from soil N fertilization, which is converted to N2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N2O emission pathways are sufficient to account for the accelerating N2O growth rate observed over the past decade.

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