Changes in the Zoobenthos Community of Acidified Bowland Lake after Whole-Lake Neutralization and Lake Trout (Salvelinus namaycush) Reintroduction

1990 ◽  
Vol 47 (2) ◽  
pp. 440-445 ◽  
Author(s):  
W. Keller ◽  
Lewis A. Molot ◽  
Ronald W. Griffiths ◽  
N. D. Yan
Keyword(s):  
Water Quality ◽  
Fish Community ◽  
Lake Trout ◽  
Size Structure ◽  
Salvelinus Namaycush ◽  
Total Abundance ◽  
Insufficient Time

The zoobenthos of Bowland Lake is described prior to, and for 2 yr after, neutralization of the lake from pH 4.9 to > 6.0 and reintroduction of lake trout (Salvelinus namaycush). Observed changes in the total abundance, biomass, and size structure of shallow and profundal zoobenthos assemblages were attributable to changes in the fish community, not to improvements in water quality. A shift toward increased importance of oligochaetes, more representative of nonacidic conditions, occurred. However, many common, acid-sensitive taxa of zoobenthos which were absent prior to neutralization had not appeared within 2 yr after treatment, indicating insufficient time for recolonization.

Prediction of Lake Trout (Salvelinus namaycush) Presence in Low-Alkalinity Lakes near Sudbury, Ontario

1992 ◽  
Vol 49 (S1) ◽  
pp. 95-101 ◽  
Author(s):  
Michael Conlon ◽  
John M. Gunn ◽  
J. Robert Morris
Keyword(s):  
Water Quality ◽  
Fish Community ◽  
Acidic Deposition ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Species Assemblages ◽  
Fish Community Structure ◽  
The Status ◽  
Measured Water ◽  
Correct Discrimination

Surveys of 30 low-alkalinity lake trout (Salvelinus namaycush) lakes near Sudbury, Ontario, were conducted to assess factors that affect lake trout presence under acidification stress. At the time of the surveys the lakes varied widely in pH (4.5–6.9), concentrations of toxic metals (Al 12–300 μg∙L−1), and the status of lake trout populations (extinct–abundant). Fish community structure (species richness, species assemblages) reflected and was readily predicted from measured water quality variables. A PCA factor composed of pH, alkalinity, and conductivity was the variable that best predicted lake trout presence (correct discrimination (> 92%). The results of this study provide managers with easily obtainable predictors for monitoring lake trout status under changing levels of acidic deposition.

Size Structure of a Lake Trout (Salvelinus namaycush) Population an Arctic Lake: Influence of Angling and Implications for Fish Community Structure

1989 ◽  
Vol 46 (12) ◽  
pp. 2153-2156 ◽  
Author(s):  
Michael E. McDonald ◽  
Anne E. Hershey
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Lake Trout ◽  
Size Structure ◽  
Salvelinus Namaycush ◽  
Fish Community Structure ◽  
Median Length ◽  
Arctic Alaska ◽  
Gill Net ◽  
Toolik Lake

The lake trout (Salvelinus namaycush) population in Toolik Lake in arctic Alaska was assessed by gill net during 1977, prior to exploitation. In 1986 we replicated the gill net study to determine the effects of recent angling pressure on the fish community. Relative composition of the catch varied between samples. Round whitefish (Prosopium cylindraceum), which are not susceptible to angling, made up 42% of the catch in 1986 and 28% in 1977. Significant reductions in the median length and weight of lake trout between the sampling periods were observed. The median size of lake trout in 1986 was below the minimum 1977 reproductive size. Differences in median length and weight of grayling (Thymallus arcticus) and of round whitefish during this period were not significantly different. The condition factor of lake trout was significantly higher in 1986. We suggest that large lake trout in Toolik Lake control salmonid recruitment and determine community structure. With continued fishing pressure further changes in the fish community and lake trophic dynamics may result.

Consequences of prey fish community dynamics on lake trout (Salvelinus namaycush) foraging efficiency in Lake Superior

1998 ◽  
Vol 55 (5) ◽  
pp. 1273-1284 ◽  
Author(s):  
Doran M Mason ◽  
Timothy B Johnson ◽  
James F Kitchell
Keyword(s):  
Fish Community ◽  
Community Dynamics ◽  
Lake Trout ◽  
Size Structure ◽  
Lake Superior ◽  
Salvelinus Namaycush ◽  
Foraging Efficiency ◽  
Prey Fish ◽  
Rainbow Smelt ◽  
Lake Herring

We used a size-structured model, indexed by age, that combines bioenergetics and foraging theory to evaluate the effects of prey fish community structure (species dominance, size structure, and density) on the diet and net foraging efficiency of lake trout (Salvelinus namaycush) in Lake Superior. Prey size structure was important for young lake trout but decreased in importance for older lake trout, especially with increasing prey density. The model predicted that rainbow smelt (Osmerus mordax) should dominate the diet of young lake trout due to the size-dependent capture limitations of larger prey. In contrast, lake herring (Coregonus artedi) should dominate the diet of oldest lake trout owing to a higher net energy return than rainbow smelt. Model results are consistent with age-specific diet and size-at-age of lake trout during the last 40 years. Diets of intermediate-sized lake trout do not reflect the recent resurgence of lake herring populations. Absence of a dietary switch is probably due to higher capture probability for rainbow smelt. Lake trout growth and production will likely be highest with a mixed prey species assemblage of young rainbow smelt and older lake herring.

Changes in the Georgian Bay fish community, with special reference to lake trout (Salvelinus namaycush) rehabilitation

Hydrobiologia ◽  
1988 ◽  
Vol 163 (1) ◽  
pp. 179-194 ◽  
Author(s):  
Bryan A. Henderson ◽  
N. Robert Payne
Keyword(s):  
Special Reference ◽  
Fish Community ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Georgian Bay

Dynamics in Year-Class Strength, Growth, and Calcified-Structure Size of Native Lake Trout (Salvelinus namaycush) Exposed to Moderate Acidification and Whole-Lake Neutralization

1992 ◽  
Vol 49 (S1) ◽  
pp. 102-113 ◽  
Author(s):  
John M. Casselman ◽  
John M. Gunn
Keyword(s):  
Water Quality ◽  
Direct Effect ◽  
Lake Trout ◽  
Calcium Content ◽  
Salvelinus Namaycush ◽  
Ambient Water ◽  
Intraspecific Interaction ◽  
Relative Growth ◽  
Class Strength

Accurate age-interpretation techniques were developed, using scales and otoliths, to examine the role of whole-lake neutralization in the resurgence of a lake trout (Salvelinus namaycush) fishery in Nelson Lake (pH 5.7) near Sudbury, Ontario. Calcified structures and data from 860 lake trout were collected from 1972 to 1987. The population was characterized by the regular cyclic occurrence of strong year classes, which were probably an effect of pulse angling, cyclic food abundance, and possibly intraspecific interaction. The majority (65.8%) of the lake trout caught in the exceptional winter fishery of 1980 (3.3 kg∙ha−1) were in the lake prior to liming in 1975–76. Young lake trout (up to age 4) of the 1975 and 1976 year classes grew bigger and had larger scales than other year classes from 1973 to 1977, coinciding with an increase in hypolimnetic zooplankton, probably related to improved water quality. Otoliths grew significantly larger and more translucent and exceeded relative growth of scales and body for all ages in 1976 (18% greater) and for the 1976 year class, confirming that otolith accretion can come from the ambient water because liming increased the calcium content by 33% that year, the only observed direct effect of the treatment.

Predation by Freshwater Seals on the Fish Community of Lower Seal Lake, Quebec

1978 ◽  
Vol 35 (6) ◽  
pp. 844-850 ◽  
Author(s):  
G. Power ◽  
Jean Gregoire
Keyword(s):  
Brook Trout ◽  
Fish Community ◽  
Lake Trout ◽  
Fork Length ◽  
Salvelinus Namaycush ◽  
Phoca Vitulina ◽  
Unit Weight ◽  
Potential Yield ◽  
Spawning Period ◽  
Show Evidence

The presence of freshwater harbor seals (Phoca vitulina) in Lower Seal Lake, Quebec, has drastically modified the lake's fish community. Lake trout (Salvelinus namaycush) are the most affected; they are small (rarely exceed 55 cm fork length), their growth rate is faster than in neighboring lakes, their longevity is greatly reduced, the age at sexual maturity has been halved, and individual fecundity per unit weight has increased at the expense of egg diameter. Brook trout (S. fontinalis), the dominant fish species in the lake, show evidence of high mortality rates in the lake, but are protected during the vulnerable spawning period because their spawning sites are dispersed in tributary streams. Rough calculation suggests the seal population is small and that it consumes the lake's potential yield of fish annually. Key words: predation, freshwater seals, Phoca vitulina, Salvelinus namaycush, Salvelinus fontinalis

Recovery of Planted Brook Trout, Splake, and Rainbow Trout from Selected Ontario Lakes

1972 ◽  
Vol 29 (2) ◽  
pp. 129-142 ◽  
Author(s):  
J. M. Fraser
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Fish Community ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Low Fertility ◽  
Salmo Gairdneri ◽  
White Sucker ◽  
The Mean ◽  
Brook Stickleback

Recoveries of hatchery-reared brook trout (Salvelinus fontinalis), splake (Salvelinus namaycush × S. fontinalis), and rainbow trout (Salmo gairdneri), planted in lakes having different resident fishes, were highest (9–30%) in a lake in which minnows and the brook stickleback were the only other fishes. Recoveries, by angling and gillnetting, were considerably lower (2–15%) in two lakes containing the white sucker and minnows, and still lower (0.5–5%,) in two lakes containing spiny-rayed species as well. Recoveries were lowest (< 0.5%) in a lake having a complex fish community that included native brook and lake trout. Planted splake and rainbow trout generally yielded higher returns, in weight, than brook trout in comparable situations.The low survival of planted fish was apparently due to the low fertility of the waters and to competition with, or predation by, resident fish species. Predation by fish-eating birds and mammals may also have had an effect.The weight of the catch of salmonids exceeded the weight planted in only one lake. Here, the mean yield of planted salmonids was 8.4 kg/ha per year in comparison with 2.6 to < 0.5 kg/ha per year in the five other study lakes.

Effects of experimental clearcut logging on water quality in three small boreal forest lake trout (Salvelinus namaycush) lakes

2000 ◽  
Vol 57 (S2) ◽  
pp. 92-96 ◽  
Author(s):  
Robert J Steedman
Keyword(s):  
Water Quality ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
First Year ◽  
Forest Lake ◽  
Clearcut Logging ◽  
Quality Response ◽  
Shield Lakes

Water quality was monitored in three 30-ha stratified headwater Precambrian Shield lakes for 5 years before and 3 years after moderate to extensive catchment deforestation. These lakes, which had water renewal times of about a decade, showed only minor changes in water quality by the third year after logging. Water quality response in a lake with moderate deforestation and intact shoreline forest was similar to that in two lakes with extensive upland and shoreline deforestation. By the second and third years after logging, May-September average volume-weighted concentrations of dissolved organic carbon, chlorophyll, total nitrogen, K+, Cl-, and Si had all increased, generally by about 10-40% over predisturbance levels, while Ca2+ and Mg2+ had declined by 10-25%. Dry weather the first year after logging was associated with temporary declines of 10-20% in dissolved organic carbon and chlorophyll.

Evaluation of the Effects of Fish Community Structure on Observed Yields of Lake Trout (Salvelinus namaycush)

1987 ◽  
Vol 44 (S2) ◽  
pp. s239-s248 ◽  
Author(s):  
C. I. Goddard ◽  
D. H. Loftus ◽  
J. A. MacLean ◽  
C. H. Olver ◽  
B. J. Shuter
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Lake Area ◽  
Fish Community Structure ◽  
Extrinsic Factors ◽  
Potential Yield ◽  
Factors Affecting ◽  
Intrinsic Factors

Creel and lake survey data from 87 Ontario lakes with self-sustaining lake trout (Salvelinus namaycush) populations were analysed to determine the effect of intrinsic factors, such as fish community structure, and extrinsic factors, such as angling-effort, on the observed yields of lake trout. Multiple regression analyses showed that angling-effort and lake area, in order of importance, explained almost 82% of the variation in annual catches. Analyses of covariance were used to test a variety of hypotheses about how community structure — the presence of forage, competitors, or alternate sports species — affected the catch of lake trout. No significant differences among groups were detected, which suggests that fish community structure has little or no effect on actual yield of lake trout. The difficulties inherent in using catch and effort data alone to evaluate the importance of factors affecting productivity (or potential yield) are discussed.

Population structure of lake trout (Salvelinus namaycush) in a large glacial-fed lake inferred from microsatellite DNA and morphological analysis

2010 ◽  
Vol 67 (7) ◽  
pp. 1171-1186 ◽  
Author(s):  
Sara Northrup ◽  
Mark Connor ◽  
Eric B. Taylor
Keyword(s):  
Microsatellite Dna ◽  
Fish Community ◽  
Morphological Analysis ◽  
Lake Trout ◽  
Morphological Diversity ◽  
Salvelinus Namaycush ◽  
Fundamental Aspect ◽  
Recreational Fisheries ◽  
Biodiversity Research ◽  
Mixed Stock

Understanding the structure of intraspecific genetic and morphological diversity within and across habitats is a fundamental aspect of biodiversity research with conservation value. Atlin Lake is the largest lake in British Columbia, Canada, and contains relatively pristine populations of lake trout ( Salvelinus namaycush ) that are key components of the lake’s fish community and local fisheries. Lake trout from Atlin Lake were examined for genetic and phenotypic variation using eight microsatellite DNA loci, body form, and colouration. Genetic assays were also conducted on lake trout from the adjoining Tagish Lake and from 17 other localities to provide spatial context for the variation within Atlin Lake. The genetic data suggested that there were three genetic subpopulations within the Atlin–Tagish lake system. Morphological analysis identified two morphological groups of lake trout within Atlin Lake. Genetic and morphological groupings in Atlin Lake were not associated with each other. A mixed-stock analysis of samples collected from Atlin Lake commercial and recreational fisheries suggested that all genetic subpopulations contributed to the fishery and that there was some contribution from fish originating from within Tagish Lake.

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