Comparing results of a spatially explicit growth model with changes in the length-weight relationship of lake trout (Salvelinus namaycush) in Flaming Gorge Reservoir

1999 ◽  
Vol 56 (S1) ◽  
pp. 162-169 ◽  
Author(s):  
Chris Luecke ◽  
M William Wengert ◽  
Roger W Schneidervin

We employed a spatially explicit simulation model to assess growth rate potential for lake trout (Salvelinus namaycush) in Flaming Gorge Reservoir, Utah-Wyoming. Late-summer water temperatures and forage fish densities in 168 habitat cells were collected from 1989 to 1996 and were used to estimate the potential growth of lake trout inhabiting each cell. Results of model simulations indicated that habitat quality for lake trout growth had decreased from 1990 to 1993. This decrease in lake trout growth rate potential was related to decreased forage fish densities during this period. Lake trout condition, as measured using length-weight analyses of individuals captured in spring gillnetting surveys, also decreased from the early 1990s to the mid-1990s. The change in the slope of the length-weight relationship was correlated with the proportion of habitat cells containing positive simulated growth rate potentials (r2 = 0.60, p = 0.024). No significant correlation between the sum of growth rate potentials in habitat cells and changes in the slope of the length-weight relationship was apparent. These correlations suggest that spatially explicit models of habitat quality have relevance to the performance of individual organisms functioning in field environments.

1995 ◽  
Vol 52 (7) ◽  
pp. 1572-1583 ◽  
Author(s):  
Doran M. Mason ◽  
Andrew Goyke ◽  
Stephen B. Brandt

We used spatially explicit modeling to compare habitat quality for chinook salmon, Oncorhynchus tshawytscha, and lake trout, Salvelinus namaycush, in Lakes Michigan and Ontario. This grid-based approach predicts a predator's physiological growth response, growth rate potential, from measured physical and biological environmental conditions and is a species-specific measure of habitat quality. Underwater acoustics was used to map prey spatial distributions, abundances, and sizes. A foraging model defined predator consumption rates from prey data. A bioenergetics model calculated growth rate potential based on consumption rates and prevailing thermal conditions. We compared habitat quality between lakes using both the mean growth rate potential and the volume (or proportion) of water capable of supporting positive growth rates. Mean growth rate potential for both chinook salmon and lake trout was similar between the lakes despite known differenes in the prey species composition and abundance. However, Lake Michigan provided a greater volume of water capable of supporting growth for both chinook salmon (26%) and lake trout (21%) compared with that for Lake Ontario (19% for both species). Our measure of habitat quality based on species-specific physiological requirements should provide a tool to compare ecosystems and quantify ecosystem change.


1983 ◽  
Vol 40 (2) ◽  
pp. 114-120 ◽  
Author(s):  
Hugh R. MacCrimmon ◽  
Christopher D. Wren ◽  
Barra L. Gots

Lake trout, Salvelinus namaycush, released into Tadenac Lake as juveniles, show a pronounced acceleration in growth rate, following a change in diet from benthic invertebrates to rainbow smelt, Osmerus mordax, beginning at age 6 (> 30 cm). An abrupt increase in the rate of mercury accumulation in white muscle of these fish occurs at the same time. Mercury levels in lake trout ([Formula: see text] = 0.24–3.44 μg/g) and coresident smelt ([Formula: see text] = 0.06–0.48 μg/g) from Tadenac and eight neighboring lakes reveal maximum levels reaching 10.0 and 0.84 μg/g, respectively. Mercury levels in lake trout from Tadenac Lake, an undisturbed PreCambrian Shield ecosystem without detected indigenous sources, exceed the "safe" level (0.5 μg/g) at sexual maturity and at a size less than generally acceptable for human utilization. Mercury accumulation by the trout is correlated with length (r = 0.92) in each lake population examined, but substantial among-lake differences occur in fish of comparable ages. As the growth rates are similar in various waters, differences in extent of mercury accumulation is attributed to differences in mercury availability among lakes. In view of a strong correlation (r = 0.96) between mercury levels in smelt and trout calculated at standardized length, it is proposed that the smelt is an appropriate indicator species for the ranking of cold-water lakes relative to the availability of mercury for uptake by lake trout and other living aquatic organisms.Key words: mercury uptake, lake trout, rainbow smelt, growth rate, diet


2011 ◽  
Vol 68 (12) ◽  
pp. 2132-2145 ◽  
Author(s):  
John M. Syslo ◽  
Christopher S. Guy ◽  
Patricia E. Bigelow ◽  
Philip D. Doepke ◽  
Brian D. Ertel ◽  
...  

Introduced lake trout ( Salvelinus namaycush ) threaten to extirpate native Yellowstone cutthroat trout ( Oncorhynchus clarkii bouvieri ) in the 34 000 ha Yellowstone Lake in Yellowstone National Park, USA. Suppression (and eventual eradication) of the lake trout population is deemed necessary for the conservation of Yellowstone cutthroat trout. A US National Park Service gill-netting program removed nearly 450 000 lake trout from Yellowstone Lake from 1995 through 2009. We examined temporal variation in individual growth, body condition, length and age at maturity, fecundity, mortality, and population models to assess the efficacy of the lake trout suppression program. Population metrics did not indicate overharvest despite more than a decade of fish removal. The current rate of population growth is positive; however, it is lower than it would be in the absence of lake trout suppression. Fishing effort needs to increase above observed levels to reduce population growth rate below replacement. Additionally, high sensitivity of population growth rate to reproductive vital rates indicates that increasing fishing mortality for sexually mature lake trout may increase the effectiveness of suppression. Lake trout suppression in Yellowstone Lake illustrates the complexities of trying to remove an apex predator to restore a relatively large remote lentic ecosystem with a simple fish assemblage.


2016 ◽  
Vol 73 (8) ◽  
pp. 1230-1236 ◽  
Author(s):  
Pierre-Olivier Benoît ◽  
Beatrix E. Beisner ◽  
Christopher T. Solomon

Dissolved organic carbon (DOC) can limit food web productivity in lakes, potentially imposing resource limitation on fishes. We asked whether the abundance or early growth rate of three fish species was negatively related to DOC in 59 lakes in southern Quebec, Canada, where DOC concentrations ranged from 4 to 16 mg·L−1 for lakes containing walleye (Sander vitreum) and yellow perch (Perca flavescens) and from 2.6 to 9 mg·L−1 for lakes containing lake trout (Salvelinus namaycush). Estimates of abundance and growth rate were more precise for walleye and lake trout than for yellow perch because of differences in sample size. Abundance was negatively related to DOC for walleye and perhaps also for lake trout and yellow perch. Early growth rate was negatively related to DOC for walleye and lake trout, but not for yellow perch. These results support a growing body of literature suggesting that the productivity of fish populations may be negatively related to DOC concentrations in lakes.


Author(s):  
Alexander Gatch ◽  
Dimitry Gorsky ◽  
Zy Biesinger ◽  
Eric Bruestle ◽  
Kelley Lee ◽  
...  

1995 ◽  
Vol 22 (5) ◽  
pp. 843 ◽  
Author(s):  
YP Wang ◽  
RM Gifford

Kernel growth after anthesis is simulated as a function of the potential kernel growth rate, current photosynthate production and mobilisation of stored reserves. The potential growth rate of the kernel is simulated as two temperature-sensitive processes, cell production and cell growth. The difference between the potential and actual growth rates of the kernel depends on the carbon supply to the free space of the kernel endosperm, while the carbon supply is itself affected by the actual kernel growth rate. Sensitivity analysis showed that the growth rate of the grain per plant is most sensitive to the potential growth rate of the kernel and number of kernels per plant. This model is able to simulate the observed rates of grain growth and leaf senescence from anthesis to physiological maturity for wheat plants grown in two CO2 concentrations. The simulated temperature response of grain growth agrees well with the experimenal observations.


1997 ◽  
Vol 54 (5) ◽  
pp. 1031-1038
Author(s):  
C A Stow ◽  
L J Jackson ◽  
J F Amrhein

We examined data from 1984 to 1994 for five species of Lake Michigan salmonids to explore the relationship between total PCB concentration and percent lipid. When we compared mean species lipid and PCB values, we found a strong linear correlation. When we compared values among individuals, we found modest positive PCB:lipid associations in brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) collected during spawning, but positive associations were not apparent among nonspawning individuals. Lake trout (Salvelinus namaycush) exhibited no discernible PCB:lipid relationship. Our results are not incompatible with previous observations that contaminants are differentially partitioned into lipids within a fish, but these results do suggest that lipids are not a major factor influencing contaminant uptake.


1980 ◽  
Vol 37 (11) ◽  
pp. 1989-2006 ◽  
Author(s):  
Everett Louis King Jr.

Criteria for the classification of marks inflicted by sea lamprey (Petromyzon marinus) into nine categories were developed from laboratory studies in an attempt to refine the classification system used in field assessment work. These criteria were based on characteristics of the attachment site that could be identified under field conditions by unaided visual means and by touching the attachment site. Healing of these marks was somewhat variable and was influenced by the size of lamprey, duration of attachment, severity of the wound at lamprey detachment, season and water temperature, and by other less obvious factors. Even under laboratory conditions staging of some wounds was difficult, especially at low water temperatures. If these criteria are to be used effectively and with precision in the field, close examination of individual fish may be required. If the feeding and density of specific year-classes of sea lampreys are to be accurately assessed on an annual basis, close attention to the wound size (as it reflects the size of the lamprey's oral disc) and character of wounds on fish will be required as well as consideration of the season of the year in which they are observed.Key words: sea lamprey, attack marks, lake trout, Great Lakes


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