Effects of light, prey size, and turbidity on reaction distances of lake trout (Salvelinus namaycush) to salmonid prey

1999 ◽  
Vol 56 (7) ◽  
pp. 1293-1297 ◽  
Author(s):  
Jason L Vogel ◽  
David A Beauchamp
Keyword(s):  
Lake Trout ◽  
Prey Size ◽  
Cutthroat Trout ◽  
Salvelinus Namaycush ◽  
Time Of Day ◽  
Oncorhynchus Clarki ◽  
Natural Environments ◽  
Reaction Distance ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Detection Capabilities

Most studies on visual foraging by fish have focused on reaction distances to invertebrate prey; however, these acuity-based results considerably overestimate reaction distances of piscivores to prey fish. In laboratory experiments, we quantified reaction distance of adult lake trout (Salvelinus namaycush) to rainbow trout (Oncorhynchus mykiss) and cutthroat trout (Oncorhynchus clarki) as a function of light (0.17-261 lx), prey size (55, 75, and 139 mm), and turbidity (0.09, 3.18, and 7.40 NTU). Reaction distances increased rapidly with increasing light from <25 cm at 0.17 lx to about 100 cm at a light threshold of 17.8 lx. Reaction distance declined as a decaying power function of turbidity. By constructing equations that describe the combined effects of light and turbidity on reaction distances, we can begin to model prey detection capabilities of piscivores at any depth at any time of day in natural environments.

An examination of the PCB: lipid relationship among individual fish

1997 ◽  
Vol 54 (5) ◽  
pp. 1031-1038
Author(s):  
C A Stow ◽  
L J Jackson ◽  
J F Amrhein
Keyword(s):  
Salmo Trutta ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Salvelinus Namaycush ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Strong Linear Correlation ◽  
Brown Trout Salmo Trutta ◽  
The Relationship

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.

Response of non-native lake trout (Salvelinus namaycush) to 15 years of harvest in Yellowstone Lake, Yellowstone National Park

2011 ◽  
Vol 68 (12) ◽  
pp. 2132-2145 ◽  
Author(s):  
John M. Syslo ◽  
Christopher S. Guy ◽  
Patricia E. Bigelow ◽  
Philip D. Doepke ◽  
Brian D. Ertel ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Yellowstone National Park ◽  
National Park ◽  
Population Growth Rate ◽  
Lake Trout ◽  
Cutthroat Trout ◽  
Salvelinus Namaycush ◽  
Yellowstone Lake ◽  
Yellowstone Cutthroat Trout

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.

Changes in the condition, early growth, and trophic position of lake trout (Salvelinus namaycush) in response to an experimental aquaculture operation

2019 ◽  
Vol 76 (8) ◽  
pp. 1376-1387
Author(s):  
Patrick J. Kennedy ◽  
Paul J. Blanchfield ◽  
Karen A. Kidd ◽  
Michael J. Paterson ◽  
Cheryl L. Podemski ◽  
...  
Keyword(s):  
Energy Use ◽  
Lake Trout ◽  
Trophic Position ◽  
Salvelinus Namaycush ◽  
Early Growth ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Mysis Diluviana ◽  
Boreal Shield

We analyzed changes in the condition, early growth, and resource use of lake trout (Salvelinus namaycush) from a Boreal Shield lake in response to an experimental aquaculture operation. Annual small-scale commercial production of rainbow trout (Oncorhynchus mykiss) resulted in increased lake trout body condition during aquaculture operations, which was positively related to minnow catch per unit effort (CPUE). Incremental increases in growth led to larger lake trout following aquaculture. While the littoral energy assimilated by lake trout did not change linearly from 2002 to 2009, we observed a shift towards littoral energy use in the last year of aquaculture and for 2 years after the experiment, coincident with low densities of Mysis diluviana. Lake trout trophic position declined from 2002 to 2009, suggesting increased foraging on secondary versus tertiary consumers. Minnow and slimy sculpin (Cottus cognatus) CPUE increased by 5.2- and 5.5-fold, respectively, and Mysis diluviana densities decreased by 93%. Changes observed in the experimental lake were much greater than those observed in a nearby reference lake. Our results suggest that moderate nutrient enrichment from aquaculture may benefit lake trout in oligotrophic Boreal Shield lakes.

Within- and among-population variation in the trophic position of a pelagic predator, lake trout (Salvelinus namaycush)

2000 ◽  
Vol 57 (4) ◽  
pp. 725-731 ◽  
Author(s):  
M Jake Vander Zanden ◽  
Brian J Shuter ◽  
Nigel P Lester ◽  
Joseph B Rasmussen
Keyword(s):  
Body Size ◽  
Total Variation ◽  
Lake Trout ◽  
Prey Size ◽  
Trophic Position ◽  
Feeding Habits ◽  
Salvelinus Namaycush ◽  
Population Variation ◽  
Prey Fish ◽  
Fish Trophic Position

Many aquatic consumers have flexible feeding habits, and the diet and trophic position of a species can be expected to vary both within and among populations. In this study, we quantify the importance of both within- and among-population trophic variation for lake trout (Salvelinus namaycush) using stable isotope designations of trophic position from 13 Ontario and Quebec lakes. Lake-to-lake differences explained 78% of the total variation in lake trout trophic position. Analysis using both stable isotopes and published dietary data demonstrated that the trophic position of lake trout failed to increase appreciably as a function of animal body size. This finding was attributed to weak predator size - prey size relationships as well as to there being no relationship between prey fish trophic position and body size. The variance in trophic position of a population reflects the extent to which individuals forage as trophic specialists; however, we did not identify any one factor that was correlated with within-population trophic variation. Our finding that much of the total variation in trophic position represents among-population differences indicates that considering the average trophic position of a population does not mask substantial within-population trophic variation.

Sign in / Sign up

Export Citation Format

Share Document