Greater predation by Double-crested Cormorants on cutthroat versus rainbow trout fingerlings stocked in a Wyoming river

1999 ◽  
Vol 77 (12) ◽  
pp. 1984-1990 ◽  
Author(s):  
James R Lovvorn ◽  
Daniel Yule ◽  
Clayton E Derby
Keyword(s):  
Rainbow Trout ◽  
Cutthroat Trout ◽  
Phalacrocorax Auritus ◽  
Limited Data ◽  
Platte River ◽  
The North ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Oncorhynchus Clarki Bouvieri ◽  
Pelecanus Erythrorhynchos ◽  
Yellowstone Cutthroat Trout

We studied the relative vulnerability of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) versus rainbow trout (Oncorhynchus mykiss) stocked as fingerlings in the North Platte River, Wyoming, to Double-crested Cormorant (Phalacrocorax auritus) predation. Cutthroat fingerlings decreased as a fraction of the population from stocking in late June to electrofishing surveys in the following October and March. In contrast, the fraction of cutthroat fingerlings among tagged fingerlings eaten by cormorants collected on the river was significantly greater than that in the population when originally stocked. More limited data from pellets regurgitated by adult cormorants at a nearby colony and in American White Pelicans (Pelecanus erythrorhynchos) collected on the river showed the same trend toward greater percentages of cutthroat trout being consumed than were present among trout stocked. There were no differences in cormorant predation rates on the Eagle Lake strain of rainbow trout reared under shaded versus partially shaded conditions, or between Auburn and Bar BC strains of Snake River (Yellowstone) cutthroat trout. On the North Platte River, cutthroat trout fingerlings were more susceptible to cormorant predation than rainbow trout of similar size that were stocked simultaneously.

Morphological and swimming stamina differences between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri), rainbow trout (Oncorhynchus mykiss), and their hybrids

2007 ◽  
Vol 64 (1) ◽  
pp. 127-135 ◽  
Author(s):  
Steven M Seiler ◽  
Ernest R Keeley
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Body Shape ◽  
Cutthroat Trout ◽  
Swimming Velocity ◽  
Swimming Ability ◽  
Geometric Morphometric ◽  
Oncorhynchus Clarkii ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Yellowstone Cutthroat Trout

We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri), rainbow trout (Oncorhynchus mykiss), and their hybrids may influence swimming ability and thus play an important role in the invasion of nonnative rainbow trout and hybrid trout into native cutthroat trout populations. We reared Yellowstone cutthroat trout, rainbow trout, and reciprocal hybrid crosses in a common environment and conducted sustained swimming trials in order to test for genetically based morphological and swimming stamina differences. Linear and geometric morphometric analyses identified differences in body shape, with cutthroat trout having slender bodies and small caudal peduncles and rainbow trout having deep bodies and long caudal peduncles. Hybrid crosses were morphologically intermediate to the parental genotypes, with a considerable maternal effect. Consistent with morphological differences, cutthroat trout had the lowest sustained swimming velocity and rainbow trout had the highest sustained swimming velocity. Sustained swimming ability of hybrid genotypes was not different from that of rainbow trout. Our results suggest that introduced rainbow trout and cutthroat-rainbow trout hybrids potentially out-compete native Yellowstone cutthroat trout through higher sustained swimming ability.

Predation on fish by cormorants and pelicans in a cold-water river: a field and modeling study

1997 ◽  
Vol 54 (7) ◽  
pp. 1480-1493 ◽  
Author(s):  
C E Derby ◽  
J R Lovvorn
Keyword(s):  
Cold Water ◽  
Pimephales Promelas ◽  
Fresh Mass ◽  
Phalacrocorax Auritus ◽  
Bird Predation ◽  
Overwinter Survival ◽  
Platte River ◽  
Bioenergetics Model ◽  
The North ◽  
Pelecanus Erythrorhynchos

We studied diets of double-crested cormorants (Phalacrocorax auritus) and American white pelicans (Pelecanus erythrorhynchos) collected on the North Platte River, Wyoming, from May to August. Rainbow (Oncorhychus mykiss) and cutthroat (O. clarki) trout 10-16 cm long were stocked in late June - early July. Cormorants ate mainly suckers (Catastomus spp., 61% of numbers, 85% of fresh mass) before trout stocking; but trout consumed increased from 17% (12% of mass) in samples before stocking to 60% (82% of mass) after stocking. Pelicans ate mostly suckers (64% of numbers, 84% of mass) and minnows (Rhinichthys cataractae, Pimephales promelas; 21% of numbers, 1% of mass) throughout the study; trout were 1% (0.1% of mass) of the pelican diet before stocking, and 22% (14% of mass) after stocking. A bioenergetics model estimated that these birds consumed up to 80% of trout stocked in 1994. In August 1993, cormorants ate mostly trout (86% of numbers, 98% of mass), suggesting that many stocked trout survived until autumn. However, the much smaller fraction of trout eaten by cormorants in spring 1994 before stocking (mean 17% of numbers, 13% of mass) than after stocking (60% of numbers, 82% of mass) suggests that stocked trout declined substantially during winter. Because overwinter survival might have limited trout recruitment between years, it is unclear whether bird predation was additive or compensatory.

Abiotic conditions are unlikely to mediate hybridization between invasive rainbow trout and native Yellowstone cutthroat trout in a high-elevation metapopulation

2020 ◽  
Vol 77 (9) ◽  
pp. 1433-1445 ◽  
Author(s):  
Kurt C. Heim ◽  
Thomas E. McMahon ◽  
Steven T. Kalinowski ◽  
Brian D. Ertel ◽  
Todd M. Koel
Keyword(s):  
Rainbow Trout ◽  
Cutthroat Trout ◽  
High Elevation ◽  
Source Population ◽  
Full Spectrum ◽  
Oncorhynchus Clarkii ◽  
Abiotic Conditions ◽  
Management Intervention ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Yellowstone Cutthroat Trout

Understanding factors mediating hybridization between native and invasive species is crucial for conservation. We assessed the spatial distribution of hybridization between invasive rainbow trout (Oncorhynchus mykiss) and native Yellowstone cutthroat trout (Oncorhynchus clarkii bouveri) in the Lamar River of Yellowstone National Park using a paired telemetry and genetic dataset. Spawning populations containing hybrids (15/30) occupied the full spectrum of abiotic conditions in the watershed (stream temperature, stream size, runoff timing), including an intermittent stream that dried completely in late June, and mainstem spawning locations. Hybrids and rainbow trout occupied an entire high-elevation (∼2500–1900 m) tributary where rainbow trout ancestry was highest in headwaters and decreased downstream. Fluvial distance to this ostensible source population was the only covariate included in top hybridization models; effects of abiotic covariates and stocking intensity were relatively weak. In this watershed, abiotic conditions are unlikely to mediate continued hybridization. We conclude that management intervention is important for the persistence of nonhybridized Yellowstone cutthroat trout and highlight the value of pairing telemetry with genetic analysis to identify and characterize populations for hybridization assessments.

Spatial and temporal spawning dynamics of native westslope cutthroat trout, Oncorhynchus clarkii lewisi, introduced rainbow trout, Oncorhynchus mykiss, and their hybrids

2009 ◽  
Vol 66 (7) ◽  
pp. 1153-1168 ◽  
Author(s):  
Clint C. Muhlfeld ◽  
Thomas E. McMahon ◽  
Durae Belcer ◽  
Jeffrey L. Kershner
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Cutthroat Trout ◽  
River System ◽  
Westslope Cutthroat Trout ◽  
Time And Space ◽  
Long Distance ◽  
Oncorhynchus Clarkii ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Spring Runoff

We used radiotelemetry to assess spatial and temporal spawning distributions of native westslope cutthroat trout ( Oncorhynchus clarkii lewisi ; WCT), introduced rainbow trout ( Oncorhynchus mykiss ; RBT), and their hybrids in the upper Flathead River system, Montana (USA) and British Columbia (Canada), from 2000 to 2007. Radio-tagged trout (N = 125) moved upriver towards spawning sites as flows increased during spring runoff and spawned in 29 tributaries. WCT migrated greater distances and spawned in headwater streams during peak flows and as flows declined, whereas RBT and RBT hybrids (backcrosses to RBT) spawned earlier during increasing flows and lower in the system. WCT hybrids (backcrosses to WCT) spawned intermediately in time and space to WCT and RBT and RBT hybrids. Both hybrid groups and RBT, however, spawned over time periods that produced temporal overlap with spawning WCT in most years. Our data indicate that hybridization is spreading via long-distance movements of individuals with high amounts of RBT admixture into WCT streams and stepping-stone invasion at small scales by later generation backcrosses. This study provides evidence that hybridization increases the likelihood of reproductive overlap in time and space, promoting extinction by introgression, and that the spread of hybridization is likely to continue if hybrid source populations are not reduced or eliminated.

Cold tolerance performance of westslope cutthroat trout (Oncorhynchus clarkii lewisi) and rainbow trout (Oncorhynchus mykiss) and its potential role in influencing interspecific hybridization

2014 ◽  
Vol 92 (9) ◽  
pp. 777-784 ◽  
Author(s):  
M.M. Yau ◽  
E.B. Taylor
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Water Temperature ◽  
Cold Water ◽  
Cutthroat Trout ◽  
Acclimation Temperature ◽  
Westslope Cutthroat Trout ◽  
Oncorhynchus Clarkii ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Differential Adaptation

Hybridization between rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) and westslope cutthroat trout (Oncorhynchus clarkii lewisi (Girard, 1856)) occurs commonly when rainbow trout are introduced into the range of westslope cutthroat trout. Typically, hybridization is most common in warmer, lower elevation habitats, but much less common in colder, higher elevation habitats. We assessed the tolerance to cold water temperature (i.e., critical thermal minimum, CTMin) in juvenile rainbow trout and westslope cutthroat trout to test the hypothesis that westslope cutthroat trout better tolerate low water temperature, which may explain the lower prevalence of rainbow trout and interspecific hybrids in higher elevation, cold-water habitats (i.e., the “elevation refuge hypothesis”). All fish had significantly lower CTMin values (i.e., were better able to tolerate low temperatures) when they were acclimated to 15 °C (mean CTMin = 1.37 °C) versus 18 °C (mean CTMin = 1.91 °C; p < 0.001). Westslope cutthroat trout tended to have lower CTMin than rainbow trout from two populations, second–generation (F2) hybrids between two rainbow trout populations, and backcrossed rainbow trout at 15 °C (cross type × acclimation temperature interaction; p = 0.018). Differential adaptation to cold water temperatures may play a role in influencing the spatial distribution of hybridization between sympatric species of trout.

The effects of low pH and elevated aluminum on yellowstone cutthroat trout (Oncorhynchus clarki bouvieri)

1993 ◽  
Vol 12 (4) ◽  
pp. 719-731 ◽  
Author(s):  
Aïda M. Farag ◽  
Daniel F. Woodward ◽  
Edward E. Little ◽  
Bryan Steadman ◽  
Frank A. Vertucci
Keyword(s):  
Cutthroat Trout ◽  
Low Ph ◽  
Oncorhynchus Clarki ◽  
Oncorhynchus Clarki Bouvieri ◽  
Yellowstone Cutthroat Trout
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