Resurrecting an Idaho Icon: How Research and Management Reversed Declines of Native Westslope Cutthroat Trout

Fisheries ◽  
2021 ◽  
Author(s):  
Jerry Mallet ◽  
Russell F. Thurow
Keyword(s):  
Cutthroat Trout ◽  
Westslope Cutthroat Trout

Metabolic performance and thermal preference of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi and non-native trout across an ecologically relevant range of temperatures

2021 ◽  
Author(s):  
Camille J. Macnaughton ◽  
Travis C. Durhack ◽  
Neil J. Mochnacz ◽  
Eva C. Enders
Keyword(s):  
Brook Trout ◽  
Cold Water ◽  
Cutthroat Trout ◽  
Intermittent Flow ◽  
Performance Curve ◽  
Westslope Cutthroat Trout ◽  
Oncorhynchus Clarkii ◽  
Thermal Niche ◽  
Preferred Temperatures ◽  
Metabolic Performance

The physiology and behaviour of fish are strongly affected by ambient water temperature. Physiological traits related to metabolism, such as aerobic scope (AS), can be measured across temperature gradients and the resulting performance curve reflects the thermal niche that fish can occupy. We measured AS of Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi) at 5, 10, 15, 20, and 22°C and compared temperature preference (Tpref) of the species to non-native Brook Trout, Brown Trout, and Rainbow Trout. Intermittent-flow respirometry experiments demonstrated that metabolic performance of Westslope Cutthroat Trout was optimal at ~15 °C and decreased substantially beyond this temperature, until lethal temperatures at ~25 °C. Adjusted preferred temperatures across species (Tpref) were comparatively high, ranging from 17.8-19.9 °C, with the highest Tpref observed for Westslope Cutthroat Trout. Results suggest that although Westslope Cutthroat Trout is considered a cold-water species, they do not prefer or perform as well in cold water (≤ 10°C), thus, can occupy a warmer thermal niche than previously thought. The metabolic performance curve (AS) can be used to develop species‐specific thermal criteria to delineate important thermal habitats and guide conservation and recovery actions for Westslope Cutthroat Trout.

Patch size but not short-term isolation influences occurrence of westslope cutthroat trout above human-made barriers

2013 ◽  
Vol 23 (4) ◽  
pp. 556-571 ◽  
Author(s):  
Douglas P. Peterson ◽  
Bruce E. Rieman ◽  
Dona L. Horan ◽  
Michael K. Young
Keyword(s):  
Patch Size ◽  
Cutthroat Trout ◽  
Westslope Cutthroat Trout ◽  
Short Term

scholarly journals Ultrasound imaging identifies life history variation in resident Cutthroat Trout

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246365
Author(s):  
Kellie J. Carim ◽  
Scott Relyea ◽  
Craig Barfoot ◽  
Lisa A. Eby ◽  
John A. Kronenberger ◽  
...  
Keyword(s):  
Life History ◽  
Ultrasound Imaging ◽  
Life Histories ◽  
Cutthroat Trout ◽  
Error Rates ◽  
Reproductive Status ◽  
Lifetime Reproductive Success ◽  
Life History Variation ◽  
Westslope Cutthroat Trout ◽  
Isolated Populations

Human activities that fragment fish habitat have isolated inland salmonid populations. This isolation is associated with loss of migratory life histories and declines in population density and abundance. Isolated populations exhibiting only resident life histories may be more likely to persist if individuals can increase lifetime reproductive success by maturing at smaller sizes or earlier ages. Therefore, accurate estimates of age and size at maturity across resident salmonid populations would improve estimates of population viability. Commonly used methods for assessing maturity such as dissection, endoscopy and hormone analysis are invasive and may disturb vulnerable populations. Ultrasound imaging is a non-invasive method that has been used to measure reproductive status across fish taxa. However, little research has assessed the accuracy of ultrasound for determining maturation status of small-bodied fish, or reproductive potential early in a species’ reproductive cycle. To address these knowledge gaps, we tested whether ultrasound imaging could be used to identify maturing female Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi). Our methods were accurate at identifying maturing females reared in a hatchery setting up to eight months prior to spawning, with error rates ≤ 4.0%; accuracy was greater for larger fish. We also imaged fish in a field setting to examine variation in the size of maturing females among six wild, resident populations of Westslope Cutthroat Trout in western Montana. The median size of maturing females varied significantly across populations. We observed oocyte development in females as small as 109 mm, which is smaller than previously documented for this species. Methods tested in this study will allow researchers and managers to collect information on reproductive status of small-bodied salmonids without disrupting fish during the breeding season. This information can help elucidate life history traits that promote persistence of isolated salmonid populations.

Cutthroat Trout: Evolutionary Biology and Taxonomy

2018 ◽  
Author(s):  
Joseph P. Brunelli
Keyword(s):  
Evolutionary Biology ◽  
Cutthroat Trout ◽  
Paternal Inheritance ◽  
Westslope Cutthroat Trout ◽  
Chromosome Marker ◽  
Mitochondrial Markers ◽  
Coastal Cutthroat Trout ◽  
Lahontan Cutthroat Trout ◽  
Yellowstone Cutthroat Trout

<em>Abstract</em>.—A Y chromosome marker shared with Rainbow Trout <em>Oncorhynchus mykiss </em>has been sequenced in many Cutthroat Trout <em>O. clarkii </em>subspecies. The marker is found in and inherited through males. It evolves more slowly than the maternally inherited mitochondrial DNA. The marker delineates the four major groups of Cutthroat Trout: the Lahontan Cutthroat Trout <em>O. c. henshawi </em>subspecies complex, the Yellowstone Cutthroat Trout <em>O. c. bouvieri</em> subspecies complex, Westslope Cutthroat Trout <em>O. c. lewisi</em>, and Coastal Cutthroat Trout <em>O. c. clarkii</em>. The paternal inheritance pattern of the Y marker makes it useful for dissecting the origins of fish with mixed ancestries. We describe a case study using both Y and mitochondrial markers in Lahontan Cutthroat Trout subspecies complex trout populations. Our results confirmed Lahontan Cutthroat Trout affinities for the Paiute Cutthroat Trout <em>O. c. seleniris</em> and Willow–Whitehorse Creek Cutthroat Trout. However, we found evidence of a complex ancestry for Guano Creek, Oregon trout, a group that has been proposed by some to be related to the Alvord Cutthroat Trout, a subspecies thought to be extinct.

Cutthroat Trout: Evolutionary Biology and Taxonomy

2018 ◽  
Keyword(s):  
Evolutionary Biology ◽  
Cutthroat Trout ◽  
Westslope Cutthroat Trout ◽  
Oncorhynchus Clarkii ◽  
Coastal Cutthroat Trout ◽  
Lahontan Cutthroat Trout ◽  
Museum Samples ◽  
Yellowstone Cutthroat Trout ◽  
The 1960S

<em>Abstract</em>.—There has been considerable interest in the systematics and classification of Cutthroat Trout since the 1800s. Cutthroat Trout native to western North America (currently classified as <em>Oncorhynchus clarkii</em>) have historically been grouped or separated using many different classification schemes. Since the 1960s, Robert Behnke has been a leader in these efforts. Introductions of nonnative trout (other forms of Cutthroat Trout, and Rainbow Trout <em>O. mykiss</em>) have obscured some historical patterns of distribution and differentiation. Morphological and meristic analyses have often grouped the various forms of Cutthroat Trout together based on the shared presence of the “cutthroat mark,” high scale counts along the lateral line, and the presence of basibranchial teeth. Spotting patterns and counts of gill rakers and pyloric caeca have in some cases been helpful in differentiation of groups (e.g., Coastal Cutthroat Trout <em>O. c. clarkii</em>, Lahontan Cutthroat Trout <em>O. c. henshawi</em>, and Westslope Cutthroat Trout <em>O. c. lewisi</em>) currently classified as subspecies. The historical genetic methods of allozyme genotyping through protein electrophoresis and chromosome analyses were often helpful in differentiating the various subspecies of Cutthroat Trout. Allozyme genotyping allowed four major groups to be readily recognized (Coastal Cutthroat Trout, Westslope Cutthroat Trout, the Lahontan Cutthroat Trout subspecies complex, and Yellowstone Cutthroat Trout <em>O. c. bouvieri </em>subspecies complex) while chromosome analyses showed similarity between the Lahontan and Yellowstone Cutthroat trout subspecies complex trout (possibly reflecting shared ancestral type) and differentiated the Coastal and Westslope Cutthroat trouts from each other and those two groups. DNA results may yield higher resolution of evolutionary relationships of Cutthroat Trout and allow incorporation of ancient museum samples. Accurate resolution of taxonomic differences among various Cutthroat Trout lineages, and hybridization assessments, requires several approaches and will aid in conservation of these charismatic and increasingly rare native fishes.

Feed Characteristics Alter Growth Efficiency of Cutthroat Trout

2015 ◽  
Vol 6 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Brian R. Ham ◽  
Christopher A. Myrick ◽  
Frederic T. Barrows ◽  
Carl J. Yeoman ◽  
Glenn C. Duff ◽  
...  
Keyword(s):  
Cutthroat Trout ◽  
Conversion Ratio ◽  
Feed Conversion Ratio ◽  
The Other ◽  
Snake River ◽  
Feed Conversion ◽  
Initial Weight ◽  
Feeding Trial ◽  
Westslope Cutthroat Trout ◽  
Fish Tank

Abstract Hatchery-cultured cutthroat trout Oncorhynchus clarkii fed some commercially available rainbow trout feeds display slow growth and increased mortality. Feed characteristics such as buoyancy and texture alter feed acceptance in some fish species, but their effects have not been adequately addressed in cutthroat trout. Therefore, the objective of this study was to examine whether feed structure and behavior preferences explain the decreased hatchery performance of juvenile cutthroat trout. To achieve this, we conducted two feeding trials in which we fed Westslope cutthroat trout O. clarkii lewisi and Snake River finespotted cutthroat trout O. clarkii behnkei a single diet formulation manufactured to display four different characteristics (floating, sinking, semimoist pellets, or a flake feed) and compared consumption, weight gain, and survival. In the first feeding trial, we stocked Westslope cutthroat trout (initial weight 11.3 g ± 0.5 g) at 20 fish/tank. We used two different sizes of tanks, with four replicate small tanks (54-L) and two replicate large tanks (96-L) per feed type. Results of the first trial demonstrated a significant effect of feed type but not tank size on weight gain of Westslope cutthroat trout with no interaction. Westslope cutthroat trout fed the flake feed gained less weight than did fish fed any of the other feed types. Feed conversion ratio was affected by both feed type and tank size with no interaction. In a second feeding trial, Snake River cutthroat trout (initial weight 19.5 g ± 0.5 g) were stocked at 20 fish/tank in 96-L tanks with four replicate tanks per feed type. Results of the second trial demonstrated that Snake River cutthroat trout fed the flake feed grew less, had higher feed conversion ratio, elevated hepatosomatic index, and reduced muscle ratio compared with fish fed the other feeds. Results demonstrate that flake feeds are not adequate for cutthroat trout at this life stage. However, additional research is needed to address other culture-related limitations because only minor differences between fish fed other feed types were detected.

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