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• 11. [Article] Characterization of a ras gene in rainbow trout

  The rainbow trout (Oncorhynchus mykiss) model of chemical carcinogenesis is becoming increasingly important as a supplement to rodent studies. However, much of the molecular biology of the carcinogenic response ...

  Citation × Citation Citation Abstract Copy Title: Characterization of a ras gene in rainbow trout Author: Mangold, Kathy A. The rainbow trout (Oncorhynchus mykiss) model of chemical carcinogenesis is becoming increasingly important as a supplement to rodent studies. However, much of the molecular biology of the carcinogenic response is still unknown in the trout model. The ras gene family has been implicated in the tumorigenesis of both spontaneous and chemically-induced tumors in mammals. This study is the first to characterize a ras proto-oncogene in rainbow trout. To accomplish this, the ras gene sequence was amplified in vitro by using polymerase chain reaction (PCR). Two synthetic and degenerative oligonucleotide sequences based on a consensus mammal/goldfish ras sequence were used as primers in the PCR procedure. An 800 base pair (bp) sequence was amplified from trout genomic DNA and hybridized with a human c-Ha-ras sequence. The initial amplifications of trout liver cDNA using the PCR procedure with the synthetic ras primers resulted in a single product of approximately 216 bps. However, this amplified "trout" 216 by product was subsequently shown to be an artifact of carryover from a human Ki-ras plasmid. Carryover is a common problem found in many laboratories involved with the PCR procedure, and extensive precautions were used to eliminate the problem in our laboratories. The 800 by PCR product was cloned and sequenced using Taq polymerase. RT-8, a clone containing the 800 bp insert, was shown to have 91% homology to the first two exons of mammalian c-Ha-ras gene and lesser homology to other ras genes. Amplification of trout liver cDNA using specific primers based on the RT-8 sequence resulted in the amplification of sequences identical to the sequence of the RT-8 insert without an intron, as well as unique sequences, which may represent additional trout ras genes. The PCR procedure was modified to identify sequence information immediately 3' of the known trout ras sequence. Partial sequences of at least two different trout ras genes are presented. With this new information, analysis of DNA sequence information from chemically initiated tumors may elucidate the role activation of ras genes plays in the trout model of carcinogenesis. Title: Characterization of a ras gene in rainbow trout Author: Mangold, Kathy A. The rainbow trout (Oncorhynchus mykiss) model of chemical carcinogenesis is becoming increasingly important as a supplement to rodent studies. However, much of the molecular biology of the carcinogenic response is still unknown in the trout model. The ras gene family has been implicated in the tumorigenesis of both spontaneous and chemically-induced tumors in mammals. This study is the first to characterize a ras proto-oncogene in rainbow trout. To accomplish this, the ras gene sequence was amplified in vitro by using polymerase chain reaction (PCR). Two synthetic and degenerative oligonucleotide sequences based on a consensus mammal/goldfish ras sequence were used as primers in the PCR procedure. An 800 base pair (bp) sequence was amplified from trout genomic DNA and hybridized with a human c-Ha-ras sequence. The initial amplifications of trout liver cDNA using the PCR procedure with the synthetic ras primers resulted in a single product of approximately 216 bps. However, this amplified "trout" 216 by product was subsequently shown to be an artifact of carryover from a human Ki-ras plasmid. Carryover is a common problem found in many laboratories involved with the PCR procedure, and extensive precautions were used to eliminate the problem in our laboratories. The 800 by PCR product was cloned and sequenced using Taq polymerase. RT-8, a clone containing the 800 bp insert, was shown to have 91% homology to the first two exons of mammalian c-Ha-ras gene and lesser homology to other ras genes. Amplification of trout liver cDNA using specific primers based on the RT-8 sequence resulted in the amplification of sequences identical to the sequence of the RT-8 insert without an intron, as well as unique sequences, which may represent additional trout ras genes. The PCR procedure was modified to identify sequence information immediately 3' of the known trout ras sequence. Partial sequences of at least two different trout ras genes are presented. With this new information, analysis of DNA sequence information from chemically initiated tumors may elucidate the role activation of ras genes plays in the trout model of carcinogenesis. Close

• 12. [Article] The feasibility of a consumptive wild trout sport fishery on the North Fork of the Middle Fork of the Willamette River

  The objective of this study was to determine whether wild populations of trout in the North Fork of the Middle Fork of the Willamette River can support a catch rate of 0.3-0.5 trout per hour at current ...

  Citation × Citation Citation Abstract Copy Title: The feasibility of a consumptive wild trout sport fishery on the North Fork of the Middle Fork of the Willamette River Author: Nicholas, Jay W. The objective of this study was to determine whether wild populations of trout in the North Fork of the Middle Fork of the Willamette River can support a catch rate of 0.3-0.5 trout per hour at current levels of effort and to predict how different size and bag limits would alter the number and ages of trout harvested. Angler use of the sport fishery in 1976 was estimated to be 2,730 angler days and 5,660 angler hours. The season average catch rate was 0.49 trout per hour. The number of trout counted in September 1975 and 1976 suggested that the trout populations had not declined between those two years. Rainbow trout are recruited to the fishery at about age II and 50% of the females are mature at age IV. Cutthroat trout are recruited to the fishery at about age III and 86% of the females are mature at that same age. Distribution of harvest among anglers and age specific lengths of native trout are used to demonstrate that size restrictions are the most effective means of selectively limiting trout harvest. The North Fork can continue to support a consumptive sport fishery with a catch rate of between 0.3 and 0.5 trout per hour at present levels of effort under the following assumptions: (1) angler use and harvest was similar in 1975 and 1976, (2) natural mortality was similar in both years, and (3) trout counts were not biased by unequal movement of fish into study pools in the second year. Title: The feasibility of a consumptive wild trout sport fishery on the North Fork of the Middle Fork of the Willamette River Author: Nicholas, Jay W. The objective of this study was to determine whether wild populations of trout in the North Fork of the Middle Fork of the Willamette River can support a catch rate of 0.3-0.5 trout per hour at current levels of effort and to predict how different size and bag limits would alter the number and ages of trout harvested. Angler use of the sport fishery in 1976 was estimated to be 2,730 angler days and 5,660 angler hours. The season average catch rate was 0.49 trout per hour. The number of trout counted in September 1975 and 1976 suggested that the trout populations had not declined between those two years. Rainbow trout are recruited to the fishery at about age II and 50% of the females are mature at age IV. Cutthroat trout are recruited to the fishery at about age III and 86% of the females are mature at that same age. Distribution of harvest among anglers and age specific lengths of native trout are used to demonstrate that size restrictions are the most effective means of selectively limiting trout harvest. The North Fork can continue to support a consumptive sport fishery with a catch rate of between 0.3 and 0.5 trout per hour at present levels of effort under the following assumptions: (1) angler use and harvest was similar in 1975 and 1976, (2) natural mortality was similar in both years, and (3) trout counts were not biased by unequal movement of fish into study pools in the second year. Close

• 13. [Article] Coexistence of top predators in headwater streams : pathways of intraguild predation between Pacific Giant salamander larvae and cutthroat trout

  The coexistence of multiple predators may have important consequences for the structure and function of communities. Interactions between predators may strongly affect their combined direct and indirect ...

  Citation × Citation Citation Abstract Copy Title: Coexistence of top predators in headwater streams : pathways of intraguild predation between Pacific Giant salamander larvae and cutthroat trout Author: Rundio, David E. The coexistence of multiple predators may have important consequences for the structure and function of communities. Interactions between predators may strongly affect their combined direct and indirect effects on prey populations and lower trophic levels. Predators often have size-structured populations, which may result in intraguild predation characterized by complex trophic and behavioral interactions. Coexistence of multiple predators may strongly depend on antipredator defenses of small size classes that reduce their vulnerability to predation. In Pacific Northwest forested ecosystems, Pacific giant salamanders (Dicamptodon tenebrosus) and coastal cutthroat trout (Oncorhynchus clarki clarki) are the top predators in many perennial headwater streams. Dicamptodon and cutthroat have size-structured populations with roughly corresponding size classes, and interactions between these species appear consistent with intraguild predation. My research objective was to determine the mechanisms contributing to the coexistence of Dicamptodon larvae with cutthroat trout in headwater streams, and the effects of this coexistence on factors related to Dicamptodon fitness. First, I tested for two general types of antipredator defenses of young-of-year Dicamptodon larvae against trout. Larvae were palatable to trout during initial and repeated offerings, which suggests that they may survive few encounters with trout. However, larvae increased refuge use in response to non-visual, chemical cues from trout, which likely reduces the probability of encounters with trout and contributes to their coexistence. Second, I measured the effects of cutthroat trout on Dicamptodon fitness parameters in a field experiment. Dicamptodon survival, growth, and behavior (activity level) did not differ between trout-present and trout-absent pools, although these results were compromised by unexplained gains or losses of larvae from most pools. Antipredator behaviors may promote coexistence of Dicamptodon and cutthroat trout, and may contribute to a complex series of behavioral and trophic interactions affecting lower trophic levels within headwater stream communities. Title: Coexistence of top predators in headwater streams : pathways of intraguild predation between Pacific Giant salamander larvae and cutthroat trout Author: Rundio, David E. The coexistence of multiple predators may have important consequences for the structure and function of communities. Interactions between predators may strongly affect their combined direct and indirect effects on prey populations and lower trophic levels. Predators often have size-structured populations, which may result in intraguild predation characterized by complex trophic and behavioral interactions. Coexistence of multiple predators may strongly depend on antipredator defenses of small size classes that reduce their vulnerability to predation. In Pacific Northwest forested ecosystems, Pacific giant salamanders (Dicamptodon tenebrosus) and coastal cutthroat trout (Oncorhynchus clarki clarki) are the top predators in many perennial headwater streams. Dicamptodon and cutthroat have size-structured populations with roughly corresponding size classes, and interactions between these species appear consistent with intraguild predation. My research objective was to determine the mechanisms contributing to the coexistence of Dicamptodon larvae with cutthroat trout in headwater streams, and the effects of this coexistence on factors related to Dicamptodon fitness. First, I tested for two general types of antipredator defenses of young-of-year Dicamptodon larvae against trout. Larvae were palatable to trout during initial and repeated offerings, which suggests that they may survive few encounters with trout. However, larvae increased refuge use in response to non-visual, chemical cues from trout, which likely reduces the probability of encounters with trout and contributes to their coexistence. Second, I measured the effects of cutthroat trout on Dicamptodon fitness parameters in a field experiment. Dicamptodon survival, growth, and behavior (activity level) did not differ between trout-present and trout-absent pools, although these results were compromised by unexplained gains or losses of larvae from most pools. Antipredator behaviors may promote coexistence of Dicamptodon and cutthroat trout, and may contribute to a complex series of behavioral and trophic interactions affecting lower trophic levels within headwater stream communities. Close

• 14. [Article] An evaluation in rainbow trout of biliary excretion of sulfobromophthalein and effects of biliary excretion on the toxicity of rotenone

  Biliary excretion has been of considerable interest in mammals but has not been extensively studied in fish. To understand the significance of biliary excretion in rainbow trout (Salmo gairdneri), two ...

  Citation × Citation Citation Abstract Copy Title: An evaluation in rainbow trout of biliary excretion of sulfobromophthalein and effects of biliary excretion on the toxicity of rotenone Author: Schmidt, Dana C. Biliary excretion has been of considerable interest in mammals but has not been extensively studied in fish. To understand the significance of biliary excretion in rainbow trout (Salmo gairdneri), two studies were conducted. The objective of the initial study was to evaluate the ability of rainbow trout to excrete a foreign compound typically excreted by the vertebrate liver. This problem was approached by evaluating biliary excretion and metabolism of sulfobromophthalein (BSP) in trout and comparing the results with literature values for mammals. Results indicated this dye is metabolized and excreted similarily in trout, dogfish (Squalus acanthias) and mammals. Large differences between trout and other species in transport maxima (Tm) of BSP based on body weights, were explained when the Tm values were based on liver blood clearance of BSP, a physiological rate reflecting blood flow. The objective of the second study was to determine if biliary excretion affects the toxicity of a foreign compound toxic to trout. This problem was approached by evaluating the effect of bile and cystic duct ligation on the mean lethal dose (LD 50) of rotenone to trout. To determine if biliary excretion affected the selective toxicity of this compound to trout, the effect of bile duct ligation on the rotenone LD 50 to rats was estimated and the results were compared with those obtained from the trout. The toxicant was administered intraperitoneally and intravenously in trout and intraperitoneally in rats. No increase in toxicity of rotenone occurred upon surgical impairment of bile flow in either the trout or the rats, Similarities in the toxicity of rotenone to trout and rats were observed when the toxicant was administered intraperitoneally, The data suggest the selective toxicity of rotenone to fish may be primarily caused by different routes of entry. The results of these experiments indicate the excretory functions of the liver of fish and mammals are similar. Title: An evaluation in rainbow trout of biliary excretion of sulfobromophthalein and effects of biliary excretion on the toxicity of rotenone Author: Schmidt, Dana C. Biliary excretion has been of considerable interest in mammals but has not been extensively studied in fish. To understand the significance of biliary excretion in rainbow trout (Salmo gairdneri), two studies were conducted. The objective of the initial study was to evaluate the ability of rainbow trout to excrete a foreign compound typically excreted by the vertebrate liver. This problem was approached by evaluating biliary excretion and metabolism of sulfobromophthalein (BSP) in trout and comparing the results with literature values for mammals. Results indicated this dye is metabolized and excreted similarily in trout, dogfish (Squalus acanthias) and mammals. Large differences between trout and other species in transport maxima (Tm) of BSP based on body weights, were explained when the Tm values were based on liver blood clearance of BSP, a physiological rate reflecting blood flow. The objective of the second study was to determine if biliary excretion affects the toxicity of a foreign compound toxic to trout. This problem was approached by evaluating the effect of bile and cystic duct ligation on the mean lethal dose (LD 50) of rotenone to trout. To determine if biliary excretion affected the selective toxicity of this compound to trout, the effect of bile duct ligation on the rotenone LD 50 to rats was estimated and the results were compared with those obtained from the trout. The toxicant was administered intraperitoneally and intravenously in trout and intraperitoneally in rats. No increase in toxicity of rotenone occurred upon surgical impairment of bile flow in either the trout or the rats, Similarities in the toxicity of rotenone to trout and rats were observed when the toxicant was administered intraperitoneally, The data suggest the selective toxicity of rotenone to fish may be primarily caused by different routes of entry. The results of these experiments indicate the excretory functions of the liver of fish and mammals are similar. Close

• 15. [Article] Food relations and production of cutthroat trout, Salmo clarki clarki Richardson, in an experimental stream

  Production, food consumption and food habits by groups of small, mixed and large sizes of cutthroat trout were studied in enriched and unenriched sections of the Berry Creek Experimental Stream, Oregon ...

  Citation × Citation Citation Abstract Copy Title: Food relations and production of cutthroat trout, Salmo clarki clarki Richardson, in an experimental stream Author: McIntyre, John D. Production, food consumption and food habits by groups of small, mixed and large sizes of cutthroat trout were studied in enriched and unenriched sections of the Berry Creek Experimental Stream, Oregon State University. Continuous introduction of sucrose and urea to portions of the stream resulted in heavy growth of Sphaerotilus natans which supported large biomasses of benthic insects. Production was estimated from monthly changes of biomass. Measurements of growth rates of experimental fish and the relationship between rates of growth and rates of food consumption of fish held in aquaria made estimates of food consumption by the stream fish possible. Analyses were made of the stomach contents of trout removed monthly from the experimental sections. The seasonal contribution to trout food consumption by the important food groups was estimated. Measurements of benthic biomass showed that insects especially midge larvae, benefited greatly from the Sphaerotilus in the enriched sections but organic drift did not increase markedly as a result of enrichment. In both enriched and unenriched sections trout production and food consumption values were highest for small trout, intermediate for mixed sizes and lowest for large trout. Production and food consumption by all size groups of trout increased greatly as a result of enrichment. Title: Food relations and production of cutthroat trout, Salmo clarki clarki Richardson, in an experimental stream Author: McIntyre, John D. Production, food consumption and food habits by groups of small, mixed and large sizes of cutthroat trout were studied in enriched and unenriched sections of the Berry Creek Experimental Stream, Oregon State University. Continuous introduction of sucrose and urea to portions of the stream resulted in heavy growth of Sphaerotilus natans which supported large biomasses of benthic insects. Production was estimated from monthly changes of biomass. Measurements of growth rates of experimental fish and the relationship between rates of growth and rates of food consumption of fish held in aquaria made estimates of food consumption by the stream fish possible. Analyses were made of the stomach contents of trout removed monthly from the experimental sections. The seasonal contribution to trout food consumption by the important food groups was estimated. Measurements of benthic biomass showed that insects especially midge larvae, benefited greatly from the Sphaerotilus in the enriched sections but organic drift did not increase markedly as a result of enrichment. In both enriched and unenriched sections trout production and food consumption values were highest for small trout, intermediate for mixed sizes and lowest for large trout. Production and food consumption by all size groups of trout increased greatly as a result of enrichment. Close

• 16. [Article] Landscape-scale evaluation of genetic structure among barrier-isolated populations of coastal cutthroat trout, Oncorhynchus clarki clarki

  Citation × Citation Citation Abstract Copy Title: Landscape-scale evaluation of genetic structure among barrier-isolated populations of coastal cutthroat trout, Oncorhynchus clarki clarki Author: Guy, Troy J. Title: Landscape-scale evaluation of genetic structure among barrier-isolated populations of coastal cutthroat trout, Oncorhynchus clarki clarki Author: Guy, Troy J. Close

• 17. [Article] Geographic variation in genetic and meristic characters of coastal cutthroat trout (Oncorhynchus clarki clarki)

  Citation × Citation Citation Abstract Copy Title: Geographic variation in genetic and meristic characters of coastal cutthroat trout (Oncorhynchus clarki clarki) Author: Williams, Thomas Herbert Title: Geographic variation in genetic and meristic characters of coastal cutthroat trout (Oncorhynchus clarki clarki) Author: Williams, Thomas Herbert Close

• 18. [Article] Bioenergetic evaluation of diel vertical migration by bull trout

  I evaluated hypotheses related to growth as a driver of depth use and diel vertical migration by bull trout (Salvelinus confluentus) in a thermally stratified reservoir. I applied a bioenergetic model ...

  Citation × Citation Citation Abstract Copy Title: Bioenergetic evaluation of diel vertical migration by bull trout Author: Eckmann, Madeleine I evaluated hypotheses related to growth as a driver of depth use and diel vertical migration by bull trout (Salvelinus confluentus) in a thermally stratified reservoir. I applied a bioenergetic model to evaluate growth of bull trout in relation to potential patterns of diel depth use by bull trout in Ross Lake, Washington. Modeled patterns of growth were derived from observed vertical distributions of temperature and prey availability. I also observed bull trout depth (and corresponding temperature) use patterns to determine if observed behaviors corresponded with those predicted to maximize growth. Results of this work suggest that bull trout migrations beyond 25 m deep in Ross Lake cannot be explained exclusively by growth and survival alone, two common explanations for diel vertical migration. These deeper excursions may be explained by a third driver that has not been previously emphasized: the importance of colder water for gametogenesis. Further evaluation of this hypothesis as a means of explaining diel vertical migration for bull trout and other fish species in similar environments is warranted. Title: Bioenergetic evaluation of diel vertical migration by bull trout Author: Eckmann, Madeleine I evaluated hypotheses related to growth as a driver of depth use and diel vertical migration by bull trout (Salvelinus confluentus) in a thermally stratified reservoir. I applied a bioenergetic model to evaluate growth of bull trout in relation to potential patterns of diel depth use by bull trout in Ross Lake, Washington. Modeled patterns of growth were derived from observed vertical distributions of temperature and prey availability. I also observed bull trout depth (and corresponding temperature) use patterns to determine if observed behaviors corresponded with those predicted to maximize growth. Results of this work suggest that bull trout migrations beyond 25 m deep in Ross Lake cannot be explained exclusively by growth and survival alone, two common explanations for diel vertical migration. These deeper excursions may be explained by a third driver that has not been previously emphasized: the importance of colder water for gametogenesis. Further evaluation of this hypothesis as a means of explaining diel vertical migration for bull trout and other fish species in similar environments is warranted. Close

• 19. [Article] The influence of natural mortality and other life history factors on the yield to the angler of planted cutthroat trout in Munsel Lake, Oregon

  Citation × Citation Citation Abstract Copy Title: The influence of natural mortality and other life history factors on the yield to the angler of planted cutthroat trout in Munsel Lake, Oregon Author: Hansen, David Title: The influence of natural mortality and other life history factors on the yield to the angler of planted cutthroat trout in Munsel Lake, Oregon Author: Hansen, David Close

• 20. [Article] Life history of rainbow trout and considerations for introducing steelhead into southern Chile

  Citation × Citation Citation Abstract Copy Title: Life history of rainbow trout and considerations for introducing steelhead into southern Chile Author: Poblete Arellano, Tirso S. Title: Life history of rainbow trout and considerations for introducing steelhead into southern Chile Author: Poblete Arellano, Tirso S. Close