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• 21. [Article] 2012 Metolius Basin bull trout redd counts

  Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance ...

  Citation × Citation Citation Abstract Copy Title: 2012 Metolius Basin bull trout redd counts Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Title: 2012 Metolius Basin bull trout redd counts Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Close

• 22. [Article] 2011 Metolius River subbasin bull trout redd counts

  Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance ...

  Citation × Citation Citation Abstract Copy Title: 2011 Metolius River subbasin bull trout redd counts Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Title: 2011 Metolius River subbasin bull trout redd counts Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Close

• 23. [Article] 2010 Metolius Basin bull trout redds

  Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance ...

  Citation × Citation Citation Abstract Copy Title: 2010 Metolius Basin bull trout redds Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Title: 2010 Metolius Basin bull trout redds Abstract -- Bull trout are indigenous to the Metolius River basin; however, they were managed as a nuisance species due to their interactions with anadromous sportfish for several decades. In 1960, nuisance management of bull trout ended and protection of bull trout began in 1983 with mandatory catch and release regulations throughout the Metolius River basin. In 1986, the Department initiated annual redd counts for bull trout throughout the basin to document the species status. Redd surveys showed low spawning numbers, and the Department responded by closing all tributaries downstream of Lake Creek to fishing in 1994. A Threatened listing of Columbia River bull trout under the Endangered Species Act in 1998 followed the fishery closure (Fies et al. 1996 and Lohr et al. ####). Bull trout redd counts continue in the basin in accordance with the goals of the Native Fish Conservation Policy. Close

• 24. [Article] Florence area stocked trout evaluation, 1993

  Abstract -- This study evaluates the hatchery rainbow trout program for seventeen dunal lakes in the Siuslaw Fish District near Florence, Oregon (Figure 1). The contribution of stocking rainbow trout in ...

  Citation × Citation Citation Abstract Copy Title: Florence area stocked trout evaluation, 1993 Abstract -- This study evaluates the hatchery rainbow trout program for seventeen dunal lakes in the Siuslaw Fish District near Florence, Oregon (Figure 1). The contribution of stocking rainbow trout in coastal lakes of Oregon has not been systematically evaluated to determine the amount of recreation provided or the catch rate of the hatchery product. Estimates of the angler catch and effort from this study will be used to meet the following three objectives: 1: Describe the current fishery at 17 mid-coast Oregon dunal lakes arid make recommendations to improve the program to increase angler satisfaction. 2: determine the utilization rate and overall contribution of hatchery trout compared to the Oregon Trout Plan statewide goal of a minimum 40¼ catch of hatchery fish. 3: Determine the hatchery trout contribution to the fisheries compared to native trout in lakes with both present. Title: Florence area stocked trout evaluation, 1993 Abstract -- This study evaluates the hatchery rainbow trout program for seventeen dunal lakes in the Siuslaw Fish District near Florence, Oregon (Figure 1). The contribution of stocking rainbow trout in coastal lakes of Oregon has not been systematically evaluated to determine the amount of recreation provided or the catch rate of the hatchery product. Estimates of the angler catch and effort from this study will be used to meet the following three objectives: 1: Describe the current fishery at 17 mid-coast Oregon dunal lakes arid make recommendations to improve the program to increase angler satisfaction. 2: determine the utilization rate and overall contribution of hatchery trout compared to the Oregon Trout Plan statewide goal of a minimum 40¼ catch of hatchery fish. 3: Determine the hatchery trout contribution to the fisheries compared to native trout in lakes with both present. Close

• 25. [Article] Timing and Location of Spawning by Bull Trout and Kokanee in the Odell Lake Watershed and Heising Spring of the Metolius River Watershed, 2003-04.

  Abstract -- Although the present size of the bull trout population within the Odell Lake Recovery Unit is unknown, it appears to be quite small. Spawning by bull trout of the Odell Lake Recovery Unit occurs ...

  Citation × Citation Citation Abstract Copy Title: Timing and Location of Spawning by Bull Trout and Kokanee in the Odell Lake Watershed and Heising Spring of the Metolius River Watershed, 2003-04. Abstract -- Although the present size of the bull trout population within the Odell Lake Recovery Unit is unknown, it appears to be quite small. Spawning by bull trout of the Odell Lake Recovery Unit occurs only in the lower 0.8 km of Trapper Creek, below a falls presumed to be a barrier. Numbers of redds observed in Trapper Creek from 1996 through 2002 have ranged from one to 24. In addition to genetic effects caused by small population size, primary threats to the sustainability of these bull trout include limited spawning and rearing habitat in all streams, hybridization with brook trout in upper Trapper Creek, competition from other fish species, particularly lake trout in Odell Lake, and superimposition of kokanee salmon (O. nerka) redds on bull trout redds. The latter threat may be particularly detrimental because of the large number of kokanee that spawn in lower Trapper Creek. To address concerns of bull trout redd superimposition by bull trout, we designed studies to: 1) Assess the impacts to bull trout reproduction caused by kokanee that spawn at the same location, and 2) Develop acceptable methods to separate bull trout and kokanee that spawn in Trapper Creek, Odell Lake. The first objective will address the concerns that kokanee redds superimposed on bull trout redds will reduce the number of bull trout progeny. During the spawning season, we will cap several undisturbed bull trout redds and an equal number of redds superimposed with kokanee salmon redds. Emergent fry will be captured, identified, and enumerated; statistical comparisons of fry abundance will be made between both groups of redds. To adjust for spawner fecundity, estimates of the size of females that make each redd will be obtained visually. We intend to conduct these studies at Heising Springs on the Metolius River, which helps support one of the healthiest bull trout populations in Oregon. The second objective addresses efforts to enhance the Odell Lake bull trout population. Recently, managers installed a weir to block passage of kokanee salmon to spawning areas in Trapper Creek; bull trout were captured and placed upstream. This activity led to opposition by anglers supportive of kokanee and loss of adult bull trout by an otter that invaded the trap. Our intent is to help managers design and implement methods that 1) prevent kokanee salmon from impacting bull trout redds in Trapper Creek, 2) enable bull trout to move into and out of Trapper Creek without capture and handling, and 3) enumerate bull trout spawning in Trapper Creek. Data collected in Trapper Creek should help with design and implementation of methodologies to separate the species during the spawning season. Title: Timing and Location of Spawning by Bull Trout and Kokanee in the Odell Lake Watershed and Heising Spring of the Metolius River Watershed, 2003-04. Abstract -- Although the present size of the bull trout population within the Odell Lake Recovery Unit is unknown, it appears to be quite small. Spawning by bull trout of the Odell Lake Recovery Unit occurs only in the lower 0.8 km of Trapper Creek, below a falls presumed to be a barrier. Numbers of redds observed in Trapper Creek from 1996 through 2002 have ranged from one to 24. In addition to genetic effects caused by small population size, primary threats to the sustainability of these bull trout include limited spawning and rearing habitat in all streams, hybridization with brook trout in upper Trapper Creek, competition from other fish species, particularly lake trout in Odell Lake, and superimposition of kokanee salmon (O. nerka) redds on bull trout redds. The latter threat may be particularly detrimental because of the large number of kokanee that spawn in lower Trapper Creek. To address concerns of bull trout redd superimposition by bull trout, we designed studies to: 1) Assess the impacts to bull trout reproduction caused by kokanee that spawn at the same location, and 2) Develop acceptable methods to separate bull trout and kokanee that spawn in Trapper Creek, Odell Lake. The first objective will address the concerns that kokanee redds superimposed on bull trout redds will reduce the number of bull trout progeny. During the spawning season, we will cap several undisturbed bull trout redds and an equal number of redds superimposed with kokanee salmon redds. Emergent fry will be captured, identified, and enumerated; statistical comparisons of fry abundance will be made between both groups of redds. To adjust for spawner fecundity, estimates of the size of females that make each redd will be obtained visually. We intend to conduct these studies at Heising Springs on the Metolius River, which helps support one of the healthiest bull trout populations in Oregon. The second objective addresses efforts to enhance the Odell Lake bull trout population. Recently, managers installed a weir to block passage of kokanee salmon to spawning areas in Trapper Creek; bull trout were captured and placed upstream. This activity led to opposition by anglers supportive of kokanee and loss of adult bull trout by an otter that invaded the trap. Our intent is to help managers design and implement methods that 1) prevent kokanee salmon from impacting bull trout redds in Trapper Creek, 2) enable bull trout to move into and out of Trapper Creek without capture and handling, and 3) enumerate bull trout spawning in Trapper Creek. Data collected in Trapper Creek should help with design and implementation of methodologies to separate the species during the spawning season. Close

• 26. [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

• 27. [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

• 28. [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

• 29. [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

• 30. [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