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• 1. [Article] Surface-Ground Water Interactions Along Oregon's Lower Walla Walla River 2000 - 2001

  Abstract -- This report describes surface - groundwater interactions in the Walla Walla River between the WA-OR border and the town of Milton-Freewater. It includes detailed sections on seepage, vertical ...

  Citation × Citation Citation Abstract Copy Title: Surface-Ground Water Interactions Along Oregon's Lower Walla Walla River 2000 - 2001 Abstract -- This report describes surface - groundwater interactions in the Walla Walla River between the WA-OR border and the town of Milton-Freewater. It includes detailed sections on seepage, vertical and horizontal hydraulic gradients, and chemical signatures. It also provides geologic and watertable mapping, conclusions, and recommendations. Title: Surface-Ground Water Interactions Along Oregon's Lower Walla Walla River 2000 - 2001 Abstract -- This report describes surface - groundwater interactions in the Walla Walla River between the WA-OR border and the town of Milton-Freewater. It includes detailed sections on seepage, vertical and horizontal hydraulic gradients, and chemical signatures. It also provides geologic and watertable mapping, conclusions, and recommendations. Close

• 2. [Article] Harney-Malheur Lakes Subbasin Assessment

  Abstract -- Harney-Malheur Lakes Subbasin Assessment was completed by the Harney County Watershed Council. The Harney-Malheur Lakes Subbasin is 894,061 acres in Harney County, Oregon. The document discusses ...

  Citation × Citation Citation Abstract Copy Title: Harney-Malheur Lakes Subbasin Assessment Abstract -- Harney-Malheur Lakes Subbasin Assessment was completed by the Harney County Watershed Council. The Harney-Malheur Lakes Subbasin is 894,061 acres in Harney County, Oregon. The document discusses the history of the Harney-Malheur Lakes Subbasin including the environmental factors associated withthe subbasin (climate, geology, hydrology, ground and surface water and water supply. Fish and wildlife, habitat and vegetation types are discussed to understand the main inhabitants and how best to manage those populations found in the subbasin. The last section of the document discusses current issues within the subbasin and the reccomendations to deal with those issues. Title: Harney-Malheur Lakes Subbasin Assessment Abstract -- Harney-Malheur Lakes Subbasin Assessment was completed by the Harney County Watershed Council. The Harney-Malheur Lakes Subbasin is 894,061 acres in Harney County, Oregon. The document discusses the history of the Harney-Malheur Lakes Subbasin including the environmental factors associated withthe subbasin (climate, geology, hydrology, ground and surface water and water supply. Fish and wildlife, habitat and vegetation types are discussed to understand the main inhabitants and how best to manage those populations found in the subbasin. The last section of the document discusses current issues within the subbasin and the reccomendations to deal with those issues. Close

• 3. [Article] NF - Effect of Bull Trout and Brook Trout Interactions on Foraging Habitat, Feeding Behavior, and Growth

  Abstract -- Observations of free-ranging sympatric bull trout Salvelinus confluentus and nonnative brook trout S. fontinalis in two eastern Oregon headwater streams provided little evidence of habitat ...

  Citation × Citation Citation Abstract Copy Title: NF - Effect of Bull Trout and Brook Trout Interactions on Foraging Habitat, Feeding Behavior, and Growth Abstract -- Observations of free-ranging sympatric bull trout Salvelinus confluentus and nonnative brook trout S. fontinalis in two eastern Oregon headwater streams provided little evidence of habitat partitioning. Both species held focal feeding points in similar microhabitats and fed primarily from the water column rather than from the surface or benthos. In an instream experiment, 20 enclosures were assigned one of three treatments: two bull trout, four bull trout, or a mix of two bull trout and two brook trout. In the enclosures, macroinvertebrate drift was restricted and trout densities were elevated, creating an environment of reduced food and habitat resources. Under these conditions, there was no indication of a niche shift by bull trout; feeding behavior and habitat use by bull trout did not differ depending on the presence or absence of brook trout. Brook trout in the mixed-species treatment were the most aggressive, maintained dominance in 75% of the enclosures, and exhibited significantly higher growth than sympatric bull trout. However, the effects of intra-and interspecific interactions on bull trout growth were equivalent. Given the absence of resource partitioning and a niche shift by bull trout in the presence of brook trout (despite obvious interference interactions), we suggest that the displacement of bull trout by brook trout is likely when resources are scarce. Title: NF - Effect of Bull Trout and Brook Trout Interactions on Foraging Habitat, Feeding Behavior, and Growth Abstract -- Observations of free-ranging sympatric bull trout Salvelinus confluentus and nonnative brook trout S. fontinalis in two eastern Oregon headwater streams provided little evidence of habitat partitioning. Both species held focal feeding points in similar microhabitats and fed primarily from the water column rather than from the surface or benthos. In an instream experiment, 20 enclosures were assigned one of three treatments: two bull trout, four bull trout, or a mix of two bull trout and two brook trout. In the enclosures, macroinvertebrate drift was restricted and trout densities were elevated, creating an environment of reduced food and habitat resources. Under these conditions, there was no indication of a niche shift by bull trout; feeding behavior and habitat use by bull trout did not differ depending on the presence or absence of brook trout. Brook trout in the mixed-species treatment were the most aggressive, maintained dominance in 75% of the enclosures, and exhibited significantly higher growth than sympatric bull trout. However, the effects of intra-and interspecific interactions on bull trout growth were equivalent. Given the absence of resource partitioning and a niche shift by bull trout in the presence of brook trout (despite obvious interference interactions), we suggest that the displacement of bull trout by brook trout is likely when resources are scarce. Close

• 4. [Article] Willamette Biological Opinion Chinook Reservoir Research 2010

  Abstract -- We investigated life-history characteristics of juvenile Chinook salmon rearing in Cougar and Lookout Point reservoirs. The study objectives were to provide information on juvenile Chinook ...

  Citation × Citation Citation Abstract Copy Title: Willamette Biological Opinion Chinook Reservoir Research 2010 Abstract -- We investigated life-history characteristics of juvenile Chinook salmon rearing in Cougar and Lookout Point reservoirs. The study objectives were to provide information on juvenile Chinook salmon distribution, relative growth rate, predator/prey interactions, and other population characteristics. In addition, we tested the feasibility of various gear-types and techniques for sampling juvenile Chinook salmon rearing in a reservoir environment. A variety of techniques were necessary to capture juvenile Chinook salmon as reservoir conditions and fish behavior, size, and distribution within the reservoir changed throughout the year. Nighttime snorkel surveys were the least invasive and most productive method to investigate habitat utilization and fry distribution early in the Spring. Minnow traps, hoop nets, Lampara seining, and mid-water trawling were largely ineffective at sampling fry and larger-sized juveniles. Oneida Lake trap nets were the most effective at capturing larger-sized juvenile Chinook salmon when reservoir surface temperatures remained cool. Title: Willamette Biological Opinion Chinook Reservoir Research 2010 Abstract -- We investigated life-history characteristics of juvenile Chinook salmon rearing in Cougar and Lookout Point reservoirs. The study objectives were to provide information on juvenile Chinook salmon distribution, relative growth rate, predator/prey interactions, and other population characteristics. In addition, we tested the feasibility of various gear-types and techniques for sampling juvenile Chinook salmon rearing in a reservoir environment. A variety of techniques were necessary to capture juvenile Chinook salmon as reservoir conditions and fish behavior, size, and distribution within the reservoir changed throughout the year. Nighttime snorkel surveys were the least invasive and most productive method to investigate habitat utilization and fry distribution early in the Spring. Minnow traps, hoop nets, Lampara seining, and mid-water trawling were largely ineffective at sampling fry and larger-sized juveniles. Oneida Lake trap nets were the most effective at capturing larger-sized juvenile Chinook salmon when reservoir surface temperatures remained cool. Close

• 5. [Article] Hult Reservoir (Siuslaw Basin) Fish Species Composition Size and Relative Abundance_Final2018

  Abstract -- Seven species of fish were encountered in Hult Reservoir in 2017: largemouth bass (Micropterus salmoides), cutthroat trout (Oncorhynchus clarkii), tainbow trout/winter steelhead (Oncorhynchus ...

  Citation × Citation Citation Abstract Copy Title: Hult Reservoir (Siuslaw Basin) Fish Species Composition Size and Relative Abundance_Final2018 Abstract -- Seven species of fish were encountered in Hult Reservoir in 2017: largemouth bass (Micropterus salmoides), cutthroat trout (Oncorhynchus clarkii), tainbow trout/winter steelhead (Oncorhynchus mykiss), bluegill (Lepomis macrochirus), reticulate sculpin (Cottus perplexus), brown bullhead (Ameiurus nebulosus) and western brook lamprey (Lampetra richardsoni). The most abundant fish observed were largemouth bass and bluegill in the summer and fall, and cutthroat in the winter. Cutthroat trout were much more prevalent in the fall and winter sampling than in the summer. Presumably, most cutthroat trout moved up into the tributaries to seek thermal refuge during the summer months and returned to the reservoir once the temperatures were more conducive to growth and survival. However, some of them likely moved downstream, were preyed upon, or perished from the high summer temperatures and low dissolved oxygen conditions in the reservoir in summer. Under current conditions, high surface temperature (>20?), bass predation, and hypoxic dissolved oxygen levels below four meters of depth show that reservoir conditions are inhospitable for juvenile salmonids in the summer. Currently there are well established fisheries for both cutthroat trout (spring, fall, winter) and largemouth bass (summer) in the reservoir, and we talked to several anglers who target each of these species. Habitat segregation in the summer between the salmonids who move out of the reservoir and the warm-water fish that remain and spawn in the reservoir results in a diversified year-round angling opportunity. There were no coho salmon (juvenile or adult) observed in Hult Reservoir in 2017, but adult coho salmon were observed spawning just downstream of the dam. This observation verifies that a proportion of the adult coho attempting to ascend the ladder at Lake Creek Falls are successful and continue migration upstream to the vicinity of Hult Reservoir. It may be possible to keep the current fishery in Hult Reservoir as it stands and still increase coho production in the system by improving adult passage at Lake Creek Falls, and possibly at Hult Dam. Title: Hult Reservoir (Siuslaw Basin) Fish Species Composition Size and Relative Abundance_Final2018 Abstract -- Seven species of fish were encountered in Hult Reservoir in 2017: largemouth bass (Micropterus salmoides), cutthroat trout (Oncorhynchus clarkii), tainbow trout/winter steelhead (Oncorhynchus mykiss), bluegill (Lepomis macrochirus), reticulate sculpin (Cottus perplexus), brown bullhead (Ameiurus nebulosus) and western brook lamprey (Lampetra richardsoni). The most abundant fish observed were largemouth bass and bluegill in the summer and fall, and cutthroat in the winter. Cutthroat trout were much more prevalent in the fall and winter sampling than in the summer. Presumably, most cutthroat trout moved up into the tributaries to seek thermal refuge during the summer months and returned to the reservoir once the temperatures were more conducive to growth and survival. However, some of them likely moved downstream, were preyed upon, or perished from the high summer temperatures and low dissolved oxygen conditions in the reservoir in summer. Under current conditions, high surface temperature (>20?), bass predation, and hypoxic dissolved oxygen levels below four meters of depth show that reservoir conditions are inhospitable for juvenile salmonids in the summer. Currently there are well established fisheries for both cutthroat trout (spring, fall, winter) and largemouth bass (summer) in the reservoir, and we talked to several anglers who target each of these species. Habitat segregation in the summer between the salmonids who move out of the reservoir and the warm-water fish that remain and spawn in the reservoir results in a diversified year-round angling opportunity. There were no coho salmon (juvenile or adult) observed in Hult Reservoir in 2017, but adult coho salmon were observed spawning just downstream of the dam. This observation verifies that a proportion of the adult coho attempting to ascend the ladder at Lake Creek Falls are successful and continue migration upstream to the vicinity of Hult Reservoir. It may be possible to keep the current fishery in Hult Reservoir as it stands and still increase coho production in the system by improving adult passage at Lake Creek Falls, and possibly at Hult Dam. Close

• 6. [Article] Length and age at maturity of female yelloweye rockfish (Sebastes rubberimus) and cabezon (Scorpaenichthys marmoratus) from Oregon waters based on histological evaluation of maturity Information Report number 2009-04

  Abstract -- Accurate estimates of female age or length at maturity are critical for the conservation of exploited fish stocks. Age at maturity is particularly important, as it strongly influences population ...

  Citation × Citation Citation Abstract Copy Title: Length and age at maturity of female yelloweye rockfish (Sebastes rubberimus) and cabezon (Scorpaenichthys marmoratus) from Oregon waters based on histological evaluation of maturity Information Report number 2009-04 Abstract -- Accurate estimates of female age or length at maturity are critical for the conservation of exploited fish stocks. Age at maturity is particularly important, as it strongly influences population model estimates of sustainable harvest rates (Clark 1991) and, along with mean body size, is an important predictor of the risk of overexploitation (Reynolds et al. 2005). For many U.S. west coast groundfish stocks, data on age and length at maturity is of poor quality. The age at maturity curves used in many stock assessments are currently based on macroscopic (visual) assessment of ovary condition. However, there is abundant evidence that histological evaluation of ovarian thin-sections, especially if combined with optimal seasonal sampling, is much more accurate (Gunderson et al. 1980, Wyllie Echeverria 1987, West 1990, Nichol and Pikitch 1994, Hannah and Parker 2007). The age data that have been used to develop curves of age at maturity for some species is also based on outdated ageing methods, such as surface aging of otoliths, as opposed to the more accurate “break and burn” technique (Barss 1989, Wyllie Echeverria 1987, Chilton and Beamish 1982). For other species, such as cabezon (Scorpaenichthys marmoratus), accurate age and growth data, based on thin-sectioning of otoliths, have just recently been developed (Grebel and Cailliet 2003). Information on age and length at maturity that is based on histological evaluation of maturity status and modern ageing techniques is therefore needed for many U.S. west coast groundfish species. Histology-based maturity data has been developed for some U.S. west coast groundfish species. These include darkblotched rockfish (Sebastes crameri, Nichol and Pikitch 1994), petrale sole (Eopsetta jordani, Hannah et al. 2002), greenstriped rockfish (Sebastes elongatus, Shaw and Gunderson 2006), Pacific ocean perch (Sebastes alutus, Hannah and Parker 2007) and rosethorn rockfish (Sebastes helvomaculatus, Shaw and Gunderson 2008). We report here on the development of similar data for female yelloweye rockfish (Sebastes rubberimus) and cabezon. Title: Length and age at maturity of female yelloweye rockfish (Sebastes rubberimus) and cabezon (Scorpaenichthys marmoratus) from Oregon waters based on histological evaluation of maturity Information Report number 2009-04 Abstract -- Accurate estimates of female age or length at maturity are critical for the conservation of exploited fish stocks. Age at maturity is particularly important, as it strongly influences population model estimates of sustainable harvest rates (Clark 1991) and, along with mean body size, is an important predictor of the risk of overexploitation (Reynolds et al. 2005). For many U.S. west coast groundfish stocks, data on age and length at maturity is of poor quality. The age at maturity curves used in many stock assessments are currently based on macroscopic (visual) assessment of ovary condition. However, there is abundant evidence that histological evaluation of ovarian thin-sections, especially if combined with optimal seasonal sampling, is much more accurate (Gunderson et al. 1980, Wyllie Echeverria 1987, West 1990, Nichol and Pikitch 1994, Hannah and Parker 2007). The age data that have been used to develop curves of age at maturity for some species is also based on outdated ageing methods, such as surface aging of otoliths, as opposed to the more accurate “break and burn” technique (Barss 1989, Wyllie Echeverria 1987, Chilton and Beamish 1982). For other species, such as cabezon (Scorpaenichthys marmoratus), accurate age and growth data, based on thin-sectioning of otoliths, have just recently been developed (Grebel and Cailliet 2003). Information on age and length at maturity that is based on histological evaluation of maturity status and modern ageing techniques is therefore needed for many U.S. west coast groundfish species. Histology-based maturity data has been developed for some U.S. west coast groundfish species. These include darkblotched rockfish (Sebastes crameri, Nichol and Pikitch 1994), petrale sole (Eopsetta jordani, Hannah et al. 2002), greenstriped rockfish (Sebastes elongatus, Shaw and Gunderson 2006), Pacific ocean perch (Sebastes alutus, Hannah and Parker 2007) and rosethorn rockfish (Sebastes helvomaculatus, Shaw and Gunderson 2008). We report here on the development of similar data for female yelloweye rockfish (Sebastes rubberimus) and cabezon. Close

• 7. [Article] Abundance Monitoring of Juvenile Salmonids In Coastal Oregon and Lower Columbia Streams, 2008 Report Number: OPSW-ODFW-2009-1

  Abstract -- As part of the Oregon Plan for Salmon and Watersheds, the Oregon Department of Fish and Wildlife (ODFW) initiated this project in 1998 to monitor the status and trend in abundance and distribution ...

  Citation × Citation Citation Abstract Copy Title: Abundance Monitoring of Juvenile Salmonids In Coastal Oregon and Lower Columbia Streams, 2008 Report Number: OPSW-ODFW-2009-1 Abstract -- As part of the Oregon Plan for Salmon and Watersheds, the Oregon Department of Fish and Wildlife (ODFW) initiated this project in 1998 to monitor the status and trend in abundance and distribution of juvenile coho salmon (Oncorhynchus kisutch) in coastal Oregon streams. This report summarizes the data collected during the summer of 2008 and, for coho salmon, compares it to data previously collected. The project originally surveyed only 1st-3rd order (tributary) streams but was expanded in 2002 to include juvenile steelhead (Oncorhynchus mykiss) and 4th-6th order (mainstem) rearing areas and in 2006 to the Oregon portion of the Lower Columbia River coho evolutionarily significant unit (ESU) (Figure 1). The sampling frame is intended to encompass all non-tidal coho and steelhead rearing habitat. The original 100k stream layer frame was replaced by a 24k frame in 2007. A Generalized Random Tessellation Stratified design (GRTS) (Stevens 2002) was used to create a spatially balanced, random point distribution. Sites were stratified by Monitoring Area (MA) and stream order (Table 1). A detailed description of the sampling frames and survey designs are found in Jepsen and Rodgers (2004) and Jepsen and Leader (2007). Field crews snorkeled all pools meeting the size criteria (6 m2 in surface area and 40 cm in maximum depth) in one kilometer of stream encompassing the GRTS point. Snorkeling was conducted during the minimum flow period from July to September using a single pass of one to four snorkelers, depending on stream width. In each pool counts were made of juvenile coho, Chinook, steelhead 90 mm, and cutthroat 90 mm. Presence was noted for dace, shiners, and trout < 90 mm. Sites with poor water clarity or quality were electrofished using a single pass without block nets to determine presence for coho, steelhead and cutthroat in each pool. To assess repeatability and quality control supervisory staff resurveyed 10% of tributary sites in each MA. Data were summarized by MA and stream order for analyses. Average pool density and percent pool occupancy for each site was averaged by MA. The percent of sites with at least one fish and with >0.7 coho/m2 are reported for each MA. 0.7 coho/m2 is regarded as full seeding after Nickelson et al. (1992) who reported full seeding based on electrofishing as 1.0 coho/m2 and Rodgers et al. (1992) who found that snorkelers observed 70% of the coho counted by electrofishing. CDFs, variances, and confidence intervals were created using tools developed by the EMAP Design and Analysis Team (EPA 2009). Title: Abundance Monitoring of Juvenile Salmonids In Coastal Oregon and Lower Columbia Streams, 2008 Report Number: OPSW-ODFW-2009-1 Abstract -- As part of the Oregon Plan for Salmon and Watersheds, the Oregon Department of Fish and Wildlife (ODFW) initiated this project in 1998 to monitor the status and trend in abundance and distribution of juvenile coho salmon (Oncorhynchus kisutch) in coastal Oregon streams. This report summarizes the data collected during the summer of 2008 and, for coho salmon, compares it to data previously collected. The project originally surveyed only 1st-3rd order (tributary) streams but was expanded in 2002 to include juvenile steelhead (Oncorhynchus mykiss) and 4th-6th order (mainstem) rearing areas and in 2006 to the Oregon portion of the Lower Columbia River coho evolutionarily significant unit (ESU) (Figure 1). The sampling frame is intended to encompass all non-tidal coho and steelhead rearing habitat. The original 100k stream layer frame was replaced by a 24k frame in 2007. A Generalized Random Tessellation Stratified design (GRTS) (Stevens 2002) was used to create a spatially balanced, random point distribution. Sites were stratified by Monitoring Area (MA) and stream order (Table 1). A detailed description of the sampling frames and survey designs are found in Jepsen and Rodgers (2004) and Jepsen and Leader (2007). Field crews snorkeled all pools meeting the size criteria (6 m2 in surface area and 40 cm in maximum depth) in one kilometer of stream encompassing the GRTS point. Snorkeling was conducted during the minimum flow period from July to September using a single pass of one to four snorkelers, depending on stream width. In each pool counts were made of juvenile coho, Chinook, steelhead 90 mm, and cutthroat 90 mm. Presence was noted for dace, shiners, and trout < 90 mm. Sites with poor water clarity or quality were electrofished using a single pass without block nets to determine presence for coho, steelhead and cutthroat in each pool. To assess repeatability and quality control supervisory staff resurveyed 10% of tributary sites in each MA. Data were summarized by MA and stream order for analyses. Average pool density and percent pool occupancy for each site was averaged by MA. The percent of sites with at least one fish and with >0.7 coho/m2 are reported for each MA. 0.7 coho/m2 is regarded as full seeding after Nickelson et al. (1992) who reported full seeding based on electrofishing as 1.0 coho/m2 and Rodgers et al. (1992) who found that snorkelers observed 70% of the coho counted by electrofishing. CDFs, variances, and confidence intervals were created using tools developed by the EMAP Design and Analysis Team (EPA 2009). Close

• 8. [Article] 2006 Borax Lake Chub Investigations Progress Reports 2006

  Abstract -- Borax Lake chub (Gila boraxobius) is represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake in Harney County, Oregon. The Borax Lake chub is a small ...

  Citation × Citation Citation Abstract Copy Title: 2006 Borax Lake Chub Investigations Progress Reports 2006 Abstract -- Borax Lake chub (Gila boraxobius) is represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake in Harney County, Oregon. The Borax Lake chub is a small minnow endemic to Borax Lake and adjacent wetlands in Oregon’s Alvord Basin (Williams and Bond 1980). Borax Lake is a natural lake, perched 10 meters above the desert floor on sinter deposits, which is fed almost exclusively by thermal groundwater. The Borax Lake chub was listed as endangered under the federal Endangered Species Act in 1982 (U.S. Fish and Wildlife Service 1982). Population abundance estimates obtained in 1991-1996 indicated a fluctuating population ranging from a low of 8,144 fish to a high of 34,634 fish (Salzer 1997). The basis for the Borax Lake chub’s listed status was not population size, but the security of a very limited, unique, isolated, and vulnerable habitat. Because Borax Lake is situated above salt deposits on the desert floor, alteration of the salt crust shoreline could reduce lake levels and the habitat quantity and quality available to Borax Lake chub. At the time of the listing, Borax Lake was threatened by habitat alteration caused by geothermal energy development and alteration of the lake shore crust to provide irrigation to surrounding pasture lands. The Borax Lake chub federal recovery plan, completed in 1987, advocated protection of the lake ecosystem through the acquisition of key private lands, protection of groundwater and surface waters, controls on access, and the removal of livestock grazing (U.S. Fish and Wildlife Service 1987). Numerous recovery measures implemented since listing have improved the conservation status of Borax Lake chub and protection of its habitat (Williams and Macdonald 2003). When the species was listed, critical habitat was designated on 259 hectares of land surrounding the lake, including 129 hectares of public lands and two 65- hectare parcels of private land. In 1983, the U.S. Bureau of Land Management designated the public land as an Area of Critical Environmental Concern. The Nature Conservancy began leasing the private lands in 1983 and purchased them in 1993, bringing the entire critical habitat into public or conservation ownership. The Nature Conservancy ended water diversion from the lake for irrigation and livestock grazing within the critical habitat. Passage of the Steens Mountain Cooperative Management and Protection Act of 2000 removed the public BLM lands from mineral and geothermal development within a majority of the basin. These actions, combined with detailed studies of the chub and their habitat have added substantially to our knowledge of the Borax Lake ecosystem (Scoppettone et al. 1995, Salzer 1992, Perkins et al. 1996). However, three primary threats remain. These include the threat to the fragile lake shoreline, wetlands, and soils from a recent increase in recreational use around the lake (particularly off-road vehicle usage), the threat of introduction of nonnative species, and potential negative impacts to the aquifer from geothermal groundwater withdrawal if groundwater pumping were to occur on private lands outside the protected areas (Williams and Macdonald 2003). Although an increase in abundance is not a goal in the successful recovery of this species, monitoring trends in abundance over time is an important management tool to assess species status. From 1998-2004, data describing the abundance of the Borax Lake chub population are not available. Abundance estimates were obtained from 1986- 1997 by The Nature Conservancy (Salzer 1997) (Figure 1). Abundance estimates for 1986-1990 are not comparable with those obtained in 1991-1997. Prior to 1991, estimates were obtained only from traps set around the perimeter of the lake. In 1991, estimates were obtained from traps set on a regularly spaced grid throughout the lake. A study comparing the methods suggests that prior to 1991 abundance was under estimated, perhaps by as much as 50 percent (Salzer 1992). A recent review of the conservation status of the Borax Lake chub by Williams and Macdonald (2003) cited the lack of recent and ongoing population and ecosystem monitoring as one argument against downlisting or delisting the species at this time. The chub population has experienced substantial fluctuations in abundance over the time period (1986-1997) when abundance data are available (Figure 1). At the time of the review, the most recent abundance estimates that were obtained in 1996 and 1997 were some of the lowest estimates since 1991. Borax Lake chub population abundance estimates from 1986 to 1997 and 2005 to 2006. Horizontal bars represent 95% confidence limits. In 1986-1990 (solid symbols), only the perimeter of the lake was trapped. After 1990 (open symbols) the entire lake was trapped. Estimates are not directly comparable across these time periods. There are limited data on population age structure that offer valuable insight into the productivity of Borax Lake chub. Williams and Bond (1983) examined lengthfrequency data and concluded that the population consisted primarily of age 1 fish, with few age 2 and age 3 fish present. Limited opercle bone aging of chub collected in 1992- 1993 also indicated that most Borax Lake were less than one year of age (67-79%), yet a few individuals were aged at 10+ years (Scoppettone 1995). Because Borax Lake chub are only found in one location and the population is apparently dominated by a single year-class of adults, the species has a high inherent risk of extinction. 3 The objectives of this study were to: 1) obtain a mark-recapture population estimate of Borax Lake chub, and 2) to evaluate ways to reduce handling of Borax Lake chub when monitoring population abundance both by modifying previous mark-recapture protocols and by developing snorkeling survey protocols to use as an alternative to mark-recapture estimates. In addition, we collected data regarding lake temperatures, chub size (age) structure, and the condition of the fragile lake shoreline and outflows. Title: 2006 Borax Lake Chub Investigations Progress Reports 2006 Abstract -- Borax Lake chub (Gila boraxobius) is represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake in Harney County, Oregon. The Borax Lake chub is a small minnow endemic to Borax Lake and adjacent wetlands in Oregon’s Alvord Basin (Williams and Bond 1980). Borax Lake is a natural lake, perched 10 meters above the desert floor on sinter deposits, which is fed almost exclusively by thermal groundwater. The Borax Lake chub was listed as endangered under the federal Endangered Species Act in 1982 (U.S. Fish and Wildlife Service 1982). Population abundance estimates obtained in 1991-1996 indicated a fluctuating population ranging from a low of 8,144 fish to a high of 34,634 fish (Salzer 1997). The basis for the Borax Lake chub’s listed status was not population size, but the security of a very limited, unique, isolated, and vulnerable habitat. Because Borax Lake is situated above salt deposits on the desert floor, alteration of the salt crust shoreline could reduce lake levels and the habitat quantity and quality available to Borax Lake chub. At the time of the listing, Borax Lake was threatened by habitat alteration caused by geothermal energy development and alteration of the lake shore crust to provide irrigation to surrounding pasture lands. The Borax Lake chub federal recovery plan, completed in 1987, advocated protection of the lake ecosystem through the acquisition of key private lands, protection of groundwater and surface waters, controls on access, and the removal of livestock grazing (U.S. Fish and Wildlife Service 1987). Numerous recovery measures implemented since listing have improved the conservation status of Borax Lake chub and protection of its habitat (Williams and Macdonald 2003). When the species was listed, critical habitat was designated on 259 hectares of land surrounding the lake, including 129 hectares of public lands and two 65- hectare parcels of private land. In 1983, the U.S. Bureau of Land Management designated the public land as an Area of Critical Environmental Concern. The Nature Conservancy began leasing the private lands in 1983 and purchased them in 1993, bringing the entire critical habitat into public or conservation ownership. The Nature Conservancy ended water diversion from the lake for irrigation and livestock grazing within the critical habitat. Passage of the Steens Mountain Cooperative Management and Protection Act of 2000 removed the public BLM lands from mineral and geothermal development within a majority of the basin. These actions, combined with detailed studies of the chub and their habitat have added substantially to our knowledge of the Borax Lake ecosystem (Scoppettone et al. 1995, Salzer 1992, Perkins et al. 1996). However, three primary threats remain. These include the threat to the fragile lake shoreline, wetlands, and soils from a recent increase in recreational use around the lake (particularly off-road vehicle usage), the threat of introduction of nonnative species, and potential negative impacts to the aquifer from geothermal groundwater withdrawal if groundwater pumping were to occur on private lands outside the protected areas (Williams and Macdonald 2003). Although an increase in abundance is not a goal in the successful recovery of this species, monitoring trends in abundance over time is an important management tool to assess species status. From 1998-2004, data describing the abundance of the Borax Lake chub population are not available. Abundance estimates were obtained from 1986- 1997 by The Nature Conservancy (Salzer 1997) (Figure 1). Abundance estimates for 1986-1990 are not comparable with those obtained in 1991-1997. Prior to 1991, estimates were obtained only from traps set around the perimeter of the lake. In 1991, estimates were obtained from traps set on a regularly spaced grid throughout the lake. A study comparing the methods suggests that prior to 1991 abundance was under estimated, perhaps by as much as 50 percent (Salzer 1992). A recent review of the conservation status of the Borax Lake chub by Williams and Macdonald (2003) cited the lack of recent and ongoing population and ecosystem monitoring as one argument against downlisting or delisting the species at this time. The chub population has experienced substantial fluctuations in abundance over the time period (1986-1997) when abundance data are available (Figure 1). At the time of the review, the most recent abundance estimates that were obtained in 1996 and 1997 were some of the lowest estimates since 1991. Borax Lake chub population abundance estimates from 1986 to 1997 and 2005 to 2006. Horizontal bars represent 95% confidence limits. In 1986-1990 (solid symbols), only the perimeter of the lake was trapped. After 1990 (open symbols) the entire lake was trapped. Estimates are not directly comparable across these time periods. There are limited data on population age structure that offer valuable insight into the productivity of Borax Lake chub. Williams and Bond (1983) examined lengthfrequency data and concluded that the population consisted primarily of age 1 fish, with few age 2 and age 3 fish present. Limited opercle bone aging of chub collected in 1992- 1993 also indicated that most Borax Lake were less than one year of age (67-79%), yet a few individuals were aged at 10+ years (Scoppettone 1995). Because Borax Lake chub are only found in one location and the population is apparently dominated by a single year-class of adults, the species has a high inherent risk of extinction. 3 The objectives of this study were to: 1) obtain a mark-recapture population estimate of Borax Lake chub, and 2) to evaluate ways to reduce handling of Borax Lake chub when monitoring population abundance both by modifying previous mark-recapture protocols and by developing snorkeling survey protocols to use as an alternative to mark-recapture estimates. In addition, we collected data regarding lake temperatures, chub size (age) structure, and the condition of the fragile lake shoreline and outflows. Close

• 9. [Article] 2009 Borax Lake Chub Investigations Progress Reports 2009

  Abstract -- The Borax Lake chub (Gila boraxobius) is a small minnow endemic to Borax Lake and adjacent wetlands in the Alvord Basin in Harney County, Oregon (Williams and Bond 1980). Borax Lake chub are ...

  Citation × Citation Citation Abstract Copy Title: 2009 Borax Lake Chub Investigations Progress Reports 2009 Abstract -- The Borax Lake chub (Gila boraxobius) is a small minnow endemic to Borax Lake and adjacent wetlands in the Alvord Basin in Harney County, Oregon (Williams and Bond 1980). Borax Lake chub are represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake. Borax Lake is a natural lake perched 10 meters above the desert floor on sinter deposits, which is fed almost exclusively by thermal groundwater. The Borax Lake chub was listed as endangered under the federal Endangered Species Act in 1982 (U.S. Fish and Wildlife Service 1982). Population abundance estimates obtained since 1991 indicate a fluctuating population ranging between approximately 4,000 and 34,000 fish (Salzer 1997; Scheerer and Jacobs 2008). The basis for the Borax Lake chub’s listed status was not population size, but the security of a very limited, unique, isolated, and vulnerable habitat. Because Borax Lake is situated above salt deposits on the desert floor, alteration of the salt crust shoreline could reduce lake levels and the habitat quantity and quality available to Borax Lake chub. At the time of the listing, Borax Lake was threatened by habitat alteration caused by geothermal energy development and alteration of the lake shore crust to provide irrigation to surrounding pasture lands. The Borax Lake chub federal recovery plan, completed in 1987, advocated protection of the lake ecosystem through the acquisition of key private lands, protection of groundwater and surface waters, controls on access, and the removal of livestock grazing (U.S. Fish and Wildlife Service 1987). Recovery measures implemented since listing have improved the conservation status of Borax Lake chub and protection of its habitat (Williams and Macdonald 2003). When the species was listed, critical habitat was designated on 259 hectares of land surrounding the lake, including 129 hectares of public lands and two 65-hectare parcels of private land. In 1983, the U.S. Bureau of Land Management designated the public land as an Area of Critical Environmental Concern. The Nature Conservancy began leasing the private lands in 1983 and purchased them in 1993, bringing the entire critical habitat into public or conservation ownership. The Nature Conservancy ended water diversion from the lake for irrigation and livestock grazing within the critical habitat. Passage of the Steens Mountain Cooperative Management and Protection Act of 2000 removed the public BLM lands from mineral and geothermal development within a majority of the basin. These actions, combined with detailed studies of the chub and their habitat, have added substantially to our knowledge of the Borax Lake ecosystem (Scoppettone et al. 1995, Salzer 1992, Perkins et al. 1996). However, three primary threats remain. These include the threat to the fragile lake shoreline, wetlands, and soils from a recent increase in recreational use around the lake (particularly off-road vehicle usage), the threat of introduction of nonnative species, and potential negative impacts to the aquifer from geothermal groundwater withdrawal if groundwater pumping were to occur on private lands outside the protected areas (Williams and Macdonald 2003). A review of the conservation status of the Borax Lake chub by Williams and Macdonald (2003) cited the lack of recent and ongoing population and ecosystem monitoring as one argument against downlisting or delisting the species at that time. Although an increase in abundance is not a goal in the successful recovery of this species, monitoring trends in abundance over time is an important management tool to assess species status. The objectives of this study were to: 1) obtain a mark-recapture population estimate of Borax Lake chub and 2) to evaluate habitat conditions at Borax Lake, including the condition of the fragile lake shoreline and outflows. This report describes results from monitoring conducted by Oregon Department of Fish and Wildlife’s Native Fish Investigations Project in 2009. Title: 2009 Borax Lake Chub Investigations Progress Reports 2009 Abstract -- The Borax Lake chub (Gila boraxobius) is a small minnow endemic to Borax Lake and adjacent wetlands in the Alvord Basin in Harney County, Oregon (Williams and Bond 1980). Borax Lake chub are represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake. Borax Lake is a natural lake perched 10 meters above the desert floor on sinter deposits, which is fed almost exclusively by thermal groundwater. The Borax Lake chub was listed as endangered under the federal Endangered Species Act in 1982 (U.S. Fish and Wildlife Service 1982). Population abundance estimates obtained since 1991 indicate a fluctuating population ranging between approximately 4,000 and 34,000 fish (Salzer 1997; Scheerer and Jacobs 2008). The basis for the Borax Lake chub’s listed status was not population size, but the security of a very limited, unique, isolated, and vulnerable habitat. Because Borax Lake is situated above salt deposits on the desert floor, alteration of the salt crust shoreline could reduce lake levels and the habitat quantity and quality available to Borax Lake chub. At the time of the listing, Borax Lake was threatened by habitat alteration caused by geothermal energy development and alteration of the lake shore crust to provide irrigation to surrounding pasture lands. The Borax Lake chub federal recovery plan, completed in 1987, advocated protection of the lake ecosystem through the acquisition of key private lands, protection of groundwater and surface waters, controls on access, and the removal of livestock grazing (U.S. Fish and Wildlife Service 1987). Recovery measures implemented since listing have improved the conservation status of Borax Lake chub and protection of its habitat (Williams and Macdonald 2003). When the species was listed, critical habitat was designated on 259 hectares of land surrounding the lake, including 129 hectares of public lands and two 65-hectare parcels of private land. In 1983, the U.S. Bureau of Land Management designated the public land as an Area of Critical Environmental Concern. The Nature Conservancy began leasing the private lands in 1983 and purchased them in 1993, bringing the entire critical habitat into public or conservation ownership. The Nature Conservancy ended water diversion from the lake for irrigation and livestock grazing within the critical habitat. Passage of the Steens Mountain Cooperative Management and Protection Act of 2000 removed the public BLM lands from mineral and geothermal development within a majority of the basin. These actions, combined with detailed studies of the chub and their habitat, have added substantially to our knowledge of the Borax Lake ecosystem (Scoppettone et al. 1995, Salzer 1992, Perkins et al. 1996). However, three primary threats remain. These include the threat to the fragile lake shoreline, wetlands, and soils from a recent increase in recreational use around the lake (particularly off-road vehicle usage), the threat of introduction of nonnative species, and potential negative impacts to the aquifer from geothermal groundwater withdrawal if groundwater pumping were to occur on private lands outside the protected areas (Williams and Macdonald 2003). A review of the conservation status of the Borax Lake chub by Williams and Macdonald (2003) cited the lack of recent and ongoing population and ecosystem monitoring as one argument against downlisting or delisting the species at that time. Although an increase in abundance is not a goal in the successful recovery of this species, monitoring trends in abundance over time is an important management tool to assess species status. The objectives of this study were to: 1) obtain a mark-recapture population estimate of Borax Lake chub and 2) to evaluate habitat conditions at Borax Lake, including the condition of the fragile lake shoreline and outflows. This report describes results from monitoring conducted by Oregon Department of Fish and Wildlife’s Native Fish Investigations Project in 2009. Close

• 10. [Article] Warner Valley Fish Investigations- Warner Suckers Progress Reports 2008

  Abstract -- The Warner sucker (Catostomus warnerensis) is endemic to the Warner Valley, an endorheic subbasin of the Great Basin in southeastern Oregon and northwestern Nevada. This species was historically ...

  Citation × Citation Citation Abstract Copy Title: Warner Valley Fish Investigations- Warner Suckers Progress Reports 2008 Abstract -- The Warner sucker (Catostomus warnerensis) is endemic to the Warner Valley, an endorheic subbasin of the Great Basin in southeastern Oregon and northwestern Nevada. This species was historically abundant and its historical range includes three permanent lakes (Hart, Crump, and Pelican), several ephemeral lakes, a network of sloughs and diversion canals, and three major tributary drainages (Honey, Deep, and Twentymile Creeks). Warner sucker abundance and distribution has declined over the past century and it was federally listed as threatened in 1985 due to habitat fragmentation and threats posed by the proliferation of piscivorous non-native game fishes (U.S. Fish and Wildlife Service 1985). The Warner Valley is a northeast-southwest trending endorheic basin which extends approximately 90 km (Figure 1). The elevation of the valley floor is approximately 1,370 m and the basin is bound by fault block escarpments, the Warner Rim on the west and Hart Mountain and Poker Jim Ridge on the east. The Warner basin was formed during the middle Tertiary and late Quaternary geologic periods as a result of volcanic and tectonic activity (Baldwin 1976). Abundant precipitation during the Pleistocene Epoch resulted in the formation of Pluvial Lake Warner (Hubbs and Miller 1948). At its maximum extent approximately 11,000 years ago, the lake reached approximately 100 m in depth and 1,300 km2 in area (Snyder et al. 1964, Weide 1975). In 2008, precipitation and snow pack were near average and Hart and Crump Lakes never filled completely. In 2007, Crump Lake water levels were very low with less than a quarter of the surface area wetted during the winter. Both lakes have been watered continuously since 1993. The Warner sucker inhabits the lakes and low gradient stream reaches of the Warner Valley. Two life history forms are present that comprise the metapopulation of Warner suckers: lake and stream morphs. The lake suckers are lacustrine adfluvial or potamodromous fish which normally spawn in the streams. However, upstream migration may be blocked by low stream flows during dry water years or by irrigation diversion dams and spawning may occur in nearshore areas of the lakes (White et al. 1990). The stream suckers inhabit and spawn in the three major tributary drainages (Honey, Deep, and Twentymile Creeks). Large lake-dwelling populations of introduced fishes in the lakes likely reduce sucker recruitment by predation on young suckers (U.S. Fish and Wildlife Service 1998). The Recovery Plan for the Threatened and Rare Native Fishes of the Warner Basin and Alkali Subbasin (U.S. Fish and Wildlife Service 1998) sets recovery criteria for delisting the species. These criteria require that (1) a self-sustaining metapopulation is distributed throughout the Twentymile, Honey, and Deep Creek (below the falls) drainages, and in Pelican, Crump, and Hart Lakes, (2) passage is restored within and among the Twentymile, Honey, and Deep Creek (below the falls) drainages so that the individual populations of Warner suckers can function as a metapopulation, and (3) no threats exist that would likely threaten the survival of the species over a significant portion of its range. In 2008, we conducted investigations in Hart and Crump Lakes to quantify the abundance and distribution of Warner suckers, to search for evidence of recent recruitment, and to estimate sucker abundance relative to nonnative fish abundance. In addition we investigated growth and movement patterns. We used Passive Integrated Transponder (PIT) tagged suckers to determine growth rates and movements, tracked radio-tagged suckers to document seasonal spawning migrations, fished a screw trap in Twelvemile Creek to monitor downstream movements, and operated a trap at the Dyke diversion dam on Twentymile Creek to monitor upstream movements. Title: Warner Valley Fish Investigations- Warner Suckers Progress Reports 2008 Abstract -- The Warner sucker (Catostomus warnerensis) is endemic to the Warner Valley, an endorheic subbasin of the Great Basin in southeastern Oregon and northwestern Nevada. This species was historically abundant and its historical range includes three permanent lakes (Hart, Crump, and Pelican), several ephemeral lakes, a network of sloughs and diversion canals, and three major tributary drainages (Honey, Deep, and Twentymile Creeks). Warner sucker abundance and distribution has declined over the past century and it was federally listed as threatened in 1985 due to habitat fragmentation and threats posed by the proliferation of piscivorous non-native game fishes (U.S. Fish and Wildlife Service 1985). The Warner Valley is a northeast-southwest trending endorheic basin which extends approximately 90 km (Figure 1). The elevation of the valley floor is approximately 1,370 m and the basin is bound by fault block escarpments, the Warner Rim on the west and Hart Mountain and Poker Jim Ridge on the east. The Warner basin was formed during the middle Tertiary and late Quaternary geologic periods as a result of volcanic and tectonic activity (Baldwin 1976). Abundant precipitation during the Pleistocene Epoch resulted in the formation of Pluvial Lake Warner (Hubbs and Miller 1948). At its maximum extent approximately 11,000 years ago, the lake reached approximately 100 m in depth and 1,300 km2 in area (Snyder et al. 1964, Weide 1975). In 2008, precipitation and snow pack were near average and Hart and Crump Lakes never filled completely. In 2007, Crump Lake water levels were very low with less than a quarter of the surface area wetted during the winter. Both lakes have been watered continuously since 1993. The Warner sucker inhabits the lakes and low gradient stream reaches of the Warner Valley. Two life history forms are present that comprise the metapopulation of Warner suckers: lake and stream morphs. The lake suckers are lacustrine adfluvial or potamodromous fish which normally spawn in the streams. However, upstream migration may be blocked by low stream flows during dry water years or by irrigation diversion dams and spawning may occur in nearshore areas of the lakes (White et al. 1990). The stream suckers inhabit and spawn in the three major tributary drainages (Honey, Deep, and Twentymile Creeks). Large lake-dwelling populations of introduced fishes in the lakes likely reduce sucker recruitment by predation on young suckers (U.S. Fish and Wildlife Service 1998). The Recovery Plan for the Threatened and Rare Native Fishes of the Warner Basin and Alkali Subbasin (U.S. Fish and Wildlife Service 1998) sets recovery criteria for delisting the species. These criteria require that (1) a self-sustaining metapopulation is distributed throughout the Twentymile, Honey, and Deep Creek (below the falls) drainages, and in Pelican, Crump, and Hart Lakes, (2) passage is restored within and among the Twentymile, Honey, and Deep Creek (below the falls) drainages so that the individual populations of Warner suckers can function as a metapopulation, and (3) no threats exist that would likely threaten the survival of the species over a significant portion of its range. In 2008, we conducted investigations in Hart and Crump Lakes to quantify the abundance and distribution of Warner suckers, to search for evidence of recent recruitment, and to estimate sucker abundance relative to nonnative fish abundance. In addition we investigated growth and movement patterns. We used Passive Integrated Transponder (PIT) tagged suckers to determine growth rates and movements, tracked radio-tagged suckers to document seasonal spawning migrations, fished a screw trap in Twelvemile Creek to monitor downstream movements, and operated a trap at the Dyke diversion dam on Twentymile Creek to monitor upstream movements. Close