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• 191. [Article] Status of Winter Rearing Habitat in Four Coho Population Units_ODFW AQI Winter Report Final 2008

  Abstract -- We described the status of habitat in four Oregon coastal coho salmon (Oncorhynchus kisutch) population units (Nehalem, Siuslaw, Coquille, South Umpqua) during winter 2007, estimated the potential ...

  Citation × Citation Citation Abstract Copy Title: Status of Winter Rearing Habitat in Four Coho Population Units_ODFW AQI Winter Report Final 2008 Abstract -- We described the status of habitat in four Oregon coastal coho salmon (Oncorhynchus kisutch) population units (Nehalem, Siuslaw, Coquille, South Umpqua) during winter 2007, estimated the potential winter rearing capacity of streams within those population units, and described the differences observed in stream habitat between winter and summer with emphasis on slow water and secondary channel habitats. Sample sites were randomly selected and spatially balanced within the distribution of coho salmon (juvenile and adult) in Oregon coastal watersheds south of the Columbia River. Twenty five sites were targeted within each of the four population units. Each survey was approximately 1000 m in length and adhered to protocols in Moore et al (2007). The Habitat Limiting Factors Model (HLFM) was used to estimate habitat capacity and quality for rearing juvenile coho. The HLFM predicted that the Nehalem and Siuslaw basins could support the highest density of juvenile coho, and the South Umpqua the least. Seasonal changes in habitat were similar to that reported in a previous study. Winter surveys facilitated the assessment of habitat status and estimating capacity because the surveys were conducted at the time when habitat is most limiting to survival of juvenile coho. Winter surveys were particularly valuable in capturing secondary channel and slow water habitat units such as beaver ponds and alcoves. We also performed a sensitivity analysis to determine the number of survey sites necessary to represent each population unit within the desired confidence range of 30% recommended in the Coho Conservation Plan. Twenty five target sites were not adequate to describe the winter parr capacity within a 95% confidence interval of +30% in each population unit. Confidence intervals of estimates of parr per km ranged from 34 to 60% and mean parr per m2 ranged from 20 to 45%. Title: Status of Winter Rearing Habitat in Four Coho Population Units_ODFW AQI Winter Report Final 2008 Abstract -- We described the status of habitat in four Oregon coastal coho salmon (Oncorhynchus kisutch) population units (Nehalem, Siuslaw, Coquille, South Umpqua) during winter 2007, estimated the potential winter rearing capacity of streams within those population units, and described the differences observed in stream habitat between winter and summer with emphasis on slow water and secondary channel habitats. Sample sites were randomly selected and spatially balanced within the distribution of coho salmon (juvenile and adult) in Oregon coastal watersheds south of the Columbia River. Twenty five sites were targeted within each of the four population units. Each survey was approximately 1000 m in length and adhered to protocols in Moore et al (2007). The Habitat Limiting Factors Model (HLFM) was used to estimate habitat capacity and quality for rearing juvenile coho. The HLFM predicted that the Nehalem and Siuslaw basins could support the highest density of juvenile coho, and the South Umpqua the least. Seasonal changes in habitat were similar to that reported in a previous study. Winter surveys facilitated the assessment of habitat status and estimating capacity because the surveys were conducted at the time when habitat is most limiting to survival of juvenile coho. Winter surveys were particularly valuable in capturing secondary channel and slow water habitat units such as beaver ponds and alcoves. We also performed a sensitivity analysis to determine the number of survey sites necessary to represent each population unit within the desired confidence range of 30% recommended in the Coho Conservation Plan. Twenty five target sites were not adequate to describe the winter parr capacity within a 95% confidence interval of +30% in each population unit. Confidence intervals of estimates of parr per km ranged from 34 to 60% and mean parr per m2 ranged from 20 to 45%. Close

• 192. [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

• 193. [Article] Escapement and Productivity of Summer Steelhead and Spring Chinook Salmon in the John Day River; Annual Report 2017

  Abstract -- The John Day River, located in northeastern Oregon, supports five wild populations of summer steelhead (Oncorhynchus mykiss) and three populations of wild spring chinook (Oncorhynchus tschawytscha) ...

  Citation × Citation Citation Abstract Copy Title: Escapement and Productivity of Summer Steelhead and Spring Chinook Salmon in the John Day River; Annual Report 2017 Abstract -- The John Day River, located in northeastern Oregon, supports five wild populations of summer steelhead (Oncorhynchus mykiss) and three populations of wild spring chinook (Oncorhynchus tschawytscha) with no hatchery supplementation. However, these populations remain depressed relative to historic levels. In 1999, the National Marine Fisheries Service (NMFS) listed the Middle Columbia River summer steelhead Distinct Population Segment (DPS), which includes the John Day River Major Population Group (MPG), as threatened under the Endangered Species Act (ESA). Although numerous habitat protection and rehabilitation projects have been implemented within the John Day River basin to improve steelhead and other salmonid freshwater production and survival, it has been difficult to estimate the effectiveness of these projects without a systematic program in place to collect information on the status, trends, and distribution of spawning activity, juvenile salmonids, and aquatic habitat conditions within the basin. Prior to the inception of this project, population and environmental monitoring of steelhead in the basin consisted of a combination of index spawning surveys and periodic monitoring of some status and trend indicators. While index spawning data is useful for drawing inference about long-term trends in adult steelhead abundance, they are limited for determining the status of steelhead escapement or distribution at the population or MPG scale because survey sites are not randomly selected and are likely biased towards streams with higher fish abundance. A broader approach to the monitoring and evaluation of status and trends in anadromous and resident salmonid populations and their habitats was needed to provide data to effectively support restoration efforts and guide alternative future management actions in the basin. The Independent Scientific Review Panel (ISRP) recommended that the region move away from index surveys and embrace probabilistic sampling for most population and habitat monitoring. To meet the ISRP recommendation, the structure and methods employed by the Oregon Plan for Salmon and Watersheds Monitoring Program were extended to the John Day basin. This approach incorporates the sampling strategy of the United States Environmental Protection Agency’s (EPA) Environmental Monitoring and Assessment Program (EMAP). This research effort employs a statistically based and spatially explicit sampling design to answer key monitoring questions, integrate on-going sampling efforts, and improve agency coordination. The current program seeks to integrate project objectives focused on summer steelhead spawning metrics, juvenile salmonid metrics, and aquatic habitat conditions. Title: Escapement and Productivity of Summer Steelhead and Spring Chinook Salmon in the John Day River; Annual Report 2017 Abstract -- The John Day River, located in northeastern Oregon, supports five wild populations of summer steelhead (Oncorhynchus mykiss) and three populations of wild spring chinook (Oncorhynchus tschawytscha) with no hatchery supplementation. However, these populations remain depressed relative to historic levels. In 1999, the National Marine Fisheries Service (NMFS) listed the Middle Columbia River summer steelhead Distinct Population Segment (DPS), which includes the John Day River Major Population Group (MPG), as threatened under the Endangered Species Act (ESA). Although numerous habitat protection and rehabilitation projects have been implemented within the John Day River basin to improve steelhead and other salmonid freshwater production and survival, it has been difficult to estimate the effectiveness of these projects without a systematic program in place to collect information on the status, trends, and distribution of spawning activity, juvenile salmonids, and aquatic habitat conditions within the basin. Prior to the inception of this project, population and environmental monitoring of steelhead in the basin consisted of a combination of index spawning surveys and periodic monitoring of some status and trend indicators. While index spawning data is useful for drawing inference about long-term trends in adult steelhead abundance, they are limited for determining the status of steelhead escapement or distribution at the population or MPG scale because survey sites are not randomly selected and are likely biased towards streams with higher fish abundance. A broader approach to the monitoring and evaluation of status and trends in anadromous and resident salmonid populations and their habitats was needed to provide data to effectively support restoration efforts and guide alternative future management actions in the basin. The Independent Scientific Review Panel (ISRP) recommended that the region move away from index surveys and embrace probabilistic sampling for most population and habitat monitoring. To meet the ISRP recommendation, the structure and methods employed by the Oregon Plan for Salmon and Watersheds Monitoring Program were extended to the John Day basin. This approach incorporates the sampling strategy of the United States Environmental Protection Agency’s (EPA) Environmental Monitoring and Assessment Program (EMAP). This research effort employs a statistically based and spatially explicit sampling design to answer key monitoring questions, integrate on-going sampling efforts, and improve agency coordination. The current program seeks to integrate project objectives focused on summer steelhead spawning metrics, juvenile salmonid metrics, and aquatic habitat conditions. Close

• 194. [Article] A Proposal for an Integrated Research Monitoring Program for Oregon Coastal Chinook Populations

  Abstract -- Among the many chinook salmon populations contributing to large, mixed stock ocean net, troll, and recreational fisheries managed by the Pacific Salmon Commission (PSC) there is a good deal ...

  Citation × Citation Citation Abstract Copy Title: A Proposal for an Integrated Research Monitoring Program for Oregon Coastal Chinook Populations Abstract -- Among the many chinook salmon populations contributing to large, mixed stock ocean net, troll, and recreational fisheries managed by the Pacific Salmon Commission (PSC) there is a good deal of diversity with respect to productivity, life history characteristics, and ocean distribution. During the years immediately following the adoption of the original 1985 Pacific Salmon Treaty (PST), lack of adequate data prevented the PSC from managing effectively for these differences. Instead, chinook management outlined in Annex IV of the original treaty was based upon long term population trends for very large aggregates of stocks. Although harvest ceilings were established as part of a PST recovery plan for over-exploited stocks, they were based on average coast-wide production trends and resulted in over harvest of weak stocks in some years and failure to take advantage of large returns in other years. By the mid-l 990's, data relative to the distribution and abundance of many salmon stocks contributing to PST fisheries was improving. At the same time, there was increasing dissatisfaction with quota-based management and strong interest in instituting annual abundance-based management for stock aggregates that share geographic proximity of spawning areas, similar life history and genetic characteristics, and similar distributions in the ocean. Abundance-based management for aggregated stocks would establish and implement annual fishery exploitation rates in fisheries that insure long-term sustainability for all aggregates and related individual stocks. In the absence of bilateral agreement between the U.S. and Canada regarding implementation of abundance-based management, the three voting U.S. PSC Commissioners signed the 1996 Letter of Agreement (LOA) that defined elements of an abundance-based management approach for chinook salmon fisheries in southeast Alaska. The LOA was designed to: 1) set the stage for future bilateral negotiations regarding abundance based management; 2) clarify the role of PST fisheries in rebuilding depressed natural stocks; and 3) provide a means for sharing conservation responsibility of far-north migrating stocks originating from watersheds in Oregon and Washington. The foundation for abundance-based management set forth in the LOA was subsequently expanded upon and incorporated as Aggregate Abundance-Based Management (AABM) in Annex IV, Chapter 3 of the 1999 PST. Application of the abundance-based management outlined in the 1996 LOA and the subsequent 1999 amendments to the PST requires knowledge of the stock recruitment relationships, biological spawning escapement goals, and annual forecasts of ocean abundance and distribution for stocks in each aggregate to regulate fishery harvest. Managers must also have annual post-season estimates of aggregate specific exploitation rates and in-river escapements to assess the effectiveness of regulatory measures. The base-monitoring program for Oregon's coastal chinook under the 1985 PSC met only a few of these data requirements. In recognition of requirements for new and more precise data, the signatories of the original LOA sought out additional federal funds for new and expanded monitoring programs. Since 1997 Congress has annually approved approximately $1.8 million for additional research and monitoring needed to implement terms of the LOA. The PSC delegated discretionary authority for the use of those funds to the U.S. Section's Chinook Technical Committee (CTC). Title: A Proposal for an Integrated Research Monitoring Program for Oregon Coastal Chinook Populations Abstract -- Among the many chinook salmon populations contributing to large, mixed stock ocean net, troll, and recreational fisheries managed by the Pacific Salmon Commission (PSC) there is a good deal of diversity with respect to productivity, life history characteristics, and ocean distribution. During the years immediately following the adoption of the original 1985 Pacific Salmon Treaty (PST), lack of adequate data prevented the PSC from managing effectively for these differences. Instead, chinook management outlined in Annex IV of the original treaty was based upon long term population trends for very large aggregates of stocks. Although harvest ceilings were established as part of a PST recovery plan for over-exploited stocks, they were based on average coast-wide production trends and resulted in over harvest of weak stocks in some years and failure to take advantage of large returns in other years. By the mid-l 990's, data relative to the distribution and abundance of many salmon stocks contributing to PST fisheries was improving. At the same time, there was increasing dissatisfaction with quota-based management and strong interest in instituting annual abundance-based management for stock aggregates that share geographic proximity of spawning areas, similar life history and genetic characteristics, and similar distributions in the ocean. Abundance-based management for aggregated stocks would establish and implement annual fishery exploitation rates in fisheries that insure long-term sustainability for all aggregates and related individual stocks. In the absence of bilateral agreement between the U.S. and Canada regarding implementation of abundance-based management, the three voting U.S. PSC Commissioners signed the 1996 Letter of Agreement (LOA) that defined elements of an abundance-based management approach for chinook salmon fisheries in southeast Alaska. The LOA was designed to: 1) set the stage for future bilateral negotiations regarding abundance based management; 2) clarify the role of PST fisheries in rebuilding depressed natural stocks; and 3) provide a means for sharing conservation responsibility of far-north migrating stocks originating from watersheds in Oregon and Washington. The foundation for abundance-based management set forth in the LOA was subsequently expanded upon and incorporated as Aggregate Abundance-Based Management (AABM) in Annex IV, Chapter 3 of the 1999 PST. Application of the abundance-based management outlined in the 1996 LOA and the subsequent 1999 amendments to the PST requires knowledge of the stock recruitment relationships, biological spawning escapement goals, and annual forecasts of ocean abundance and distribution for stocks in each aggregate to regulate fishery harvest. Managers must also have annual post-season estimates of aggregate specific exploitation rates and in-river escapements to assess the effectiveness of regulatory measures. The base-monitoring program for Oregon's coastal chinook under the 1985 PSC met only a few of these data requirements. In recognition of requirements for new and more precise data, the signatories of the original LOA sought out additional federal funds for new and expanded monitoring programs. Since 1997 Congress has annually approved approximately $1.8 million for additional research and monitoring needed to implement terms of the LOA. The PSC delegated discretionary authority for the use of those funds to the U.S. Section's Chinook Technical Committee (CTC). Close

• 195. [Article] Hood River Bull Trout Abundance, Life History, and Habitat Connectivity, 2007 Progress Reports 2007

  Abstract -- Hood River bull trout are thought to exist as two independent reproductive units (USFWS 2004), known as local populations (Rieman and McIntyre 1995). The Clear Branch local population is isolated ...

  Citation × Citation Citation Abstract Copy Title: Hood River Bull Trout Abundance, Life History, and Habitat Connectivity, 2007 Progress Reports 2007 Abstract -- Hood River bull trout are thought to exist as two independent reproductive units (USFWS 2004), known as local populations (Rieman and McIntyre 1995). The Clear Branch local population is isolated above Clear Branch Dam, which provides limited downstream fish passage during infrequent and sporadic periods of spill and no upstream passage. Bull trout in this population inhabit Laurance Lake Reservoir and tributaries upstream of Clear Branch Dam. The Hood River local population occurs in the mainstem Hood River and Middle Fork Hood River downstream of the Clear Branch Dam and a small number of adult bull trout migrate each year into the Hood River from the Columbia River (Figure 1). The status of both populations is extremely precarious. The Clear Branch population is at risk of a random extinction event due to low numbers, negative interactions with non-native smallmouth bass, isolation and limited spawning habitat (USFWS, 1998). The Hood River population also appears to be small and is threatened by passage barriers, unscreened irrigation systems, impaired water quality and periodic siltation of spawning substrate by glacial outbursts. Clear Branch bull trout spawn in Clear Branch and Pinnacle Creek. After rearing in these two natal streams for an unknown time period, most are believed to migrate downstream to Laurance Lake Reservoir. Clear Branch bull trout have been documented passing over the dam spillway during high water events (Pribyl et al. 1996) and may provide a recruitment source for the Hood River local population. Adult bull trout tagged at Powerdale Dam have been observed at Coe Branch irrigation diversion and in a trap at the base of Clear Branch dam. These fish may have been attempting to reach spawning areas located upstream of the dam. However, the success of bull trout migrating downstream via the spillway or the possibility of successfully navigating through the diversion network has never been determined. Depending on the water year, the Middle Fork Irrigation District (MFID) may not spill at all, or the timing of the spill may not coincide with the timing of downstream migration, which is currently unknown (East Fork Hood River and Middle Fork Hood River Watershed analysis). Smallmouth bass were discovered in Lake Laurance Reservoir in the 1990s. Creel surveys have shown that large adult bass are caught occasionally in the reservoir and schools of bass fry have been seen by district fish biologist (Rod French, ODFW, personal communication), suggesting that they are spawning successfully. This illegal introduction poses a potential threat to the Clear Branch bull trout population, but its magnitude is unknown because the bass population size and degree of interaction between the two species are unknown. Bull trout and smallmouth bass have significantly different temperature preferences and tolerances, with bull trout being one of the most sensitive coldwater species and bass being a warm water species. Lake Laurance, a relatively high-altitude reservoir at 890 m (2,920 feet), does not provide ideal bass habitat so these two species may have largely non-overlapping distributions or differing activity periods (Terry Shrader, ODFW warmwater fish biologist, personal communication). However, based on past reservoir temperature data (Berger et al. 2005), there are periods in the reservoir when there is potential for bull trout and bass interaction: periods when bull trout are susceptible to bass predation and when juvenile fish might compete for resources. Spawning activity of the Hood River local population has been observed in a few locations within the Middle Fork of Hood River (Figure 1). Although consistent and extensive spawning areas for this population are not known, some of the locations where juvenile rearing or potential bull trout redds have been observed include the Middle Fork Hood River and some of its tributaries: Bear Creek, Compass Creek and Coe Branch (USFWS 2004). However, Coe Branch, Compass Creek, and the Middle Fork are glacial streams with a high volume of sand and silt which may compromise spawning success. No bull trout spawning or rearing has been observed on the East and West Forks of Hood River. The Middle Fork and mainstem Hood River provide foraging, migration and overwintering habitat. Hood River bull trout are also known to migrate into the Columbia River. Two bull trout tagged at Powerdale Dam (RK 7.2 of mainstem Hood River) were recovered near Drano Lake in Washington State; and one was captured 11 kilometers downstream of the confluence of the Hood and Columbia Rivers (USFWS 2004). Every year (usually between May and July), adult bull trout, presumably migrating upstream from the Columbia River, are captured and anchor tagged at Powerdale Dam. Although some of these tagged fish have been observed upstream (one in Coe Branch and three below Clear Branch dam), the spawning destination of fluvial adults within the Hood River basin is largely unknown. Dispersing juvenile bull trout and migrating adults in this local population are threatened by flow diversions with inadequate screening and passage facilities. Several structures are suspected to impede upstream migration or entrain juvenile and adult bull trout into irrigation works (Pribyl et al. 1996, HRWG 1999). These structures include: the diversion at Clear Branch Dam (passage and screening), Coe Branch (passage and screening), and the Farmers Irrigation District diversion (screening) on the mainstem Hood River (HRWG 1999). However, little research has been conducted to assess the impacts of these structures on migrating bull trout. Beyond a general knowledge of the distribution of Hood River bull trout and the nature of anthropogenic factors that potentially restrict their life history and habitat connectivity, little is known about this recovery unit. Baseline information about adult abundance is lacking for both local populations, the potential of a source (Clear Branch) and sink (Hood River) relationship between the two local populations has not been explored, and the migratory life history of adult fish caught at Powerdale Dam is unknown. The degree to which irrigation and hydropower diversions hamper connectivity within the Hood River basin is also poorly understood. Migratory life histories have been viewed as key to species persistence (Rieman and McIntyre 1995; Dunham and Rieman 1999), and understanding movement patterns and associated habitat requirements are critical to maintaining those migratory forms (Muhlfeld and Morotz 2005; Hostettler 2005). Gaining this information is also critical to evaluating bull trout recovery in the Hood River Subbasin (Coccoli 2004). The Oregon Department of Fish and Wildlife (ODFW) initiated a study in 2006 to improve our understanding of the abundance, life history, and potential limiting factors of the bull trout in this recovery unit. This report describes findings for the first two years of the study (2006-2007). Specific study objectives for the first two years were: 1. Determine the migratory life history of Hood River bull trout and assess the potential impacts of flow diversions and two new falls on the Middle Fork Hood River (scoured by the November 2006 glacial outburst) on bull trout migrations. 2. Determine current distribution of bull trout reproduction and early rearing in historical and potential bull trout streams in the Hood River Subbasin. 3. Determine the juvenile and adult life history the Clear Branch local population and develop a statistically reliable and cost-effective protocol for monitoring the abundance of adult Clear Branch bull trout. 4. Assess the potential impact of smallmouth bass on bull trout in Laurance Lake Reservoir. Title: Hood River Bull Trout Abundance, Life History, and Habitat Connectivity, 2007 Progress Reports 2007 Abstract -- Hood River bull trout are thought to exist as two independent reproductive units (USFWS 2004), known as local populations (Rieman and McIntyre 1995). The Clear Branch local population is isolated above Clear Branch Dam, which provides limited downstream fish passage during infrequent and sporadic periods of spill and no upstream passage. Bull trout in this population inhabit Laurance Lake Reservoir and tributaries upstream of Clear Branch Dam. The Hood River local population occurs in the mainstem Hood River and Middle Fork Hood River downstream of the Clear Branch Dam and a small number of adult bull trout migrate each year into the Hood River from the Columbia River (Figure 1). The status of both populations is extremely precarious. The Clear Branch population is at risk of a random extinction event due to low numbers, negative interactions with non-native smallmouth bass, isolation and limited spawning habitat (USFWS, 1998). The Hood River population also appears to be small and is threatened by passage barriers, unscreened irrigation systems, impaired water quality and periodic siltation of spawning substrate by glacial outbursts. Clear Branch bull trout spawn in Clear Branch and Pinnacle Creek. After rearing in these two natal streams for an unknown time period, most are believed to migrate downstream to Laurance Lake Reservoir. Clear Branch bull trout have been documented passing over the dam spillway during high water events (Pribyl et al. 1996) and may provide a recruitment source for the Hood River local population. Adult bull trout tagged at Powerdale Dam have been observed at Coe Branch irrigation diversion and in a trap at the base of Clear Branch dam. These fish may have been attempting to reach spawning areas located upstream of the dam. However, the success of bull trout migrating downstream via the spillway or the possibility of successfully navigating through the diversion network has never been determined. Depending on the water year, the Middle Fork Irrigation District (MFID) may not spill at all, or the timing of the spill may not coincide with the timing of downstream migration, which is currently unknown (East Fork Hood River and Middle Fork Hood River Watershed analysis). Smallmouth bass were discovered in Lake Laurance Reservoir in the 1990s. Creel surveys have shown that large adult bass are caught occasionally in the reservoir and schools of bass fry have been seen by district fish biologist (Rod French, ODFW, personal communication), suggesting that they are spawning successfully. This illegal introduction poses a potential threat to the Clear Branch bull trout population, but its magnitude is unknown because the bass population size and degree of interaction between the two species are unknown. Bull trout and smallmouth bass have significantly different temperature preferences and tolerances, with bull trout being one of the most sensitive coldwater species and bass being a warm water species. Lake Laurance, a relatively high-altitude reservoir at 890 m (2,920 feet), does not provide ideal bass habitat so these two species may have largely non-overlapping distributions or differing activity periods (Terry Shrader, ODFW warmwater fish biologist, personal communication). However, based on past reservoir temperature data (Berger et al. 2005), there are periods in the reservoir when there is potential for bull trout and bass interaction: periods when bull trout are susceptible to bass predation and when juvenile fish might compete for resources. Spawning activity of the Hood River local population has been observed in a few locations within the Middle Fork of Hood River (Figure 1). Although consistent and extensive spawning areas for this population are not known, some of the locations where juvenile rearing or potential bull trout redds have been observed include the Middle Fork Hood River and some of its tributaries: Bear Creek, Compass Creek and Coe Branch (USFWS 2004). However, Coe Branch, Compass Creek, and the Middle Fork are glacial streams with a high volume of sand and silt which may compromise spawning success. No bull trout spawning or rearing has been observed on the East and West Forks of Hood River. The Middle Fork and mainstem Hood River provide foraging, migration and overwintering habitat. Hood River bull trout are also known to migrate into the Columbia River. Two bull trout tagged at Powerdale Dam (RK 7.2 of mainstem Hood River) were recovered near Drano Lake in Washington State; and one was captured 11 kilometers downstream of the confluence of the Hood and Columbia Rivers (USFWS 2004). Every year (usually between May and July), adult bull trout, presumably migrating upstream from the Columbia River, are captured and anchor tagged at Powerdale Dam. Although some of these tagged fish have been observed upstream (one in Coe Branch and three below Clear Branch dam), the spawning destination of fluvial adults within the Hood River basin is largely unknown. Dispersing juvenile bull trout and migrating adults in this local population are threatened by flow diversions with inadequate screening and passage facilities. Several structures are suspected to impede upstream migration or entrain juvenile and adult bull trout into irrigation works (Pribyl et al. 1996, HRWG 1999). These structures include: the diversion at Clear Branch Dam (passage and screening), Coe Branch (passage and screening), and the Farmers Irrigation District diversion (screening) on the mainstem Hood River (HRWG 1999). However, little research has been conducted to assess the impacts of these structures on migrating bull trout. Beyond a general knowledge of the distribution of Hood River bull trout and the nature of anthropogenic factors that potentially restrict their life history and habitat connectivity, little is known about this recovery unit. Baseline information about adult abundance is lacking for both local populations, the potential of a source (Clear Branch) and sink (Hood River) relationship between the two local populations has not been explored, and the migratory life history of adult fish caught at Powerdale Dam is unknown. The degree to which irrigation and hydropower diversions hamper connectivity within the Hood River basin is also poorly understood. Migratory life histories have been viewed as key to species persistence (Rieman and McIntyre 1995; Dunham and Rieman 1999), and understanding movement patterns and associated habitat requirements are critical to maintaining those migratory forms (Muhlfeld and Morotz 2005; Hostettler 2005). Gaining this information is also critical to evaluating bull trout recovery in the Hood River Subbasin (Coccoli 2004). The Oregon Department of Fish and Wildlife (ODFW) initiated a study in 2006 to improve our understanding of the abundance, life history, and potential limiting factors of the bull trout in this recovery unit. This report describes findings for the first two years of the study (2006-2007). Specific study objectives for the first two years were: 1. Determine the migratory life history of Hood River bull trout and assess the potential impacts of flow diversions and two new falls on the Middle Fork Hood River (scoured by the November 2006 glacial outburst) on bull trout migrations. 2. Determine current distribution of bull trout reproduction and early rearing in historical and potential bull trout streams in the Hood River Subbasin. 3. Determine the juvenile and adult life history the Clear Branch local population and develop a statistically reliable and cost-effective protocol for monitoring the abundance of adult Clear Branch bull trout. 4. Assess the potential impact of smallmouth bass on bull trout in Laurance Lake Reservoir. Close