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111. [Article] Lower Snake River Compensation Plan; Oregon Spring Chinook Salmon Harvest Monitoring - 2014 Annual Progress Report
Abstract -- The Imnaha and Grande Ronde River spring Chinook hatchery programs are components of the Lower Snake River Compensation Plan (LSRCP), funded through the U.S. Fish and Wildlife Service (USFWS), ...Citation Citation
- Title:
- Lower Snake River Compensation Plan; Oregon Spring Chinook Salmon Harvest Monitoring - 2014 Annual Progress Report
Abstract -- The Imnaha and Grande Ronde River spring Chinook hatchery programs are components of the Lower Snake River Compensation Plan (LSRCP), funded through the U.S. Fish and Wildlife Service (USFWS), developed to mitigate for wild fish production lost as a result of construction of the four lower Snake River dams. Hatchery Chinook and steelhead smolts in the Snake River basin are produced at LSRCP hatcheries in Washington, Idaho and Oregon. Subsequent adult returns are meant to provide tribal and recreational (sport) fisheries and, in some cases, enhance natural spawner numbers. The Oregon Department of Fish and Wildlife initiated the Imnaha and Grande Ronde spring Chinook hatchery program in 1982 under the LSRCP. Subsequent program management has been coordinated between ODFW, Confederated Tribes of the Umatilla Indian Reservation (CTUIR), and Nez Perce Tribe (NPT). The Imnaha and Grande Ronde River hatchery programs are comprised of five components, each with smolt acclimation and adult collection facilities located on the Imnaha River, upper Grande Ronde River, Lookingglass and Catherine Creeks, and the Lostine River. The Lostine River program interacts with natural production within the broader Wallowa-Lostine population unit. Other hatchery program components are discrete to specific populations indicated. The Lookingglass Creek portion of the program focuses on reintroduction of spring Chinook to that stream and targets the release of 250,000 smolts originating from the Catherine Creek population. Each of the four remaining program components integrates natural-origin fish returning to each respective tributary into production. Smolt release goals, developed to meet LSRCP mitigation responsibilities, include 490,000 for the Imnaha, 250,000 for the Lostine and upper Grande Ronde rivers, and 150,000 for Catherine Creek. Fisheries that target returns to the Imnaha and Grande Ronde hatchery programs are guided by Fishery Management and Evaluation Plans (FMEP), approved by NOAA fisheries under limit 4 of the final 4(d) rule of the Endangered Species Act (ODFW 2011, ODFW and WDFW 2012). The objective of the FMEP is to provide recreational fishing opportunities and related benefits derived from harvest of Imnaha and Grande Ronde basin hatchery-origin spring Chinook salmon in Oregon and Washington in a manner that supports the continued survival and future recovery of natural-origin Chinook salmon. Each respective FMEP utilizes a management framework for harvest of adipose-clipped, hatchery-origin Snake River spring/summer Chinook salmon using abundance-based sliding scales to set annual fishery impacts. Fisheries are prescribed maximum impact rates for both direct and incidental mortality of natural-origin adult salmon in sport and tribal fisheries. Impacts are assessed for each population in relation to critical and minimum abundance thresholds (MAT) as described by the Interior Columbia Technical Recovery Team (ICTRT 2007). Population designations for the Imnaha and Grande Ronde Basins are listed in Table 1, and are based upon an analysis of Chinook salmon life history traits, distribution, abundance, and productivity, and geographical and ecological characteristics of the landscape within the Snake River Spring/Summer Chinook Salmon ESU (McElhany et al. 2000). The abundance-based harvest rate schedule for Imnaha and Grande Ronde Basin fisheries to be shared by all fishing entities in the basin is described in Table 2. Harvest is not considered when hatchery run size does not exceed the number of adults identified for broodstock and supplementation needs as described by sliding scale management plans set for each population’s hatchery program. Surplus is generally defined as the adult hatchery run projection less hatchery adults needed for broodstock. This approach limits sport harvest during years when wild fish runs are below MAT and hatchery fish runs are of similar size. In addition, near the lower end of the harvest rate scale, fisheries are not implemented until the allowable hatchery fish harvest exceeds 20 fish due to potential to over harvest within a single week. Fishery impacts to listed Snake River spring/summer Chinook salmon are assessed on a collective basis (i.e., the sum of recreational and tribal fisheries) by NOAA fisheries. However, the coordination of impact amongst states and tribes is a key component of executing conservation-based fisheries in the Imnaha and Grande Ronde Basins. Co-managers within each basin have developed, and implement annually, an impact sharing agreement that is described in Table 3. Within each fishery scenario, this agreement provides tribal fisheries more of the natural-origin impacts to reflect the non-selective nature of traditional fishing techniques. Recreational fisheries are provided a larger portion of the hatchery harvest such that all available impacts (hatchery and natural collectively) are shared equally (Table 3). Recreational fisheries administered by the states limit harvest (retention) of spring/summer Chinook hatchery-origin salmon with a clipped adipose fin (as evidenced by a healed scar). All salmon with an intact adipose fin (natural-origin) must be released back to the water. Therefore, incidental mortality impacts occur from catch and release of unclipped Snake River spring/summer Chinook salmon in fisheries targeting adipose-clipped hatchery Chinook salmon, and/or from the illegal retention of unclipped fish. It is generally assumed throughout the Columbia River Basin that the mortality rate resulting from the catch and release of salmon in fisheries is 10%. However, for Lookingglass Creek comanagers, with concurrence from NOAA fisheries, assume a slightly lower rate of 7.5% (ODFW and WDFW 2012). As stated in the FMEP, fisheries are adjusted or terminated when the total ESA take limit identified in Table 2 and 3 has been reached. Therefore, once fisheries are initiated regular monitoring is required to ensure consistency with co-manager agreements and FMEP requirements. The objective of this LSRCP project was to conduct statistical creel surveys to determine spring Chinook and steelhead ESA impact levels, harvest and release rates, and to inform decisions regarding fishery status in the Imnaha and Grande Ronde Basins in 2014. In this report, we describe creel surveys conducted and estimates of angler effort, catch, and harvest. In addition we compare these estimates in relation to estimates of natural and hatchery-origin returns to each population to assess consistency with prescribed impacts under FMEP guidelines. Lower Snake River Compensation Plan (LSRCP) ODFW
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112. [Article] Lower Snake River Compensation Plan; Oregon Spring Chinook Salmon Harvest Monitoring - 2013 Annual Progress Report
Abstract -- The Imnaha and Grande Ronde River spring Chinook hatchery programs are components of the Lower Snake River Compensation Plan (LSRCP), funded through the U.S. Fish and Wildlife Service (USFWS), ...Citation Citation
- Title:
- Lower Snake River Compensation Plan; Oregon Spring Chinook Salmon Harvest Monitoring - 2013 Annual Progress Report
Abstract -- The Imnaha and Grande Ronde River spring Chinook hatchery programs are components of the Lower Snake River Compensation Plan (LSRCP), funded through the U.S. Fish and Wildlife Service (USFWS), developed to mitigate for wild fish production lost as a result of construction of four lower Snake River dams. Hatchery Chinook and steelhead smolts in the Snake River basin are produced at LSRCP hatcheries in Washington, Idaho and Oregon. Subsequent adult returns are meant to provide tribal and recreational (sport) fisheries and, in some cases, enhance natural spawner numbers. The Oregon Department of Fish and Wildlife initiated the Imnaha and Grande Ronde spring Chinook hatchery program in 1982 under the LSRCP. Subsequent program management has been coordinated between ODFW, Confederated Tribes of the Umatilla Indian Reservation (CTUIR) and Nez Perce Tribe (NPT). The Imnaha and Grande Ronde River hatchery programs are comprised of five components, each with smolt acclimation and adult collection facilities located on the Imnaha River, upper Grande Ronde River, Lookingglass and Catherine Creeks, and the Lostine River. The Lostine River program interacts with natural production within the broader Wallowa-Lostine population unit. Other hatchery program components are discrete to specific populations indicated. The Lookingglass Creek portion of the program focuses on reintroduction of spring Chinook to that stream and targets the release of 250,000 smolts originating from the Catherine Creek population. Each of the four remaining program components integrates natural-origin fish returning to each respective tributary into production. Smolt release goals, developed to meet LSRCP mitigation responsibilities, include 490,000 for the Imnaha, 250,000 for the Lostine and upper Grande Ronde rivers, and 150,000 for Catherine Creek. Fisheries that target returns to the Imnaha and Grande Ronde hatchery programs are guided by Fishery Management and Evaluation Plans (FMEP), approved by NOAA fisheries under limit 4 of the final 4(d) rule of the Endangered Species Act (ODFW 2011, ODFW and WDFW 2012). The objective of the FMEP is to provide recreational fishing opportunities and related benefits derived from harvest of Imnaha and Grande Ronde basin hatchery-origin spring Chinook salmon in Oregon and Washington in a manner that supports the continued survival and future recovery of natural-origin Chinook salmon. Each respective FMEP utilizes a management framework for harvest of adipose-clipped, hatchery-origin Snake River spring/summer Chinook salmon using abundance-based sliding scales to set annual fishery impacts. Fisheries are prescribed maximum impact rates for both direct and incidental mortality of natural-origin adult salmon in sport and tribal fisheries. Impacts are assessed for each population in relation to critical and minimum abundance thresholds (MAT) as described by the Interior Columbia Technical Recovery Team (ICTRT 2007). Population designations for the Imnaha and Grande Ronde Basins are listed in Table 1, and are based upon an analysis of Chinook salmon life history traits, distribution, abundance, and productivity, and geographical and ecological characteristics of the landscape within the Snake River Spring/Summer Chinook Salmon ESU (McElhany et al. 2000). The abundance-based harvest rate schedule for Imnaha and Grande Ronde Basin fisheries to be shared by all fishing entities in the basin is described in Table 2. Harvest is not considered when hatchery run size does not exceed the number of adults identified for broodstock and supplementation needs as described by sliding scale management plans set for each population’s hatchery program. Surplus is generally defined as adult hatchery run projection less hatchery adults needed for broodstock. This approach limits sport harvest during years when wild fish runs are below MAT and hatchery fish runs are of similar size. In addition, near the lower end of the harvest rate scale, fisheries are not implemented until allowable hatchery fish harvest exceeds 20 fish due to potential to over harvest within a single week. Fishery impacts to listed Snake River spring/summer Chinook salmon are assessed on a collective basis (i.e., the sum of recreational and tribal fisheries) by NOAA fisheries. However, the coordination of impact amongst states and tribes is a key component of executing conservation-based fisheries in the Imnaha and Grande Ronde Basins. Co-managers within each basin have developed, and implement annually, an impact sharing agreement that is described in Table 3. Within each fishery scenario, this agreement provides tribal fisheries more of the natural-origin impacts to reflect the non-selective nature of traditional fishing techniques. Recreational fisheries are provided more of the hatchery harvest such that all available impacts (hatchery and natural collectively) are shared equally (Table 3). Recreational fisheries administered by the states limit harvest (retention) of spring/summer Chinook hatchery-origin salmon with a clipped adipose fin (as evidenced by a healed scar). All salmon with an intact adipose fin (natural-origin) must be released back to the water. Therefore, incidental mortality impacts occur from catch and release of unclipped Snake River spring/summer Chinook salmon in fisheries targeting adipose-clipped hatchery Chinook salmon, and/or from the illegal retention of unclipped fish. It is generally assumed throughout the Columbia River Basin that the mortality rate resulting from the catch and release of salmon in fisheries is 10%. However, for Lookingglass Creek comanagers, with concurrence from NOAA fisheries, assume a slightly lower rate of 7.5% (ODFW and WDFW 2012). As stated in the FMEP, fisheries are adjusted or terminated when the total ESA take limit identified in Table 2 and 3 has been reached. Therefore, once fisheries are initiated regular monitoring is required to ensure consistency with co-manager agreements and FMEP requirements. The objective of this LSRCP project was to conduct statistical creel surveys determine spring Chinook and steelhead ESA impact levels, harvest and release rates, and to inform decisions regarding fishery status in the Imnaha and Grande Ronde Basins in 2013. In this report, we describe creel surveys conducted and estimates of angler effort, catch, and harvest. In addition we compare these estimates in relation to post-season preliminary estimates of natural and hatchery-origin returns to each population to assess consistency with prescribed impacts under FMEP guidelines. Lower Snake River Compensation Plan (LSRCP) ODFW
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Abstract -- The species Oncorhynchus mykiss expresses a complex array of life histories across much of its range as well as considerable geographic variation. Several subspecies have been proposed (Behnke ...
Citation Citation
- Title:
- Factors that Influence Evolutionary Significant Unit Boundaries and Status Assessment in a Highly Polymorphic Species, Oncorhynchus mykiss, in the Columbia Basin
Abstract -- The species Oncorhynchus mykiss expresses a complex array of life histories across much of its range as well as considerable geographic variation. Several subspecies have been proposed (Behnke 1992), although none of them are formally recognized. Two of the proposed subspecies in North America include both trout and steelhead life histories: O.m. irideus, or Coastal rainbow/steelhead, and O.m. gairdneri, or Inland redband/steelhead. A third subspecies that includes an anadromous life history occurs in Asia, while all other North American subspecies are entirely trout. In the Pacific Northwest, the boundary between the coastal and inland subspecies occurs in the Columbia Gorge, where the Columbia River cuts through the Cascade Mountain Range. The steelhead and trout life histories within these two subspecies are genetically more similar to each other than to fish with the same life history in the other subspecies, indicating that the different life histories within a geographic area share an evolutionary origin (Allendorf 1975). Recent molecular systematic surveys suggest that this proposed taxonomic model of North American 0. mykiss subspecies may be over simplified and inaccurate (Currens 1997, Busby et al. 1996, F. Utter, U. of Washington); however, it remains the available model until final revisions to the taxonomy are adopted. The NOAA Fisheries Service (NMFS) further divided 0. mykiss into multiple "Evolutionarily Significant Units" (ESUs)(Waples 1991, 56 FR 58612, Waples 1995) for listing consideration under the federal Endangered Species Act (ESA). The ESA considers "distinct" populations of taxonmnic species to be "species" eligible for legal protection (16 U.S.C. 1532[161). NMFS adopted the concept of ESUs to serve as distinct population segments in their ESA listing decisions, along with specific criteria for defining them. Evidence for whether or not rainbow trout and steelhead are in the same ESUs is presented in this report according to the criteria provided by NMFS policy (56 FR 58612). The U.S. Fish and Wildlife Service (USFWS) likewise recognizes "Distinct Population Segments" (DPSs) that may be listed under ESA. The agencies share jurisdiction over 0. mykiss for ESA decisions, with NMFS overseeing the anadromous steelhead and USFWS overseeing the freshwater trout. NMFS has described ESUs for all Northwest steelhead, whether they have been listed or not (Busby et al. 1996); however, the USFWS has not generally described DPSs for Northwest 0. mykiss trout. During the original coast-wide status review of steelhead conducted in the 1990s, the NMFS Biological Review Team concluded that, in general, 0. mykiss trout are part of steelhead ESUs in cases where the two forms are sympatric and have an opportunity to interbreed (Busby et al. 1996). The review team was less conclusive about whether trout above artificial barriers were part of the ESUs. Trout that are sympatric with steelhead were also included in the ESUs by NMFS in the final listing determinations, but they were not listed. The steelhead in five of the ESUs in the Pacific Northwest were listed, including the Lower Columbia (63 FR 13347), Willamette, Mid-Columbia (64 FR 14517), Upper Columbia and Snake ESUs (62 FR 43937), all of which are in the Columbia Basin. As a result of two recent court cases NMFS is now reexamming the biological relationship between trout and steelhead populations in the ESUs where steelhead are listed and is reassessing the extinction risk of the whole ESUs from the perspective of both life histories. First, the Hogan decision in Oregon concluded that the Services may describe distinct population segments for ESA listing, but once ESUs or DPSs are described, the Services cannot list only part of one of one of them (Alsea Valley Alliance v. Evans [161 F.Supp. 2d 1154, D. Oreg. 2001]). So if NMFS finds trout to be part of an ESU along with steelhead, the Service cannot assess the extinction risk of only the steelhead in the ESU or list only the steelhead. Second, lawsuits in California about nonanadromous 0. mykiss upstream of man-made barriers (mostly impassible dams) made a similar argument, stating that such populations are related to the steelhead populations below the barriers and should be included in the ESUs and listed (EDC v. Evans, SACV- 00-1212-AHS (EEA), United States District Court, C.D. California). The purpose of this report is to provide more detailed information about trout and steelhead in the Columbia Basin listed ESUs. This report will address two major issues. The first section provides information that will be used to review whether trout and steelhead populations are biologically part the same ESUs, as defined by NMFS criteria. The second section provides information that will be used to review the extinction risks of entire ESUs if trout are considered along with steelhead. A similar, separate report is being prepared for California ESUs where steelhead are listed.
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114. [Article] Umatilla Basin Natural Production Monitoring and Evaluation; Annual Progress Report 1994 - 1995
Abstract -- This report summarizes the activities of the Umatilla Basin Natural Production Monitoring and Evaluation Project (UBNPME) from September 30, 1994 to September 29, 1995. This program was funded ...Citation Citation
- Title:
- Umatilla Basin Natural Production Monitoring and Evaluation; Annual Progress Report 1994 - 1995
Abstract -- This report summarizes the activities of the Umatilla Basin Natural Production Monitoring and Evaluation Project (UBNPME) from September 30, 1994 to September 29, 1995. This program was funded by Bonneville Power Administration and was managed under the Fisheries Program, Department of Natural Resources, Confederated Tribes of the Umatilla Indian Reservation. An estimated 36.7 km (22.6 miles) of stream habitat were inventoried on the Umatilla River, Moonshine, Mission, Cottonwood and Coonskin Creeks. A total of 384 of 3,652 (10.5%) habitat units were electrofished. The number of juvenile fish captured follows: 2,953 natural summer steelhead (including resident rainbow tout; Oncorhynchus mykiss), one hatchery steelhead, 341 natural chinook salmon (0. tshawytscha), 163 natural coho salmon (0. kisutch), five bull trout (Salvelinus confluentus), 185 mountain whitefish (Prosopium williamsoni), and six northern squawfish (Ptychocheilus oregonensis). The expanded population estimate for the areas surveyed was 73,716 salmonids with a mean density of 0.38 fish/m2. The following number of non-salmonids were visually estimated: 7,572 speckled dace (Rhinichthys osculus), 5,196 sculpin (Cottus spp.), 532 suckers (Catostomus spp.) and 191 redside shiners (Richardsonius balteatus). The gross estimated density of all non-salmonids combined was 0.84 fish/m2. The estimated ratio of non-salmonids to salmonids was 2.4: 1. Relative salmonid abundance, seasonal distribution and habitat utilization were monitored at index sites throughout the basin. During index site monitoring, the following species were collected in addition to those listed above: american shad (Alosa sapidissima), smallmouth bass (Micropterus dolomieu), carp (Cyprinus Carpio) and chiselmouth (Acrocheilus alutaceus). Thirty nine sites were electrofished during the spring and summer seasons, while 36 sites were sampled in the fall season. Index sites with the. highest mean salmonid catch/minute (fish/min.) during the three sample periods were located at the following sites: East Birch Creek (3.4 fish/min.), Boston Canyon Creek (3.2 fish/min.), Spring Creek (3.1 fish/min.) and upper Squaw Creek (3.0 fish/min.). The highest electrofishing catch rates were observed in the Umatilla River tributaries above river mile (RM) 70 in the August and September sample period (Table J-2 catalogs river miles with associated landmarks). During the November sample period, catch rates were highest in Birch Creek tributaries. Most salmonids were captured in slow water near the bank during the November and March sampling periods. A study of the migration movements and homing requirements of adult salmonids in the Umatilla River was conducted during the 1994-95 return years. Radio telemetry was used to evaluate the movements of adult salmonids past diversion dams in the lower Umatilla River and to determine migrational movements of salmonids following upstream transport. Radio transmitters were placed in 30 summer steelhead, 15 spring chinook, nine fall chinook, and eight coho salmon. Salmon were released at Three Mile Falls Dam (TMD). An additional 11 summer steelhead and ten spring chinook salmon were tagged, hauled upstream, and released at either Barnhart, Nolin, Thornhollow, or Imeques C-mem-ini-kem. On average, summer steelhead required 36 days to successfully migrate from TMD to Stanfield Dam. Spring chinook required 18 days. Average passage times for summer steelhead (hours and minutes) at Westland, Feed Canal, and Stanfield Dams were 13:06, 83:24, and 2:58, respectively. Spring chinook salmon required 04:30 at Westland, 89:42 at Feed Canal, and 04:01 at Stanfield Dams. Migrational delays were observed at Feed Canal Dam at flows ranging from 563 to 1,601 cubic feet/second (cfs). Thirty-eight percent of the fish ladder at Westland Dam, 75% at Feed canal, and 31% at Stanfield Dam. Average passage times at Feed Canal Dam (1995) were more than 15 times those at Stanfield Dam in 1994 and more than 20 times those at Stanfield Dam in 1995. Data related to homing and passage needs of Umatilla River salmonids was investigated in an attempt to maximize homing to the Umatilla River. Straying rates of adult summer steelhead and spring chinook salmon were found to be low while coho and fall chinook salmon stray rates were high in some groups, particularly adult returns from subyearling smolt releases of fall chinook salmon. Attraction flows of from the mouth of the Umatilla River of at least 150 cfs were required to encourage migration and reduce straying of fall chinook and coho salmon. Significant numbers of summer steelhead entered when flows exceeded 500 cfs. Spring chinook salmon entry was variable with fish entering at flows ranging from 150 to more than 2,000 cfs. Adult anadromous salmonids potentially available to spawn above TMD from August 26, 1994 to June 27, 1995 included: 593 adult and 530 jack fall chinook salmon (1994 brood), 879 adult and 54 jack coho salmon (1994 brood), 784 natural and 509 hatchery summer steelhead (1995 brood), and 378 adult and 62 jack spring chinook salmon (1995 brood). During escapement surveys (fall of 1994), a total of 82 fall chinook salmon redds, 24 coho salmon redds and seven unidentified salmon redds (112 redds total, 2.6/mile) were enumerated along 42.3 miles of the mainstem above TMD. In 1995, we enumerated and flagged 126 summer steelhead redds (3.6 redds/mile) along 35.3 miles of lateral tributaries of the Umatilla River. Also enumerated were 90 spring chinook salmon redds (1.6 redds/mile) along 55.8 miles of the mainstem. Ninety-six percent of the adult fall chinook salmon carcasses examined had spawned while 94% of the coho had spawned; 66.8 % of the spring chinook salmon carcasses examined bad spawned. A total of 49.3% of spring chinook salmon released above TMD were sampled during spawning ground surveys and 60 coded wire tags (CWTs) were recovered from 78 adipose clipped fish. The rotary screw trap in the Umatilla River (RM 76) operated 63 of 113 days from September 21, 1994 to January 13, 1995. The trap captured 596 juvenile steelhead with a mean trap efficiency rate of 9.9%. A total of 1,368 juvenile chinook salmon were captured with a mean trap efficiency rate of 28. 8 % . The rotary screw trap at the Imeques C-mem-ini-kem site (RM 79.5) operated 43 out of 43 days from May 5 through June 16, 1995. The trap captured 304 natural juvenile steelhead with a mean trap efficiency rate of 6.6%. A total of 102 natural juvenile chinook salmon were captured with a mean trap efficiency rate of 10.5%. The rotary screw trap at the Barnhart site (RM 42,2) operated 87 out of 125 days from March 3 to June I, 1995. The trap captured 105 natural juvenile steelhead, 247 natural juvenile chinook salmon, five natural coho salmon, 6,265 hatchery juvenile chinook salmon, 467 hatchery steelhead and 16,844 hatchery coho salmon. Mean trap efficiency rates ranged from 2.3 to 5.7% . Harvest monitors estimated that tribal anglers harvested 25 hatchery and five natural summer steelhead during the spring of 1995. There was no spring chinook salmon fishery in the Umatilla River during 1995 because of the low number of returning adults. Scale analysis determined that over 85 .0% of naturally produced juvenile summer steelhead sampled during biological and index surveys were age O+ or l +. Naturally produced summer steelhead adults, returning to the Umatilla River in 1994-95, were mostly from the 1990 (46.4%) and 1991 (33.9%) brood years.
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115. [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
- 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.