Conditions affecting the 2011 and 2012 Fall Chinook Adult Returns to Spring Creek National Fish Hatchery.

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1 FISH PASSAGE CENTER 1827 NE 44 th Ave., Suite 240, Portland, OR Phone: (503) Fax: (503) us at MEMORANDUM TO: Liz Hamilton, NSIA FROM: Michele DeHart, FPC DATE: March 27, 2012 RE: Conditions affecting the 2011 and 2012 Fall Chinook Adult Returns to Spring Creek National Fish Hatchery. In response to your request the Fish Passage Center staff reviewed the juvenile outmigration conditions and program factors affecting the 2012 fall Chinook adult return to Spring Creek National Fish Hatchery. The decreasing numbers of the BPH tule fall Chinook returns in 2011 and the predicted decrease in the 2012 adult returns precipitated your request. Changes in hatchery production programs and downstream migration conditions likely affected the BPH adult returns in 2011 and will affect the returns in The FPC maintains data bases of Columbia basin hatchery releases and river and passage conditions. We utilized the age composition of the adult return of Bonneville Pool Hatchery (BPH) fall Chinook from Jackman et al. (2012) to determine the appropriate out-migration years as the focus of our review. Historically, BPH fall Chinook were made up of Spring Creek NFH fall Chinook tules and a small number of wild fall Chinook tules mostly returning to the Big White Salmon River below Condit Dam. However, since out-migration year 2009, this group consists of fall Chinook tules that are released from Spring Creek NFH and Little White Salmon NFH, along with the wild returns to the Big White Salmon River and other limited natural production areas above Bonneville Dam. In the following discussion, we review the history of Spring Creek NFH program and the juvenile outmigration conditions that were experienced by the 2012 fall Chinook adult return to Spring Creek NFH. Our concluding points, regarding factors affecting the 2012 fall Chinook adult return are summarized below followed by detailed discussion.

2 Based upon adult return age composition, the reprogramming of Spring Creek production implemented through the October 2008 MOA, affecting the first outmigration of 2009, would first have affected the adult returns. The Spring Creek NFH 2008 MOA implementation has reduced the Tule Fall Chinook return to the BPH area. Besides discontinuing the March release of Spring Creek Tule Fall Chinook, one of the objectives of the 2008 MOA was to maintain overall Tule and Upriver Bright (URB) Fall Chinook production while moving some of the URB production above Bonneville Dam. This necessitated moving some Spring Creek production below Bonneville Dam which reduces the return of Tule Fall Chinook to BPH area. Based upon age composition of adult returns, the reduction of Tule fall Chinook to BPH would be expected to first occur in 2010, with the return of jacks from the 2009 outmigration. The effect of the Spring Creek NFH reprogramming on adult returns, and fisheries, is the result of the fundamental changes in the hatchery programs. Specifically, adult returns to Spring Creek NFH, are a component of the BPH group return for fisheries management. However, the progeny (2.8 million smolts) of a component of the BPH fall Chinook adult return become part of the Lower River Hatchery (LRH) management group, because they are released below Bonneville Dam in Tanner Creek. At this time, Tule Fall Chinook adult returns are collected at Tanner Creek/Bonneville hatchery for brood stock. For fisheries management of the LRH group, there is no adult return adjustment to account for the additional smolt production in the LRH group. LRH harvest rates will continue to be driven by the exploitation rates allowed in NOAA Fisheries ESA consultations on West Coast and in-river fisheries to protect the Lower Columbia River Chinook ESU, which is listed as a threatened species. These abundance-based exploitation rates that apply to all fisheries, including Canadian fisheries, generally range between 30 and 41%.and are much reduced from historical exploitation rates for this ESU. With these reduced harvest rates, LRH hatchery returns surplus to brood stock needs are a common occurrence. Bonneville Pool Hatchery fall Chinook out-migrants in 2008, 2009, and 2011 experienced average to above average flows during their passage through Bonneville Dam. In 2010, Spring Creek juvenile migrants experienced low flows and spill at Bonneville Dam. Spill for fish passage was provided at Bonneville Dam for all releases in However, low spill of only ~37 Kcfs was provided for the March 2008 release. Juvenile BPH fall Chinook out-migrating in April of 2008, 2009 and 2011 benefited from spill for fish passage at BON of 100 Kcfs. For the 2010 out-migrants, spill for fish passage at BON was lower, at Kcfs for the April releases and Kcfs for the May migrants. These lower spill levels were due primarily to low flow conditions during this period and powerhouse minimum flow requirement. Based upon age composition, the lower spill levels, and lower flows experienced by 2010 out migrants would be expected to primarily affect 2012 and 2013 adult returns. Historic releases from Spring Creek NFH typically reached BON within hours of release. The passage timing of post-moa releases of BPH fall Chinook is similar, with most fish passing BON within 4-5 days of release. Since the implementation of the MOA, the April and May releases from Spring Creek NFH have a smaller size-at-release. 2

3 Assuming a brood stock goal of 7,000 (4,000 females) adults to supply 16.5 million eggs, Spring Creek NFH achieved its brood stock goal since the implementation of the Reprogramming MOA. Background/History The Spring Creek National Fish Hatchery is located on the Columbia River in Underwood, Washington, and 167 river miles from the ocean. Spring Creek NFH has raised and released tule fall Chinook salmon since These fish originated from, and are native to, the White Salmon River, located less than one mile from the hatchery. The hatchery is funded by the U.S. Army Corps of Engineers and the Mitchell Act, which is administered by the National Oceanic and Atmospheric Administration. The Spring Creek tule fall Chinook stock (Figure 1) is extremely important in terms of contributing to the harvest of mixed stock fisheries. Harvests of Spring Creek NFH Tule Fall Chinook for brood years equaled approximately 18,000 and 19,000 fish in the ocean and Columbia River, respectively, with a mean annual return of greater than 19,000 adult fish back to the hatchery. Because of the significance of this stock to various fisheries, drastic measures have been taken over the years to protect this stock and reach hatchery escapement goals. Reductions in both ocean and in-river harvests were mandated under the Pacific Salmon Treaty in the late 1980s, as well as closing lower Columbia River fisheries, initiating trapping programs at Bonneville Dam and making major changes to hatchery operations. These hatchery changes included: returning to a single stock program by moving upriver bright fall Chinook stocks out of Spring Creek, re-plumbing the entire hatchery, rehabilitating the filter bed, decreasing the nitrogen levels in the water re-use system, reducing the density of fish in the rearing ponds, undertaking efforts to reduce disease; and, in general, improving salmon culture practices in the raceways. Figure 1. Breakdown of percent recoveries of tule fall Chinook in various fisheries 3

4 Historical production at Spring Creek NFH was to release 15.1 million fish annually in March (7.5 million), April (4.3 million) and May (3.3 million), but has changed to releasing 10.5 million fish with the implementation of Spring Creek Reprogramming MOA. Juvenile passage mortality has been an issue at Bonneville Dam (BON). Non-turbine passage routes at BON include spill, juvenile bypass passage, and the corner collector. Providing protection for the March release has always been problematic, since it occurs outside of the primary fish passage season. Spill has been considered to be the best route of passage at this project. However, spill is generally constrained at BON due to the total dissolved gas at the Camas/Washougal monitoring station. The Camas/Washougal monitoring station is no longer required by either the State of Washington or Oregon, yet remains in the Annual Fish Operations Plan as part of the rolling over of existing operations from year to year under the Court Order. Spill was provided since the early 1980 s to make available a safe passage route past BON. In the early years, the fishery agencies and tribes requested 10 days of spill protection for these fish due to their depressed status, modifying it in subsequent years to a minimum of five days and extending to up to 10 days dependent on passage numbers. The Action Agencies usually responded by providing 5 days of spill (extending to 7 days in a few years), and in 2002 reduced the spill period to just 3 days. Once the BON corner collector became operational in 2004, it was proposed for primary passage protection. However, the performance of the corner collector appears to be associated with a much lower survival to adulthood, relative to spill passage. Studies were conducted by USFWS in 2004 to compare two routes of passage (spill vs. corner collector) for the March Spring Creek tule fall Chinook release. A single year of CWT-marking evaluated the two operations at a reduced level of spill (50 Kcfs). In 2004 and years prior, calibration errors in spill rates resulted in actual spill rates that were less than estimated. In this case actual spill was 25 Kcfs instead of the target of 50 Kcfs. In spite of this discrepancy, and in spite of the fact that the spill levels were considerably less than included in the Biological Opinion, the smolt to adult return rate showed a 45% reduction for the fish that passed during the corner collector operation when compared to the smolt to adult return rate for fish that passed during the spill operation (Haeseker and Wills 2007). In 2005 and 2006, the Action Agencies only provided corner collector operation without any concurrent spill. In 2007 a study comparing the corner collector versus spill was again proposed based on the data collected in the 2004 USFWS study (Haeseker and Wills 2007). The proposal was denied and no spill occurred. Subsequently, unusually high juvenile mortality was observed for fish collected at the powerhouse bypass collection system. In response to the high juvenile mortality observed in 2007, spill was provided for three days in 2008 at a level of 36 Kcfs to reduce the density of the powerhouse passage of the Spring Creek fish. Beginning in 2009 there has been no fish spill at Bonneville Dam in March since under the Spring Creek Reprogramming MOA March releases no longer occur from Spring Creek NFH. In addition, operation of the second powerhouse has been modified such that the turbines are operated at the lower end of the 1% efficiency range, which is thought to be better for fish survival. This modified operation typically takes place during the 3-5 day window when juveniles from Spring Creek NFH are passing BON. 4

5 In October 2008, a Memorandum of Agreement was signed by the USFWS, Bonneville Power Administration, U.S. Army Corps of Engineers, and the National Marine Fisheries Service to implement changes in fish production at Federally-funded mitigation hatcheries in the Columbia River Gorge. Under the new MOA, Spring Creek NFH now releases 6.0 million subyearling fall Chinook tules in April and 4.5 million fall Chinook tules in May. In addition, Spring Creek NFH transfers 1.7 million juvenile fall Chinook tules to Little White Salmon NFH for acclimation and release in April and 3 million fall Chinook tule eggs to Bonneville Hatchery for rearing and eventual release in May. Bonneville Hatchery is operated by Oregon Department of Fish and Wildlife and releases take place below Bonneville Dam. The transfer of smolts and eggs to Little White Salmon NFH and Bonneville Hatchery eliminated the need for a March release from Spring Creek NFH and, thus, the need to request spill at Bonneville Dam. The first year of releases under this MOA was the 2009 out-migration. According to the last three Spring Creek NFH annual updates ( ), a return of 7,000 adult fall Chinook salmon (4,000 females) are necessary to achieve the collection goal of 16.5 million eggs to accomplish an on-station release of 10.5 million smolts and transfers of 1.7 million juveniles to Little White Salmon NFH and 3.0 million eggs to Bonneville Hatchery. The FPC acquired return data for Spring Creek NFH since According to these data, the goal of 7,000 adults returning to the hatchery was met in 2008 through These are the only years where this goal would apply, as these are the years where the Reprogramming MOA would be in place. Furthermore, the goal of 16.5 million eggs was also met in return years 2008 through Even after the Spring Creek Reprogramming MOA, brood stock collection for BPH fall Chinook only comes from adults returning to Spring Creek NFH. None of the BPH fall Chinook adults returning to Little White Salmon NFH or Bonneville Hatchery are collected for spawning. Besides discontinuing the March release of Spring Creek Tule Fall Chinook, one of the objectives of the 2008 MOA was to maintain overall Tule and Upriver Bright Fall Chinook production while moving some of the URB production above Bonneville Dam. This necessitated moving some Spring Creek production below Bonneville Dam which reduces the return of Tule Fall Chinook to BPH area Returns and 2012 Prediction of Bonneville Pool fall Chinook: Historically, the Bonneville Pool Hatchery (BPH) fall Chinook were made up of hatchery fall Chinook tules that were reared and released at Spring Creek NFH and returned to limited natural production areas above Bonneville Dam. However, since 2009 these BPH fall Chinook have been reared at Spring Creek NFH and released at Spring Creek NFH, Little White Salmon NFH, and Bonneville Hatchery, Tanner Creek. According to Jackman et al. (2012), the 2011 return of BPH fall Chinook to the Columbia River mouth was 79,100 (including jacks), which was below the 10-year average ( ) of nearly 116,300 (Figure 2). Of the 2011 BPH fall Chinook returns, approximately 70% were 3-year olds (MY 2009), 19% were 4-year olds (MY 2008), and 11% were 2-year olds (MY 2010) (Figure 2, Figure 3). There were no 5-year olds in the 2011 returns. 5

6 Figure 2. Returns and age composition of Bonneville Pool Hatchery adults to the Columbia River Mouth, Return Year 2011 Return Year 2012 Figure 3. Age composition of 2011 BPH adult returns (left) and expected 2012BPH adult returns (right) to the Columbia River Mouth, by migration year. Jackman et al. (2012) also provides estimates of the predicted return of BPH fall Chinook to the Columbia River mouth for The 2012 forecast for BPH fall Chinook is 63,800, which is lower than the 2011 return and the 10-year average. Based on the age composition of the 2011 return and sibling cohort relationships, the 2012 returns of BPH fall Chinook will largely be made up of 2010 out-migrants, with smaller portions of age four 2009 outmigrants and jacks returning from the 2011 out-migration (Figure 3). The conditions experienced by those out-migrants, the hatchery release, and migration characteristics are summarized for those years in the following discussion. 6

7 Out-migration Conditions for BPH fall Chinook returning in 2011 and 2012 Migration Year 2008 According to Jackman et al. (2012), approximately 19% of the 2011 BPH fall Chinook return was made up of 4-year olds (Figures 2 and 3). These 4-year olds would have out-migrated in 2008 (Figure 3). Based on age-composition of the 2011 return and historical age composition for BPH fall Chinook, we estimate that juveniles out-migrating in 2008 will comprise less than 1% of the 2012 return. Flow Migration year 2008 was a relatively average to high flow year in the Lower Columbia River (Figure 4). Hatchery Releases In 2008, Spring Creek NFH released approximately 7.4 million fall Chinook juveniles in early March (Figure 4). In addition, nearly 4.0 million and 3.5 million juveniles were released from Spring Creek NFH in mid-april and early May, respectively (Figure 4). These later releases occurred after the initiation of the spring spill program. Spill for Fish Passage Due to the high juvenile mortality that was seen in March 2007 (SMP sampling) when no spill was provided, the action agencies provided spill of ~37 Kcfs for the peak passage period for the March 2008 release. The 37 Kcfs spill in 2008 was provided from Mar. 7 to Mar. 10, 2008 (Figure 4). The April and May releases in 2008 occurred after the initiation of the spring spill program. These out-migrants experienced spill of approximately Kcfs at BON (Figure 4). Powerhouse Operations During the juvenile migration BON was operating Powerhouse 2 (PH2) at the lower end of the 1% peak efficiency range, which is generally thought to be better for these small hatchery fish. This lower end of 1% operation was implemented for all three release periods. Due to high flows and high debris levels in mid-may, the bypass screens at BON were pulled. The screens were pulled off and on from May 13 to May 21 and then permanently from May 22 to June 20. However, it is unlikely this operation had much effect on the May release of Spring Creek fall Chinook, as 90% of the Spring Creek PIT-tagged juveniles had passed BON by May 5, 2008 (Jan. 3, 2012 FPC memo). 7

8 Figure 4. Daily average flow and spill at Bonneville Dam in 2008 (Mar. 1-May 31). Migration Characteristics The Smolt Monitoring Program (SMP) collects passage data for juvenile salmonids at BON from March 1 st through October 31 st. Based on the 2008 sampling, it appears that the Spring Creek NFH releases in March, April, and May arrived at BON within hours of their release and the majority of the release was typically passed BON within five days of release (Figure 5). Mortality rates for Spring Creek NFH releases were generally low, with a couple daily mortality estimates of greater than 5%. The daily mortality rates for the March release ranged from 0.4% to 33.5% (Mar. 7-14) (Figure 5). However, the high mortality seen on March 14 th (33.5%) occurred right after a VBS screen cleaning, which dislodged 114 dead subyearling Chinook smolts. These dead smolts were washed into the sampling facility where they were quantified into the March 14 th sample. Otherwise, smolts arriving in the sampling facility on this date were in good condition, with very little mortality prior and after the VBS cleaning. It is likely that most of these dead smolts had been dead for several days. This means that the mortality rates of the days prior to March 14 th are likely underestimates. The degree to which they are underestimates is difficult to determine. Not including March 14 th, the daily mortality of the March release ranged from 0.4% to 7.0%. Daily mortality rates for the April release ranged from 1.1% to about 2.5% (April 11-16) (Figure 5). There were high estimates of daily mortality on April 19 th and April 24 th. However, these higher estimates of mortality occurred on days with low sample counts for subyearling Chinook, thus, caution is warranted when interpreting these estimates. Finally, the daily mortality rates for the May release ranged from 0.0% to 1.6% (May 4-10) (Figure 5). 8

9 % Daily Proportion Passing BON Daily Passage Pct Moratlity 30% 25% 20% 15% 10% 5% Daily Percent Morality % Date Figure passage timing and mortality data of subyearling Chinook at BON. Migration Year 2009 Approximately 70% of the 2011 BPH fall Chinook return would have out-migrated in 2009 (Jackman et al., 2012). Based on age-composition of the 2011 return and the total run size projections in Jackman et al. (2012), we estimate that juveniles out-migrating in 2009 will comprise about 19% of the 2012 total annual return in The Spring Creek Reprogramming MOA (MOA) went into effect in Prior to the MOA, Spring Creek NFH released fall Chinook tules in March, April, and May. Under the MOA, the March release was eliminated by shifting some of the releases to the Little White Salmon NFH (located above BON) and Bonneville Hatchery (located below BON). Flow Migration year 2009 was an average flow year in the Lower Columbia River (Figure 6). Hatchery Releases On April 13, 2009, approximately 8.3 million fall Chinook juveniles were released above BON. Of these, about 6.48 million were released from Spring Creek NFH and 1.85 million were released from Little White Salmon NFH (Figure 6). On May 1 st, Spring Creek NFH released approximately 4.8 million fall Chinook juveniles, followed by nearly 2.5 million juveniles being released from Bonneville Hatchery below BON on May 15 (Figure 6). Spill for Fish Passage Both of the releases in April 2009 took place after the initiation of spring spill at BON. During this time, spill at BON was ~100 Kcfs. The fall Chinook juveniles released from Spring Creek NFH in May also experienced ~100 Kcfs spill at BON. Those juveniles that were released from Bonneville Hatchery were released below BON and, therefore, were not subject to BON operations 9

10 Powerhouse Operations As with 2008, BON was operating Powerhouse 2 (PH2) at the lower end of the 1% peak efficiency range during the passage period for both the April and May upstream releases. Figure 6. Daily average flow and spill at Bonneville Dam in 2009 (Mar. 1-May 31). Migration Characteristics Based on the 2009 SMP sampling, it appears that the releases from Spring Creek NFH and Little White Salmon NFH in April and May arrived at BON within hours of their release. The peak passage date at BON for the April releases was April 15 th (Figure 7). Passage numbers for these releases declined from this point on. It appears that the majority of this group had passed BON by April 26 th (Figure 7). The peak passage date for the May release from Spring Creek NFH was May 3 rd (Figure 7). Passage numbers quickly declined from this point and it appears that the majority of the May release had passed BON by May 8 th (Figure 7). Mortality rates for the 2009 releases were generally low, with a range of 0.0% to 2.4% for the April releases and 0.0% to 0.7% for the May release (Figure 7). 10

11 Daily Proportion Passing BON Daily Passage Pct Mortality 35% 30% 25% 20% 15% 10% 5% Daily Percent Mortality % Figure passage timing and mortality data of subyearling Chinook at BON. Migration Year 2010 According to Jackman et al. (2012), approximately 11% of the 2011 BPH fall Chinook return would have out-migrated in Based on age-composition of the 2011 return and the total run size projections in Jackman et al. (2012), we estimate that juveniles out-migrating in 2010 will comprise about 70% of the 2012 annual return. Date Flow Migration year 2010 was a relatively low flow year in the Lower Columbia River, particularly during the period when Spring Creek fall Chinook tules were out-migrating (Figure 8). Hatchery Releases Migration year 2010 was the second year with the Spring Creek Reprogramming MOA in effect. In mid-april, approximately 6.2 million fall Chinook juveniles were released from Spring Creek NFH and 1.8 million were released from Little White Salmon NFH, (Figure 8). On May 3 rd, Bonneville Hatchery released nearly 2.9 million fall Chinook juveniles below Bonneville Dam. The May release from Spring Creek NFH occurred a little later (May 10 th ), with about 4.6 million juveniles being released (Figure 8). Spill for Fish Passage Juveniles from the April releases would have experienced ~70-75 Kcfs spill at BON (Figure 8). These lower spill volumes at BON were due primarily to the low flow conditions during this time and the requirement to maintain powerhouse minimums. The May release from Spring Creek NFH fish would have experienced ~75-90 Kcfs spill at BON (Figure 8). The May release from Bonneville Hatchery occurred below BON and, therefore, these fish were not subject to BON operations. Powerhouse Operations As with 2008 and 2009, BON was operating Powerhouse 2 (PH2) at the lower end of the 1% peak efficiency range during the passage period for both the April and May upstream releases. 11

12 Figure 8. Daily average flow and spill at Bonneville Dam in 2010 (Mar. 1- May 31). Figure passage timing and mortality data of subyearling Chinook at BON. Migration Characteristics As with previous years, the BPH fall Chinook released from Spring Creek and Little White Salmon NFH in April and May arrived at BON within hours of their release. The peak passage date at BON for the April releases was April 15 th (Figure 9). Passage numbers for these releases declined from this point on. It appears that the majority of this group had passed BON by April 26 th (Figure 9). The peak passage date for the May release from Spring Creek NFH was May 13 th (Figure 9). The Passage numbers quickly declined from this point and it appears that the majority of the May release had passed BON by May 16 th (Figure 9). Mortality rates for the 2010 releases were generally low, with a range of 0.0% to 0.8% for the April releases and 0.0% to 0.3% for the May release (Figure 9). The relatively high 12

13 levels of daily mortality prior to April 12 th were mostly from Chinook fry, which typically have higher mortality through the juvenile bypass. Migration Year 2011 Based on the age composition data in Jackman et al. (2012), we estimate that about 11% of the total 2012 BPH fall Chinook return may consist of 2011 out-migrants. Jack returns are not predicted but generally comprise 5-15% of the total annual return. Flow Migration year 2011 was a high flow year in the Lower Columbia River (Figure 10). In fact, flows were so high that spill began at BON in late March, due to flows being in excess of hydraulic capacity. Hatchery Releases Migration year 2011 was the third year of the Spring Creek Reprogramming MOA in effect. As with previous years of the MOA, nearly 8.0 million total fall Chinook juveniles were released from Spring Creek NFH and Little White Salmon NFH in mid-april (Figure 10). In addition, about 4.6 million fall Chinook juveniles were released from Spring Creek NFH in early May, followed by nearly 2.8 million juveniles being released from Bonneville Hatchery in late May (Figure 10). Spill for Fish Passage Both the April and May releases from Spring Creek and Little White Salmon NFH would have experienced spill of ~100 Kcfs at BON. The May release from Bonneville Hatchery occurred below BON and, therefore, these fish were not subject to BON operations. Powerhouse Operations During the passage period for these April and May releases, BON was operating Powerhouse 2 (PH2) at the lower end of the 1% peak efficiency range. Figure 10. Daily average flow and spill at Bonneville Dam in 2011 (Mar. 1- May 31). Migration Characteristics The peak passage date at BON for the April releases was April 13 th (Figure 11). Passage numbers for these releases declined from this point on and 13

14 the majority of these April release groups had passed BON by April 22 nd (Figure 11). The peak passage date for the May release from Spring Creek NFH was May 6 th (Figure 11). The passage numbers quick declined from this point and it appears that the majority of the May release had passed BON by May 15 th (Figure 11). Mortality rates for the 2010 releases were generally low, with a range of 0.5% to 3.4% for the April releases and 0.0% to 0.7% for the May release (Figure 11). The relatively high levels of daily mortality prior to April 12 th were mostly from Chinook fry, which typically have higher mortality through the juvenile bypass. Figure passage timing and mortality data of subyearling Chinook at BON. Size-at-Release of Hatchery Releases: Prior to the Spring Creek NFH Reprogramming MOA, the March release from Spring Creek NFH was comprised of mostly small fish. The fish released in the April and May releases were subsequently larger. The FPC Hatchery Database has records of all Spring Creek NFH releases, dating back to Size at release for these releases is recorded as fish per pound (FPP) in the FPC Hatchery Database. A large value for FPP corresponds to a release of smaller fish, whereas a smaller FPP value corresponds to a release of larger fish. Over the most recent ten years ( ), the March release occurred in 2002 through During this time, the average FPP for this March release was (Figure 12). There has been an April release from Spring Creek NFH in all years of the last decade. During the period before the MOA ( ), the average FPP for this April release was 96.2, whereas the average FPP since the MOA ( ) is (Figure 12). It appears that the average size-at-release for post-moa April releases is slightly smaller than for those that occurred prior to the MOA. Finally, at 114.9, the average FPP for the April release from Little White Salmon NFH is smaller than that for the Spring Creek NFH (Figure 12). There has been a May release from Spring Creek NFH in all years of the last decade. During the period before the MOA ( ), the average FPP for this May release was 71.4, whereas the average FPP since the MOA ( ) was 86.8 (Figure 12). As with the April release, the average size-at-release for post-moa May releases is slightly smaller than for releases that occurred prior to the MOA. Finally, the average FPP for the May release from 14

15 Bonneville Hatchery (released below Bonneville Dam) is 87.3 (Figure 12). These Bonneville Hatchery fish are very close in size to the May release from Spring Creek NFH. Figure 12. Average size at release (fish per pound) of BPH fall Chinook released from Spring Creek NFH (SpCrk), Little White Salmon NFH (LSWH), and Bonneville Hatchery (BONH), Note: taller bars represent smaller size-at-release. Literature Cited: FPC Memos: January 3, 2012 Columbia Gorge Complex Hatchery Report 2011 ( Haeseker, S.L. and David Wills, Preliminary evaluation of two operations at Bonneville Dam on the return rate of fall Chinook salmon to Spring Creek National Fish Hatchery. February 6, 2007 memo attached to System Operational Request # Jackman, B., B. Spellman, Q. Daugherty, and R. Roler Run Size Forecast for the Return of Columbia River Fall Chinook Salmon Stocks in Washington Department of Fish and Wildlife. Columbia River Progress Report February 16, US Fish and Wildlife Service. Spring Creek NFH Annual Updates 2008, 2009,

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