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Assessing compliance with fish survival standards: a case study at Rock Island Dam, Washington
environmental science & policy 18 (2012) 45–51
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/envsci
Assessing compliance with fish survival standards: a case study at Rock Island Dam, Washington John R. Skalski a,*, Tracey W. Steig b, Steven L. Hemstrom c a
Columbia Basin Research, School of Aquatic and Fishery Sciences, University of Washington, 1325 Fourth Avenue, Suite 1820, Seattle, WA 98101-2509, USA b Hydroacoustic Technology, Inc., 715 NE Northlake Way, Seattle, WA 98105, USA c Public Utility District No. 1 of Chelan County, 327 North Wenatchee Avenue, Wenatchee, WA 98011, USA
article info Published on line 9 February 2012 Keywords: Juvenile salmon survival Yearling Chinook salmon Steelhead Sockeye salmon Columbia River Habitat Conservation Plan Fish tagging Hydroelectric project Hydro power Endangered Species Act
1.
abstract Safe fish passage through hydroprojects is of paramount importance in the Pacific Northwest of the United States where anadromous runs of salmon smolts pass through as many as nine dams on the Columbia River on their way to the ocean. Minimum survival standards through the dams or hydroprojects (i.e., reservoir and dam) have been established by the 2008 Federal Columbia River Power System (FCRPS) Biological Opinion or by Habitat Conservation Plans (HCPs) in order to protect salmon stocks. These federal requirements have prompted the need to conduct scientifically and statistically rigorous and precise smolt survival studies at federally and publicly operated hydroprojects throughout the SnakeColumbia River Basin. Successful studies have been the cooperative results of regulators, hydro managers, fish biologists, engineers, and biometricians working together to conduct these high value investigations. Rock Island Dam, Washington, is used as a case study where a total of 17 release-recapture studies were conducted over a nine-year period on three salmonid species to assess compliance with HCP survival standards.
Introduction
Management of inland waters requires balancing often conflicting social, economic, industrial, and recreational needs of the public and private sectors with the desire for a healthy and sustainable ecosystem. In the Pacific Northwest of the United States, this means balancing hydroelectric production and irrigation withdrawals with sustainable anadromous populations of salmonids. An important part of these efforts is to provide safe passage through the hydroprojects for salmonid smolts outmigrating to the ocean and upriver returning adult salmon (Quinn, 2005, pp. 226–228). Survival standards for fish passage at hydroprojects have been established by resource agencies to help assure viable populations of salmon. At federally operated dams in the
# 2012 Elsevier Ltd. All rights reserved.
Columbia River, such standards have been established in the 2008 Biological Opinion (BiOp) on the Federal Columbia River Power System (FCRPS) (National Marine Fisheries Service, 2008) under the Endangered Species Act (ESA) of 1973 (16 U.S.C. § 1531–1544). At three public utility dams on the Mid-Columbia River, smolt survival standards have been established in Habitat Conservation Plans (HCPs) developed with the National Oceanic and Atmospheric Administration (NOAA) Fisheries and U.S. Fish and Wildlife Service to conform to National Environmental Policy Act (NEPA) and the Endangered Species Act as part of the Federal Energy Regulatory Commission (FERC) relicensing agreements. In the Columbia River Basin, smolt survival studies are used to either demonstrate compliance with the survival standards or guide mitigation actions at the hydroprojects until compliance has been achieved (Skalski et al., 2009, 2010). The
* Corresponding author. Tel.: +1 206 616 4851. E-mail address: [email protected] (J.R. Skalski). 1462-9011/$ – see front matter # 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.envsci.2012.01.001
46
environmental science & policy 18 (2012) 45–51
outcome of these high value tagging studies can have significant financial consequences to hydro operations and important ramifications to the iconic salmon populations of the Pacific Northwest. The typical cost of a seasonal survival study for one species of salmon smolt exceeds $1 M. Tagging studies that fail to meet design or precision requirements must be repeated, and delays in achieving compliance can have other even more costly financial consequences, depending on the agreements with regulatory and resource agencies and statutory compliance with the ESA. The purpose of this paper is to illustrate by example how compliance testing was successfully implemented at Rock Island Dam in the Mid-Columbia River, Washington. The case history at this hydroproject illustrates the long-term strategy that was used to successfully evaluate compliance with survival standards for three different salmonid species. This process included converting to a new tag technology that made the testing feasible, and finding an operating condition that was beneficial to both hydroelectric production and fish passage survival. This nine-year study also illustrates the benefits of a strong interdisciplinary research team and good working relationships between hydro operations and regulatory agencies.
2.
Study area
Rock Island Dam is located on the Columbia River, approximately 21 km downstream of the city of Wenatchee, Washington, at river kilometer (rkm) 729.7 (Fig. 1). The original
project consisted of a single powerhouse and spillway, and was completed in 1933. In 1979, a second powerhouse was added near the west shore. The original powerhouse, Powerhouse #1, has a total of 11 vertical-axis kaplan turbine units, each with 3 intakes. A house unit, with 2 intakes, is used exclusively to produce power to operate the project. The spillway consists of a total of 32 spillbays separated at spillbay 15, which is occupied by the central adult fish ladder. Therefore, 14 spillbays are located to the east of the ladder and 17 to the west. Powerhouse #2 has 8 horizontal-axis bulb turbine units, each with 2 intakes. The dam has a total generating capacity of 624 megawatts. The reservoir extends to Rocky Reach Dam (rkm 764) and is 33 km in length.
3.
Survival standards
The smolt passage survival standards differ substantially between the federally operated and public utility operated dams. In the Mid-Columbia, where three public utility district (PUD) dams are guided by HCPs and two other dams are guided under relicensing agreements, the standard is project passage survival (i.e., dam and reservoir) of 0.93. Compliance requires three annual estimates with an average greater than or equal to the threshold. For an individual study to be acceptable, the project passage survival must be estimated with a standard error (SE) of 0.025, and river flow conditions must be within the middle 90% of the historical distribution. The same criteria apply for yearling Chinook salmon, steelhead, and sockeye
Fig. 1 – Location of Rock Island Dam on the Columbia River near Wenatchee, Washington.
environmental science & policy 18 (2012) 45–51
salmon smolts. The paired release-recapture design of Burnham et al. (1987) based on the Cormack (1964) single release-recapture model is the most common approach to estimating project passage survival at these PUD operated dams. At federally operated projects, the 2008 BiOp requires dam passage survival to be 0.96 for spring stocks (i.e., yearling Chinook salmon and steelhead) and 0.93 for summer stocks (i.e., subyearling Chinook salmon). Compliance requires two annual estimates with an average greater than or equal to the threshold. For an individual study to be acceptable, the estimate of dam passage survival must have a SE 0.015 and river flows must be within the middle 90% of historical distributions. The logistics of isolating the estimate of smolt survival through only the dam itself (i.e., dam face to the tailrace mixing zone) is more complicated than estimating project passage survival. Currently, the virtual/paired-release design of Skalski et al. (2010) which requires three release groups of fish is being used at federal facilities. As a rule of thumb, halving the size of the SE for a survival estimate requires quadrupling the release sizes of a tagging study (Cormack, 1964). Consequently, the need for three releases when conducting a virtual/paired-release design, instead of just two release groups for paired-release design, and the much larger number of tagged fish per release result in the BiOp specifications being much more demanding than the HCP study requirements. However, the BiOp requires only two years of successful tagging studies compared to three years for the HCP, and the BiOp has a provision for a lower survival rate for subyearling Chinook salmon in the summer, which the HCP does not. Overall, neither set of study standards is inherently easier to attain than the other.
4.
Methods
Fish tagging studies based on the statistical principles of mark-recapture or release-recapture theory must be used to estimate smolt passage survival. The tagging models allow the processes of survival and detection to be differentiated, thereby permitting estimates of absolute survival. The statistical models that are used to derive the survival estimates also provide the means to estimate the uncertainty in the sampling process and provide estimates of standard errors (SEs). In 2002, when the compliance studies began at Rock Island Dam, the passive integrated transponder (PIT) tag was the dominant and most prevalent technology in use at that time in the Columbia Basin (Prentice et al., 1990; Skalski et al., 1998). To estimate project passage survival, a group of PIT-tagged fish would be released at the top of the reservoir and another group of PIT-tagged fish released in the tailrace below the dam (Fig. 2). To estimate absolute survival from each release group, a minimum of two downstream detection sites is required. Detection can only occur at downstream hydroprojects equipped with PIT-tag detectors located in smolt bypass systems. For studies at Rock Island Dam, this meant detection sites at McNary, John Day, and Bonneville, 259 km, 382 km, and 495 km, respectively, downriver. Although PIT tags are small enough to be injected into a fish with a 5–10 ml syringe
47
and a 12-gauge, veterinary-grade needle (Columbia Basin Fish and Wildlife Authority, PIT Tag Steering Committee, 1999) and are inexpensive ($2–$3 per tag), detection rates are generally low (0.08–0.20) and the fixed detection locations at smolt bypass systems preclude collection of finer-resolution information on fish movement and survival. The low detection rates also mean that many tens of thousands of fish have to be reared and marked for each survival study. On average, the PIT-tag survival studies at Rock Island Dam (i.e., 2002–2004) used a total of 100,000 fish per species per year for each survival investigation. Looking into the future, Chelan PUD saw the need to convert from PIT tags to the then relatively new acoustic tag for conducting survival studies for several reasons. Acousticdetection arrays can be constructed almost anywhere (with power available) with detection probabilities often exceeding 0.90. This allowed detection arrays to be placed in midreservoir and at the face of the dam to partition project survival into dam and pool components and to estimate routespecific passage proportions and survival probabilities at the dam (Skalski et al., 2009). This information was highly valuable in diagnosing passage problems if survival standards were not met and in developing corrective actions to help achieve the standards. Secondly, the high detection probabilities, shorter travel distances, and correspondingly higher survival rates to the downstream detection arrays meant tag release sizes could be greatly reduced. A survival study could now be conducted with 800–900 fish (Steig et al., 2005). These sample sizes also permitted tagging the run-of-river (ROR) fish rather than only hatchery fish in the survival studies, thereby permitting direct inferences to the population of interest. The reduced sample sizes also allowed species such as sockeye salmon which do not have large hatchery reserves to be studied using ROR fish. The acoustic-tag survival studies used the same pairedrelease locations as the PIT-tag survival studies (Fig. 3). However, the mandatory minimum two downriver detection locations were now installed in the adjacent downriver reservoir, 18 and 37 km below Rock Island Dam. The smolts were internally tagged with either the HTI Model 795E Acoustic Tags (weight, 1.5 g in air), the HTI Model 795 m Acoustic Tags (weight, 0.75 g in air), or the HTI Model 795Lm Acoustic Tags (weight, 0.65 g in air), depending on the fish stock ($200 per tag). The detection arrays consisted of the HTI Model 290 Acoustic Tag Receiver operating at 307 kHz, with 8 hydrophones across the river at Crescent Bar, Washington, and 10 hydrophones at Sunland Estates, Washington (Fig. 3). Survival from the release locations to these downstream detection sites typically exceeded 0.90 and detection rates at the arrays themselves often exceeded 0.98 – all of which contributed greatly to the reduced sample sizes needed for the acoustic-tag survival studies. Paired releases of PIT-tagged or acoustic-tagged fish were performed every 2–3 days over the course of the species outmigration in order to make inferences to season-wide survival. A weighted average of the replicate PIT-tag estimates of project passage survival was computed to obtain an annual estimate, weighing inversely proportional to the coefficient of variation (CV) squared. The small individual releases of acoustic-tagged fish were pooled to obtain an annual estimate.
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environmental science & policy 18 (2012) 45–51
Fig. 2 – Schematic of a PIT-tag survival study using a paired release-recapture design at Rock Island Dam, Washington, with releases in the tailraces above (R1) and below (R2) the project, and detection sites at three downriver dams and associated estimated parameters. Estimate of project passage survival calculated as the ratio Sˆ RI ¼ Sˆ 1 =Sˆ 2 .
During 2002–2004, three consecutive years of dual PIT-tag and acoustic-tag estimates of project passage survival for yearling Chinook salmon smolts were performed. The purpose was both to assess compliance with survival standards, and to assess whether the acoustic-tag and PIT-tag studies produced comparable survival estimates that the fisheries community could trust. From 2005 onward, only acoustic-tag survival studies were performed. The fish used in the PIT-tag studies came from the Turtle Rock Hatchery operated by the PUD, while the much smaller sample sizes of acoustic-tagged run-of-river fish were obtained from the Rocky Reach juvenile sampling facility. Minimum size of yearling Chinook salmon and steelhead smolts with acoustic tags was set at 150 mm in length. For sockeye, minimum fish size was 95 mm in length. Length criteria were selected to assure tag burden <5% of body weight. Fish with obvious injuries, deformities, or >20% scale loss were excluded.
5.
Results
The nine-year history of compliance testing at Rock Island Dam encompassed three fish species, two different tag technologies and two different operating conditions at the dam (Table 1). From 2002 to 2006, Rock Island Dam was operated at a 20% spill level during the smolt outmigration. This 20% spill level was selected because prior tag investigations suggested this operating condition had a good chance of achieving the required survival standards. From 2002 to 2004, yearling Chinook salmon survival was evaluated using both PIT- and acoustic-tag technologies. Each of the six investigations produced estimates of project passage survival with acceptable standard errors of 0.025. Four of the six annual studies also had survival estimates above the required threshold (i.e., Sˆ 0:93) and the three-year means exceeded the survival threshold for both tag types (i.e., Sˆ¯ 0:93) (Table 1).
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environmental science & policy 18 (2012) 45–51
Table 1 – Summary of yearling Chinook salmon, steelhead, and sockeye salmon smolt survival estimates at Rock Island Project. Survival estimates for individual studies, associated standard errors (in parentheses), and cross-year arithmetic averages are presented. Species Yearling Chinook salmon
Year c
2002 2003c 2004c 2002–2004 Arith. Avg.: 2007b 2008b 2010b
PIT-tag
Acoustic-tag
0.9555 (0.0249) 0.9339 (0.0115) 0.9139 (0.0227) 0.9344
0.9520 (0.0263) 0.9387 (0.0157) 0.9419 (0.0118) 0.9442
2007–2010 Arith. Avg.: Steelhead
2004c 2005c 2006c 2004–2006 Arith. Avg.: 2008b 2010b 2008, 2010 Arith. Avg.:
Fig. 3 – Schematic of acoustic-tag releases (R1 and R2) used to estimate project passage survival at Rock Island Dam, Washington, with downriver detection sites at Crescent Bar and Sunland Estates, Washington.
Sockeye salmon
2007–2009 Arith. Avg.: a b c
The PIT-versus acoustic-tag comparisons were also deemed successful, with the annual estimates not significantly different (P > 0.05) between tag types using a Z-test. At the end of 2004, yearling Chinook salmon was considered in compliance with the survival standard at an operational spill level of 20%, and acoustic-tag survival studies were approved as a valid study approach henceforth. During 2004–2006, steelhead survival studies using acoustic tags were conducted under the 20% spill program previously approved for yearling Chinook salmon. All three annual steelhead estimates of season-wide passage survival achieved the precision requirement (i.e., SE 0.025) and the three-year mean survival met HCP requirements with a value of Sˆ¯ ¼ 0:9404 (Table 1). Starting in 2007, the PUD requested the HCP Committee to reevaluate compliance of yearling Chinook salmon and steelhead at a lower spill level of 10%. Compliance had previously been achieved at the 20% spill level, but the PUD was seeking a more efficient operating condition that still met HCP survival standards. In 2007, 2008, and again in 2010, yearling Chinook salmon survival was estimated at a 10% spill level using acoustic tags. All three studies met their precision requirements and the three-year average exceeded the compliance threshold with an estimate of Sˆ¯ ¼ 0:9375 (Table 1). In 2008 and again in 2010, steelhead passage survival was estimated at the 10% spill level, and the two survival studies met their precision requirements with a two-year average of Sˆ¯ ¼ 0:9675 (Table 1). The HCP committee, working with the PUD, agreed a
2007a 2008b 2009b
0.9725 (0.0185) 0.8972 (0.0157) 0.9428 (0.0081) 0.9375
0.9658 (0.0114) 0.9158 (0.0154) 0.9396 (0.0132) 0.9404 0.9699 (0.0133) 0.9652 (0.0122) 0.9675
0.9188 (0.0123) 0.9335 (0.0163) 0.9457 (0.0159) 0.9327
Single-release survival estimate with 10% project spill. Paired-release study conducted with 10% project spill. Paired-release study conducted with 20% project spill.
third year of steelhead survival studies was not needed, given the previous two years of results. A third steelhead study would have had to result in a survival estimate below 0.8549 not to exceed the three-year average 0.93. The HCP committee considered this highly unlikely because no previous survival estimate was ever that low. Consequently, both the yearling Chinook salmon and steelhead met compliance requirements under a 10% spill condition. The size of the acoustic tag was reduced from an initial size of 1.5 g in 2004, to 0.75 g in 2007, and to 0.65 g in 2010. This permitted the PUD to begin evaluating the feasibility of conducting project passage survival studies on the smaller sockeye salmon smolt. In 2007, a single release-recapture study (i.e., only the upstream treatment release of the pairedrelease design) was performed from the tailrace of Rocky Reach Dam to Crescent Bar below Rock Island Dam. Survival from the Rocky Reach tailrace to Crescent Bar was estimated at c ¼ 0:0123Þ. In 2008 and 2009, standard paired Sˆ ¼ 0:9188 ðSE release-recapture studies were performed; both met the precision requirement (i.e., SE < 0.025) and both exceeded the survival threshold (i.e., S > 0.93) (Table 1). Because the 2007 single-release estimate of survival included mortalities in the next reservoir, it was a negatively biased estimate of project passage survival. Nevertheless, the three-year average exceed the survival standard with a value of Sˆ¯ ¼ 0:9327 (Table 1). The HCP Coordinating Committee acknowledged the 2007 estimate as negatively biased and accepted the three-year average of sockeye salmon as attaining the HCP survival requirement.
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environmental science & policy 18 (2012) 45–51
Hence, sockeye salmon survival was also found in compliance with HCP requirements at a 10% spill level.
6.
Discussion
The Rock Island Dam is the second PUD operated dam to meet its HCP survival standards for spring migrants in the Columbia River Basin. The Wells Dam operated by Douglas County PUD was the first, completing testing in 2000, and successfully completing a 10-year checkup in 2010. The other three PUD operated dams have compliance studies underway. Compliance testing began at the federally operated dams in 2010 with efforts expected to expand substantially in the years to come. The extensive testing that went on at Rock Island dam was due to two factors. The first factor was the shift from the previously accepted PIT-tag technology to the new acoustictag technology and its long-term advantages. The calibration testing conducted from 2002 to 2004 on yearling Chinook salmon smolts by Chelan PUD opened the way for other hydroprojects to directly employ the new tag technology without further testing. Currently, all compliance testing in the Columbia River Basin is based on acoustic-tag studies. The second factor was the compliance testing at two different operating conditions, first at 20% and then at 10% spill. The strategy Chelan PUD used in achieving compliance with the smolt survival standard was a risk averse approach. Failure to achieve compliance with survival standards under the HCP agreement could result in turning over partial control of the dam operations to the resource agencies. Consequently, an initial set of operating conditions was selected (i.e., 20% spill) that had good prospects of achieving the survival standards. Once compliance was achieved under those conditions, the PUD then worked at fine tuning hydro operations (i.e., 10% spill) where both fish protection and efficient hydroelectric production could be simultaneously achieved. In this manner, hydro operations could be optimized while at the same time safeguarding fish resources. The history of compliance testing at Rock Island Dam reflects a good working relationship between the PUD and the resource agencies. The acceptance of the 2007 single-release study as part of the sockeye salmon compliance testing and foregoing the third year of steelhead testing reflects this working relationship based on good science and wellconducted studies. All 17 of 17 compliance tests met their precision requirements and provided all parties with confidence in the results and the sincerity of the research efforts. When adequate evidence had been amassed, the interested parties could make decisions with an acceptable level of uncertainty. This confidence in the test results was the product of a successful interdisciplinary effort by biologists, engineers, biometricians, hydro operators, and representatives from resource agencies, who shared a common interest in resource stewardship and good science.
Acknowledgments We wish to thank Chelan Public Utility District for supporting this work and this manuscript.
references
Burnham, K.P., Anderson, D.R., White, G.C., Brownie, C., Pollock, K.H., 1987. Design and analysis methods for fish survival experiments based on release-recapture. American Fisheries Society Monograph 5. Columbia Basin Fish and Wildlife Authority, PIT Tag Steering Committee, 1999. PIT Tag Marking Procedures Manual. Version 2.0. Copy Available From PIT Tag Information System (PTAGIS) at http://www.ptagis.org/ptagis/ frame.jsp?menu=3&main=main.jsp?menu=3. Cormack, R.M., 1964. Estimates of survival from the sighting of marked animals. Biometrika 51, 429–438. National Marine Fisheries Service, 2008. Endangered Species Act Section 7(a)(2) consultation biological opinion and Magnuson-Stevens Fishery Conservation and Management Act essential fish habitat consultation: Consultation on remand for operation of the Federal Columbia River Power System, 11 Bureau of Reclamation projects in the Columbia Basin and ESA Section 10(a)(1)(A) Permit for juvenile fish transportation program. May 5, 2008. Prentice, E.F., Flagg, T.A., McCutcheon, C.S., 1990. Feasibility of using implantable passive integrated transponder (PIT) tags in salmonids. American Fisheries Society Symposium 7, 317–322. Quinn, T.P., 2005. The Behavior and Ecology of Pacific Salmon and Trout. American Fisheries Society in association with University of Washington Press, Seattle. Skalski, J.R., Buchanan, R.A., Townsend, R.L., Steig, T.W., Hemstrom, S., 2009. A multiple-release model to estimate route-specific and dam passage survival at a hydroelectric project. North American Journal of Fisheries Management 29, 670–679. Skalski, J.R., Smith, S.G., Iwamoto, R.N., Williams, J.G., Hoffmann, A., 1998. Use of PIT-tags to estimate survival of migrating juvenile salmonids in the Snake and Columbia Rivers. Canadian Journal of Fisheries and Aquatic Sciences 55, 1484–1493. Skalski, J.R., Townsend, R.L., Steig, T.W., Hemstrom, S., 2010. Comparison of two alternative approaches for estimating dam passage survival using acoustic-tagged sockeye salmon smolts. North American Journal of Fisheries Management 30, 142–156. Steig, T.W., Skalski, J.R., Ransom, B.H., 2005. Comparison of acoustic and PIT tagged juvenile Chinook, steelhead, and sockeye salmon (Oncorhynchus spp.) passing dams on the Columbia River, USA. In: Spedicato, M.T., Lembo, G., Marmulla, G. (Eds.), Aquatic Telemetry: Advances and Applications. Food and Agriculture Organization of the United Nations, Rome, pp. 275–286. John R. Skalski is Professor of Biological Statistics at the University of Washington in the School of Aquatic & Fishery Sciences. He is also an adjunct professor in Wildlife Science in the School of Forest Resources. He is a member of the Center for Quantitative Science in Forestry, Fisheries, and Wildlife. He has written over 50 peer-reviewed papers and 100 technical reports on tag analyses. Other areas of study include demographic analyses, assessment of energy-related effects on mobile species, impact and accident assessment, and sampling theory. Tracey W. Steig is Senior Project Engineer for Hydroacoustic Technology, Inc. (HTI). Tracey has Bachelor of Science and Master of Science degrees in Civil Engineering from the University of Washington. He has conducted numerous hydroacoustic- and acoustic-tag studies on the Columbia and Snake rivers since 1982. Tracey is currently the Project Engineer for the acoustic-tag
environmental science & policy 18 (2012) 45–51
studies being conducted at Rocky Reach Dam and has conducted acoustic-tag studies for Chelan County PUD during the previous 12 years at Rocky Reach and Rock Island dams. Steven Hemstrom is a senior fisheries biologist for Chelan County Public Utility District, Wenatchee, Washington. He holds a B.S. in Fisheries Management from the University of Idaho, Moscow, Idaho. He has 22 years of experience studying resident and anadromous fish populations in hydroelectric reservoirs in the
51
Northwest. Currently, he designs and implements juvenile salmon and steelhead survival studies in the mid-Columbia River as part of Chelan PUD’s Anadromous Fish Agreements and Habitat Conservation Plans (HCPs) for the Rocky Reach and Rock Island Hydroelectric Projects. In addition, he oversees annual pikeminnow predator control programs for Chelan PUD’s HCPs and conducts radiotelemetry research studies on adfluvial bull trout in Rocky Reach and Rock Island reservoirs as part project license requirements for ESA-listed resident fish.
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/envsci
Assessing compliance with fish survival standards: a case study at Rock Island Dam, Washington John R. Skalski a,*, Tracey W. Steig b, Steven L. Hemstrom c a
Columbia Basin Research, School of Aquatic and Fishery Sciences, University of Washington, 1325 Fourth Avenue, Suite 1820, Seattle, WA 98101-2509, USA b Hydroacoustic Technology, Inc., 715 NE Northlake Way, Seattle, WA 98105, USA c Public Utility District No. 1 of Chelan County, 327 North Wenatchee Avenue, Wenatchee, WA 98011, USA
article info Published on line 9 February 2012 Keywords: Juvenile salmon survival Yearling Chinook salmon Steelhead Sockeye salmon Columbia River Habitat Conservation Plan Fish tagging Hydroelectric project Hydro power Endangered Species Act
1.
abstract Safe fish passage through hydroprojects is of paramount importance in the Pacific Northwest of the United States where anadromous runs of salmon smolts pass through as many as nine dams on the Columbia River on their way to the ocean. Minimum survival standards through the dams or hydroprojects (i.e., reservoir and dam) have been established by the 2008 Federal Columbia River Power System (FCRPS) Biological Opinion or by Habitat Conservation Plans (HCPs) in order to protect salmon stocks. These federal requirements have prompted the need to conduct scientifically and statistically rigorous and precise smolt survival studies at federally and publicly operated hydroprojects throughout the SnakeColumbia River Basin. Successful studies have been the cooperative results of regulators, hydro managers, fish biologists, engineers, and biometricians working together to conduct these high value investigations. Rock Island Dam, Washington, is used as a case study where a total of 17 release-recapture studies were conducted over a nine-year period on three salmonid species to assess compliance with HCP survival standards.
Introduction
Management of inland waters requires balancing often conflicting social, economic, industrial, and recreational needs of the public and private sectors with the desire for a healthy and sustainable ecosystem. In the Pacific Northwest of the United States, this means balancing hydroelectric production and irrigation withdrawals with sustainable anadromous populations of salmonids. An important part of these efforts is to provide safe passage through the hydroprojects for salmonid smolts outmigrating to the ocean and upriver returning adult salmon (Quinn, 2005, pp. 226–228). Survival standards for fish passage at hydroprojects have been established by resource agencies to help assure viable populations of salmon. At federally operated dams in the
# 2012 Elsevier Ltd. All rights reserved.
Columbia River, such standards have been established in the 2008 Biological Opinion (BiOp) on the Federal Columbia River Power System (FCRPS) (National Marine Fisheries Service, 2008) under the Endangered Species Act (ESA) of 1973 (16 U.S.C. § 1531–1544). At three public utility dams on the Mid-Columbia River, smolt survival standards have been established in Habitat Conservation Plans (HCPs) developed with the National Oceanic and Atmospheric Administration (NOAA) Fisheries and U.S. Fish and Wildlife Service to conform to National Environmental Policy Act (NEPA) and the Endangered Species Act as part of the Federal Energy Regulatory Commission (FERC) relicensing agreements. In the Columbia River Basin, smolt survival studies are used to either demonstrate compliance with the survival standards or guide mitigation actions at the hydroprojects until compliance has been achieved (Skalski et al., 2009, 2010). The
* Corresponding author. Tel.: +1 206 616 4851. E-mail address: [email protected] (J.R. Skalski). 1462-9011/$ – see front matter # 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.envsci.2012.01.001
46
environmental science & policy 18 (2012) 45–51
outcome of these high value tagging studies can have significant financial consequences to hydro operations and important ramifications to the iconic salmon populations of the Pacific Northwest. The typical cost of a seasonal survival study for one species of salmon smolt exceeds $1 M. Tagging studies that fail to meet design or precision requirements must be repeated, and delays in achieving compliance can have other even more costly financial consequences, depending on the agreements with regulatory and resource agencies and statutory compliance with the ESA. The purpose of this paper is to illustrate by example how compliance testing was successfully implemented at Rock Island Dam in the Mid-Columbia River, Washington. The case history at this hydroproject illustrates the long-term strategy that was used to successfully evaluate compliance with survival standards for three different salmonid species. This process included converting to a new tag technology that made the testing feasible, and finding an operating condition that was beneficial to both hydroelectric production and fish passage survival. This nine-year study also illustrates the benefits of a strong interdisciplinary research team and good working relationships between hydro operations and regulatory agencies.
2.
Study area
Rock Island Dam is located on the Columbia River, approximately 21 km downstream of the city of Wenatchee, Washington, at river kilometer (rkm) 729.7 (Fig. 1). The original
project consisted of a single powerhouse and spillway, and was completed in 1933. In 1979, a second powerhouse was added near the west shore. The original powerhouse, Powerhouse #1, has a total of 11 vertical-axis kaplan turbine units, each with 3 intakes. A house unit, with 2 intakes, is used exclusively to produce power to operate the project. The spillway consists of a total of 32 spillbays separated at spillbay 15, which is occupied by the central adult fish ladder. Therefore, 14 spillbays are located to the east of the ladder and 17 to the west. Powerhouse #2 has 8 horizontal-axis bulb turbine units, each with 2 intakes. The dam has a total generating capacity of 624 megawatts. The reservoir extends to Rocky Reach Dam (rkm 764) and is 33 km in length.
3.
Survival standards
The smolt passage survival standards differ substantially between the federally operated and public utility operated dams. In the Mid-Columbia, where three public utility district (PUD) dams are guided by HCPs and two other dams are guided under relicensing agreements, the standard is project passage survival (i.e., dam and reservoir) of 0.93. Compliance requires three annual estimates with an average greater than or equal to the threshold. For an individual study to be acceptable, the project passage survival must be estimated with a standard error (SE) of 0.025, and river flow conditions must be within the middle 90% of the historical distribution. The same criteria apply for yearling Chinook salmon, steelhead, and sockeye
Fig. 1 – Location of Rock Island Dam on the Columbia River near Wenatchee, Washington.
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salmon smolts. The paired release-recapture design of Burnham et al. (1987) based on the Cormack (1964) single release-recapture model is the most common approach to estimating project passage survival at these PUD operated dams. At federally operated projects, the 2008 BiOp requires dam passage survival to be 0.96 for spring stocks (i.e., yearling Chinook salmon and steelhead) and 0.93 for summer stocks (i.e., subyearling Chinook salmon). Compliance requires two annual estimates with an average greater than or equal to the threshold. For an individual study to be acceptable, the estimate of dam passage survival must have a SE 0.015 and river flows must be within the middle 90% of historical distributions. The logistics of isolating the estimate of smolt survival through only the dam itself (i.e., dam face to the tailrace mixing zone) is more complicated than estimating project passage survival. Currently, the virtual/paired-release design of Skalski et al. (2010) which requires three release groups of fish is being used at federal facilities. As a rule of thumb, halving the size of the SE for a survival estimate requires quadrupling the release sizes of a tagging study (Cormack, 1964). Consequently, the need for three releases when conducting a virtual/paired-release design, instead of just two release groups for paired-release design, and the much larger number of tagged fish per release result in the BiOp specifications being much more demanding than the HCP study requirements. However, the BiOp requires only two years of successful tagging studies compared to three years for the HCP, and the BiOp has a provision for a lower survival rate for subyearling Chinook salmon in the summer, which the HCP does not. Overall, neither set of study standards is inherently easier to attain than the other.
4.
Methods
Fish tagging studies based on the statistical principles of mark-recapture or release-recapture theory must be used to estimate smolt passage survival. The tagging models allow the processes of survival and detection to be differentiated, thereby permitting estimates of absolute survival. The statistical models that are used to derive the survival estimates also provide the means to estimate the uncertainty in the sampling process and provide estimates of standard errors (SEs). In 2002, when the compliance studies began at Rock Island Dam, the passive integrated transponder (PIT) tag was the dominant and most prevalent technology in use at that time in the Columbia Basin (Prentice et al., 1990; Skalski et al., 1998). To estimate project passage survival, a group of PIT-tagged fish would be released at the top of the reservoir and another group of PIT-tagged fish released in the tailrace below the dam (Fig. 2). To estimate absolute survival from each release group, a minimum of two downstream detection sites is required. Detection can only occur at downstream hydroprojects equipped with PIT-tag detectors located in smolt bypass systems. For studies at Rock Island Dam, this meant detection sites at McNary, John Day, and Bonneville, 259 km, 382 km, and 495 km, respectively, downriver. Although PIT tags are small enough to be injected into a fish with a 5–10 ml syringe
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and a 12-gauge, veterinary-grade needle (Columbia Basin Fish and Wildlife Authority, PIT Tag Steering Committee, 1999) and are inexpensive ($2–$3 per tag), detection rates are generally low (0.08–0.20) and the fixed detection locations at smolt bypass systems preclude collection of finer-resolution information on fish movement and survival. The low detection rates also mean that many tens of thousands of fish have to be reared and marked for each survival study. On average, the PIT-tag survival studies at Rock Island Dam (i.e., 2002–2004) used a total of 100,000 fish per species per year for each survival investigation. Looking into the future, Chelan PUD saw the need to convert from PIT tags to the then relatively new acoustic tag for conducting survival studies for several reasons. Acousticdetection arrays can be constructed almost anywhere (with power available) with detection probabilities often exceeding 0.90. This allowed detection arrays to be placed in midreservoir and at the face of the dam to partition project survival into dam and pool components and to estimate routespecific passage proportions and survival probabilities at the dam (Skalski et al., 2009). This information was highly valuable in diagnosing passage problems if survival standards were not met and in developing corrective actions to help achieve the standards. Secondly, the high detection probabilities, shorter travel distances, and correspondingly higher survival rates to the downstream detection arrays meant tag release sizes could be greatly reduced. A survival study could now be conducted with 800–900 fish (Steig et al., 2005). These sample sizes also permitted tagging the run-of-river (ROR) fish rather than only hatchery fish in the survival studies, thereby permitting direct inferences to the population of interest. The reduced sample sizes also allowed species such as sockeye salmon which do not have large hatchery reserves to be studied using ROR fish. The acoustic-tag survival studies used the same pairedrelease locations as the PIT-tag survival studies (Fig. 3). However, the mandatory minimum two downriver detection locations were now installed in the adjacent downriver reservoir, 18 and 37 km below Rock Island Dam. The smolts were internally tagged with either the HTI Model 795E Acoustic Tags (weight, 1.5 g in air), the HTI Model 795 m Acoustic Tags (weight, 0.75 g in air), or the HTI Model 795Lm Acoustic Tags (weight, 0.65 g in air), depending on the fish stock ($200 per tag). The detection arrays consisted of the HTI Model 290 Acoustic Tag Receiver operating at 307 kHz, with 8 hydrophones across the river at Crescent Bar, Washington, and 10 hydrophones at Sunland Estates, Washington (Fig. 3). Survival from the release locations to these downstream detection sites typically exceeded 0.90 and detection rates at the arrays themselves often exceeded 0.98 – all of which contributed greatly to the reduced sample sizes needed for the acoustic-tag survival studies. Paired releases of PIT-tagged or acoustic-tagged fish were performed every 2–3 days over the course of the species outmigration in order to make inferences to season-wide survival. A weighted average of the replicate PIT-tag estimates of project passage survival was computed to obtain an annual estimate, weighing inversely proportional to the coefficient of variation (CV) squared. The small individual releases of acoustic-tagged fish were pooled to obtain an annual estimate.
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Fig. 2 – Schematic of a PIT-tag survival study using a paired release-recapture design at Rock Island Dam, Washington, with releases in the tailraces above (R1) and below (R2) the project, and detection sites at three downriver dams and associated estimated parameters. Estimate of project passage survival calculated as the ratio Sˆ RI ¼ Sˆ 1 =Sˆ 2 .
During 2002–2004, three consecutive years of dual PIT-tag and acoustic-tag estimates of project passage survival for yearling Chinook salmon smolts were performed. The purpose was both to assess compliance with survival standards, and to assess whether the acoustic-tag and PIT-tag studies produced comparable survival estimates that the fisheries community could trust. From 2005 onward, only acoustic-tag survival studies were performed. The fish used in the PIT-tag studies came from the Turtle Rock Hatchery operated by the PUD, while the much smaller sample sizes of acoustic-tagged run-of-river fish were obtained from the Rocky Reach juvenile sampling facility. Minimum size of yearling Chinook salmon and steelhead smolts with acoustic tags was set at 150 mm in length. For sockeye, minimum fish size was 95 mm in length. Length criteria were selected to assure tag burden <5% of body weight. Fish with obvious injuries, deformities, or >20% scale loss were excluded.
5.
Results
The nine-year history of compliance testing at Rock Island Dam encompassed three fish species, two different tag technologies and two different operating conditions at the dam (Table 1). From 2002 to 2006, Rock Island Dam was operated at a 20% spill level during the smolt outmigration. This 20% spill level was selected because prior tag investigations suggested this operating condition had a good chance of achieving the required survival standards. From 2002 to 2004, yearling Chinook salmon survival was evaluated using both PIT- and acoustic-tag technologies. Each of the six investigations produced estimates of project passage survival with acceptable standard errors of 0.025. Four of the six annual studies also had survival estimates above the required threshold (i.e., Sˆ 0:93) and the three-year means exceeded the survival threshold for both tag types (i.e., Sˆ¯ 0:93) (Table 1).
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Table 1 – Summary of yearling Chinook salmon, steelhead, and sockeye salmon smolt survival estimates at Rock Island Project. Survival estimates for individual studies, associated standard errors (in parentheses), and cross-year arithmetic averages are presented. Species Yearling Chinook salmon
Year c
2002 2003c 2004c 2002–2004 Arith. Avg.: 2007b 2008b 2010b
PIT-tag
Acoustic-tag
0.9555 (0.0249) 0.9339 (0.0115) 0.9139 (0.0227) 0.9344
0.9520 (0.0263) 0.9387 (0.0157) 0.9419 (0.0118) 0.9442
2007–2010 Arith. Avg.: Steelhead
2004c 2005c 2006c 2004–2006 Arith. Avg.: 2008b 2010b 2008, 2010 Arith. Avg.:
Fig. 3 – Schematic of acoustic-tag releases (R1 and R2) used to estimate project passage survival at Rock Island Dam, Washington, with downriver detection sites at Crescent Bar and Sunland Estates, Washington.
Sockeye salmon
2007–2009 Arith. Avg.: a b c
The PIT-versus acoustic-tag comparisons were also deemed successful, with the annual estimates not significantly different (P > 0.05) between tag types using a Z-test. At the end of 2004, yearling Chinook salmon was considered in compliance with the survival standard at an operational spill level of 20%, and acoustic-tag survival studies were approved as a valid study approach henceforth. During 2004–2006, steelhead survival studies using acoustic tags were conducted under the 20% spill program previously approved for yearling Chinook salmon. All three annual steelhead estimates of season-wide passage survival achieved the precision requirement (i.e., SE 0.025) and the three-year mean survival met HCP requirements with a value of Sˆ¯ ¼ 0:9404 (Table 1). Starting in 2007, the PUD requested the HCP Committee to reevaluate compliance of yearling Chinook salmon and steelhead at a lower spill level of 10%. Compliance had previously been achieved at the 20% spill level, but the PUD was seeking a more efficient operating condition that still met HCP survival standards. In 2007, 2008, and again in 2010, yearling Chinook salmon survival was estimated at a 10% spill level using acoustic tags. All three studies met their precision requirements and the three-year average exceeded the compliance threshold with an estimate of Sˆ¯ ¼ 0:9375 (Table 1). In 2008 and again in 2010, steelhead passage survival was estimated at the 10% spill level, and the two survival studies met their precision requirements with a two-year average of Sˆ¯ ¼ 0:9675 (Table 1). The HCP committee, working with the PUD, agreed a
2007a 2008b 2009b
0.9725 (0.0185) 0.8972 (0.0157) 0.9428 (0.0081) 0.9375
0.9658 (0.0114) 0.9158 (0.0154) 0.9396 (0.0132) 0.9404 0.9699 (0.0133) 0.9652 (0.0122) 0.9675
0.9188 (0.0123) 0.9335 (0.0163) 0.9457 (0.0159) 0.9327
Single-release survival estimate with 10% project spill. Paired-release study conducted with 10% project spill. Paired-release study conducted with 20% project spill.
third year of steelhead survival studies was not needed, given the previous two years of results. A third steelhead study would have had to result in a survival estimate below 0.8549 not to exceed the three-year average 0.93. The HCP committee considered this highly unlikely because no previous survival estimate was ever that low. Consequently, both the yearling Chinook salmon and steelhead met compliance requirements under a 10% spill condition. The size of the acoustic tag was reduced from an initial size of 1.5 g in 2004, to 0.75 g in 2007, and to 0.65 g in 2010. This permitted the PUD to begin evaluating the feasibility of conducting project passage survival studies on the smaller sockeye salmon smolt. In 2007, a single release-recapture study (i.e., only the upstream treatment release of the pairedrelease design) was performed from the tailrace of Rocky Reach Dam to Crescent Bar below Rock Island Dam. Survival from the Rocky Reach tailrace to Crescent Bar was estimated at c ¼ 0:0123Þ. In 2008 and 2009, standard paired Sˆ ¼ 0:9188 ðSE release-recapture studies were performed; both met the precision requirement (i.e., SE < 0.025) and both exceeded the survival threshold (i.e., S > 0.93) (Table 1). Because the 2007 single-release estimate of survival included mortalities in the next reservoir, it was a negatively biased estimate of project passage survival. Nevertheless, the three-year average exceed the survival standard with a value of Sˆ¯ ¼ 0:9327 (Table 1). The HCP Coordinating Committee acknowledged the 2007 estimate as negatively biased and accepted the three-year average of sockeye salmon as attaining the HCP survival requirement.
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Hence, sockeye salmon survival was also found in compliance with HCP requirements at a 10% spill level.
6.
Discussion
The Rock Island Dam is the second PUD operated dam to meet its HCP survival standards for spring migrants in the Columbia River Basin. The Wells Dam operated by Douglas County PUD was the first, completing testing in 2000, and successfully completing a 10-year checkup in 2010. The other three PUD operated dams have compliance studies underway. Compliance testing began at the federally operated dams in 2010 with efforts expected to expand substantially in the years to come. The extensive testing that went on at Rock Island dam was due to two factors. The first factor was the shift from the previously accepted PIT-tag technology to the new acoustictag technology and its long-term advantages. The calibration testing conducted from 2002 to 2004 on yearling Chinook salmon smolts by Chelan PUD opened the way for other hydroprojects to directly employ the new tag technology without further testing. Currently, all compliance testing in the Columbia River Basin is based on acoustic-tag studies. The second factor was the compliance testing at two different operating conditions, first at 20% and then at 10% spill. The strategy Chelan PUD used in achieving compliance with the smolt survival standard was a risk averse approach. Failure to achieve compliance with survival standards under the HCP agreement could result in turning over partial control of the dam operations to the resource agencies. Consequently, an initial set of operating conditions was selected (i.e., 20% spill) that had good prospects of achieving the survival standards. Once compliance was achieved under those conditions, the PUD then worked at fine tuning hydro operations (i.e., 10% spill) where both fish protection and efficient hydroelectric production could be simultaneously achieved. In this manner, hydro operations could be optimized while at the same time safeguarding fish resources. The history of compliance testing at Rock Island Dam reflects a good working relationship between the PUD and the resource agencies. The acceptance of the 2007 single-release study as part of the sockeye salmon compliance testing and foregoing the third year of steelhead testing reflects this working relationship based on good science and wellconducted studies. All 17 of 17 compliance tests met their precision requirements and provided all parties with confidence in the results and the sincerity of the research efforts. When adequate evidence had been amassed, the interested parties could make decisions with an acceptable level of uncertainty. This confidence in the test results was the product of a successful interdisciplinary effort by biologists, engineers, biometricians, hydro operators, and representatives from resource agencies, who shared a common interest in resource stewardship and good science.
Acknowledgments We wish to thank Chelan Public Utility District for supporting this work and this manuscript.
references
Burnham, K.P., Anderson, D.R., White, G.C., Brownie, C., Pollock, K.H., 1987. Design and analysis methods for fish survival experiments based on release-recapture. American Fisheries Society Monograph 5. Columbia Basin Fish and Wildlife Authority, PIT Tag Steering Committee, 1999. PIT Tag Marking Procedures Manual. Version 2.0. Copy Available From PIT Tag Information System (PTAGIS) at http://www.ptagis.org/ptagis/ frame.jsp?menu=3&main=main.jsp?menu=3. Cormack, R.M., 1964. Estimates of survival from the sighting of marked animals. Biometrika 51, 429–438. National Marine Fisheries Service, 2008. Endangered Species Act Section 7(a)(2) consultation biological opinion and Magnuson-Stevens Fishery Conservation and Management Act essential fish habitat consultation: Consultation on remand for operation of the Federal Columbia River Power System, 11 Bureau of Reclamation projects in the Columbia Basin and ESA Section 10(a)(1)(A) Permit for juvenile fish transportation program. May 5, 2008. Prentice, E.F., Flagg, T.A., McCutcheon, C.S., 1990. Feasibility of using implantable passive integrated transponder (PIT) tags in salmonids. American Fisheries Society Symposium 7, 317–322. Quinn, T.P., 2005. The Behavior and Ecology of Pacific Salmon and Trout. American Fisheries Society in association with University of Washington Press, Seattle. Skalski, J.R., Buchanan, R.A., Townsend, R.L., Steig, T.W., Hemstrom, S., 2009. A multiple-release model to estimate route-specific and dam passage survival at a hydroelectric project. North American Journal of Fisheries Management 29, 670–679. Skalski, J.R., Smith, S.G., Iwamoto, R.N., Williams, J.G., Hoffmann, A., 1998. Use of PIT-tags to estimate survival of migrating juvenile salmonids in the Snake and Columbia Rivers. Canadian Journal of Fisheries and Aquatic Sciences 55, 1484–1493. Skalski, J.R., Townsend, R.L., Steig, T.W., Hemstrom, S., 2010. Comparison of two alternative approaches for estimating dam passage survival using acoustic-tagged sockeye salmon smolts. North American Journal of Fisheries Management 30, 142–156. Steig, T.W., Skalski, J.R., Ransom, B.H., 2005. Comparison of acoustic and PIT tagged juvenile Chinook, steelhead, and sockeye salmon (Oncorhynchus spp.) passing dams on the Columbia River, USA. In: Spedicato, M.T., Lembo, G., Marmulla, G. (Eds.), Aquatic Telemetry: Advances and Applications. Food and Agriculture Organization of the United Nations, Rome, pp. 275–286. John R. Skalski is Professor of Biological Statistics at the University of Washington in the School of Aquatic & Fishery Sciences. He is also an adjunct professor in Wildlife Science in the School of Forest Resources. He is a member of the Center for Quantitative Science in Forestry, Fisheries, and Wildlife. He has written over 50 peer-reviewed papers and 100 technical reports on tag analyses. Other areas of study include demographic analyses, assessment of energy-related effects on mobile species, impact and accident assessment, and sampling theory. Tracey W. Steig is Senior Project Engineer for Hydroacoustic Technology, Inc. (HTI). Tracey has Bachelor of Science and Master of Science degrees in Civil Engineering from the University of Washington. He has conducted numerous hydroacoustic- and acoustic-tag studies on the Columbia and Snake rivers since 1982. Tracey is currently the Project Engineer for the acoustic-tag
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studies being conducted at Rocky Reach Dam and has conducted acoustic-tag studies for Chelan County PUD during the previous 12 years at Rocky Reach and Rock Island dams. Steven Hemstrom is a senior fisheries biologist for Chelan County Public Utility District, Wenatchee, Washington. He holds a B.S. in Fisheries Management from the University of Idaho, Moscow, Idaho. He has 22 years of experience studying resident and anadromous fish populations in hydroelectric reservoirs in the
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Northwest. Currently, he designs and implements juvenile salmon and steelhead survival studies in the mid-Columbia River as part of Chelan PUD’s Anadromous Fish Agreements and Habitat Conservation Plans (HCPs) for the Rocky Reach and Rock Island Hydroelectric Projects. In addition, he oversees annual pikeminnow predator control programs for Chelan PUD’s HCPs and conducts radiotelemetry research studies on adfluvial bull trout in Rocky Reach and Rock Island reservoirs as part project license requirements for ESA-listed resident fish.