Idaho Natural Production Monitoring and Evaluation : Annual Progress Report February 1, 2007 - January 31, 2008.
Populations of anadromous salmonids in the Snake River basin declined precipitously following the construction of hydroelectric dams in the Snake and Columbia rivers. Raymond (1988) documented a decrease in survival of emigrating steelhead trout Oncorhynchus mykiss and Chinook salmon O. tshawytscha from the Snake River following the construction of dams on the lower Snake River during the late 1960s and early 1970s. Although Raymond documented some improvements in survival through the early 1980s, anadromous populations remained depressed and declined even further during the 1990s (Petrosky et al. 2001; Good et al. 2005). The effect was disastrous for all anadromous salmonid species in the Snake River basin. Coho salmon O. kisutch were extirpated from the Snake River by 1986. Sockeye salmon O. nerka almost disappeared from the system and were declared under extreme risk of extinction by authority of the Endangered Species Act (ESA) in 1991. Chinook salmon were classified as threatened with extinction in 1992. Steelhead trout were also classified as threatened in 1997. Federal management agencies in the basin are required to mitigate for hydroelectric impacts and provide for recovery of all ESA-listed populations. In addition, the Idaho Department of Fish and Game (IDFG) has the long-term goal of preserving naturally reproducing salmon and steelhead populations and recovering them to levels that will provide a sustainable harvest (IDFG 2007). Management to achieve these goals requires an understanding of how salmonid populations function (McElhany et al. 2000) as well as regular status assessments. Key demographic parameters, such as population density, age composition, recruits per spawner, and survival rates must be estimated annually to make such assessments. These data will guide efforts to meet mitigation and recovery goals. The Idaho Natural Production Monitoring and Evaluation Project (INPMEP) was developed to provide this information to managers. The Snake River stocks of steelhead and spring/summer Chinook salmon still have significant natural reproduction and thus are the focal species for this project's investigations. The overall goal is to monitor the abundance, productivity, distribution, and stock-specific life history characteristics of naturally produced steelhead trout and Chinook salmon in Idaho (IDFG 2007). We have grouped project tasks into three objectives, as defined in our latest project proposal and most recent statement of work. The purpose of each objective involves enumerating or describing individuals within the various life stages of Snake River anadromous salmonids. By understanding the transitions between life stages and associated controlling factors, we hope to achieve a mechanistic understanding of stock-specific population dynamics. This understanding will improve mitigation and recovery efforts. Objective 1. Measure 2007 adult escapement and describe the age structure of the spawning run of naturally produced spring/summer Chinook salmon passing Lower Granite Dam. Objective 2. Monitor the juvenile production of Chinook salmon and steelhead trout for the major population groups (MPGs) within the Clearwater and Salmon subbasins. Objective 3. Evaluate life cycle survival and the freshwater productivity/production of Snake River spring/summer Chinook salmon. There are two components: update/refine a stock-recruit model and estimate aggregate smolt-to-adult survival. In this annual progress report, we present technical results for work done during 2007. Part 2 contains detailed results of INPMEP aging research and estimation of smolt-to-adult return rates for wild and naturally produced Chinook salmon (Objectives 1 and 3). Part 3 is a report on the ongoing development of a stock-recruit model for the freshwater phase of spring/summer Chinook salmon in the Snake River basin (Objective 3). Part 4 is a summary of the parr density data (Objective 2) collected in 2007 using the new site selection procedure. Data are maintained in computer databases housed at the IDFG Nampa Fisheries Research office (described in the Appendix) and are available from the first author. Other project accomplishments during 2007 (e.g., professional presentations) are also summarized in the Appendix.
- Research Organization:
- Bonneville Power Administration (BPA), Portland, OR (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- 36423
- OSTI ID:
- 961827
- Report Number(s):
- P109197; R&D Project: 1991-073-00; TRN: US200915%%295
- Country of Publication:
- United States
- Language:
- English
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