Upper Columbia Spring Chinook Salmon, Steelhead, and Bull Trout Recovery
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- 4.1Guiding Principles
- 4.2Recovery Strategy
- 4.2.1Abundance
- 4.2.2Productivity
- 4.2.3Spatial Structure
- 4.2.4Diversity
- 4.2.5Combining VSP Parameters
4Delisting Criteria
In the previous sections, this plan described the status of ESA-listed populations in the Upper Columbia Basin and reasons for their decline. In this section, the plan identifies goals, objectives, reclassification criteria and recovery criteria for naturally produced spring Chinook salmon, steelhead, and bull trout in the Upper Columbia Basin. This plan differentiates between “reclassification” and “recovery” criteria (NOAA 2004). “Reclassification” criteria represent the levels of abundance, productivity, spatial structure, and diversity necessary for “endangered” species (spring Chinook) to be classified as “threatened” under the ESA. “Recovery” criteria are the same as “delisting” criteria, which represent the levels of abundance, productivity, spatial structure, and diversity necessary for each species to be removed from ESA listing. Recovery levels are higher than reclassification levels. It should be noted, however, that these biological criteria (VSP parameters) are only one component of the decision-making process of whether or not listed fish are reclassified and de-listed. Before the species can be reclassified or de-listed, NOAA Fisheries and USFWS must evaluate if the existing and ongoing institutional measures are sufficient to address the threats (see Section 3.11) to ensure that the populations and the ESU and DPS remain viable. 4.1Guiding PrinciplesAlthough there are no specific regulations regarding recovery, the statutory language of the ESA offers some guidance in recovery planning. Section 4(f) of the ESA addresses the development and implementation of recovery plans. The following are the key provisions of the Act for development of recovery plans:
In summary, statutory (e.g., Freedom of Information Act, Federal Advisory Committee Act, Administration Procedure Act, National Environmental Policy Act, Paperwork Reduction Act, and the Information Quality Act) guidance requires certain elements to be included in the plan. Within these “sideboards,” plan developers are given considerable discretion to determine the details of how they develop the plan. This plan is science-based and relied on the guidance provided by the ICBTRT and the Bull Trout Draft Recovery Plan. Delisting criteria were developed by the ICBTRT in concert with the three Eastern Washington Regions (including Tribes), WDFW, and USFWS. The following criteria provide guidance to decision makers within each region. 4.2Recovery StrategyAt the time of listing, spring Chinook and steelhead in the Upper Columbia Basin exhibited low abundance and productivity (see Section 2). Trends in abundance were mostly downward and replacement ratios were low. Likewise, bull trout abundance in the Upper Columbia Basin was relatively low (see Section 2). Most bull trout populations (or subpopulations) exhibited depressed or unknown trends. Since 2000, naturally produced spring Chinook and steelhead abundance and productivity have increased. However, they still remain at levels that are considered below recovered population levels. The strategy of this plan is to recommend goals, objectives, and actions that address the primary factors within each “H” (Hydro, Hatchery, Harvest, and Habitat) that limit the abundance, productivity, spatial structure, and diversity of naturally produced spring Chinook, steelhead, and bull trout in the Upper Columbia Basin.70 Each action is linked directly to a specific limiting factor (see Section 5). For example, recommended actions within the hydropower system are intended to increase survival of juveniles and adults passing through dams and reservoirs; recommended actions within hatcheries are intended to address abundance, productivity, and diversity issues associated with propagation of stocks; recommended actions within harvest are intended to reduce incidental take of listed species; and recommended actions within habitat are directed at protecting important habitats and minimizing stresses (various land-use and management activities) that degrade spawning and rearing habitat conditions.71 Ultimately, the implementation of specific recovery actions should lead to the restoration of naturally produced spring Chinook salmon, steelhead, and bull trout populations such that they become viable components of the ecosystem managed within the context of multiple land uses and natural resource management. These actions will also benefit other fish species and some wildlife, and lessen the chance for additional listings in the Upper Columbia Basin. For all listed species, recovery requires reducing or eliminating threats to the long-term persistence of populations, maintaining widely distributed populations across diverse habitats of their native ranges, and preserving genetic diversity and life history characteristics. Successful recovery of the species means that populations, DPS, and ESU have met certain measurable criteria associated with viable salmonid populations (ICBTRT 2005). This plan focuses on four viable salmonid population (VSP) parameters: abundance, productivity, spatial structure, and diversity of naturally produced fish (see ICBTRT 2005a, b for a detailed discussion on VSP parameters) and bull trout goals and objectives. Importantly, this plan does not expect listed species where they did not occur historically, nor does it expect abundances that occurred historically.
This plan also recognizes the primary importance of smolts/redd as a metric for habitat productivity. That is, in addition to evaluating productivity for the entire life cycle (mean spawner:spawner ratios), this plan uses smolts/redd to isolate the function of tributary habitat, without the confounding effects of mortality outside the subbasin. Although this plan currently lacks the information needed to identify recovery criteria based on smolts/redd, monitoring programs are in place or planned that will allow the use of this index as a consistent approach to evaluating restoration actions in the future. 4.2.3Spatial StructureSpatial structure concerns the geographic distribution of a population and the processes that affect the distribution. Populations with restricted distributions and few spawning areas are at a higher risk of extinction due to catastrophic environmental events (e.g., a single landslide) than populations with more widespread and complex spatial structures. A population with complex spatial structure will include multiple spawning areas and will allow the expression of natural patterns of gene flow and life-history characteristics. Some populations, such as Entiat spring Chinook, have a naturally simple spatial structure and therefore have an inherently higher risk of extinction. As noted earlier, this plan does not expect spatial structure where it did not exist historically. 4.2.4DiversityPopulation diversity concerns the phenotypic (morphology, behavior, and life-history traits) and genotypic (DNA) characteristics of populations. Because environments continually change due to natural process (e.g., fires, floods, drought, landslides, volcanism, etc.) and anthropogenic influences, populations exhibiting greater diversity are more resilient to both short- and long-term changes. Phenotypic diversity allows more diverse populations to use a wider array of environments and protects populations against short-term temporal and spatial environmental changes. Genotypic diversity (DNA), on the other hand, provides populations with the ability to survive long-term changes in the environment. It is the combination of phenotypic and genotypic diversity expressed in a natural setting that provides populations with the ability to adapt to long-term changes. In some cases, the mixing of hatchery fish (or excessive numbers of out-of-basin stocks) with naturally produced fish on spawning grounds can actually decrease genetic diversity within the population (Hallerman 2003). According to the ICBTRT (2005a, b), diversity of naturally produced populations, ESUs, and DPSs can decrease because of hatchery adaptations of domestication, losses of genetic variability through supportive breeding, and erosion of natural population structure through homogenization. Recovery actions should be designed to reduce domestication and homogenization, and prevent gene flow rates greater than natural levels. 4.2.5Combining VSP ParametersAbundance and productivity are closely linked. That is, rates of productivity at relatively low abundance should be, on average, sufficiently greater than 1.0 to allow the population to rapidly return to abundance target levels.74 In contrast, productivity rates can be closer to 1.0 when population abundance is at target levels. The relationship between productivity and abundance is called a viability curve and it describes those combinations of abundance and productivity that yield a particular risk threshold. The ICBTRT has developed viability curves for spring Chinook and steelhead of different population size groups. The ICBTRT identified different size groups based on estimates of historically accessible spawning and rearing habitat. Spring Chinook populations within the Upper Columbia ESU fall within the “basic” (Entiat population) and “large” (Wenatchee and Methow populations) size categories (Figure 4 .31). Steelhead populations within the Upper Columbia DPS fall within the “basic” (Entiat and Okanogan populations) and “intermediate” (Wenatchee and Methow populations) size categories (Figure 4 .32). The Okanogan steelhead population is categorized as “basic” in the U.S. and “intermediate” if streams in Canada are included. Further analyses may redefine the minimum numbers for Upper Columbia Basin populations. This could change the designation of populations within the ESU and the DPS in the Upper Columbia Basin. Viability curves truncate at minimum spawner numbers that differ depending on population size categories. Regardless of population productivity, basic populations must maintain a minimum spawner abundance of 500 spawners, intermediate a minimum of 1,000 spawners, and large populations must maintain a minimum of 2,000 spawners to be considered viable. These minimum levels were developed by the ICBTRT (2005a, b). Note that the area above the viability curves indicates that the populations are at a low risk of extinction, while areas below the curves represent high risk. Under historical conditions, it is likely that most populations demonstrated combinations of intrinsic production potential and abundance above the 5% viability curve. There are no viability curves for bull trout and therefore separate criteria are identified for bull trout abundance and productivity (see Section 4.4.3). Spatial structure and diversity are also closely related. Because spatial structure is the process that drives diversity, the two (spatial structure and diversity) are very difficult to separate (ICBTRT 2005a, b). Therefore, following the recommendations of the ICBTRT (2005a, b), this plan will evaluate spatial structure and diversity together. The mechanisms, factors, and metrics used to assess spatial structure and diversity are presented in Table 4 .8. Further analyses may redefine the factors and metrics used to assess spatial structure and diversity. This could change the designation of populations within the ESU and DPS in the Upper Columbia Basin. 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