Reviews, narrative and other documents for proposal
201003200: Imnaha River Steelhead Status Monitoring (was 200205600)
ISRP final recommendation: Meets Scientific criteria? Response requested
The proponents provided satisfactory explanations for some of the issues raised by the ISRP. They did not, however, address the important question of why a coefficient of variation (CV) is the appropriate way of determining precision of adult abundance estimates. It seems that the proponents are using CV as a precision estimate without questioning its validity. The issue is programmatic in that it applies to most of the Fast Track projects. The response reiterated much of what was in the original proposal, but the proponents did add some helpful details. The proposal and response focus appropriately on obtaining accurate and precise numbers rather than testing hypotheses, say about the effects of habitat or temperature on juvenile survival. Perhaps that is all that should be expected. The high detection efficiency of the PIT tag arrays is beneficial to project data collection. Comments on Response to Specific ISRP Questions 1. The proponents provided a detailed response to this question. They cited numerous studies to justify measurements of discharge and water temperature as important determinants of adult migration and spawning, and juvenile survival and growth. They did not, however, explain how the physical data would be analyzed and related to adult returns. There is still some question about whether measurement of temperature and discharge is appropriate for a fast track proposal. The proponents assert that VSP parameters can only be interpreted in the context of the environment in which the fish exist. This may be true as a relative concept, but it is not the point of the fast-track proposals. They are intended to collect data in 2010 that is required to fulfill BiOp RPAs and that were vetted during the summer and fall 2009 regional and basinwide workshops. 2. The proponents reiterate much of the explanation and calculations provided in the proposal. The sample size for this project and the power analysis are appropriate. 3. The proponents provided a satisfactory justification for use of different types of weirs in different tributaries and the reasons for their locations. Their rationale is logical. The Imnaha Subbasin has diverse physical conditions (e.g., annual hydrograph) that require different types of weirs suitable for these conditions. Some of the weirs were in place prior to this project proposal and are being utilized opportunistically for the proposed work. Others will be installed, in conjunction with this project, in targeted areas of importance (e.g. Sheep Creek). 4. The proponents propose to estimate adult abundance at each weir or array location using mark-recapture techniques. Thus, they assert, adult return data will be comparable between tributaries with different types of weirs for sampling adults. There remains the question of accuracy of estimates for the different adult sampling methods and how this will influence data comparability between sampling locations. It would take a modeling exercise to determine the effect on viability analysis from error rates caused by different enumeration methods. Juvenile production issue. Juvenile migrants will be monitored as part of separate projects, apparently with standard techniques. The proponents currently are evaluating PIT-tag arrays as a method for detecting migrants in Imnaha tributaries but are unable to provide results at this time because the evaluations were only begun last year. Comparison of adult sampling methods. The proponents do not propose to test the efficacy of different types of sampling methods (PIT-tag arrays, floating, resistivity, fixed weirs) for estimating adult returns. They assert that the ISEMP project is undertaking this evaluation.
from Apr 2010 ISRP 2010-10 report
Narrative and other documents
|201003200.Adult Steelhead Escapement Monitoring Imnaha River Subbasin.doc|
|201003200n NPT(1).doc (narrative)|
ISRP preliminary recommendation: Meets scientific criteria? Response requested
While the proposed work has the potential to provide useful information on an important anadromous population in the Snake River basin, information that may be transferable (in some way to other subbasins), there are several major issues that need clarification and expansion. These issues include: 1. Better justification for Objective 3 2. Better explanation of the power analysis and data analysis 3. Justification for using different types of adult sampling methods and the rationale for their locations 4. Issues relating to comparability of data between tributaries whose adults were sampled using different techniques. 1. Technical Justification, Program Significance and Consistency, and Project Relationships The purpose of the proposed work is to quantify, with a "high degree of precision," escapement and spatial distribution of steelhead in the Imnaha River. The steelhead population in the Imnaha is part of the Snake River steelhead ESU declared Threatened under the Endangered Species Act. The proponents state that the Regional RM&E Collaboration strategies for the Snake River called for high precision estimates of adult abundance, with a coefficient of variation of 15% or less, "in at least one population per life history type per Major Population Group." This CV apparently was based on a recommendation by NOAA-Fisheries for monitoring VSP parameters (Crawford and Rumsey 2009, draft). In accordance with this strategy, the Coordinated Anadromous Workshop identified Imnaha steelhead as a "high precision priority population" so accurate estimates of escapement are needed. This is one of the more compelling justifications for the proposed work, but the proponents need to explain how the determination that the Imnaha was a priority population was made. However, the ISRP notes that CV (coefficient of variation) is not usually associated with precision of data, but with the variation associated with a state of nature. That is, salmon abundance across years has a CV, fall steelhead parr length has a CV. These are descriptions of the state of variation. They are not appropriate to determine confidence intervals. Crawford and Rumsey (2009) reference Carlile et al. (2008), which makes recommendations for coefficients of variation for estimates of total spawning escapement. The reference is to standard error of the estimate, not to variation in the population. More importantly, the statistical and biological basis for the recommendation in Carlile et al. (2008) has not been reviewed. The justification that the standard represents a realistic goal for planning because it corresponds to an acceptable risk (one year of one stock in six) of failing to label a stock of concern when warranted appears to be arbitrary. The observation that the standard has proven to be attainable for many escapement estimation studies does not mean that this is the appropriate data standard. Further justification for sample size targets is required. Further justification for expanding monitoring of A-run steelhead in the Imnaha includes: "The Imnaha River steelhead population is unique in the Snake River DPS in that it: 1) is physically small enough to conduct sampling of steelhead (mainstem flow and manageable number of spawning/rearing aggregates), 2) has a dendritic structure of spawning areas occurring across the entire range of elevations available to Snake basin DPS steelhead (spawning in areas from 1,000 feet up to 6,000 feet), and 3) has a supplementation program occurring in just two of its spawning aggregates." Also, "Steelhead redd counts are not physically possible throughout most the Imnaha River drainage due to inaccessibility and high turbidity". This justification appears meaningful. It seems consistent with the BiOp and the Imnaha Subbasin Plan. However, the justification could be stronger. The proposal makes the point that the work outlined is needed to fill a "critical data gap." A better justification would show how management of Imnaha steelhead could be improved if the new data were available. The proponents assert that monitoring the status of steelhead in individual tributaries within the Imnaha basin provides more detailed information on the status of the species than does an aggregate measure of abundance. Tributary population monitoring is needed to more effectively evaluate the efficacy of the Imnaha steelhead production program and the status and trends of the naturally-spawning steelhead population in the subbasin. Additionally, most estimates of adult steelhead abundance in Snake River tributaries occur at Lower Granite dam with apparently little information on steelhead escapement for subbasins and tributaries upstream of Lower Granite. This project proposes to provide this kind of information for the Imnaha subbasin and several of its tributaries. Considerable attention in the proposal is devoted to identifying general connections between this project and Columbia River Basin Fish and Wildlife Program, Imnaha Subbasin Plan, 2008 BiOp, PNAMP/CSMEP/AHSWG reports and recommendations by the ISRP, Council, NOAA- Fisheries and BPA. The project is consistent with RPAs in the BiOp, the Fish and Wildlife Program, and is complementary to other projects ongoing in the Snake River. It meets several needs identified in the Imnaha Subbasin Plan pertaining to adult summer steelhead escapement, distribution, and movement The proposed work will be similar to that of two others: a) ISEMP in its fast-track proposal has requested funding to install two PIT tag arrays in the Lower Imnaha River to assist this project in quantification of the distribution and abundance of steelhead in the Imnaha River basin, and b) the Lower Snake River Compensation Plan monitoring through the NPT and ODFW. Is the proposed work fully compatible with these projects? 2. Project History and Results This is new project. Information on Imnaha steelhead escapement and distribution gathered by previous projects is briefly summarized to provide background and context for this proposal. A version of this project was proposed as a new project in 2002 (#200205600) and received favorable reviews by the ISRP but was not funded. 3. Objectives, Work Elements, and Methods Objectives were clearly described and seem appropriate. The goal of the project is to establish steelhead population status information in the Imnaha River Subbasin. More specific objectives were embedded in a series of questions with specific tasks identified as objectives such as 1) Installing and maintaining of floating weirs and PIT tag arrays, 2) Quantifying steelhead escapement and collecting fish condition, tag, and tissue data, and 3) Collection of annual stream temperature and discharge. Objective 3 could be better justified. What is the benefit of measuring temperature and discharge relative to the proposals objectives? How will measurement of these parameters refine escapement estimates? The proposal seems to concentrate mostly on monitoring adult returns. It appears that juvenile production will be monitored but that is not explained with any detail. The proponents should describe to what extent outmigrants will be monitored? Will the proposed work complete all that is needed for Imnaha steelhead monitoring? The description of the power analysis [as recommended by NOAA-Fisheries (Crawford and Rumsey 2009, draft)] and methods of data analysis were provided in some detail, but were not entirely satisfactory. Better explanation of power analysis assumptions is necessary and the data analysis section needs to be clarified. References such as Thomson (2002) were not given, although relevant material can be found in Chapter 9 of Thompson, 1992 (“Sampling,” Wiley Interscience). Some notation should be clarified. Note that V(Ratio) is simply V(Ntotal)/(Ntag)2 and define Nno-tag, perhaps in terms of Ntag and Ntotal. A major objective of the proposed work is to install floating weirs and PIT tag arrays to estimate adult escapement, gather life history data, and collect tissues for genetic analysis of population structure. One set of PIT tag arrays will be placed near the mouth of the Imnaha to estimate subbasin adult escapement and two others will be located on tributaries. Several weirs, including fixed and resistivity weirs are already in place on a number of Imnaha tributaries. The proponents contend that the suite of arrays and weirs (in place and proposed) will allow precise estimation of steelhead escapement. Funding for the PIT tag arrays at the Imnaha mouth was not requested in this proposal. Rather, the proponents are depending on funding of ISEMP's fast-track proposal (proposal 2003-017-000) which proposes to install the arrays. The proponents of this proposal actually provide a better justification for installation of the arrays than the ISEMP proposal. It is of interest that the proponents did not request funding for the array at the Imnaha mouth in this proposal, but rather they trust that this apparently important part of their work would be funded through another proposal. Are there contingencies in the event that the ISEMP proposal for the Imnaha is not funded? The proponents should justify why the work requires different types of weirs (floating, resistivity, fixed) as well as PIT tag arrays. They also should clearly present the rationale for location of the weirs and the tributary arrays. Could the proposed work, in coordination with ISEMP, present an opportunity for testing the efficacy of different types of sampling methods (PIT-tag arrays, floating, resistivity, fixed weirs) for estimating adult returns? If so, it should be one of the objectives with corresponding methods for testing and analysis. Can basinwide adult estimates be derived from the set of upstream arrays and weirs and compared to estimates from the arrays at the river mouth? A possible concern is comparability of data between tributaries when different methods, with different efficiencies for sampling returning adults (e.g., arrays, different types of weirs) are used. For example, some tests of resistivity weirs in Alaska have identified serious biases in detecting returning adults. How do the proponents plan to handle this potentially confounding issue? Will the efficiencies and biases of the different sampling techniques be directly evaluated in the proposed work? The proposed M&E work could provide important information on status and trends of adult steelhead abundance in the Imnaha River. Its designation as a high precision population suggests the importance of the steelhead run, although justification for this designation was not clearly presented in the proposal. It seems that the intent is to use the Imnaha as a sort of index stream for other Snake River subbasins and tributaries, but the proponents are not explicit about this use.
from Feb 2010 ISRP 2010-7 report