At the Council’s January 13, 2011 request, the ISRP reviewed Idaho Department of Fish and Game’s (IDFG) response to a preliminary ISRP review of the Accord proposal, Idaho Nutrient Enhancement Project (2008-607-00). This pilot project’s objective is to introduce selected nutrient sources to Idaho streams with the goal of providing benefits to Idaho steelhead populations. A paired treatment/control approach is proposed to evaluate the effectiveness of the nutrient enhancements. The ISRP’s preliminary review requested greater detail on six methodological issues related to the design and potential implementation of the project (ISRP 2010-30). The ISRP’s review follows below, organized by the six issues.
The ISRP finds that the proposal does not meet scientific review criteria.
Four of the six issues raised by the ISRP in their first review of this project were adequately addressed in the response. However, the ISRP remains doubtful that the statistical power of the study and the proposed methods are adequate for monitoring fish response. As a study "to develop the expertise and experience with commercially available products to conduct large-scale nutrient enhancement projects in Idaho," the project could yield useful information. However, as the biological effectiveness of fertilizer application still remains unclear, it seems premature to be devoting considerable effort and resources to operational considerations. As a study "to confirm that the addition of such nutrients can measurably increase steelhead population productivity in central Idaho streams," the project lacks statistical power to achieve such an extrapolation. As this study is designed, the results obtained could be used to draw conclusions only about the four streams included in the study; it will not confirm whether or not other streams selected for nutrient enrichment would respond in a similar manner.
Although the assessment of biological response to stream nutrient addition in this project is of limited value because of the inability to extend these results to other systems, as a case study, it has the potential to provide some insight as to an appropriate design for a more comprehensive study of steelhead response. However, the ISRP believes that the design and methods proposed are not adequate to evaluate steelhead response. At a minimum, accurate estimates of spawner abundance (at each study reach) and smolt production are required. Enhancements to the measurement of nutrient concentrations and primary production also would strengthen the study.
The ISRP recognizes that the proposal states that this project is not intended to be a rigorous assessment of the effectiveness of nutrient addition. However, until enough information has been generated to ascertain where and when this technique will be beneficial to salmon and steelhead recovery, all nutrient additions should be treated as experimental and include sampling rigorous enough to determine if the fish respond. If the funding for this project precludes the inclusion of a more appropriate sampling strategy, the ISRP suggests reducing project scale to enable biological response to be measured or utilizing the resources requested for this project to expand one of the ongoing nutrient addition evaluations in Idaho. If these options are not feasible, we would propose that the project be postponed until other studies in the basin provide information on effectiveness of this method. Should the technique be proven effective, an evaluation of the operational logistics of implementing large-scale stream nutrient enrichment in relatively small, occasionally remote streams would be appropriate.
The comments above emphasize the need for close collaboration among the various projects investigating fish response to nutrient addition in the basin. Such collaboration could greatly enhance the compatibility among projects in experimental design and methods and eventually provide data from enough locations to provide a general indication of the effectiveness of this technique.