At the Council’s February 26, 2016 request, the ISRP reviewed a response to our January 25, 2016 review of the Spokane Tribe of Indians’ Fiscal Year 2016 proposed “Lake Roosevelt Northern Pike Suppression Plan.” This proposed suppression effort is a scope change for the ongoing Lake Roosevelt Fisheries Evaluation Program (Data Collection) project (#1994-043-00). In our January review (hereafter “preliminary review”), we requested a response on eight issues (ISRP 2016-2) to improve the proposal’s scientific credibility. On February 9, 2016, the Council considered the proposal, our recommendation, and public comments, and recommended support for the March 2016 gill netting effort. However, the Council conditioned support for the remaining proposal efforts on a favorable ISRP and Council response review.
The proposed effort is intended to reduce the proliferation of northern pike in Lake Roosevelt through immediate suppression actions guided by studies evaluating the proposed techniques. This proposal is based on baseline data from a pilot study on the northern pike population in Lake Roosevelt (reported within the proposal), which indicated a recent marked increase in abundance of northern pike. Northern pike are voracious predators that are a likely threat to native species and non-native game fishes and they could potentially move downstream in the Columbia River and possibly impact the recovery of ESA listed salmon. The project proponents contend that “it is critical that a monitoring and suppression plan be developed immediately while abundance is still relatively low…to reduce the risk of Northern Pike numbers expanding within Lake Roosevelt and beyond.”
ISRP Recommendation: Meets Scientific Review Criteria (Qualified)
The ISRP appreciates the gracious and constructive approach of the proponents in addressing the ISRP review comments. The proponents have provided a useful revision of their proposal, supplemental information, and responses to the preliminary comments. The effort largely meets scientific review criteria, but the ISRP identifies the following qualifications that can be addressed when finalizing the statement of work for the Council and Bonneville Power Administration (BPA):
- Include explicit hypotheses to be tested by the proposed activities and provide quantitative objectives for what is to be achieved.
- Include quantitative objectives for the northern pike suppression effort as a means to evaluate program success (e.g., reduce northern pike CPUE by __% and reduce the relative abundance of large northern pike [> __ mm total length] by __% by the year 20___). Quantitative objectives should be developed for each metric used to evaluate northern pike suppression, and a time frame should also be included in each objective.
- Include quantitative objectives regarding the protection of native fishes captured as bycatch.
- Revisit the elements of proposal that describe criteria for assessing the effects of bycatch and actions to alleviate the effects of bycatch on native species. The focus should be on preventing population-level effects of bycatch on native species. We question bycatch limitations for non-native piscivorous fishes (e.g., walleye) as they do not appear to be consistent with the Council’s Fish and Wildlife Program to protect native fishes.
- The planned use of 4-hour gillnet sets during daylight hours using nets with panels of five different mesh sizes needs to be supported. A detailed review of literature or a comparative study of catch rates during the day and at night, for varying durations of gillnet sets, and for different mesh sizes is needed to determine the design of gillnets and sets that will optimize catch efficiency for northern pike.
- Include a study design and description of the otolith microchemistry methods the project will use to determine the natal origins of northern pike sampled in Lake Roosevelt. Discuss how knowledge of natal origins will inform adaptive management decisions regarding northern pike suppression in Lake Roosevelt.
Progress toward meeting quantitative objectives should be evaluated by the proponents and documented in annual progress reports, and the relative success of the results should justify continuation, modification, or termination of the suppression effort. Under the section “Anticipated Future Work,” the proponents’ proposal states that “work completed for the proposed request for scope change and budget increase will be used by Lake Roosevelt Co-Managers (STOI, WDFW, CCT) to develop a short-term, three year Northern Pike relative abundance survey and suppression plan for FY17, FY18 and FY19.” If requested, the ISRP could review the co-managers three-year plan before implementation.