The response was adequate to address ISRP questions and provided additional information. The project proponents understand and are forthcoming about the limitations of their data. The results of this project are limited in space and time, but the results could justify further studies, that together with this project, could provide a more complete understanding of potential delayed mortality. The results could bear on future decisions on dam configuration and operations. This study is responsive to the ISAB's Latent Mortality Report and past ISRP reviews.

Concerning Q5 on ocean conditions, and the number of study years needed to bracket a range of those conditions, the proponents state later on in their response that, “Seven data points should give us a good feel for what is happening to hatchery Chinook.” And “If managers in the region would like to see additional years of study, or other species added, we are open to that.” The ISRP suggests that the proponents consult with oceanographers to get an impression if, in fact, seven years are enough, given our present knowledge of the time scales of change in the oceans. Some even say there are cycles and, if so, to properly answer the latent mortality questions the peaks and troughs of the cycles might need to be sampled.

The desirability of extending the project to obtain more years of data, or to include additional species, can be better evaluated after three or more years of completed adult returns are available. Although, as the project proponents acknowledge, no experimental design can simulate migration through a free-flowing Snake River, the results of the study will either support the hypothesis that survival is decreased by migration through the three lower dams and reservoirs, or fail to support an effect large enough to be detected, given the power of the tests.

A response is requested that provides: 1. evidence that sample sizes are sufficient to detect meaningful differences in SARs between the two Lower Granite release groups; 2. evidence that the assumption of lognormally distributed LG/IH ratio is tenable; 3. an assessment of the extent to which hatchery fish used in this study are representative of wild stocks; 4. more details explaining the method used to estimate the number of juveniles that survived and were detected at McNary Dam; 5. a more complete assessment of the influence of ocean conditions on results to date. This is a very significant program that has the potential to answer some of the key questions about possible latent mortality due to dam passage. The proposal is well written. The objectives are straightforward and explained well. Accomplishments are reasonable and summarized well for each year of the project. The technical background is generally well done. The history of this project is not well described, and the proposal would benefit from more detailed information on how it developed. There is the issue of the extent to which the LG/IH ratio is analogous to the differential mortality parameter, D. Also, there is a question as to whether or not the length of time for the study will be adequate to obtain meaningful results because there are really only three years of data now rather than five years. These issues should be addressed in a response.

This is a high priority project that deserves funding. The problem addressed in this project is delayed mortality. This project addresses the lack of empirical experiments designed to quantify delayed effects associated with hydrosystem passage. The proposal refers to the ISRP Retrospective Report (2005) and the BiOp Remand as requesting similar research needs as those stated in this project's objectives.

The overall objectives are clearly stated. The proposal states that the project will use smolt-to-adult return rates (SAR) of PIT-tagged yearling Chinook salmon smolts exposed to two different migrational experiences within the FCRPS to test the hypothesis of extra or delayed passage mortality. The response clarifies how the three treatment groups will be compared and what the implications of all comparisons are. Also, the response provided additional details on the estimation of standard error for the L/I ratio that is fundamental in determining target sample sizes.

The proposal documented some other funded work in the area, and the response provided a more complete summary. Relationships to other projects were clearly identified in the response. The history of the project is briefly described by noting reasons for lack of progress. Although the project has recently started, the results have been reported, including a paper in Transactions of the American Fisheries Society.

In summary, the sponsors of the proposal agreed with all of the ISRP review comments and recommendations and responded with appropriate and adequate revisions to the proposal.