Review of 2017 Lamprey Synthesis Report

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In response to the Northwest Power and Conservation Council’s November 21, 2017 request, the ISRP reviewed the report Synthesis of Threats, Critical Uncertainties, and Limiting Factors in Relation to Past, Present and Future Priority Restoration Actions for Pacific Lamprey in the Columbia River Basin, November 15, 2017 (hereafter Lamprey Synthesis) prepared by the Columbia River Inter-Tribal Fish Commission (CRITFC), Confederated Tribes of the Umatilla Indian Reservation, Confederated Tribes of the Warm Springs Indian Reservation, and Confederated Tribes and Bands of the Yakama Reservation. The ISRP also considered a report with supporting information from the Confederated Tribes of the Warm Springs Indian Reservation. A detailed description of the review process leading up to this 2017 Lamprey Synthesis and ISRP review is provided in the Lamprey Synthesis document.

The ISRP concludes that the Lamprey Synthesis provides a comprehensive account of current knowledge about the Pacific lamprey and its conservation status in the Columbia River Basin. It concisely documents the history and scope of partnerships, collaborative research, management, and restoration efforts. The Lamprey Synthesis also provides substantial guidance toward identification of critical uncertainties, limiting factors, and priority management actions that should inform future research and restoration efforts within the Fish and Wildlife Program. Questions previously posed by the Council, ISAB, and ISRP were largely addressed to the ISRP’s satisfaction.

One fundamental question that warrants further attention is: do Pacific lamprey exist as partially reproductively isolated, locally adapted populations within the Columbia River Basin? The Lamprey Synthesis does not provide much discussion of genetic evidence from recent studies and does not consider the implications of this uncertainty for restoration strategies. It states (p. 9): “Although more work is needed to better understand lamprey genetics, Pacific Lamprey appear to exhibit low genetic differentiation among regional stocks, and population structure reflects a single broadly distributed population across much of the Pacific Northwest.” This statement is potentially misleading. The low level of differentiation observed in neutral gene frequencies does indicate greater historical gene flow among regions in Pacific lamprey than in Pacific salmon, presumably reflecting weaker philopatry, but it does not preclude genetic differentiation in adaptive gene frequencies or selection for local adaptations at the watershed scale. Divergent natural selection among groups of lamprey spawning in different watersheds would not be surprising given that Pacific lamprey spend 5 to 9 years (over half the total life cycle) as relatively sedentary ammocoetes in sediments accessed shortly after hatching and which likely vary among watersheds (i.e., spawning locations). More direct measurement of straying rates (perhaps through tagging studies) and modeling is needed to determine whether observed straying rates would prevent local adaptation at plausible rates of natural selection. A better understanding of the spatial scale of local adaptation within the basin is needed to guide precautionary strategies for supplementation.

Another general concern involves Section 6.2 (Remaining Restoration, Research and Monitoring Needs). It is difficult to identify or evaluate specific evidence or analyses that the authors have used to develop the conclusions presented in Section 6.2. For example, supplementation for restoration is identified as a priority (in Section 6.2.2, Range-wide Themes, and also on page 100), but this prioritization warrants further discussion and justification in relation to habitat restoration.

See the full ISRP memo for detailed comments.