Charles E. Petrosky

Evidence Linking Delayed Mortality of Snake River Salmon to Their Earlier Hydrosystem Experience

Abstract The numbers of Snake River salmon and steelhead Oncorhynchus spp. have substantially declined since the completion of the Columbia River hydrosystem. We used analytical approaches to identify management options for halting the decline of these stocks, such as removal of Snake River dams and improvements to the existing hydrosystem. The benefits these actions are predicted to have in terms of salmon recovery hinge on whether the mortality that takes place in the estuary and early in their ocean residence is related to earlier hydrosystem experience during downstream migration. Evidence from the literature demonstrates numerous mechanisms that would explain this delayed mortality in relation to a fishs experience passing through the hydrosystem. Spatial and temporal comparisons of stock performance provide indirect evidence of delayed mortality and evidence that delayed mortality is linked to hydrosystem experience. Recent mark–recapture data also provide evidence of differences in delayed mortali...

Evolutionary effects of alternative artificial propagation programs: implications for viability of endangered anadromous salmonids

Most hatchery programs for anadromous salmonids have been initiated to increase the numbers of fish for harvest, to mitigate for habitat losses, or to increase abundance in populations at low abundance. However, the manner in which these programs are implemented can have significant impacts on the evolutionary trajectory and long‐term viability of populations. In this paper, we review the potential benefits and risks of hatchery programs relative to the conservation of species listed under the US Endangered Species Act. To illustrate, we present the range of potential effects within a population as well as among populations of Chinook salmon (Oncorhynchus tshawytscha) where changes to major hatchery programs are being considered. We apply evolutionary considerations emerging from these examples to suggest broader principles for hatchery uses that are consistent with conservation goals. We conclude that because of the evolutionary risks posed by artificial propagation programs, they should not be viewed as a substitute for addressing other limiting factors that prevent achieving viability. At the population level, artificial propagation programs that are implemented as a short‐term approach to avoid imminent extinction are more likely to achieve long‐term population viability than approaches that rely on long‐term supplementation. In addition, artificial propagation programs can have out‐of‐population impacts that should be considered in conservation planning.

Assessing Hydrosystem Influence on Delayed Mortality of Snake River Stream-Type Chinook Salmon

Abstract Snake River stream-type Chinook salmon Oncorhynchus tshawytscha exhibited substantial delayed mortality despite recent improvements in oceanic and climatic conditions. These salmon declined sharply with the completion of the Columbia River hydrosystem in addition to other anthropogenic impacts and changes in oceanic conditions. Previous analytical approaches have compared management options for halting the population decline. The predicted benefits of these options on salmon recovery hinged on whether the source of the mortality that takes place in the estuary and during early ocean residence is related to earlier hydrosystem experience during downstream migration (i.e., delayed hydrosystem mortality). We analyzed the spatial and temporal patterns of mortality for Chinook salmon populations to determine whether delayed mortality for the Snake River populations decreased during the recent period of favorable oceanic and climatic conditions. We found that Snake River stream-type Chinook salmon popu...

Idaho’s Salmon: Can We Count Every Last One?

Since the late 1950s, Idaho Department of Fish and Game (IDFG) biologists have collected standardized information about the status of salmon (Oncorhynchus spp.) in Idaho to assist fisheries management. Currently, IDFG uses indices of production such as redd and parr counts for streams, and adult salmon counts at dams and weirs to assess the recent history of our salmon runs. We depict Idaho anadromous salmon trends using indices for sockeye (O. nerka); spring, summer, and fall chinook salmon (O. tshawytscha); and steelhead (O. mykiss). Counts of redds in index areas provide the best historical indicator of trends and status of spring and summer chinook salmon. Numbers of redds have declined sharply through the last 33 years. All of the naturally reproducing Snake River anadromous salmonid populations, excluding chinook salmon in the Clearwater River drainage and Snake River steelhead, have been listed as endangered pursuant to the federal Endangered Species Act. Hydroelectric development of the mainstem Snake and Columbia rivers is widely recognized as the major factor causing the decline of these populations.

Judging cost-effectiveness of management of Snake River salmon: response to Halsing and Moore.

PAUL H. WILSON,∗§ HOWARD A. SCHALLER,∗ CHARLES E. PETROSKY,† AND JOHN LOOMIS‡ ∗Columbia River Fisheries Program Office, U.S. Fish and Wildlife Service, 1211 SE Cardinal Court, Suite 100, Vancouver, WA 98683, U.S.A. †Idaho Department of Fish and Game, 600 South Walnut Avenue, P.O. Box 25, Boise, ID 83707, U.S.A. ‡Department of Agricultural and Resource Economics, Colorado State University, Fort Collins, CO 80523, U.S.A.

Idaho Habitat and Natural Production Monitoring Part III, 1993 Annual Report.

The Idaho Department of Fish and Game (IDFG) has been monitoring and evaluating proposed and existing habitat improvement projects for rainbow-steelhead trout Oncorhynchus mykiss and chinook salmon O. tshawytscha in the Clearwater River and Salmon River drainages for the past 7 years. Projects included in the evaluation are funded by, or proposed for funding by, the Bonneville Power Administration (BPA) under the Northwest Power Planning Act as off-site mitigation for downstream hydropower development on the Snake and Columbia rivers. This evaluation project is also funded under the same authority (Fish and Wildlife Program, Northwest Power Planning Council [NPPC]). A mitigation record is being developed using increased carrying capacity and/or survival as the best measure of benefit from a habitat enhancement project. Determination of full benefit from a project depends on completion or maturation of the project and presence of adequate numbers of fish to document actual increases in fish production. The depressed status of upriver anadromous stocks has precluded measuring full benefits of any habitat project in Idaho. Partial benefit is credited to the mitigation record in the interim period of run restoration.

Idaho Habitat/Natural Production Monitoring, Pt. I: General Monitoring Subproject : Annual Progress Report 1990.

The Idaho Department of Fish and Game (IDFG) has been monitoring and evaluating proposed and existing habitat improvement projects for rainbow-steelhead trout Oncorhynchus mykiss, hereafter called steelhead, and chinook salmon O. tshawytscha, hereafter called chinook, in the Clearwater and Salmon River drainages for the past seven years. Projects included in the evaluation are funded by, or proposed for funding by, the Bonneville Power Administration (BPA) under the Northwest Power Planning Act as off-site mitigation for downstream hydropower development on the Snake and Columbia rivers. This evaluation project is also funded under the same authority (Fish and Wildlife Program, Northwest Power Planning Council). A mitigation record is being developed using increased carrying capacity and/or survival as the best measure of benefit from a habitat enhancement project. Determination of full benefit from a project depends on completion or maturation of the project and presence of adequate numbers of fish to document actual increases in fish production. The depressed status of upriver anadromous stocks has precluded measuring full benefits of any habitat project in Idaho. Partial benefit is credited to the mitigation record in the interim period of run restoration.