Howard Schaller

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.

Understanding the Significance of Redd Counts: A Comparison between Two Methods for Estimating the Abundance of and Monitoring Bull Trout Populations

Abstract For salmonids that exhibit multiple life history forms within a single population, it may be necessary to evaluate the inconsistencies associated with population monitoring techniques. We compared mark– resight population estimates with those based on annual redd counts for bull trout Salvelinus confluentus in eastern Oregon. Our data suggest that across years, the trends in population estimates based on expanded redd count data and those based on the mark–resight method may be similar within basins. Across basins, however, there appear to be inconsistencies between mark–resight population estimates for different size-classes of bull trout and the expanded redd count data. In some systems, only the larger, potentially migratory fish are represented in redd counts, whereas in others some combination of small resident and large, potentially migratory fish is represented. The disparity between redd counts and population estimates for the reproductive population suggests that caution be invoked when ...

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...

A Spatial Model to Assess the Effects of Hydropower Operations on Columbia River Fall Chinook Salmon Spawning Habitat

Abstract Priest Rapids Dam on the Columbia River produces large daily and hourly streamflow fluctuations throughout the Hanford Reach during the period when fall Chinook salmon Oncorhynchus tshawytscha are selecting spawning habitat, constructing redds, and actively engaged in spawning. Concern over the detrimental effects of these fluctuations prompted us to quantify the effects of variable flows on the amount and persistence of fall Chinook salmon spawning habitat in the Hanford Reach. Specifically, our goal was to develop a management tool capable of quantifying the effects of current and alternative hydrographs on predicted spawning habitat in a spatially explicit manner. Toward this goal, we modeled the water velocities and depths that fall Chinook salmon experienced during the 2004 spawning season, plus what they would probably have experienced under several alternative (i.e., synthetic) hydrographs, using both one- and two-dimensional hydrodynamic models. To estimate spawning habitat under existing...

Conserving Pacific Lamprey through Collaborative Efforts

Pacific Lamprey (Entosphenus tridentatus) have been an important part of the ecological community and co-evolved with aquatic species of the western rivers of the United States. Scarce information on Pacific Lamprey has hindered conservation and management efforts. To assess and conserve Pacific Lamprey, we developed a conservation initiative composed of three parts: assessment, conservation agreement, and regional implementation plans. We applied a novel ranking system that characterized risk to Pacific Lamprey throughout the U.S. range. We found that the majority of watersheds are at relatively high risk of extirpation, with few secure. The risk assessment results were instrumental in gaining partners’ support for a conservation agreement, with the goal of achieving long-term persistence and supporting traditional tribal cultural use of Pacific Lamprey. This extensive support has led to a collaborative effort in developing implementation plans and delivering numerous conservation actions. This approach ...

Conservation Challenges and Research Needs for Pacific Lamprey in the Columbia River Basin

The Pacific Lamprey Entosphenus tridentatus, an anadromous fish native to the northern Pacific Ocean and bordering freshwater habitats, has recently experienced steep declines in abundance and range contractions along the West Coast of North America. During the early 1990s, Native American tribes recognized the declining numbers of lamprey and championed their importance. In 2012, 26 entities signed a conservation agreement to coordinate and implement restoration and research for Pacific Lamprey. Regional plans have identified numerous threats, monitoring needs, and strategies to conserve and restore Pacific Lamprey during their freshwater life stages. Prime among these are needs to improve lamprey passage, restore freshwater habitats, educate stakeholders, and implement lamprey-specific research and management protocols. Key unknowns include range-wide trends in status, population dynamics, population delineation, limiting factors, and marine influences. We synthesize these key unknowns, with a focus on ...

Snorkelers' In-Water Observations Can Alter Salmonid Behavior

Abstract Direct underwater observation techniques (e.g., snorkel surveys) are widely used in fisheries science. Data collected from these surveys are used to estimate species abundance, detect presence and absence, and construct statistical models that predict microhabitat use and nonuse. To produce an unbiased estimate or model, fish should ideally behave as if there were no observer present. We conducted a study using underwater video to test whether snorkeling can elicit a change in fish behavior. Four behavioral metrics were measured: upstream movement, downstream movement, total movement, and number of fish in the field-of-view. Significant differences were detected in upstream, downstream, and total movements as a function of the in-water observer. These results suggest that an in-water observer can disturb fish, resulting in altered behavior, which in turn may bias study results. We suggest researchers use caution in making inferences to an entire population when data-collection methods have potent...

Rearing environment influences boldness and prey acquisition behavior, and brain and lens development of bull trout

Animals reared in barren captive environments exhibit different developmental trajectories and behaviors than wild counterparts. Hence, the captive phenotypes may influence the success of reintroduction and recovery programs for threatened and endangered species. We collected wild bull trout embryos from the Metolius River Basin, Oregon and reared them in differing environments to better understand how captivity affects the bull trout Salvelinus confluentus phenotype. We compared the boldness and prey acquisition behaviors and development of the brain and eye lens of bull trout reared in conventional barren and more structurally complex captive environments with that of wild fish. Wild fish and captive reared fish from complex habitats exhibited a greater level of boldness and prey acquisition ability, than fish reared in conventional captive environments. In addition, the eye lens of conventionally reared bull trout was larger than complex reared captive fish or same age wild fish. Interestingly, we detected wild fish had a smaller relative cerebellum than either captive reared treatment. Our results suggest that rearing fish in more complex captive environments can create a more wild-like phenotype than conventional rearing practices. A better understanding of the effects of captivity on the development and behavior of bull trout can inform rearing and reintroduction programs though prediction of the performance of released individuals.

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.