Stephen N. Bennett

A Comparison of the Performance and Compatibility of Protocols Used by Seven Monitoring Groups to Measure Stream Habitat in the Pacific Northwest

Abstract To comply with legal mandates, meet local management objectives, or both, many federal, state, and tribal organizations have monitoring groups that assess stream habitat at different scales. This myriad of groups has difficulty sharing data and scaling up stream habitat assessments to regional or national levels because of differences in their goals and data collection methods. To assess the performance of and potential for data sharing among monitoring groups, we compared measurements made by seven monitoring groups in 12 stream reaches in northeastern Oregon. We evaluated (1) the consistency (repeatability) of the measurements within each group, (2) the ability of the measurements to reveal environmental heterogeneity, (3) the compatibility of the measurements among monitoring groups, and (4) the relationships of the measurements to values determined from more intensive sampling (detailed measurements used as a standard for accuracy and precision in this study). Overall, we found that some stre...

Propagule pressure and stream characteristics influence introgression: cutthroat and rainbow trout in British Columbia

Hybridization and introgression between introduced and native salmonids threaten the continued persistence of many inland cutthroat trout species. Environmental models have been developed to predict the spread of introgression, but few studies have assessed the role of propagule pressure. We used an extensive set of fish Stocking records and geographic information system (GIS) data to produce a spatially explicit index of potential propagule pressure exerted by introduced rainbow trout in the Upper Kootenay River, British Columbia, Canada. We then used logistic regression and the information-theoretic approach to test the ability of a set of environmental and spatial variables to predict the level of introgression between native westslope cutthroat trout and introduced rainbow trout. Introgression was assessed using between four and seven co-dominant, diagnostic nuclear markers at 45 sites in 31 different streams. The best model for predicting introgression included our GIS propagule pressure index and an environmental variable that accounted for the biogeoclimatic zone of the site (r2=0.62). This model was 1.4 times more likely to explain introgression than the next-best model, which consisted of only the propagule pressure index variable. We created a composite model based on the model-averaged results of the seven top models that included environmental, spatial, and propagule pressure variables. The propagule pressure index had the highest importance weight (0.995) of all variables tested and was negatively related to sites with no introgression. This study used an index of propagule pressure and demonstrated that propagule pressure had the greatest influence on the level of introgression between a native and introduced trout in a human-induced hybrid zone.

Progress and Challenges of Testing the Effectiveness of Stream Restoration in the Pacific Northwest Using Intensively Monitored Watersheds

Across the Pacific Northwest, at least 17 intensively monitored watershed projects have been implemented to test the effectiveness of a broad range of stream restoration actions for increasing the freshwater production of salmon and steelhead and to better understand fish–habitat relationships. We assess the scope and status of these projects and report on challenges implementing them. We suggest that all intensively monitored watersheds should contain key elements based on sound experimental design concepts and be implemented within an adaptive management framework to maximize learning. The most significant challenges reported by groups were (1) improving coordination between funders, restoration groups, and researchers so that restoration and monitoring actions occur based on the project design and (2) maintaining consistent funding to conduct annual monitoring and evaluation of data. However, we conclude that despite these challenges, the intensively monitored watershed approach is the most reliable me...

Levels of Introgression in Westslope Cutthroat Trout Populations Nine Years after Changes to Rainbow Trout Stocking Programs in Southeastern British Columbia

Abstract Introgressive hybridization (introgression) between native westslope cutthroat trout Oncorhynchus clarkii lewisi and introduced rainbow trout O. mykiss in the upper Kootenay River, British Columbia, appears to be recent and is partly attributed to rainbow trout stocking in Koocanusa Reservoir starting in 1988. In 1998, rainbow trout stocking was stopped or replaced with the stocking of triploids throughout the watershed. The goal of this research was to determine the effect of the change in stocking practices on the level of introgression between westslope cutthroat trout and rainbow trout. We monitored 14 sites from 1999 to 2007 using four co-dominant, diagnostic nuclear markers. Sample sites were categorized as (1) open if no fish migration barriers existed between the site and the reservoir or (2) closed if migration barriers were present between the site and the reservoir. We classified fish as pure westslope cutthroat trout if no rainbow trout alleles were detected; fish were classified as h...

Adapting Adaptive Management for Testing the Effectiveness of Stream Restoration: An Intensively Monitored Watershed Example

Adapting Adaptive Management for Testing the Effectiveness of Stream Restoration: An Intensively Monitored Watershed Example Nicolaas Bouwes, Stephen Bennett & Joe Wheaton To cite this article: Nicolaas Bouwes, Stephen Bennett & Joe Wheaton (2016) Adapting Adaptive Management for Testing the Effectiveness of Stream Restoration: An Intensively Monitored Watershed Example, Fisheries, 41:2, 84-91, DOI: 10.1080/03632415.2015.1127806 To link to this article: http://dx.doi.org/10.1080/03632415.2015.1127806

Comparison of Tributary Survival Estimates of Steelhead using Cormack–Jolly–Seber and Barker Models: Implications for Sampling Efforts and Designs

AbstractWe conducted simulations to compare the precision and bias of survival estimates from Cormack–Jolly–Seber (CJS) and Barker models to known parameter values based on empirical data for steelhead/resident Rainbow Trout Oncorhynchus mykiss from the John Day River, Oregon. We simulated seasonal differences in recapture and survival rates, and we varied the number of fish tagged, recapture and resight rates, sample site size, and fish movement (migratory or resident). Survival estimates from the Barker model had higher precision and lower or equal bias in comparison with estimates from the CJS model under almost all simulation scenarios. The precision of Barker survival estimates increased the most as the number of tagged fish increased from 50 to 200 (CV = 0.4–0.09). The Barker models superior performance was dependent on the availability of resight data; such data are becoming more readily available, especially in places where large numbers of individuals are PIT-tagged and where an interrogation in...

A comparison of asymmetric before-after control impact (aBACI) and staircase experimental designs for testing the effectiveness of stream restoration

Before-after-control-impact (BACI) experimental designs are commonly used in large-scale experiments to test for environmental impacts. However, high natural variability of environmental conditions and populations, and low replication in both treatment and control areas in time and space hampers detection of responses. We compare the power of two asymmetric BACI (aBACI) designs to two staircase designs for detecting changes in juvenile steelhead (Oncorhynchus mykiss) abundance associated with a watershed-scale stream restoration experiment. We performed a simulation study to estimate the effect of a 25% increase in steelhead abundance using spatial and temporal estimates of variance from an ongoing study, and determined the power of each design. Experimental designs were then applied to three streams and each stream was composed of three 4 km long sections. We compared the power of a single treatment section in one stream (BACI-1), three simultaneous treatments of all sections in one stream (BACI-3), three sequential treatments in one stream (STAIRCASE-1), and three sequential treatments in one section in each stream (STAIRCASE-3). All designs had ≥ 94% power to detect a 25% increase in abundance assuming average variance. Under worst-case variance (i.e., upper 95% confidence limits of historical variance estimates), the STAIRCASE-3 design outperformed the BACI-1, BACI-3, and STAIRCASE-1 designs (i.e., 77%, 41%, 8%, and 33% power respectively). All the designs estimated the effect of the simulated 25% abundance increase, but the length of the confidence interval was much shorter for the STAIRCASE-3 design compared to the other designs, which had confidence intervals 58-596% longer. The STAIRCASE-3 design continued to have high power (88%) to detect a 10% change in abundance, but the power of the other designs was much lower (range 34-56%). Our study demonstrates that staircase designs can have significant advantages over BACI designs and therefore should be more widely used for testing environmental impacts.

What are the Conditions of Riparian Ecosystems? Identifying Impaired Floodplain Ecosystems across the Western U.S. Using the Riparian Condition Assessment (RCA) Tool

Environmental stressors associated with human land and water-use activities have degraded many riparian ecosystems across the western United States. These stressors include (i) the widespread expansion of invasive plant species that displace native vegetation and exacerbate streamflow and sediment regime alteration; (ii) agricultural and urban development in valley bottoms that decouple streams and rivers from their floodplains and reduce instream wood recruitment and retention; and (iii) flow modification that reduces water quantity and quality, degrading aquatic habitats. Here we apply a novel drainage network model to assess the impacts of multiple stressors on reach-scale riparian condition across two large U.S. regions. In this application, we performed a riparian condition assessment evaluating three dominant stressors: (1) riparian vegetation departure from historical condition; (2) land-use intensity within valley bottoms; and (3) floodplain fragmentation caused by infrastructure within valley bottoms, combining these stressors in a fuzzy inference system. We used freely available, geospatial data to estimate reach-scale (500 m) riparian condition for 52,800 km of perennial streams and rivers, 25,600 km in Utah, and 27,200 km in 12 watersheds of the interior Columbia River Basin (CRB). Model outputs showed that riparian condition has been at least moderately impaired across ≈70% of the streams and rivers in Utah and ≈49% in the CRB. We found 84% agreement (Cohen’s ĸ = 0.79) between modeled reaches and field plots, indicating that modeled riparian condition reasonably approximates on-the-ground conditions. Our approach to assessing riparian condition can be used to prioritize watershed-scale floodplain conservation and restoration by providing network-scale data on the extent and severity of riparian degradation. The approach that we applied here is flexible and can be expanded to run with additional riparian stressor data and/or finer resolution input data.

An Assessment of the Geographic Closure Assumption in Mark–Recapture Abundance Estimates of Anadromous Steelhead Populations

AbstractClosed population models are commonly used to estimate stream salmonid abundances using mark–recapture information collected during electrofishing surveys. To meet the model assumption of geographic closure, block nets are often used to prevent emigration and immigration of fish during the survey. Increased sampling and tagging efforts in an open site may be an appealing trade-off given the time it takes to properly deploy block nets, but it also increases an abundance estimate’s vulnerability to bias. We assessed the extent of geographic closure violation from emigration in open sites between mark and recapture passes utilizing PIT antennas as virtual block nets. This allowed us to quantify emigration rates of juvenile steelhead Oncorhynchus mykiss from 60 fish surveys across multiple seasons and watersheds. Our goals were to determine how season and site length influence emigration, examine how the life history of an anadromous salmonid may induce bias on mark–recapture abundance estimates, and ...