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File ECMAScript program Detecting Temporal Trends in Freshwater Fisheries Surveys: Statistical Power and the Important Linkages between Management Questions and Monitoring Objectives
by T.Wagner et al., ABSTRACT: Monitoring to detect temporal trends in biological and habitat indices is a critical component of fisheries management. Thus, it is important that management objectives are linked to monitoring objectives. This linkage requires a definition of what constitutes a management-relevant “temporal trend.” It is also important to develop expectations for the amount of time required to detect a trend (i.e., statistical power) and for choosing an appropriate statistical model for analysis. We provide an overview of temporal trends commonly encountered in fisheries management, review published studies that evaluated statistical power of long-term trend detection, and illustrate dynamic linear models in a Bayesian context, as an additional analytical approach focused on shorter term change. We show that monitoring programs generally have low statistical power for detecting linear temporal trends and argue that often management should be focused on different definitions of trends, some of which can be better addressed by alternative analytical approaches.
Located in News & Events / / Brook Trout and Stream Temperature Workshop Information / Resource Materials: Reprints
File Troff document Fall and Early Winter Movement and Habitat Use of Wild Brook Trout
Abstract Brook Trout Salvelinus fontinalis populations face a myriad of threats throughout the species’ native range in the eastern United States. Understanding wild Brook Trout movement patterns and habitat requirements is essential for conserving existing populations and for restoring habitats that no longer support self-sustaining populations. To address uncertainties related to wild Brook Trout movements and habitat use, we radio-tracked 36 fish in a headwater stream system in central Pennsylvania during the fall and early winter of 2010–2011. We used generalized additive mixed models and discrete choice models with random effects to evaluate seasonal movement and habitat use, respectively. There was variability among fish in movement patterns; however, most of the movement was associated with the onset of the spawning season and was positively correlated with fish size and stream flow. There was heterogeneity among fish in selection of intermediate (0.26–0.44 m deep) and deep (0.44–1.06 m deep) residual pools, while all Brook Trout showed similar selection for shallow (0.10–0.26 m) residual pools. There was selection for shallow residual pools during the spawning season, followed by selection for deep residual pools as winter approached. Brook Trout demonstrated a threshold effect for habitat selection with respect to pool length, and selection for pools increased as average pool length increased up to approximately 30 m, and then use declined rapidly for pool habitats greater than 30 m in length. The heterogeneity and nonlinear dynamics of movement and habitat use of wild Brook Trout observed in this study underscores two important points: (1) linear models may not always provide an accurate description of movement and habitat use, which can have implications for management, and (2) maintaining stream connectivity and habitat heterogeneity is important when managing self-sustaining Brook Trout populations.
Located in News & Events / / Brook Trout and Stream Temperature Workshop Information / Resource Materials: Reprints
File Modeling spatially varying landscape change points in species occurrence thresholds
by T. Wagner and S. Miday, Abstract. Predicting species distributions at scales of regions to continents is often necessary, as largescale phenomena influence the distributions of spatially structured populations. Land use and land cover are important large-scale drivers of species distributions, and landscapes are known to create species occurrence thresholds, where small changes in a landscape characteristic results in abrupt changes in occurrence. The value of the landscape characteristic at which this change occurs is referred to as a change point. We present a hierarchical Bayesian threshold model (HBTM) that allows for estimating spatially varying parameters, including change points. Our model also allows for modeling estimated parameters in an effort to understand large-scale drivers of variability in land use and land cover on species occurrence thresholds. We use range-wide detection/nondetection data for the eastern brook trout (Salvelinus fontinalis), a stream-dwelling salmonid, to illustrate our HBTM for estimating and modeling spatially varying threshold parameters in species occurrence. We parameterized the model for investigating thresholds in landscape predictor variables that are measured as proportions, and which are therefore restricted to values between 0 and 1. Our HBTM estimated spatially varying thresholds in brook trout occurrence for both the proportion agricultural and urban land uses. There was relatively little spatial variation in change point estimates, although there was spatial variability in the overall shape of the threshold response and associated uncertainty. In addition, regional mean stream water temperature was correlated to the change point parameters for the proportion of urban land use, with the change point value increasing with increasing mean stream water temperature. We present a framework for quantify macrosystem variability in spatially varying threshold model parameters in relation to important largescale drivers such as land use and land cover. Although the model presented is a logistic HBTM, it can easily be extended to accommodate other statistical distributions for modeling species richness or abundance.
Located in News & Events / / Brook Trout and Stream Temperature Workshop Information / Resource Materials: Reprints
Resource Materials: Previous Workshops
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NorEaST Workshop - December 2014
Co-hosted by the US Geological Survey, Michigan State University and University of Wisconsin – Platteville. This meeting was organized as part of the “NorEaST – Stream Temperature Web Portal Demonstration and Application” project funded by the USGS Northeast Climate Science Center. Presentations are available for download.
Located in News & Events / / Brook Trout and Stream Temperature Workshop Information / Resource Materials: Previous Workshops
File NorEaST - invitation
NorEaST – Stream Temperature Web Portal Demonstration and User Testing. USGS Wisconsin Water Science Center, Middleton, WI, December 9th-10th, 2014.
Located in News & Events / / Resource Materials: Previous Workshops / NorEaST Workshop - December 2014
File Octet Stream NorEaST - agenda
Meeting Objectives: • Provide overview of stream temperature monitoring protocols and data management • Introduce and demonstrate the NorEaST Stream Temperature Web Portal • Conduct User testing of the NorEaST Web Portal and gain feedback • Demonstrate ways to automate data analysis and quality assurance of data • Demonstrate and discuss applications of continuous stream temperature data • Discuss leveraging NorEaST web portal with other efforts • Discuss moving NorEaST into the future (development needs, funding mechanisms/models, other site types, expanded geography, etc.)
Located in News & Events / / Resource Materials: Previous Workshops / NorEaST Workshop - December 2014
Go to link to download all presentations as a zip file
Located in News & Events / / Resource Materials: Previous Workshops / NorEaST Workshop - December 2014
2014 Stream Temperature Modeling (Meeting II)
Located in News & Events / / Brook Trout and Stream Temperature Workshop Information / Resource Materials: Previous Workshops
2014 Workshop - May 1st Stream Temperature Data and Modeling Meeting II
Co-hosted by EPA Region 1, U.S. Fish and Wildlife Service, North Atlantic Landscape Conservation Cooperative, USGS Northeast Climate Science Center, and USGS Conte Anadromous Fish Research Center. Presentations are available - see agenda below for a link to the files.
Located in News & Events / / Resource Materials: Previous Workshops / 2014 Stream Temperature Modeling (Meeting II)