Rebecca A. Buchanan

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• Doctor of Philosophy
• Senior Researcher at University of Washington

Greater understanding of the survival, travel time, and spatial distribution of juvenile salmonids among migration routes between their natal streams and the ocean is critical to the recovery of these threatened species. In the Sacramento–San Joaquin River Delta (Delta), a highly modified estuary in central California, USA, there is a critical need...

Objective Low survival of emigrating salmonid smolts through the interior regions of California's Sacramento–San Joaquin River Delta (hereafter, “Delta”) and large‐scale water extraction from that region have prompted managers to seek to predict and manipulate smolt route use through the tidal Delta. The local flow variables previously used in mode...

From 2008 to 2018, acoustic telemetry studies were conducted to evaluate dam passage survival of spring migrant Chinook salmon and steelhead smolts at seven of the eight federally operated dams on the lower Snake and Columbia rivers. Data from over 87 000 dam passage events were evaluated using regression modeling to identify the effect of spill op...

This document is a compilation and synthesis of the many references relevant to tag predation in salmonid studies in the Central Valley, as well as pertinent studies outside the region. There are four main sections: (1) background, (2) categorization tables, (3) annotated bibliography, and (4) appendices. Our aim is to provide researchers in the Ce...

Extirpation of the Central Valley spring-run Chinook salmon (Oncorhynchus tshawytscha) evolutionary significant unit (ESU) from the San Joaquin River is emblematic of salmonid declines across the western seaboard of the United States. Habitat restoration and fish reintroduction efforts are ongoing, but recent telemetry studies have revealed low out...

Effective management of natural resources and migratory fish populations depends on understanding the relationship between life cycle parameters, management decisions, and environmental conditions. Yet the difficulty of data collection can result in small or non‐representative data sets and thus limit the accuracy and utility of modeling results. T...

Background Acoustic telemetry is a powerful tool for studying fish behavior and survival that relies on the assumption that tag detection reflects the presence of live study subjects. This assumption is violated when tag signals continue to be recorded after consumption by predators. When such tag predation is possible, it is necessary for research...

Acoustic telemetry is a powerful tool for studying fish behavior and survival that relies on the assumption that tag detection reflects the presence of live study subjects. This assumption is violated in cases where tag signals continue to be recorded after predators have consumed tagged study subjects. When such tag predation is possible, it becom...

Southern salmon populations face increased risk from a warming climate. New analysis of salmon ear bones shows outsized reliance on rarely used cold-water habitat for population survival through drought years — habitat that is expected to shrink under climate change.

Extirpation of the Central Valley spring-run Chinook Salmon ESU (Oncorhynchus tshawytscha) from the San Joaquin River is emblematic of salmonid declines across the Pacific Northwest. Habitat restoration and fish reintroduction efforts are ongoing, but recent telemetry studies have revealed low outmigration survival of juveniles to the ocean. Previo...

All VAMP reports are available online at http://tuolumnerivertac.com/documents.htm

All VAMP reports are available online at http://tuolumnerivertac.com/documents.htm

All VAMP reports are available online at http://tuolumnerivertac.com/documents.htm

Juvenile steelhead (Oncorhynchus mykiss) are exposed to numerous threats in heterogeneous, estuarine environments, yet understanding of survival patterns and processes during this migratory stage is often limited by studies that use surrogate species or are restricted in duration and spatial specificity. Lack of detailed survival information in thi...

Survival of juvenile fall-run Chinook Salmon Oncorhynchus tshawytscha from the San Joaquin River (SJR) during their migration through the Sacramento-San Joaquin Delta of California has been low in recent years, and there is uncertainty about the role of river flow on survival. Five years (2010–2014) of acoustic telemetry data from juvenile hatchery...

Predation by non-native fishes in the McNary Reservoir and Hanford Reach of the Columbia River reduces the productivity of anadromous fish populations that rear in and migrate through this area. Recent work shows very low juvenile Chinook salmon survival, high consumption rates of juvenile salmonids by smallmouth bass and walleye, and high non-nati...

Survival of juvenile fall‐run Chinook Salmon Oncorhynchus tshawytscha through the San Joaquin River Delta of California, USA, has been low for most estimates since 2002, and has been consistently low since 2010. From 2010 through 2015, annual estimates of the probability of surviving through the Delta (from Mossdale to Chipps Island, approximately...

Background Multistate release–recapture models are used to study the movements and survival of animals when multiple migration pathways exist. Model complexity increases exponentially as the number of possible migration pathways increases. ResultsProgram Branch was developed as freeware to allow users to construct multistate release–recapture model...

As juvenile salmon enter the Sacramento-San Joaquin River Delta ("the Delta") they disperse among its complex channel network where they are subject to channel-specific processes that affect their rate of migration, vulnerability to predation, feeding success, growth rates, and ultimately, survival. In the decades before 2006, tools available to qu...

Survival of juvenile anadromous Pacific salmonids from their earliest age of seaward movement (“out‐migration”) through the tributaries that connect their rearing grounds to larger‐order rivers (“cohort survival”) is an important yet often unmonitored factor in the complex life history of these species. Populations with variable age at out‐migratio...

Background: Acoustic-tag studies with their high to very high detection rates defy traditional statistical wisdom regarding analysis of tagging studies. Conventional wisdom has been to use a parsimonious model with the fewest parameters that adequately describes the data to estimate survival parameters in release-recapture studies in order to find...

The survival of juvenile Chinook Salmon through the lower San Joaquin River and Sacramento–San Joaquin River Delta in California was estimated using acoustic tags in the spring of 2009 and 2010. The focus was on route use and survival within two major routes through the Delta: the San Joaquin River, which skirts most of the interior Delta to the ea...

The advent of small acoustic telemetry tags has greatly expanded our ability to track movements of juvenile salmonids as they migrate to the ocean. We are now able to track tagged fish as they move through complex environments such as river deltas and estuaries, and can begin to address such questions as: What routes do salmon smolts take through d...

The combined juvenile and adult detections of Snake River yearling Chinook salmon Oncorhynchus tshawytscha implanted with passive integrated transponder tags migrating through the hydroelectric facilities in the Federal Columbia River Power System were analyzed using the ROSTER statistical release–recapture model. This model was used to estimate th...

A multistate mark-recapture (MSMR) model of the adult salmonid migration through the lower Columbia River and into the Snake River was developed, designed for radiotelemetry detections at dams and tributary mouths. The model focuses on upstream-directed travel, with states determined from observed fish movement patterns indicating directed upstream...

Data from live and dead fish counts at salmonid spawning areas have been used for decades to estimate stream residence time. Simulation studies indicate that the peak-to-peak and median-to-median estimates of stream residence time will have at least a 50% negative bias under the best of circumstances. A new estimation technique called the “expectat...

To determine whether the Juvenile Salmon Acoustic Telemetry System (JSATS) technology was suitable for conducting subyearling Chinook salmon survival studies in the Priest Rapids Project, we tagged 546 Priest Rapids Hatchery-origin subyearling fall Chinook salmon (mean fork length = 104 mm) with a newly developed delayed-start acoustic transmitter...

A total of 1154 acoustic-tagged subyearling fall Chinook salmon (Oncorhynchus tshawytscha) were monitored during their movement through Lower Monumental Reservoir, Snake River, Washington, USA. A releaserecapture design was developed to partition their fates into migration, delayed migration (i.e., holdover or temporary residualization), and mortal...

The survival of very small fish can have a major impact on the dynamics of fisheries stocks. Numerous marking techniques have been developed or adapted to small fish in order to investigate either early life histories or small-sized species. Some techniques provide batch marks, while others provide individually unique identification with or without...

Previous methods of estimating route-specific passage and survival probabilities for anadromous salmonids past hydroelectric dams have often failed because of faulty assumptions. We present a robust, multiple-release model that combines release–recapture methods that are known to solve parts of the overall problem. Release 1 allows estimation of ro...

The combined juvenile and adult detection histories of PIT-tagged wild salmonids migrating through the Federal Columbia River Power System (FCRPS) were analyzed using the ROSTER (River-Ocean Survival and Transportation Effects Routine) statistical release-recapture model. This model, implemented by software Program ROSTER, was used to estimate surv...

The U.S. Army Corps of Engineers Portland District (CENWP) funds numerous evaluations of fish passage and survival on the Columbia River. In 2007, the CENWP asked Pacific Northwest National Laboratory to conduct an acoustic telemetry study to estimate the survival of juvenile Chinook salmon passing the spillway at Bonneville Dam. This report docume...

Juvenile Snake River fall Chinook salmon (Oncorhyncus tshawytscha) typically emigrate as age-0 fish from the Snake River to the Pacific Ocean between early June and September, with the majority of the fish swimming seaward between mid-June and mid-July. The fish emigrating later in the season have a higher likelihood of remaining in freshwater for...

In 2005, the University of Washington developed a new statistical model to analyze the combined juvenile and adult detection histories of PIT-tagged salmon migrating through the Federal Columbia River Power System (FCRPS). This model, implemented by software Program ROSTER (River-Ocean Survival and Transportation Effects Routine), has been used to...

Since 1987, millions of juvenile salmonids (smolts; Oncorhynchus species) in the Snake and upper Columbia rivers have been tagged with Passive Integrated Transponder (PIT) tags, and detected at hydroelectric projects as theymigrate downriver to the Pacific Ocean. Since the late 1990s, detection of PIT-tagged adults has been possible at some dams. E...

The finite annual rate of population increase (λ) is a fundamental demographic parameter that characterizes the relative annual change in animal numbers. Uncertainty in the estimation of λ from demographic population viability analyses (PVAs) has been largely limited to sensitivity analysis, calculating a pseudo-distribution for λˆ using Monte Carl...

Smolt transportation is a major mitigation strategy in the Columbia River hydrosystem, yet measures of its effects on adult return rates are often unclear. Managers use a variety of transportation effect measures that need to be clearly defined and easy to understand. We develop eight alternative transportation effect measures based on a release–re...

Ship wakes produced by deep-draft vessels transiting the lower Columbia River have been observed to cause stranding of juvenile salmon. Proposed deepening of the Columbia River navigation channel has raised concerns about the potential impact of the deepening project on juvenile salmon stranding. The Portland District of the U.S. Army Corps of Engi...

Ranked set sampling (RSS) can be a useful environmental sampling method when measurement costs are high but ranking costs are low. RSS estimates of the population mean can have higher precision than estimates from a simple random sample (SRS) of the same size, leading to potentially lower sampling costs from RSS than from SRS for a given precision....

Thesis (Ph. D.)--University of Washington, 2005. Release-recapture models for two types of tagging data from migrating salmonids in the Columbia and Snake rivers are presented. The first model uses both juvenile and adult PIT-tag data to analyze the seaward and spawning migrations through the hydrosystem. This branching model accommodates transport...