David A. Boughton

• Doctor of Philosophy
• Research Fishery Biologist at National Oceanic and Atmospheric Administration

The use of PIT tags for studying fish behavior and demography in medium‐large rivers is hindered by antenna designs that are susceptible to damage in those environments and low detection efficiencies. We designed a vertically‐oriented, flexible PIT tag antenna for half‐duplex tags that is simple to construct and deploy, resilient to the dynamic riv...

Introduction Understanding how abundance, productivity and distribution of individual species may respond to climate change is a critical first step towards anticipating alterations in marine ecosystem structure and function, as well as developing strategies to adapt to the full range of potential changes. Methods This study applies the NOAA (Nati...

Ecological traps can be caused when partial restoration leads organisms to make maladaptive habitat choices. One example of this is fishways (e.g., fish ladders) that provide upstream passage at dams but are not paired with adequate downstream passage. We tested the hypothesis that attracting anadromous fishes to spawn above a dam, but blocking dow...

This technical document expands upon the California Coastal Monitoring Plan framework for anadromous salmonids first outlined in Fish Bulletin 180 (Adams et al. 2011). This plan focuses on methods for estimating population status and trend for steelhead (anadromous Rainbow Trout) inhabiting California coastal streams from the Pajaro River south.

Recovery of anadromous salmonid populations is complicated by their complex life histories. We examined the spatiotemporal interplay of stream temperature, geomorphic features, and a species’ thermal sensitivity mediated by biological interactions in a case study of steelhead trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha)...

Historically, anadromous steelhead Oncorhynchus mykiss and spring‐run Chinook Salmon O. tshawytscha used high‐elevation rivers in the Sierra Nevada of California but were extirpated in the 20th century by construction of impassable dams. Plans to reintroduce the fish by opening migratory passage across the dams and reservoirs can only succeed if up...

Annual report for Carmel River steelhead research.

Major ecological realignments are already occurring in response to climate change. To be successful, conservation strategies now need to account for geographical patterns in traits sensitive to climate change, as well as climate threats to species-level diversity. As part of an effort to provide such information, we conducted a climate vulnerabilit...

Dam removal provides a valuable opportunity to measure the fluvial response to changes in both sediment supply and the processes that shape channel morphology. We present the first study of river response to the removal of a large (32‐m‐high) dam in a Mediterranean hydroclimatic setting, on the Carmel River, coastal California, USA. This before‐aft...

Threshold effects are common in ecosystems and can generate counterintuitive outcomes in management interventions. A threshold effect proposed for steelhead trout (Oncorhynchus mykiss) is size-conditional smolting and marine survival. Steelhead are anadromous, maturing in the ocean but migrating to freshwater to spawn, where their offspring reside...

Bioenergetics model. Description of the bioenergetics model used to project growth of juvenile steelhead from October to 1 April. (DOCX)

Additional Figures. (DOCX)

Despite a growing consensus on the importance of floods in structuring river ecosystems, predicting the geomorphic and habitat response to specific flood pulses across a range of scales remains challenging. We used a large reservoir release in a semi-arid river to characterize geomorphic and habitat responses to a flood pulse, using an integrated f...

Estuaries along the California coast are recognized as critical rearing habitat for juvenile salmonids, particularly because they provide abundant feeding opportunities that support rapid growth. However, these estuaries exhibit a high degree of spatial and temporal variability in both food availability and elements of risk such as predation risk a...

doi: 10.1080/00028487.2014.986338

Climate change affects seasonal weather patterns, but little is known about the relative importance of seasonal weather patterns on animal population vital rates. Even when such information exists, data are typically only available from intensive fieldwork (e.g. mark-recapture studies) at a limited spatial extent. Here we investigated effects of se...

A strategy for recovering endangered species during climate change is to restore ecosystem processes that moderate effects of climate shifts. In mid-latitudes, storm patterns may shift their intensity, duration, and frequency. These shifts threaten flooding in human communities and reduce migration windows (conditions suitable for migration after a...

Aquatic species are threatened by climate change but have received comparatively less attention than terrestrial species. We gleaned key strategies for scientists and managers seeking to address climate change in aquatic conservation planning from the literature and existing knowledge. We address 3 categories of conservation effort that rely on sci...

This study considered whether different population viability analyses give similar estimates of extinction risk across management contexts. We compared the performance of population viability analyses developed by numerous scientific teams to estimate extinction risk of anadromous Pacific salmonids listed under the U.S. Endangered Species Act and c...

We address the growing need for accurate water temperature predictions in regulated rivers to inform decision support systems and protect aquatic habitats. Although many suitable river temperature models exist, few simultaneously model water temperature dynamics while considering uncertainty of predictions and assimilating observations. Here, we em...

Statistical and heat budget methods for analyzing temperature dynamics of creeks are limited by the ability to resolve thermal processes and fine-grained thermal structures, respectively. Here we describe a hybrid method that identifies distinct thermal components in a stream's heat budget using only temperature data and an algorithm that employs m...

Biologists commonly assume that restoration or partial-restoration of natural processes to river systems will increase the resilience of fish populations to climate change. We describe a modeling study that examines this assumption for steelhead (Oncorhynchus mykiss) during a specific phase of its life-cycle (upstream migration) in a particular riv...

In California, there are four recovery domains of Pacific salmon and steelhead. For each of these recovery domains, a Technical Recovery Team (TRT) was formed to develop the technical foundation on which recovery planning would be built. The Viable Salmon Populations (VSP) approach provided a consistent conceptual base for TRTs throughout the West...

Steelhead, Oncorhynchus mykiss, are currently listed under the United States Endangered Species Act (ESA) in central and southern California. In most of this region, steelhead are considered threatened, but the Southern California Distinct Population Segment (DPS), comprising populations in Santa Barbara County and southward is listed as endangered...

The number of individuals in a spawning run of anadromous fish can be estimated by tagging juveniles with passive integrated transponders during the freshwater phase and the subsequent monitoring of adult upstream migrants by use of instream tag readers. The method may enable monitoring of steelhead Oncorhynchus mykiss in systems where other method...

Temperature has long been used as an indicator of ecosystem health and suitability for aquatic species, particularly in sensitive areas crucial to the survival of declining important fish populations. Typically, temperature surveys are of long duration but very limited in spatial extent. In recent years, considerable attention has been paid to asse...

Abstract –  The salmonid Oncorhynchus mykiss tends to inhabit forested or snow-fed streams having cold reliable flows, but in the California chaparral they inhabit rain-fed stream networks with extensive areas of intermittent flow. We hypothesised that hydrological mechanisms in such watersheds tend to spatially segregate spawning and over-summerin...

Genetic analyses of coastal Oncorhynchus mykiss, commonly known as steelhead/rainbow trout, at the southern extreme of their geographic range in California are used to evaluate ancestry and genetic relationships of populations both above and below large dams. Juvenile fish from 20 locations and strains of rainbow trout commonly planted in reservoir...

1. We asked whether an increase in food supply in the field would increase the ability of fish populations to withstand climate warming, as predicted by certain bioenergetic models and aquarium experiments. 2. We subsidised the in situ food supply of wild juvenile steelhead (Oncorhynchus mykiss) in a small stream near the species’ southern limit. H...

"We explore the thesis that stochasticity in successional-disturbance systems can be an agent of species extinction. The analysis uses a simple model of patch dynamics for seral stages in an idealized landscape; each seral stage is assumed to support a specialist biota. The landscape as a whole is characterized by a mean patch birth rate, mean patc...

Theory predicts source-sink dynamics can occur in species with the ideal preemptive distribution but not with the ideal free distribution. Source-sink dynamics can also occur in species with passive dispersal, in which a fixed fraction of the population disperses each generation. However, in nature, dispersal often approximates random diffusion rat...

Theory predicts source‐sink dynamics can occur in species with the ideal preemptive distribution but not with the ideal free distribution. Source‐sink dynamics can also occur in species with passive dispersal, in which a fixed fraction of the population disperses each generation. However, in nature, dispersal often approximates random diffusion rat...

ABSTRACT Regional vulnerability assessment, or ReVA, is an approach to place-based ecological risk assessment that is currently under development by the Office of Research and Development of the U.S. Environmental Protection Agency (EPA). The assessment is done at the scale of EPA regions and builds on data collected for the Environmental Monitorin...

Describes the metapopulation structure of Euphydryas editha.

Increasing emphasis is being placed on the large-scale and long-term dynamics of populations. A butterfly (Euphydryas editha) metapopulation that was naturally restricted to rocky outcrops in an area of coniferous forest suffered two major perturbations in 30 yr. First, humans clear-cut patches of forest in about 1967. The butterfly colonized the c...

The jaw morphology of needlefishes (Beloniformes: Belomdae) passes through distinctive ontogenetic stages. When hatched, larvae have short jaws of equal length. The lower jaw first elongates to produce a "halfbeak" form, then the upper jaw elongates to produce the adult "needlenose" morphology. Onset and duration of the halfbeak stage vary among be...