David Beauchamp

• Doctor of Philosophy
• Ecology Section Chief at Western Fisheries Research Center, US Geological Survey, Seattle

Juvenile salmon experience rapid change during early marine stages in estuarine, nearshore, and offshore marine habitats. Size and growth, particularly in offshore habitats, strongly influence survival to adulthood and are linked to food supply, predators, and environmental conditions. The Salish Sea Marine Survival Project (SSMSP) found that food...

Overview of Chapter 7 within 2nd edition of the book "Standard Methods for Sampling North American Freshwater Fishes" published by the American Fisheries Society.

Aquatic invasive species can affect food web structure, native fish growth, and production, depending on the traits of the invasive species and the pre-invasion conditions of the ecosystem. Thermal tolerances and behavioral traits can further influence differential exploitation of resources shared between native and invasive species. An unauthorize...

Introducing anadromous fish upstream of migration barriers has frequently been proposed as a conservation strategy, but existing conditions and future changes to the ecosystems above barriers such as invasive species, climate change, and varying water operations influence the capacity to support such introductions. In the Upper Skagit River, Washin...

Predation can play an important role in structuring ecological communities, and predator–prey dynamics can be altered following the introduction of new species. An unauthorized introduction of redside shiner ( Richardsonius balteatus ) into reservoirs in the Upper Skagit River, Washington, USA created concern that a consequent shift in predator–pre...

Water clarity, defined in this study using measurements of the downwelling diffuse light attenuation coefficient (Kd) and turbidity, is an important indicator of lake trophic status and ecosystem health. We used in-situ measurements to evaluate existing semi-analytical models for Kd and turbidity, developed a regional turbidity model based on spect...

Objective In the Pacific Northwest (USA), Pacific salmon Oncorhynchus spp. populations have been declining significantly for decades, prompting stakeholders to respond with a variety of conservation and restoration measures. One such measure being considered in the Skagit River basin (Washington, USA) is the introduction of steelhead Oncorhynchus m...

Lakes provide important habitat for salmonids that may use them as a primary feeding area between periods of reproduction. The seasonal changes in vertical thermal structure in lakes can affect the distribution of salmonids on seasonal and diel time scales as they search for, consume, and digest prey that also exploits the water column's distributi...

A series of species introductions, overexploitation, and habitat modification preceded the extirpation of Lahontan cutthroat trout (Oncorhynchus clarkii henshawi; LCT), historically the apex predator, from Lake Tahoe, California-Nevada, USA. Studies evaluating limiting factors for LCT emphasise the need to elucidate food web interactions, yet impor...

Objective Redside Shiner Richardsonius balteatus has expanded from its native range in the Pacific Northwest region of North America to establish populations in six other western states. This expansion has fueled concerns regarding competition between Redside Shiner and native species, including salmonids. We developed a bioenergetic model for Reds...

Population models, using empirical survival rates estimates for different life stages, can help managers explore whether various management options could stabilize a declining population or restore it to former levels of abundance. Here we used two decades of data on five life stages of the Cedar River, USA Sockeye Salmon, Oncorhynchus nerka, popul...

Evaluations of resource use among native piscivores in natural lakes have consistently documented significant partitioning that supports coexistence. Partitioning may be less prominent in reservoirs where water-level fluctuations can compress habitat and trophic diversity, but studies are lacking. Stable isotopes and bioenergetic models were used t...

Visual encounter distance models are important tools for predicting how light and water clarity mediate visual predator-prey interactions that affect the structure and function of aquatic ecosystems at multiple spatial, temporal, and organizational scales. The two main varieties of visual encounter distance models, mechanistic and empirical, are us...

The estuarine habitat mosaic supports the reproduction, growth, and survival of resident and migratory fish species by providing a diverse portfolio of unique habitats with varying physical and biological features. Global climate change is expected to result in increasing temperatures, rising sea levels, and changes in riverine hydrology, which wil...

Emerging evidence suggests that zooplankton production is affected by physiological and nutritional constraints due to climate change and eutrophication, which in turn could have broad implications for food-web dynamics and fisheries production. In this study, we developed a resource-based zooplankton production dynamics model that causally links f...

Fatty acid (FA) content and composition of zooplankton in Puget Sound, Washington (USA) was studied to investigate the nutritional quality of diverse zooplankton prey for juvenile salmon ( Oncorhynchus spp.) in terms of their essential fatty acid (EFA) content. The study focus was on eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arac...

Tabor RA, Perkin EK, Beauchamp DA, Britt LL, Haehn R, Green J, Robinson T, Stolnack S, Lantz DW, Moore ZJ. 2021. Artificial lights with different spectra do not alter detrimental attraction of young Chinook salmon and sockeye salmon along lake shorelines. Lake Reserv Manage. XX:XXX–XXX. Artificial light at night (ALAN) is common in lakes with devel...

Biophysical processes that affect subsurface water clarity play a key role in ecosystem function. However, subsurface water clarity is poorly monitored in marine ecosystems because doing so requires in-situ sampling that is logistically difficult to conduct and sustain. Novel solutions are thus needed to improve monitoring of subsurface water clari...

Growth during the early marine critical period is positively associated with survival and recruitment for Pacific salmon Oncorhynchus spp., so it is important to understand how certain foraging strategies may bolster growth in estuarine and marine environments. To elucidate how spatiotemporal and demographic differences in diet contribute to growth...

This is a Technical report for the Salish Sea Marine Survival Project on food quality of juvenile salmonids in Puget Sound. https://marinesurvivalproject.com/ Summary Diets rich in essential fatty acids (EFAs) are critical for the nutritional physiology of many fish, particularly during juvenile life stages. EFAs can be limiting in aquatic food we...

Previous studies evaluating potential limiting factors for reintroduced Lahontan cutthroat trout emphasized the need to elucidate food web interactions, yet important knowledge gaps regarding trophic interactions among pelagic fishes and invertebrates in Lake Tahoe remain. We quantified the abundance and consumption demand of planktivores with an e...

Animal migrations act to couple ecosystems and are undertaken by some of the world’s most endangered taxa. Predators often exploit migrant prey, but the movements taken by these consumers are rarely studied or understood. We define such movements, where migrant prey induce large-scale movements of predators, as migratory coupling. Migratory couplin...

Large river deltas are complex ecosystems that are believed to play a pivotal role in promoting the early marine growth and survival of threatened Chinook Salmon Oncorhynchus tshawytscha. We used a fish bioenergetics model to assess the functional role of multiple delta habitats across a gradient of salinities and vegetation types, where consumptio...

Mandarin fish Siniperca chuatsi, a valuable piscivorous fish, have been stocked into many lakes in China since the 1990s. This study did the first attempt to evaluate the ecological effects of hatchery-reared mandarin fish stocking in the Yangtze River basin lakes. Our study demonstrated a significant change in fish community composition after mand...

The need to protect biostructure is increasingly recognized, yet empirical studies of how human exploits affect ecological networks are rare. Studying the effects of variation in human disturbance intensity from decades past can help us understand and anticipate ecosystem change under alleviated or amplified disturbance over decades to come. Here,...

Expanding human population and urbanization alters freshwater systems through structural changes to habitat, temperature effects from increased runoff and reduced canopy cover, altered flows, and increased toxicants. Current stream assessments stop short of measuring health or condition of species utilizing these freshwater habitats and fail to lin...

Habitat use can be complex, as tradeoffs among physiology, resource abundance, and predator avoidance affect the suitability of different environments for different species. Green sturgeon (Acipenser medirostris), an imperiled species along the west coast of North America, undertake extensive coastal migrations and occupy estuaries during the summe...

Juvenile salmon (Oncorhynchus spp.) use of reservoir food webs is understudied. We examined the feeding behavior of subyearling Chinook salmon (O. tshawytscha) and its relation to growth by estimating the functional response of juvenile salmon to changes in the density of Daphnia, an important component of reservoir food webs. We then estimated sal...

Results of functional response trials for subyearling Chinook salmon and Daphnia. (PDF)

Understanding the mechanisms regulating population fluctuations, such as births, reproduction, and deaths, remains a persistent question in ecology. Mortality can be incurred at any point during the lifecycle, but mortality rates can be high for juvenile animals in particular. One source of this early life history mortality is via predation. Accura...

We used a large lampara seine coupled with nonlethal gastric lavage to examine the diets and estimate consumption rates of subyearling Chinook Salmon Oncorhynchus tshawytscha during July and August 2013. During August we also examined the diet and consumption rates of juvenile American Shad Alosa sapidissima, a potential competitor of subyearling C...

Non-native lake trout Salvelinus namaycush displaced native bull trout Salvelinus confluentus in Flathead Lake, Montana, USA, after 1984, when Mysis diluviana became abundant following its introduction in upstream lakes in 1968–1976. We developed a simulation model to determine the fishing mortality rate on lake trout that would enable bull trout r...

The reintroduction of anadromous salmonids in reservoirs is being proposed with increasing frequency, requiring baseline studies to evaluate feasibility and estimate the capacity of reservoir food webs to support reintroduced populations. Using three reservoirs on the north fork Lewis River as a case study, we demonstrate a method to determine juve...

Pacific salmon Oncorhynchus spp. are adept at colonizing habitat that has been reopened to anadromous passage. Sockeye Salmon O. nerka are unique in that most populations require lakes to fulfill their life history. Thus, for Sockeye Salmon to colonize a system, projects like dam removals must provide access to lakes. However, if the lakes contain...

Body mass and temperature are primary determinants of metabolic rate in ectothermic animals. Oxygen consumption of post-larval Galaxias maculatus was measured in respirometry trials under different temperatures (5–21 °C) and varying body masses (0.1– >1.5 g) spanning a relevant range of thermal conditions and sizes. Specific respiration rates (R in...

Increased freshwater growth of juvenile steelhead Oncorhynchus mykiss improved survival to smolt and adult stages, thus prompting an examination of factors affecting growth during critical periods that influenced survival through subsequent life stages. For three tributaries with contrasting thermal regimes, a bioenergetics model was used to evalua...

http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12565/full Understanding the limits of consumption is important for determining trophic influences on ecosystems and predator adaptations to inconsistent prey availability. Fishes have been observed to consume beyond what is sustainable (i.e. digested on a daily basis), but this phenomenon of hy...

The feasibility of reintroducing anadromous salmonids into reservoirs above high-head dams is affected by the suitability of the reservoir habitat for rearing and the interactions of the resident fish with introduced fish. We evaluated the predation risk to anadromous salmonids considered for reintroduction in Merwin Reservoir on the North Fork Lew...

The Threespine Stickleback Gasterosteus aculeatus is widely distributed across northern hemisphere ecosystems, has ecological influence as an abundant planktivore, and is commonly used as a model organism, but the species lacks a comprehensive model to describe bioenergetic performance in response to varying environmental or ecological conditions....

In many food webs, species in similar trophic positions can interact either by competing for resources or boosting shared predators (apparent competition), but little is known about how the relative strengths of these interactions vary across environmental gradients. Introduced Mysis diluviana shrimp interact with planktivorous fishes such as kokan...

The Columbia River has been colonized by an ever increasing number of nonnative species raising concerns that competition for food may be limiting the growth of juvenile Salmon, many of which are listed under the ESA. In particular, fall Chinook Salmon (Oncorhynchus tshawytscha) that migrate through the Columbia River later in the season face poten...

Bull Trout Salvelinus confluentus are typically top predators in their host ecosystems. The Skagit River in northwestern Washington State contains Bull Trout and Chinook Salmon Oncorhynchus tshawytscha populations that are among the largest in the Puget Sound region and also contains a regionally large population of steelhead O. mykiss (anadromous...

Many ecologists have called for mechanism‐based investigations to identify the underlying controls on species distributions. Understanding these controls can be especially useful to construct robust predictions of how a species range may change in response to climate change or the extent to which a non‐native species may spread in novel environment...

Stomach contents were collected and analysed from 22 bull trout Salvelinus confluentus at the edge of the Chilko Lake and Chilko River in British Columbia, Canada, during spring outmigration of sockeye salmon Oncorhynchus nerka smolts. Twenty of the 22 (>90%) stomachs contained prey items, virtually all identifiable prey items were outmigrant O. ne...

Clark & Levy ( American Naturalist , 131 , 1988, 271–290) described an antipredation window for smaller planktivorous fish during crepuscular periods when light permits feeding on zooplankton, but limits visual detection by piscivores. Yet, how the window is influenced by the interaction between light regime, turbidity and cloud cover over a broad...

Most predators eat only a subset of possible prey. However, studies evaluating diet selection rarely measure prey availability in a manner that accounts for temporal–spatial overlap with predators, the sensory mechanisms employed to detect prey, and constraints on prey capture. We evaluated the diet selection of cutthroat trout ( Oncorhynchus clark...

We evaluated freshwater growth and survival from juvenile (ages 0–3) to smolt (ages 1–5) and adult stages in wild steelhead Oncorhynchus mykiss sampled in different precipitation zones of the Skagit River basin, Washington. Our objectives were to determine whether significant size‐selective mortality (SSM) in steelhead could be detected between ear...

Visual foraging models provide a useful framework for predicting distribution,foraging success,and predation risk in pelagic communities; however,the visual prey detection capabilities of different predator species within and among taxonomic groups have not been sufficiently evaluated. Our primary objective was to more adequately characterize varia...

We examined trophic interactions of the nonnative salmonids Rainbow Trout Oncorhynchus mykiss, Brown Trout Salmo trutta, and Brook Trout Salvelinus fontinalis and the main native predator Creole Perch Percichthys trucha in Lake Nahuel Huapi (Patagonia, Argentina) to determine the relative impact of each predator on their forage base and to evaluate...

Management of pelagic food webs under a shifting climate requires an understanding of how behavior, physiological tolerance, and the environment interact to mediate the foraging rates of consumers. However, analyses that treat each of these factors explicitly in a framework that captures interdependenciesare lacking. We linked a visual foraging mod...

We examined trophic interactions of the nonnative salmonids Rainbow Trout Oncorhynchus mykiss, Brown Trout Salmo trutta, and Brook Trout Salvelinus fontinalisand the main native predator Creole Perch Percichthys trucha in Lake Nahuel Huapi (Patagonia, Argentina) to determine the relative impact of each predator on their forage base and to evaluate...

We conducted laboratory experiments to parameterize a bioenergetics model for wild Bull Trout Salvelinus confluentus, estimating the effects of body mass (12–1,117 g) and temperature (3–20°C) on maximum consumption (C max) and standard metabolic rates. The temperature associated with the highest C max was 16°C, and C max showed the characteristic d...

Well-functioning food webs are fundamental for sustaining rivers as ecosystems and maintaining associated aquatic and terrestrial communities. The current emphasis on restoring habitat structure-without explicitly considering food webs-has been less successful than hoped in terms of enhancing the status of targeted species and often overlooks impor...

Introduced long-lived predators often cause significant impacts on their prey, but these impacts can be masked from detection due to high "predatory inertia": time lags in population growth and dietary ontogeny. We evaluated whether predation by introduced lake trout Salvelinus namaycush could explain the 88% decline in escapement of kokanee Oncorh...

As lake trout Salvelinus namaycush have simultaneously declined or been extirpated in their native range and have been successfully introduced elsewhere, a significant discrepancy in the management of lake trout populations has emerged. Lake Tahoe, CA - NV and Bear Lake, UT - ID are both large, natural, oligotrophic lakes that were formerly home to...

Non-native lake trout attract popular trophy fisheries in large western lakes and reservoirs, but have also fundamentally altered the structure and function of recipient systems, and have resulted in severe declines or extirpation of native salmonids in some cases. Lake trout were introduced into many large western lakes in North America over the p...

Food web interactions are strongly influenced by heterogeneity of prey and consumers across time and space. We describe distribution patterns in acoustic backscatter from epi-pelagic fishes over the critical summer growth period in Puget Sound during 2011. This period is critical for growth of ESA-listed Chinook salmon (Oncorhynchus tshawytscha); s...

Declining light and increasing turbidity reduce reaction distances, search volumes, and prey encounters at disproportionately higher rates for piscivores than for planktivores. However, given a predator-prey encounter, capture success for piscivores improves in degraded optical conditions. These asymmetric threshold responses interact with vertical...

Copper contamination in surface waters is common in watersheds with mining activities or agricultural, industrial, commercial, and residential human land uses. This widespread pollutant is neurotoxic to the chemosensory systems of fish and other aquatic species. Among Pacific salmonids (Oncorhynchus spp.), copper-induced olfactory impairment has pr...

Energetic responses of steelhead Oncorhynchus mykiss to climate-driven changes in marine conditions are expected to affect the species’ ocean distribution, feeding, growth, and survival. With a unique 18-year data series (1991–2008) for steelhead sampled in the open ocean, we simulated interannual variation in prey consumption and growth efficiency...

We sampled three limnetic fish species: juvenile sockeye salmon (Oncorhynchus nerka), three-spine stickleback (Gasterosteus aculeatus) and longfin smelt (Spirinchus thaleichthys) in Lake Washington to quantify species-specific patterns of diel vertical migration (DVM). Catch-per-unit-effort data analysed from 15 years of midwater trawling documente...

We conducted laboratory experiments to estimate the maximum consumption rates (Cmax) and standard (SMR) and active (AMR) metabolic rates of wild bull trout to parameterize a bioenergetics model. Cmax was significantly influenced by temperature, with mean values for fish with an average (± SD) mass of 87 (± 25) g being highest at 16°C (ca. 0.1 g·g-1...

In pelagic environments, the potential foraging success of visually feeding piscivores is determined by the intersection of overlapping diel-vertical distributions of predators and prey, and the effects of ambient visual conditions on the predation sequence. Movements of piscivores can be influenced by temporally dynamic factors that affect both vi...

Declining light and increasing turbidity reduce reaction distances, search volumes, and prey encounters at disproportionately higher rates for piscivores than for planktivores. However, given a predator-prey encounter, capture success for piscivores improves in degraded optical conditions. These asymmetric threshold responses interact with vertical...

If we are to increase adult run sizes, salmon recovery programs need to consider factors that improve survival and growth of salmon throughout their life cycle. Therefore, habitat relations and biological responses should be linked to life stage-specific abundance, growth, and survival performance of populations during potentially critical life sta...

Lake Nahuel Huapi is the biggest (554 km2) and deepest ultraoligotrophic lake in Northern Patagonia, centered within Nahuel Huapi National Park. In 2005, we started an ongoing project to provide National Park and Municipal and regional authorities scientifically based information to aid in management. Short and long term objectives were establishme...

Bioenergetics models can help develop a mechanistic understanding of factors affecting growth and survival of salmon and steelhead in the Columbia River Basin. Survival of anadromous salmonids has been strongly linked to size or growth at one or more critical periods during freshwater or early marine life. Delayed mortality might be influenced by g...

Many metals are neurotoxic to aquatic animals. Copper is a common aquatic pollutant resulting from mining, industrial, agricultural, and urban land uses. Outside of mine drainage, concentrations in waters receiving runoff enriched in copper are usually <100 ppb, and commonly <10 ppb. Dissolved copper in the low parts per billion range is neurotoxic...

When introduced species cause variable impacts on biological communities, identifying the mechanisms driving these impacts can aid prediction and management efforts. Introductions of the opossum shrimp Mysis diluviana and apex fish predators such as lake trout Salvelinus namaycush have altered hundreds of lake and reservoir ecosystems throughout we...

Most studies on visual foraging by fish have focused on reaction distances to invertebrate prey; however, these acuity-based results considerably overestimate reaction distances of piscivores to prey fish. In laboratory experiments, we quantified reaction distance of adult lake trout (Salvelinus namaycush) to rainbow trout (Oncorhynchus mykiss) and...

We developed a visual foraging model for piscivores that predicts search volume as a function of light and turbidity. We combined this model with diel hydroacoustic measurements of depth-specific prey fish densities during summer stratification in Lake Tahoe, Lake Washington, and Strawberry Reservoir to examine differences in diel, depth-specific v...

We examined the effect of early marine entry timing and body size on the marine (smolt-to-adult) survival of Puget Sound Chinook salmon (Oncorhynchus tshawytscha). We used data from coded wire tag release groups of hatchery Chinook salmon to test whether hatchery release date, release size, and size in offshore waters in July and September influenc...

Introductions or invasions of nonnative organisms can mediate major changes in the trophic structure of aquatic ecosystems. Here we document multitrophic level impacts in a spatially extensive system that played out over more than a century. Positive interactions among exotic vertebrate and invertebrate predators caused a substantial and abrupt shi...

On the basis of stable isotope analysis, we estimated the marine diet of the most abundant anadromous salmonid species in Patagonian Atlantic basins. The results were coupled with bioenergetic and population models to estimate the consumption of food by salmonids and was compared with that by seabirds, the most abundant top predators in the area. A...

Marine growth and survival of juvenile Chinook salmon Oncorhynchus tshawytscha depend in part on the quality and quantity of prey consumed during this potentially critical life stage; however, little is known about the early marine diet of these fish or factors that affect the diet's variability. We examined the recent (2001–2007) dietary habits of...

The 2007 Lake Chelan Fishery Plan charges fishery managers to prioritize the conservation and restoration of native species, while maintaining healthy recreational fisheries. Achieving these goals requires an accurate understanding of the relationships between the major predators and their prey in the lake. The aim of this study was to provide guid...

Atka mackerel Pleurogrammus monopterygius make up the single largest biomass of groundfish in the Aleutian Islands, Alaska, and are an important component of this marine ecosystem. Atka mackerel show a significant decrease in size from east to west. We compared fish from two study areas reflecting this size cline: Seguam Pass in the eastern Aleutia...

A bioenergetic model of juvenile pink salmon (Oncorhynchus gorbuscha) was used to estimate daily prey consumption and growth potential of four ocean habitats in the Gulf of Alaska during 2001 and 2002. Growth potential was not significantly higher in 2002 than in 2001 at an alpha level of 0.05 (P=0.073). Average differences in growth potential acro...

Exotic rainbow trout Oncorhynchus mykiss support an economically valuable recreational fishery in Patagonia but also create concern for impacts on native organisms. These concerns are intensified by the possibility of hatchery release programs in this region. We estimated losses of different prey from predation by rainbow trout in Lake Moreno, Río...

Lakes Sammamish and Washington are two large, urban lakes in close proximity to Seattle, Washington. The two lakes have similar assemblages of apex predators, but differences in lake size, species richness, and forage fish assemblages contribute to contrasting trophic relationships. We used stable isotope and diet analyses to assess lake-specific d...