R. Andrew Goodwin

Fish navigation of large dams emerges from their modulation of flow field experience.

Significance Whereas adult salmon swimming upstream through a ladder visibly illustrates the challenge a dam presents to fish returning home to spawn, the downstream passage of juveniles swimming toward the ocean is often a greater, although more unseen, challenge to their survival. Decades of work have identified many factors that affect fish behavior near dams, but why downstream passage structures may work well at one dam but not at another is poorly understood. We use a computer model to show that observed downstream passage patterns could result from a generic strategy that fish may use to navigate flow field obstacles. Our findings identify environmental and biological factors warranting further evaluation for sustaining native species amid economic development. Navigating obstacles is innate to fish in rivers, but fragmentation of the world’s rivers by more than 50,000 large dams threatens many of the fish migrations these waterways support. One limitation to mitigating the impacts of dams on fish is that we have a poor understanding of why some fish enter routes engineered for their safe travel around the dam but others pass through more dangerous routes. To understand fish movement through hydropower dam environments, we combine a computational fluid dynamics model of the flow field at a dam and a behavioral model in which simulated fish adjust swim orientation and speed to modulate their experience to water acceleration and pressure (depth). We fit the model to data on the passage of juvenile Pacific salmonids (Oncorhynchus spp.) at seven dams in the Columbia/Snake River system. Our findings from reproducing observed fish movement and passage patterns across 47 flow field conditions sampled over 14 y emphasize the role of experience and perception in the decision making of animals that can inform opportunities and limitations in living resources management and engineering design.

Simulating Movement Patterns of Blueback Herring in a Stratified Southern Impoundment

Abstract J. Strom Thurmond Lake (Georgia-South Carolina) strongly stratifies during the summer, producing a temperature-dissolved oxygen “squeeze” for landlocked blueback herring Alosa aestivalis. A coupled Eulerian-Lagrangian hybrid (CEL hybrid) model was developed to improve understanding of and better predict the in-reservoir movements of blueback herring in response to these limiting conditions. An existing application of CE-QUAL-W2, a two-dimensional, laterally averaged water quality and hydrodynamic model, was used to simulate the spatial and temporal dynamics of summer water temperature, dissolved oxygen, and hydraulics. The biological module was parameterized by using mobile hydroacoustic survey data supplemented with species composition data from gill-net surveys. The simulation accurately described the longitudinal (r 2 = 0.67) and vertical (r 2 = 0.93) distributions observed for blueback herring. The model results suggest that the longitudinal distribution of blueback herring in summer is best ...

Can north american fish passage tools work for South american migratory fishes

Na America do Norte, o Numerical Fish Surrogate (NFS) e utilizado no projeto de sistemas de transposicao de juvenis de salmao em seus deslocamentos dos habitats de desova e desenvolvimento inicial para o de adultos, no oceano. O NFS e estruturado em tres modulos interconectados: 1) um modelo computacional de dinâmica de fluidos (CFD) que descreve o complexo escoamento acima da barragem em uma escala suficientemente apropriada para analisar, entender e prever os movimentos dos peixes, 2) um modelo de rastreamento de particulas que interpola informacoes hidraulicas dos nos da malha do modelo computacional para localizacoes multiplas relevantes ao peixe em migracao, 3) um modelo comportamental que simula o conhecimento e o comportamento de cada peixe em resposta a dinâmica do escoamento predita pelo modelo computacional. Esses tres modulos juntos criam uma realidade virtual onde peixes virtuais exibem um comportamento realistico de aproximacao da barragem e podem ser contados de uma forma similar a do mundo real. Uma vez calibrado e validado com medicoes do movimento dos peixes e dados de passagem, o NFS pode predizer acuradamente a proporcao de passagem de peixes, com suficiente precisao para permitir que engenheiros selecionem uma alternativa otima dentre as varias opcoes estruturais e operacionais. Embora as especies de peixes Sul Americanas sejam diferentes das especies da America do Norte, e provavel que a arquitetura computacional basica e os metodos numericos do NFS possam ser usados para a conservacao de peixes na America do Sul. Consequentemente, o grande investimento feito na criacao do NFS nao precisa ser repetido na America do Sul. Contudo, seu uso na America do Sul exigira que a resposta comportamental dessa fauna aos sinais hidrodinâmicos seja descrita, codificada e testada antes que o NFS possa ser usado na conservacao de peixes pelo seu emprego na projecao de sistemas de transposicao eficientes. Nesse contexto, o presente trabalho identifica estudos que poderiam ser utilizados para descrever o comportamento migratorio de peixes da America do Sul com um nivel de detalhamento suficiente para que possa ser utilizado no desenvolvimento, calibracao e validacao de uma versao sul-americana do NFS.

Memory Effects on Movement Behavior in Animal Foraging

An individual’s choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

Relating Turbulence and Fish Habitat: A New Approach for Management and Research

Understanding how fish perceive turbulence characteristics to utilize complex habitats (large wood, rock, channel bedforms, etc.) is a critical, but poorly understood component of aquatic habitat restoration. Many recent studies attempt to relate turbulence characteristics to habitat utilization, but results are inconsistent for two reasons. First, turbulence is a complex, multi-scale manifestation of fluid flow that can be characterized in different ways with different interpretations. Second, fish behavioral response to flow field features is also complex because both acclimation and learning are important. For example, some studies show that turbulence decreases swimming stability, increases energy expenditure for a given swimming speed, and alters feeding behavior, whereas others show turbulence to decrease energy needed to swim at a given speed and correlates with fish abundance. We describe a Turbulence Attraction and Avoidance (TAA) hypothesis to reconcile inconsistent, even seemingly contradictory, findings. The TAA hypothesis creates a new perspective of turbulence, habitat complexity, and fish habitat occupancy by acknowledging that fish, like all animals, perceive their environment at their own relevant scales and in a conditional manner, dependent on their prior exposure history.

Species-Specific Spatial and Temporal Distribution Patterns of Emigrating Juvenile Salmonids in the Pacific Northwest

The vertical and horizontal distribution of juvenile salmonid migrants on approach to the dams influences bypass success in rivers. Accordingly, fish distributions have been studied for nearly three decades. These studies, however, have not been integrated and summarized in a single body of work to determine overall patterns in the spatial distribution of emigrants. We reviewed peer-reviewed and gray literature to summarize species-specific trends in the horizontal and vertical distributions of emigrating salmonids as measured by several different methods. We found that there were no species-specific differences in horizontal distributions and that fish were often oriented with the river thalweg. There were weak differences between species in vertical distributions, e.g., juvenile yearling steelhead were shallower during the day than yearling Chinook salmon. For sockeye, coho, and subyearling Chinook salmon, the data were limited or conflicting. Studies were purposefully designed to measure distributions at certain dams under particular environmental conditions for specific, local purposes. The non-standard sampling design has hampered the development of testable hypothesis on fish distributions in the Snake and Columbia rivers. Recent advances in individual-based models are offering the potential to forecast fish distributions near dams and facilitate improved bypass system design.

Hydraulic Modeling of Large Roughness Elements with Computational Fluid Dynamics for Improved Realism in Stream Restoration Planning

Many stream restoration design procedures are based on user experience in distributing standard stream design features into stream channel types based on a stream classification scheme. Computational fluid dynamics (CFD) models, increasingly used to represent stream flow fields, offer a more quantitative path forward. However, CFD models, in practice, parameterize roughness on too large a scale and therefore do not explicitly represent discrete features such as large rocks and large woody material whose placement is the focus of stream restoration activities. The Stream Habitat Assessment Package (SHAPE), made possible by rapid advances and availability of high-performance computing resources and increased sophistication of both in-house and commercial software, overcomes barriers that prevent the routine use of CFD modeling in stream restoration planning. Capabilities of SHAPE that improve stream restoration planning include (1) realistically representing natural streambeds from potentially coarse sets of field measurements, (2) easily deforming the streambed surface with a virtual excavator, (3) selecting complex objects from a library and embedding them within the surface (e.g., rocks and fallen trees), (4) successfully meshing the channel surface and its surrounding volume in accordance with established mesh quality criteria, and (5) sufficiently resolving flow field solutions. We illustrate these capabilities of SHAPE using a coarse set of field data taken from one of four study sites along a 1.5 mile stretch along the Robinson Restoration project of the Merced River, California, along with respective challenges, solution strategies, and resulting outcomes. Flow field solutions are conducted using parallelized finite element/volume solvers.

Forecast simulations of 3-D fish response to hydraulic structures

Utility of a theoretically - and computationally-robust mathematical model for decoding the movement patterns of individual fish i n 3-D space-time is described. Hydrodynamic stimuli queried from a 3-D CFD model (U 2 RANS) are used to elicit spatially-explicit virtual fish behavior. The modeling scheme, coupled Eulerian Lagrangian agent individual-based modeling (CEL Agent IBM), is intuitive and based on well-established principles in computer science, fluid and water quality dynamics, computational fluid dynamics (CFD) modeling, and game and foraging theories. We demonstrate the utility of a prototype CEL Agent IBM (the Numerical Fish Surrogate) developed for outmigrating juvenile salmon in the Pacific Northwest. The Numerical Fish Surrogate is used by the US Army Corps of Engineers to decode behavior and then, using results from back -casting analysis, forecast the response of salmon to virtual designs of proposed alternative bypass structures to aid project selection and design. CEL Agent IBMs and the Numerical Fish Surrogate provide the means to integrate high fidelity CFD and water quality modeling and individual based modeling to improve biological simulation of aquatic wildlife for water resource decision-support and reduce reliance on the build -and-test paradigm.

Remembering the good and the bad: memory-based mediation of the food–safety trade-off in dynamic landscapes

Predator–prey interactions are central to fitness as animals simultaneously avoid death and consume resources to ensure growth and reproduction. Along with direct effects, predators can also exert strong non-consumptive effects. For example, prey shift habitat use in the presence of predators, a potentially learned behavior. The impact of cognition on movement and predator interactions is largely unexplored despite evidence of learned responses to predation threat. We explore how learning and spatial memory influence predator–prey dynamics by introducing predators into a memory-driven movement modeling framework. To model various aspects of risk, we vary predator behavior: their persistence and spatial correlation with the prey’s resources. Memory outperforms simpler movement processes most in patchy environments with more predictable predators that are more easily avoided once learned. In these cases, memory aids foragers in managing the food–safety trade-off. For example, particular parameterizations of the predation memory reduce encounters while maintaining consumption. We found that non-consumptive effects are highest in landscapes of concentrated, patchy resources. These effects are intensified when predators are highly correlated with the forager’s resources. Smooth landscapes provide more opportunities for foragers to simultaneously consume resources and avoid predators. Predators are able to effectively guard all resources in very patchy landscapes. These non-consumptive effects are also seen with the shift away from the best quality habitat compared to foraging in a predator-free environment.