Virtual Fish Research Articles

Modeling fish aggregation sounds in very shallow water to estimate numbers of calling fish in aggregations.

Many fishes in the Family Sciaenidae produce courtship sounds associated with spawning. Some estuarine sciaenid species such as weakfish Cynoscion regalis, spotted seatrout C. nebulosus, and silver perch Bairdiella chrysoura occur in very shallow water (water depths 3–10 m) aggregations so large that individual calls are no longer audible above the combined sound of calling fish in the aggregation. We have measured sound levels in these aggregations that are 30 dB greater than the estimated received level of an individual fish at a distance of 1 m. To estimate the number of individual calling fish that would result in these sound levels, we have produced a model of virtual fish aggregations based on echosounder data. We used a finite difference time domain (FDTD) model to calculate the pulsed sounds from the individual fish in randomized aggregations at our virtual hydrophone location. We produced many randomized instances of fish aggregations to obtain statistical distributions of sound levels produced by different densities of calling fish. The characteristics of aggregation sounds will be presented for different densities of calling fish for these species. These calculations could lead to better estimations of fish densities from single‐hydrophone measurements.

PopGen Fishbowl: A Free Online Simulation Model of Microevolutionary Processes

Natural selection and other components of evolutionary theory are known to be particularly challenging concepts for students to understand. To help illustrate these concepts, we developed a simulation model of microevolutionary processes. The model features all the components of Hardy-Weinberg theory, with population size, selection, gene flow, nonrandom mating, and mutation all being demonstrated in the simulations. By using this freely available computer model, students can develop and test hypotheses with replicated virtual experiments. Because the model is an agent-based simulation, there is biologically realistic variability in the results. Students using the model see results both numerically and graphically, and these are reinforced by an animation of the virtual fish in the simulated experiment.

가상수족관 시스템 구축을 위한 어류 생태 시뮬레이터

가상수족관을 구성하는 요소들 중 어류 객체의 행동방식은 사용자의 시각적인 측면에서 가장 중요한 요소이다. 어류 객체의 개별 동작이나 행동뿐 아니라 객체의 속성을 통한 객체들 간의 상호작용은 가상세계의 역동성 및 사실성을 증대시킬 수 있다. 본 논문은 어류 객체들의 생명력, 이동량, 분포 가능한 최대 수심 및 식성 주기 등의 주요 습성들을 분석하고, 이에 따른 움직임과 다른 어류 객체들과의 상호작용, 평균 수명 데이터를 조정함으로써 해저 생태계의 균형을 시뮬레이션 하는 방법을 제안한다. 제안 방법은 어류 객체의 고유 속성값을 자유롭게 변경하여, 다양한 해저환경을 표현하는 가상수족관, 수족관 화면 보호기, 물고기 육성 게임 등에 활용되어질 수 있다. In a virtual aquarium, the behavior of fish objects is the most important factor in respect of visual effects. In addition to the individual behavior of fish object, the interactions between objects due to their attributes, can improve the dynamics and reality of the virtual world. In this paper, we analyze the principal habits of fish objects such as the vitality, the range of movement, the maximum depth of water they can live, and the cycle of eating. Then, we suggest a method for simulating the stable marine ecosystem with controlling the behaviors, the interaction with other species, the average span of life, and all that sort of thing based on the result of analysis. Because we can freely modify the behavior of fish object by altering the values of attributes, it can be utilized in the dynamic virtual aquarium, the 3D aquarium screen saver, and the virtual fish game, and so on.

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

In North America, the Numerical Fish Surrogate (NFS) is used to design fish bypass systems for emigrating juvenile salmon as they migrate from hatchery outfalls and rearing habitats to adult habitat in the oceans. The NFS is constructed of three linked modules: 1) a computational fluid dynamics model describes the complex flow fields upstream of dams at a scale sufficiently resolved to analyze, understand and forecast fish movement, 2) a particle tracking model interpolates hydraulic information from the fixed nodes of the computational fluid model mesh to multiple locations relevant to migrating fish, and 3) a behavior model simulates the cognition and behavior of individual fish in response to the fluid dynamics predicted by the computational fluid dynamics model. These three modules together create a virtual reality where virtual fish exhibit realistic dam approach behaviors and can be counted at dam exits in ways similar to the real world. Once calibrated and validated with measured fish movement and passage data, the NFS can accurately predict fish passage proportions with sufficient precision to allow engineers to select one optimum alternative from among many competing structural or operational bypass alternatives. Although South American fish species are different from North American species, it is likely that the basic computational architecture and numerical methods of the NFS can be used for fish conservation in South America. Consequently, the extensive investment made in the creation of the NFS need not be duplicated in South America. However, its use in South America will require that the behavioral response of the continent's unique fishes to hydrodynamic cues must be described, codified and tested before the NFS can be used to conserve fishes by helping design efficient South American bypass systems. To this end, we identify studies that could be used to describe the movement behavior of South American fishes of sufficient detail that they could be used to develop, calibrate and validate a South American version of the NFS.

Application of an Eulerian–Lagrangian–Agent method (ELAM) to rank alternative designs of a juvenile fish passage facility

The Eulerian–Lagrangian–Agent method (ELAM) couples three modelling approaches into a single, integrated simulation environment: (i) Eulerian descriptions, (ii) Lagrangian formulations, and (iii) agent reference frameworks. ELAMS are particularly effective at decoding and simulating the motion dynamics of individual aquatic organisms, using the output of high fidelity computational fluid dynamics (CFD) models to represent complex flow fields. Here we describe the application of an ELAM to design a juvenile fish passage facility at Wanapum Dam on the Columbia River in the United States. This application is composed of three parts: (1) an agent-based model, that simulates the movement decisions made by individual fish, (2) an Eulerian CFD model that solves the 3D Reynolds-averaged Navier–Stokes (RANS) equations with a standard k–ɛ turbulence model with wall functions using a multi-block structured mesh, and (3) a Lagrangian particle-tracker used to interpolate information from the Eulerian mesh to point locations needed by the agent model and to track the trajectory of each virtual fish in three dimensions. We discuss aspects of the computational mesh topology and other CFD modeling topics important to this and future applications of the ELAM model for juvenille salmon, the Numerical Fish Surrogate. The good match between forecasted (virtual) and measured (observed) fish passage proportions demonstrates the value-added benefit of using agent-based models (i.e. the Numerical Fish Surrogate model) as part of common engineering practice for fish passage design and, more fundamentally, to simulate complex ecological processes.

Information transfer, behavior of vessels and fishing efficiency: an individual-based simulation approach

A simulator dedicated to the modeling of individual search behaviors of fishing vessels has been built using multi-agents systems methodology. The harvesting activity of a virtual fleet is simulated and applied to a static virtual fish population, distributed in a bi-dimensional spatially explicit environment. The resource population can differ depending on different degrees of aggregation. Each vessel of the fleet is modeled as a singular and autonomous agent of the fishery system. The model focuses on the representation of information transfer among vessels, which results in an orientation of search effort. The informative search behavior is compared to a stochastic search, in order to estimate efficiency gains allowed by information transfers. Results show a strong dependence of the fleet's efficiency towards the level of aggregation of the resource. For higher levels of aggregation the informative behavior results in important gains in efficiency. Conversely, a misleading of information appears in the weakest aggregations. The informative behavior leads to the progressive convergence and the gathering of the agents. When the aggregation is strong, this pack effect is stable in time and enables the vessels to make quick catches. For the weakest aggregation levels, the pack effect is unstable and leads the ships to a perpetual pursuit state, without catches. Thus, the size of existing networks appears as a key parameter of vessel behaviors. This approach, using an individual-based simulator, seems quite appropriate to connect individual behaviors to the dynamics of the fishing efficiency, which are generally studied in an aggregated manner. It allows to quantify the effects of the exchange of information among vessels, which is commonly considered as a qualitative phenomenon. Such an approach should be enlarged to a more global modeling of all of the components of the individual search behaviors of vessels.

Forecasting 3-D fish movement behavior using a Eulerian–Lagrangian–agent method (ELAM)

We describe a Eulerian–Lagrangian–agent method (ELAM) for mechanistically decoding and forecasting 3-D movement patterns of individual fish responding to abiotic stimuli. A ELAM model is an individual-based model (IBM) coupling a (1) Eulerian framework to govern the physical, hydrodynamic, and water quality domains, (2) Lagrangian framework to govern the sensory perception and movement trajectories of individual fish, and (3) agent framework to govern the behavior decisions of individuals. The resulting ELAM framework is well suited for describing large-scale patterns in hydrodynamics and water quality as well as the much smaller scales at which individual fish make movement decisions. This ability of ELAM models to simultaneously handle dynamics at multiple scales allows them to realistically represent fish movements within aquatic systems. We introduce ELAMs with an application to aid in the design and operation of fish passage systems in the Pacific Northwest, USA. Individual virtual fish make behavior decisions about every 2.0 s. These are sub-meter to meter-scale movements based on hydrodynamic stimuli obtained from a hydraulic model. Movement rules and behavior coefficients are systematically adjusted until the virtual fish movements approximate the observed fish. The ELAM model introduced in this paper is called the Numerical Fish Surrogate. It facilitated the development of a mechanistic biological-based hypothesis describing observed 3-D movement and passage response of downstream migrating juvenile salmon at 3 hydropower dams on 2 rivers with a total of 20 different structural and operational configurations. The Numerical Fish Surrogate is presently used by the U.S. Army Corps of Engineers and public utility districts during project planning and design to forecast juvenile salmon movement and passage response to alternative bypass structures.

Designing for Presence and Performance: The Case of the Virtual Fish Tank

Although much research work has focused on identifying different factors that affect presence, it is still not clear how to effectively combine these results to create a content with high presence with respect to a given hardware set-up and limited computing resources. This paper proposes a concept of level of presence (LOP) in which we attempt to select a set of presence elements and their levels to maximize their “contribution” toward the overall presence subject to system resources. Such an optimization scheme would require a reasonable characterization of the computational costs and a sufficient knowledge of the relative and collective merits of various presence elements. We made an attempt to apply the LOP concept to VR system design for a particular application, a virtual fish tank. The purpose of this study is to assess the usefulness of the LOP concept and introduce science into content creation. We selected two important presence elements—the field of view (FOV) and the simulation level of detail (SLOD)—and quantified their costs in terms of the required computation time. Next, we ran a simple experiment to quantify the relative benefits of those two presence factors. For this application, it was found that providing more lifelike simulation, for instance, incurred needlessly expensive computations compared to the amount of increased benefits. Based on the result, the virtual fish tank was configured with the appropriate FOV and SLOD for maximum presence under different conditions, such as the preferred frame rate and total number of objects. We discuss the merits of such a presence-driven VR system development approach.

Three-Dimensional Image Information Media. Animation Synthesis of Virtual Fish by Motion Extraction from Video.

In this paper, estimation method of fish position and posture from video using object matching technique is proposed. In the object matching, 3D reference model is divided into three parts, head, body and fins to accelerate the object matching process. NURBS (Non-Uniform Rational B-Spline) is employed for body model in order to represent flexible fish body postures using a small number of control points. The control points of the model is obtained by nine motion parameters, i.e. the center of gravity, the inclination of a fish's head and the angles between skeletons which represent the posture of the body. Some basic behaviors are segmented from the obtained 3D positions and postures by using the characteristics of the motion of fish. Finally, a novel locomotion is generated using the segmented basic behaviors according to the segment connection rule.

The partial-occlusion effect

This study investigates human performance when using semitransparent tools in interactive 3D computer graphics environments. The article briefly reviews techniques for presenting depth information and examples of applying semitransparency in computer interface design. We hypothesize that when the user moves a semitransparent surface in a 3D environment, the “partial-occlusion” effect introduced through semitransparency acts as an effective cue in target localization—an essential component in many 3D interaction tasks. This hypothesis was tested in an experiment in which subjects were asked to capture dynamic targets (virtual fish) with two versions of a 3D box cursor, one with and one without semitransparent surfaces. Results showed that the partial-occlusion effect through semitransparency significantly improved users' performance in terms of trial completion time, error rate, and error magnitude in both monoscopic and stereoscopic displays. Subjective evaluations supported the conclusions drawn from performance measures. The experimental results and their implications are discussed, with emphasis on the relative, discrete nature of the partial-occlusion effect and on interactions between different depth cues. The article concludes with proposals of a few future research issues and applications of semitransparency in human-computer interaction.

魚群探知機単体記録の判別計数に関する研究-V

In order to evaluate fish density from echo pattern counts obtained by the pattern counting method reported previously, the relationship between fish density and pattern count was analyzed by the simulation method. 1) Models of fish are located randomly in the virtual sampling volume. Seven levels of density (20-800 fishes/106m8) are considered. 2) The hypothetical fish detector has the searching performance equivalent to that equipped on R. V. Hakuho Maru, and can detect fish in the water volume for three levels of ship speed (2, 4 and 6knots), and records the echo signal from 50m to 150m. 3) The lower slice level (SL) was set and echo data which were nore than the level of SL are selected and stored. These data have the same format as that obtained by AD-II, the attachment device reported in the first paper of this series. 4) Module AMDESS designed the dcho mask from this echo data produced from the echo signal of which the virtual fish density was 200 in each condition for other parameters. 5) Echo patterns were judged by Module AUPACS which used the echo mask designed in the previous step. Three counts of echo patterns were obtained in each 1200 acoustic transmissions. 6) In all 45 cases for the following conditions (ship speed 3 levels, slice level 3 levels and depth layer 5 levels), the regression of the echo counts upon the fish density was significant. 7) From results of covariance analysis, values of the regression coefficient (β) were varied significantly, even when β was not significant, and the adjusted mean (α) had considerable difference between some blocks. 8) Though there are several exceptions, it was possible to standardize the regression line of echo counts upon the density for a limited range of each condition.