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

Claudio Rafael Mariano Baigún,John Michael Nestler,Norberto Oscar Oldani,R. Andrew Goodwin,Larry J. Weber

doi:10.1590/s1679-62252007000200004

Abstract

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.

Highlights

Fragmentation by dams throughout the world has been linked to the loss of populations and species of fish
We describe a ‘plug-and-play’ simulation tool that integrates spatial/cognitive ecology, particle-tracking, and computational fluid dynamics (CFD) modeling to realistically and accurately forecast the volitional movement of emigrants in response to alternative designs of bypasses, guidance structures or project operations
The Numerical Fish Surrogate (NFS) is run on the highly resolved output of a computational fluid dynamics (CFD) model that simulates the flow field associated with a design or operational alternative

Summary

Introduction

Fragmentation by dams throughout the world has been linked to the loss of populations and species of fish. Improvements to bypass design depend on a better understanding of hydrodynamic cues used by emigrants to guide fine-scale swim path selection. Most attempts to develop simple bypass design criteria typically focus on the behavior of emigrants near dams. Using this approach, even after decades of study, few generalizations can be made about the behaviors of emigrants near dams. We use three guiding principles to forge a new path to understand and explain fish movement behavior: a) Fish migration behavior is related to the hydro-geomorphology of free-flowing rivers. The key to good hydraulic design criteria for bypass systems is in understanding the interrelationship between fluvial geomorphology and resultant flow pattern that must constitute the basis of swim path selection behavior

Methods

Results

Conclusion