It's going to be a busy week for our fish passage experts. Researchers, practitioners, engineers, funders, government officials, and world-renowned experts from across the globe are gathered for Fish Passage 2022 and the 11th International Conference on River Connectivity. Among the delegates are representatives from Alden, two of whom will be presenting at various sessions throughout the 3-day conference.

Steve Amaral, Senior Fisheries Biologist will present the Evaluation of the Whooshh Fish Transport System for Passing American Shad Upstream at Hydropower Dams in a session devoted to New and emerging technologies in fish passage. He will also partake in a session asking the question "Is there a silver bullet for silver eels?"  and will discuss Understanding and Estimating Turbine and Total Project Survival of Silver Eels.

Senior Engineer, Benjamin Mater, PhD, PE will be showcasing recent work in his presentation titled  Innovative Designs Require Innovative Approaches: CFD-based Design of the Saccarappa Falls
Nature-Like Fishway in a session covering design, application, and performance of nature-like fishways. In addition, he'll also be talking about a novel fish-protection screen intended to prevent entrainment of small
aquaticorganisms in his presentation Deal with the Devilfish: A Nature-Inspired Fish Protection Screen. This discussion in support of a session focused on Fish protection R&D: Interagency coordination under the US Federal Hydropower MOU.

Fish-Protection-Prize-American-Made-DOE-DevilfishSee also: Team Devilfish Named as Grand Prize Winner

Fish Passage 2022 is a great opportunity to exchange findings and experiences on fish passage and river connectivity best practices with international colleagues and expert. Alden is proud to be a sponsor of this annual event. 

To find out more about these topics and more, visit the conference website. For inquiries related directly to the topics presented by Alden's fish passage enthusiasts, contact us


Understanding and Estimating Turbine and Total Project Survival of Silver Eels

Steve Amaral, Alden Research Laboratory, LLC

Downstream passage of silver eels at hydropower dams has been the focus of considerable research with
respect to injury and mortality suffered during turbine passage and the development of technologies and
approaches for reducing turbine entrainment. Not surprisingly, unique behaviors, morphology, and physical attributes that are specific to silver eels have separated them from other species when it comes to
estimating turbine survival and developing effective fish passage facilities. To understand the level of
protection required for silver eels passing downstream at hydropower projects, it is important to
determine baseline total project survival rates. This presentation will explore what has been learned from
field evaluations of silver eel turbine passage and discuss desktop models for estimating turbine and total
project survival. This will include examination of the effects of turbine type and various design parameters
on eel survival rates, as well as why theoretical blade strike probability and mortality models used for
other fish species (e.g., salmonids, clupeids, and various freshwater fishes) are not applicable to silver
eels. The use of appropriate survival models should facilitate the selection and design of passage facilities
capable of achieving target survival rates for silver eels at any given project.

Evaluation of the Whooshh Fish Transport System for Passing American Shad Upstream at Hydropower Dams

Steve Amaral Alden Research Laboratory, LLC; Kim Capone, Alden Research Laboratory LLC; Jenna Rackovan, Alden Research Laboratory LLC; Jake LaFontaine,  Alden Research Laboratory LLC; Chad Holbrook, Santee Cooper; Janine Bryan, Whooshh Innovations; Paul Jacobson, EPRI; Paul Jacobson, EPRI

Providing effective passage facilities for American Shad and river herring at hydropower dams is a
priority for resource agencies due to declining stocks and ongoing restoration efforts. Fish passage can be
problematic for these species with respect to biological, engineering, and project operation considerations,
as well as being costly to install and maintain. As an alternative to traditional designs, Whooshh
Innovations has developed a low cost technology designed to safely, autonomously, volitionally, and
efficiently pass fish upstream. The Whooshh Passage Portal (WPP) moves fish through a tube using water
mist for lubrication and differential air pressure. To provide data on the performance of a complete system
(i.e., volitional entry components, image scanner, accelerator, and passage tube), we conducted a field
evaluation of American Shad passage through a WPP installed at a hydropower project on the Santee
River in South Carolina. To the extent possible, the study investigated volitional entry, sorting, and passage
of shad with respect to transport-associated injury and mortality. The study results will provide dam owners
and resource agencies with information to assess the suitability of the WPP asa low cost and effective
alternative to conventional fishways that are typically used for shad.

Innovative Designs Require Innovative Approaches: CFD-based Design of the Saccarappa Falls Nature-Like Fishway

Benjmain Mater, Alden Research Laboratory, LLC; Gregory Allen, Alden Research Laboratory, LLC

Three-dimensional (3D)Computational Fluid Dynamics (CFD) modeling is becoming widely utilized as a
tool for designing fish passage measures. Traditional measures, such as fish ladders, lend themselves well
to CFD analysis thanks to regular, relatively simple geometries. Nature-Like Fishways, however, are
characterized by complex geometries that present a practical hurdle to CFD-based design efforts. This talk
presents a case study in the novel use of CFD as a practical tool in the design of a complex NLF on the
Presumpscot River (Westbrook, ME). The final design was achieved by way of iteration between a 3D
CAD terrain model and a 2D/3D hybrid CFD model. Channel roughness elements were explicitly
considered in the model. An evaluation of fish passage effectiveness was performed using results from the
CFD simulations, wherein likelihood of passage by fish size was determined based on the swim speeds
and endurance. Construction on the project was recently completed, therefore, practical lessons-learned in
implementing such a complex, non-traditional design will also be presented. The Saccarappa NLF stands
as an example of how careful and creative modeling can push NLF design beyond relatively simple rock
ramps and unlock the potential for more creative designs while reducing project uncertainty.

Deal with the Devilfish: A Nature-Inspired Fish Protection Screen

Benjmain Mater (; Alden Research Laboratory, LLC; Charles Coutant, Coutant Aquatics

This talk presents a novel fish-protection screen intended to prevent entrainment of small
aquatic organisms. The prototype screen resembles conventional, slotted fish-protection screens with
parallel bars; however, the prototype bars are shaped to mimic the filter elements in the mouths of the
filter-feeding devil ray (Mobula tarapacana). Millions of years of evolution have perfected these
structures to provide energetically-efficient and clog-resistant filtering of zooplankton from seawater. The
prototype screen exploits these mechanisms for the protection of small organisms in settings where
flow sweeps parallel to the screen face and perpendicular to the screen bars. The screen concept was
awarded the U.S. Department of Energy’s 2020 Fish Protection Prize which provided financial and
technical support for concept testing. Using computer modeling and laboratory flume testing, the
prototype screen was compared to a conventional wedge-wire screen. The interactions of 1-mm surrogate
fish eggs with the screen faces were of primary focus. The study did not reveal meaningful differences
between the prototype and the conventional analog; however, a wealth of information was generated to
aid design refinement. Broad-impact findings related to entrainment risk versus flow velocity for
similar screen types in sweeping flow will be presented.