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#           Passage Technologies for American Eels      

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      By Eastern Ecological Science Center      July 24, 2019    

            -              Overview           

The American eel (*Anguilla rostrata*) migrates into freshwater in the juvenile (glass eel and elver) stage, feeds and grows in freshwater habitats, and migrates downstream to the ocean to spawn as an adult. Migrating eels frequently encounter barriers in river environments, primarily in the form of dams, that limit access of juveniles to upstream growth habitat, and can injure or kill adult downstream migrant eels that pass through turbines or over spillways.  Recent concerns of a decline in recruitment of American eels has prompted efforts to restore this species to historic habitats by providing safe, timely, and effective passage for both juveniles and adults at riverine barriers, including hydroelectric dams.  

Traditional fishways and fish lifts are generally inefficient in passing eels. Specialized upstream eel passage structures (e.g., climbing ramps) can be more effective, but many aspects of their performance are poorly understood, and they require additional refinement and standardization. Technologies for preventing mortality and injury of downstream migrant eels passing through turbines at hydropower projects are also not well developed.

This research seeks to design, evaluate, and improve technologies for passing eels upstream at dams and other structures, and to provide safe and effective passage of downstream migrant eels at hydropower dams and other barriers.

Specific objectives include:
                                - Laboratory evaluation of performance of upstream eel passage structures, primarily in the form of eel climbing ramp and trap devices, but also with limited testing of traditional small-scale fishways (e.g., Denil, Alaska steeppass, pool-and-weir types) which currently have unknown performance for passing juvenile eels.
                                - Laboratory evaluation of downstream passage mitigation structures, including reduced intake bar rack spacing or overlays, varying approach velocity, behavioral barriers (light, electricity) and bypass systems.
                                - Field evaluation of downstream passage of eels at several sequential dams within a single watershed.

Application of the results will ultimately have relevance to quantification and reduction of potential impacts of dams and other barriers on migrating juvenile and adult eels. Information on operation and design gained from these studies can be directly applied to formulating guidelines and improvements of passage structures and their operation that will benefit regulating agencies (USFWS, NMFS, States), the private sector, and various NGOs.

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### Contacts

#### Alexander Haro, Ph.D.

##### Fish Biologist

Eastern Ecological Science Center

aharo@usgs.gov

413-863-3806

### Explore Search

                      - Fish Behavior
                      - Fish Passage
                      - Fish Passage
                      - Fish and Aquatic Species Conservation
                      - Fish Passage Technologies
                      - Fish and Aquatic Species
                      - Biology
                      - Ecosystems

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The American eel (*Anguilla rostrata*) migrates into freshwater in the juvenile (glass eel and elver) stage, feeds and grows in freshwater habitats, and migrates downstream to the ocean to spawn as an adult. Migrating eels frequently encounter barriers in river environments, primarily in the form of dams, that limit access of juveniles to upstream growth habitat, and can injure or kill adult downstream migrant eels that pass through turbines or over spillways.  Recent concerns of a decline in recruitment of American eels has prompted efforts to restore this species to historic habitats by providing safe, timely, and effective passage for both juveniles and adults at riverine barriers, including hydroelectric dams.  

Traditional fishways and fish lifts are generally inefficient in passing eels. Specialized upstream eel passage structures (e.g., climbing ramps) can be more effective, but many aspects of their performance are poorly understood, and they require additional refinement and standardization. Technologies for preventing mortality and injury of downstream migrant eels passing through turbines at hydropower projects are also not well developed.

This research seeks to design, evaluate, and improve technologies for passing eels upstream at dams and other structures, and to provide safe and effective passage of downstream migrant eels at hydropower dams and other barriers.

Specific objectives include:
                                - Laboratory evaluation of performance of upstream eel passage structures, primarily in the form of eel climbing ramp and trap devices, but also with limited testing of traditional small-scale fishways (e.g., Denil, Alaska steeppass, pool-and-weir types) which currently have unknown performance for passing juvenile eels.
                                - Laboratory evaluation of downstream passage mitigation structures, including reduced intake bar rack spacing or overlays, varying approach velocity, behavioral barriers (light, electricity) and bypass systems.
                                - Field evaluation of downstream passage of eels at several sequential dams within a single watershed.

Application of the results will ultimately have relevance to quantification and reduction of potential impacts of dams and other barriers on migrating juvenile and adult eels. Information on operation and design gained from these studies can be directly applied to formulating guidelines and improvements of passage structures and their operation that will benefit regulating agencies (USFWS, NMFS, States), the private sector, and various NGOs.

View Media Details

View Media Details

View Media Details

View Media Details

View Media Details

### Contacts

#### Alexander Haro, Ph.D.

##### Fish Biologist

Eastern Ecological Science Center

aharo@usgs.gov

413-863-3806

### Explore Search

                      - Fish Behavior
                      - Fish Passage
                      - Fish Passage
                      - Fish and Aquatic Species Conservation
                      - Fish Passage Technologies
                      - Fish and Aquatic Species
                      - Biology
                      - Ecosystems

View All **