Fish passage: Difference between revisions
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[[File:John_Day_Dam_fish_ladder.jpg|400px|framed|right|Figure 1. A fish ladder at a hydraulic dam.<ref>Wikimedia Commons. (August 28, 2015). ''John Day Dam Fish Ladder'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/0/0c/John_Day_Dam_fish_ladder.jpg</ref>]] | [[File:John_Day_Dam_fish_ladder.jpg|400px|framed|right|Figure 1. A fish ladder at a hydraulic dam.<ref>Wikimedia Commons. (August 28, 2015). ''John Day Dam Fish Ladder'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/0/0c/John_Day_Dam_fish_ladder.jpg</ref>]] | ||
<onlyinclude>A '''fish passage''' is any device used to promote and regulate safe fish migration across [[hydroelectric facility|hydroelectric facilities]]. If fish cannot migrate upstream beyond hydroelectric dams, populations can be impacted significantly.</onlyinclude><ref name="RE2">NOAA. (August 28, 2015). ''Fish Passage'' [Online]. Available: http://www.habitat.noaa.gov/ourwork/fishpassage.html</ref> Fish passages help to prevent harm from coming to river [[ecosystem]]s by providing fish and other forms of aquatic life safe methods of bypassing [[hydroelectric facilities]]. Types of fish passage include fish ladders, fish lifts, and juvenile bypass systems. | |||
Although fish can bypass dams when moving downstream by taking the path that [[water]] does through the [[hydro turbine|turbines]], the spinning blades usually cause death or injury. Fish may also undergo stress and disorientation when pushed through the high [[velocity]] passage, which makes them susceptible to predators at the end of the passage. Though the safety of turbine designs have been improved through the use of rounded parts, they still pose significant risks for fish migration.<ref>NOAA. (August 28, 2015). ''New Turbines are Safer for Fish'' [Online]. Available: http://www.westcoast.fisheries.noaa.gov/fish_passage/about_dams_and_fish/turbines.html</ref> | |||
==Types of Fish Passages== | |||
===Fish Ladder=== | ===Fish Ladder=== | ||
A fish ladder is a structure that | A fish ladder is a structure comprised of a series of stepped slopes and pools that allow fish to climb to a higher elevation. Usually constructed at a less than 10% grade, this sloped stairway includes a series of pools bounded by small retention walls known as '''weirs'''.<ref name="RE1">Office of Technological Assessment. (August 28, 2015). ''Upstream Fish Passage Technologies: How Well Do They Work?'' [Online]. Available: http://www.princeton.edu/~ota/disk1/1995/9519/951905.PDF</ref> These pools allow fish to rest as they climb the ladder without having to constantly fight the current, helping to reduce stress and energy expenditure. | ||
Fish ladders pose issues for weaker or non-jumping species, as they are generally designed for stronger swimming fish or jumping fish such as trout and salmon.<ref name="RE1"/> | In order to attract migrating fish, the ladder must accurately simulate the river's downstream flow. By simulating this flow, fish will naturally swim up-current and climb the ladder<ref name="RE1"/>. Fish ladders pose issues for weaker or non-jumping species, as they are generally designed for stronger swimming fish or jumping fish such as trout and salmon.<ref name="RE1"/> | ||
===Fish Lift=== | ===Fish Lift=== | ||
Fish elevators and locks are collectively known as fish lifts. Fish lifts | Fish elevators and locks are collectively known as '''fish lifts'''. Fish lifts are not species specific, nor are they flow dependent like fish ladders are. These lifts attract fish to a chamber filled with water at the downstream side of the hydroelectric facility and transport them over and beyond to the upstream side.<ref name="RE1"/> | ||
Similar to fish ladders, the lifts attract fish into a hopper or chamber with the use of flowing water, which guides the fish into the elevator. After a set amount of time or if a sufficient amount of fish has been detected in the chamber, the elevator will carry the contents up to the forebay level and release the fish onto the upstream side of the dam.<ref name="RE1"/> | Similar to fish ladders, the lifts attract fish into a hopper or chamber with the use of flowing water, which guides the fish into the elevator. After a set amount of time or if a sufficient amount of fish has been detected in the chamber, the elevator will carry the contents up to the forebay level and release the fish onto the upstream side of the dam.<ref name="RE1"/> | ||
Fish lifts have several benefits over the use of fish ladder technologies. | Fish lifts have several benefits over the use of fish ladder technologies. They tend to work better when large numbers of fish are migrating, or the migrating fish are not suited for leaping out of the water in order to move up a fish ladder. A downside to these systems is that crowding can occur during peak migratory periods.<ref name="RE1"/> Although the usage of fish lifts may accommodate for a larger quantity and variety of species, the lifts are prone to failure and thus can lead to a higher operating and maintenance cost as well as time lost due to malfunctioning or maintenance.<ref>M. Larinier, F. Travade. (August 28, 2015). ''Fish Locks and Fish Lifts'' [Online]. Available: http://www.kmae-journal.org/articles/kmae/pdf/2002/04/kmae2002364s102.pdf</ref> | ||
===Juvenile Bypass Systems=== | ===Juvenile Bypass Systems=== | ||
A juvenile bypass system allows young fish to move across hydroelectric dams as they migrate downstream from their upstream spawning grounds. This system channels young or smaller fish into a small upwards current known as a gatewell through the use of a [[fish screen]]. From the gatewell, the small fish are collected and transported through a special channel from the turbine into the downstream reservoir.<ref>NOAA. (August 28, 2015). ''Juvenile Bypass Systems Help Fish Avoid Turbines'' [Online].Available: http://www.westcoast.fisheries.noaa.gov/fish_passage/about_dams_and_fish/juvenile_bypass_systems.html</ref> | |||
== For Further Reading == | |||
For further information please see the related pages below: | |||
* [[Hydropower]] | |||
* [[Hydroelectricity]] | |||
* [[Hydrologic cycle]] | |||
* [[Environmental impacts of hydropower]] | |||
* [[Fish screen]] | |||
==References== | ==References== | ||
{{reflist}} | {{reflist}}[[Category:Uploaded]] | ||
Revision as of 23:38, 27 May 2021
A fish passage is any device used to promote and regulate safe fish migration across hydroelectric facilities. If fish cannot migrate upstream beyond hydroelectric dams, populations can be impacted significantly.[2] Fish passages help to prevent harm from coming to river ecosystems by providing fish and other forms of aquatic life safe methods of bypassing hydroelectric facilities. Types of fish passage include fish ladders, fish lifts, and juvenile bypass systems.
Although fish can bypass dams when moving downstream by taking the path that water does through the turbines, the spinning blades usually cause death or injury. Fish may also undergo stress and disorientation when pushed through the high velocity passage, which makes them susceptible to predators at the end of the passage. Though the safety of turbine designs have been improved through the use of rounded parts, they still pose significant risks for fish migration.[3]
Types of Fish Passages
Fish Ladder
A fish ladder is a structure comprised of a series of stepped slopes and pools that allow fish to climb to a higher elevation. Usually constructed at a less than 10% grade, this sloped stairway includes a series of pools bounded by small retention walls known as weirs.[4] These pools allow fish to rest as they climb the ladder without having to constantly fight the current, helping to reduce stress and energy expenditure.
In order to attract migrating fish, the ladder must accurately simulate the river's downstream flow. By simulating this flow, fish will naturally swim up-current and climb the ladder[4]. Fish ladders pose issues for weaker or non-jumping species, as they are generally designed for stronger swimming fish or jumping fish such as trout and salmon.[4]
Fish Lift
Fish elevators and locks are collectively known as fish lifts. Fish lifts are not species specific, nor are they flow dependent like fish ladders are. These lifts attract fish to a chamber filled with water at the downstream side of the hydroelectric facility and transport them over and beyond to the upstream side.[4]
Similar to fish ladders, the lifts attract fish into a hopper or chamber with the use of flowing water, which guides the fish into the elevator. After a set amount of time or if a sufficient amount of fish has been detected in the chamber, the elevator will carry the contents up to the forebay level and release the fish onto the upstream side of the dam.[4]
Fish lifts have several benefits over the use of fish ladder technologies. They tend to work better when large numbers of fish are migrating, or the migrating fish are not suited for leaping out of the water in order to move up a fish ladder. A downside to these systems is that crowding can occur during peak migratory periods.[4] Although the usage of fish lifts may accommodate for a larger quantity and variety of species, the lifts are prone to failure and thus can lead to a higher operating and maintenance cost as well as time lost due to malfunctioning or maintenance.[5]
Juvenile Bypass Systems
A juvenile bypass system allows young fish to move across hydroelectric dams as they migrate downstream from their upstream spawning grounds. This system channels young or smaller fish into a small upwards current known as a gatewell through the use of a fish screen. From the gatewell, the small fish are collected and transported through a special channel from the turbine into the downstream reservoir.[6]
For Further Reading
For further information please see the related pages below:
References
- ↑ Wikimedia Commons. (August 28, 2015). John Day Dam Fish Ladder [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/0/0c/John_Day_Dam_fish_ladder.jpg
- ↑ NOAA. (August 28, 2015). Fish Passage [Online]. Available: http://www.habitat.noaa.gov/ourwork/fishpassage.html
- ↑ NOAA. (August 28, 2015). New Turbines are Safer for Fish [Online]. Available: http://www.westcoast.fisheries.noaa.gov/fish_passage/about_dams_and_fish/turbines.html
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Office of Technological Assessment. (August 28, 2015). Upstream Fish Passage Technologies: How Well Do They Work? [Online]. Available: http://www.princeton.edu/~ota/disk1/1995/9519/951905.PDF
- ↑ M. Larinier, F. Travade. (August 28, 2015). Fish Locks and Fish Lifts [Online]. Available: http://www.kmae-journal.org/articles/kmae/pdf/2002/04/kmae2002364s102.pdf
- ↑ NOAA. (August 28, 2015). Juvenile Bypass Systems Help Fish Avoid Turbines [Online].Available: http://www.westcoast.fisheries.noaa.gov/fish_passage/about_dams_and_fish/juvenile_bypass_systems.html
