Many eels never made it past the turbines<\/h2>\n
During monitoring done at the site in 2012 and 2013, high numbers of tagged eels were found to have died. Survival rates were 52% and 69%.<\/p>\n
Dead eels were also seen in the tailrace after the turbines.<\/p>\n
At the time, the facility used a traditional trash rack and bottom bypass.<\/p>\n
Evidence shows that this design was not helping protect the migrating eels.<\/p>\n
So, they wondered if changing the design would help more fish avoid the turbines.<\/p>\n
A different route through the plant offered a safer way forward<\/h3>\n
In 2024 they made a large change. Adding a new design with a small gap between the bars (15mm) and a low sloped rack.<\/p>\n
This would ensure the migrating eels would go towards the top bypass<\/strong>.<\/p>\n The eels should follow the rack and avoid the turbines. This was an attempt to solve this issue.<\/p>\n They wanted to see if having a new escape route would improve survival.<\/p>\n The eels were released upstream in 2024 and 2025 and monitored.<\/p>\n All individuals survived and moved down to the river mouth! This was a huge improvement.<\/p>\n Many eels had failed to survive during the earlier monitoring period. Now 100% of the monitored individuals survived<\/strong>.<\/p>\n This suggests that having a new bypass with the rack has greatly improved downstream passage for eels.<\/p>\n This is the main finding reported in the study published in Ecology of Freshwater Fish<\/em><\/a>.<\/p>\n The study was also featured by the Norwegian Institute for Water Research<\/a>.<\/p>\n They also saw some new information about when the eels migrated. Most migration happened when it was dark.<\/p>\n The eels also tended to migrate when there was high or rising discharge in the river. This matches what we already know from previous studies.<\/p>\n The new migration route seems to be working with the natural cues that the eels have<\/strong>.<\/p>\n Knowing this could help in the future when trying to create protections.<\/p>\n This study didn\u2019t show that all problems had been solved.<\/p>\n Although survival has improved massively, the eels were taking longer to get past the hydropower plant<\/strong> than downstream sections of the river.<\/p>\n While they successfully bypassed the turbine blades, lingering around the intake structure means they burn precious energy reserves<\/a> during a life stage when every ounce counts.<\/p>\n The retrofit has successfully addressed the immediate mortality risk, but these lingering delays show that questions remain about how to make the passage faster and smoother.<\/p>\n Improving survival for a critically endangered species can have large impacts.<\/p>\n The results from Fosstveit show that using a small, spaced sloped rack and top bypass can help protect migrating eels. However, this study shows that further work needs to be done.<\/p>\n Future work should focus on making the migration quicker<\/strong>.<\/p>\n Adaptive flow management could help with downstream movement. This shows that making changes can help the migrating eels.<\/p>\n The next step is to ensure that more hydropower plants offer routes that they can survive and continue their migration without being delayed<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" European eels face a major challenge during their journey to the sea. Many of the critically endangered fish hit a dangerous point during their downstream migration, where they come across hydroelectric plants. These can cause serious harm and death during a critical stage of the eel’s life cycle. To find out if changing their escape … Read more<\/a><\/p>\n","protected":false},"author":27,"featured_media":46208,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_focus_keyword":"eel,migration","rank_math_title":"","rank_math_description":"A narrow-barred escape route at a Norwegian hydropower plant allowed every tracked eel to survive its downstream journey, avoiding the turbine channel.","footnotes":""},"categories":[8],"tags":[],"class_list":["post-46112","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-energy"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/46112","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/users\/27"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/comments?post=46112"}],"version-history":[{"count":10,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/46112\/revisions"}],"predecessor-version":[{"id":46226,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/46112\/revisions\/46226"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media\/46208"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media?parent=46112"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/categories?post=46112"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/tags?post=46112"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.ecoportal.net\/en\/wp-content\/uploads\/2026\/11\/Norways-Fosstveit-hydropower-plant-tests-a-narrow-barred-escape-route-for-migrating-eels-with-every-tracked-fish-surviving-downstream-passage.jpg\" "\\"\\"")
<\/h2>\n
Every tracked eel survived the downstream journey<\/h2>\n
Migration timing followed cues the eels already knew<\/h3>\n
One challenge still remained after the redesign<\/h2>\n
Faster journeys may be the next challenge<\/h3>\n