Citizen Science: Tracking Changes in River Herring Populations


River Herring are a part of the 1% of all fish species that are migratory between freshwater and marine habitats. They live most of their lives in the ocean, and they migrate to freshwater rivers and lakes to lay their eggs. Because of this rare characteristic, river herring have a crucial role in both marine and freshwater ecosystems. Unfortunately, the river herring population is being threatened by overfishing, poor water quality, and dams obstructing their migrations. On the bright side, recent technologies, known as fish ladders, have emerged that allow river herring to pass through dams. Since implementation, the amount of migrating river herring populations have increased tremendously.

Illustrations by Diane Rome Peebles


The Department of Marine and Environmental Affairs in Massachusetts established the herring run project in 2008 in association with The University of Massachusetts Amherst and the Massachusetts Division of Marine Fisheries. This project has been very successful in generating a near estimate of the population of river herring in the area, which allows scientists to determine the health of the crucial species. Another great thing about this project is that you can help support it!


To track migratory river herring on what’s known as the “herring run”, there is an underwater camera located on the fish ladder at the Jenny Grist Mill dam. This camera can detect movement, and will record short 10-60 second videos of the fish as they swim upstream. In the 2020 migratory season (April 13th-May 21st) there were 38,398 video clips recorded. There are so many videos to watch to correctly track the number of herring migrating, and this is where your help comes in! Visiting this link will redirect you to a website that allows you to watch these video clips and input the number of herring you see. Some key instructions to the project are as follows: only count the number of fish you see swimming from left to right across the screen (this means that they are swimming upstream, and counting fish going downstream would be counterproductive), submit a count of zero if you don’t see any fish, and utilize the slow-mo and full-screen tools if the amount of fish is to difficult to count otherwise. It’s a very simple project and it’s a lot of fun to watch the herring swim across your computer screen.


To learn more about their project and learn more about the creators of the herring run project, visit their website.




NOAA Fisheries. (2020). Removing seven barriers to herring migration in historical Plymouth. Successful Fish Passage Efforts Across the Nation. https://www.fisheries.noaa.gov/insight/successful-fish-passage-efforts-across-nation



Plymouth River Herring. (2020). Town Brook Herring Run. Department of Marine and Environmental Affairs. https://www.plymouthriverherring.org/new-page


Our Urban Wildlife Migration: What are River Herring? Mystic River Watershed Association. https://www.mysticherring.org/about/herring

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