Watershed Gazette :: The Herring Times

More than 815,000 river herring passed through the fish ladder at the Mystic Lakes Dam in 2025. This was the largest migration ever recorded in the state of MA. These results prove the HUGE return on our investment and validate our efforts to restore the Mystic River Watershed. 

Students from Curtis Tufts worked with scientists from the Mystic River Watershed Association to restore habitat, increase biodiversity, remove fish migration barriers (add fish ladders), and count the increases in the annual migrating biomass. These efforts improved the natural flow of the river, reduced pollution, protected critical breeding grounds, and restored more than a half-million breeding river herring to Boston Harbor and the Atlantic Ocean. We protected habitat, reduced toxic waste, extracted invasive species, removed barriers to spawning grounds, counted spawning fish on the ladder, validated future investments, and released protected eels into the Mystic Lakes.

1. Students removed invasive species, like garlic mustard, from the Mystic River (ensuring flow, reducing pollution, enhancing biodiversity, and stabilizing ecosystems). 
2. Students removed pollution from surrounding riverbanks (reducing toxic waste, improving water quality, restoring breeding grounds, ensuring a healthy ecosystem).
3. Students counted migrating river herring swimming up fish ladders to spawn in the Mystic Lakes (species/ habitat restoration, increase biodiversity, keystone species mgt., return on investment).
4. Students released American Eels into the Mystic Lakes with scientists from MRWA (keystone species management, improving biodiversity, filtering/ cleaning the water).
5. CTHS student volunteers ranked 9th on the MRWA total fish count leaderboard (contributing to ROI data and helping a key migratory fish species return to our local food chain).
    

• American eels (a keystone species) help clean local waterways by supporting freshwater mussels, which filter and clean our water.
• River herring pass critical nutrients up/ down the food chain and between land and sea (terrestrial > freshwater > brackish > marine). 
• River herring eat phytoplankton, insects, zooplankton/ crustaceans... 
• River herring feed many species of whales, fish, and eels (humpbacks, dolphins, tuna, cod, halibut, salmon, mackerel, and eels eat herring). 
• River herring feed countless species of birds (eagles, osprey, hawks, great blue heron, gulls, and cormorants). 
• River herring feed land/ terrestrial predators (otters, foxes, coyotes, bears, raccoons). 
• When river herring decompose, their nutrients are transferred back through the food chain.
   

CTHS students helped preserve the quality of life in Boston Harbor by protecting our watershed, improving water quality, and helping restore two critical keystone species. The river herring and American eels we supported, serve as key foundational "forage" food sources for a number of commercially and recreationally important fish (tuna, cod, salmon, mackerel) and countless species of birds and mammals. In addition, herring and eels both migrate between freshwater and the ocean providing a crucial nutrient link and moving energy between freshwater and marine ecosystems. The eels further improve our water quality by supporting the breeding of freshwater mussels, which are important filter feeders and clean our water.

Tommy's Class ranked 9th for total fish counting activity on the MRWA's 2025 River Herring Leaderboard. We counted about 3,000 individual fish, over 514 videos, and ranked 9th on the leaderboard. The true winners are the local wildlife and people of the Mystic River Watershed.