Strong Herring Migration Documented at Mystic Lakes

Since 2012, the Mystic River Watershed Association (MyRWA) has been working with hundreds of volunteers to count river herring passing through the fish ladder at the Mystic Lakes Dam to spawn in Upper Mystic Lake. In 2016, ninety trained citizen scientists counted the largest number of herring since the monitoring program began, documenting another strong Mystic River herring migration at nearly half a million fish. This estimate is similar to last year’s migration and represents nearly a 100% increase over the counts in prior years.

River herring collectively refer to two species of herring, Blueback (Alosa aestivilis) and Alewife (Alosa pseudoharengus).  These two species are referred to as “anadromous” fish as they live the majority of their life in salt water but lay eggs (spawn) in fresh water. The billions of river herring eggs that are produced in Upper Mystic Lake will develop into juvenile herring within just a few days. These juveniles will stay in the fresh water for up to 4 months before swimming downstream to live in estuarine waters.  The river herring that survive will reach an age to reproduce after 3-4 years and usually return to the same waters where they were born. 

The Mystic River is one of 78 river herring runs in Massachusetts. River herring are an important component of ocean fisheries, and they need access to freshwater systems to survive.  Over the past several decades, populations of river herring have dramatically declined.

The Mystic River Watershed Association works each year to train a set of volunteers to perform visual counts at the fish ladder Mystic Lakes Dam. The volunteers agree to perform at least one 10-minute observation each week.  Volunteers in the 2016 program performed 786 ten minute observations and counted 62,562 fish from April through June.  The data are plugged into a sophisticated model developed by the Massachusetts Division of Marine Fisheries (MA-DMF) that yields the population estimate of 448,060 +/- 48,113 for 2016.

Work is underway to build upon the successes of the Herring Monitoring Program.  MyRWA is working with MA-DMF and local river herring advocates to install a fish ladder at the Center Falls Dam in Winchester to allow herring access to Wedge Pond and potentially Horn Pond in Woburn. Construction of the fish ladder is slated for Fall 2016. MyRWA is working with local municipalities to identify opportunities to improve habitat and water quality throughout the watershed.

Additionally, MyRWA will be bringing the herring migration into local schools through the installation of monitoring cameras at the fish ladder. Students will be able to count fish, interact with data and learn more about the river ecosystem through a new web platform dedicated to the Mystic River herring migration.

“We are excited to expand upon the Herring Monitoring Program and engage youth and the broader public in this annual rite of spring,” said Beth MacBlane, Outreach and Communications Director at MyRWA. “The herring are testament to a vibrant river system that needs to be cared for.”

The Mystic River Watershed is a vital natural resource for the more than 500,000 people who live in 22 Mystic River communities.  For more information about the Mystic River Watershed Association please see