In 2017, volunteers in our Herring Monitoring Program observed a record setting 91,997 herring across 81 days and 791 counting slots. The total estimated Mystic River herring run this year was 630,098 +/- 60,599. This estimate represents a growing migration!



The Mystic River Watershed supports two species of river herring: Alewife (Alosa psuedoharenous) and Blueback Herring (Alosa aestivalis). Both fish are anadromous: they spend most of their lives at sea and return to freshwater habitats—like the Mystic River’s upper reaches—to spawn, or lay eggs.


In colonial times and earlier, herring in the Mystic River were extraordinarily abundant.  But from the 1900’s until today a much smaller population of river herring is present.

According to the Herring Alliance some river herring runs on the Atlantic Coast have declined by 95% or more over the past 20 years. In 2006 the National Marine Fisheries Service designated river herring as a species of concern. Population decline may be associated with numerous factors including by-catch, habitat loss and degradation, water pollution, poaching, access to spawning habitat, and natural predators.

Prior to renovations in 2011, the DCR Upper Mystic Lake Dam prevented river herring from reaching the Upper Mystic Lake. In the past, a volunteer-run bucket brigade hoisted the fish over the dam. Thanks to the Upper Mystic Lake Dam Rehabilitation project, a new fish ladder allows passage for river herring and the opportunity to monitor herring.


The Herring Monitoring Program utilizes volunteer efforts to count herring passing through a fish ladder at the DCR Mystic Lakes Dam in Medford. Counting occurs each spring (April - June) following the Massachusetts Division of Marine Fisheries (MA-DMF) protocol. The data collected is used to estimate the total herring run size in the Mystic River and is shared with the MA-DMF to help inform trends across the Commonwealth.

The Program collects valuable data about herring populations as they make their way up the Mystic River to reach their native spawning grounds and provides a rich educational opportunity. We hope that through participation, volunteers will increase their understanding and stewardship of the Mystic River and the watershed.

MyRWA would like to thank the Massachusetts Division of Marine Fisheries. Massachusetts Department of Conservation and Recreation, Medford Boat Club and all of the monitors for supporting this program.

To find out more about this project email herring@mysticriver.org

*NEW* Herring Education Project

Launched in 2017, the Herring Education Project connects students and others to the remarkable river herring migration and the science behind it using technology, data gathering and analysis, curriculum, and field visits.  Help us collect data on the river herring migration by watching a short underwater video and counting fish!


2017: 91,997 herring counted resulting in an estimated run size of 630,098 +/- 60,599 herring.

2016: 62,562 herring were counted yielding an estimated run size of 448,060 +/- 48,113 herring.

2015: 57,617 herring were observed resulting in an estimated 477,827 +/- 40,674 herring run size.

2014: 31,063 herring were counted resulting in an estimated 239,059 +/- 37,288 herring run size.

2013: 23,635 herring were observed yielding an estimated run size of 193,125 +/- 24,250 herring.

2012: 21,052 herring were counted by citizen scientists. Using modeling software provided by the MA-DMF, the Mystic River herring run was estimated to be 198,932 +/- 18,062 herring. This was the first year of the Mystic River Herring Monitoring Program.

Eel Monitoring

MyRWA also monitors American Eel (Anguilla rostrata) passing through the Upper Mystic Lake Dam. Eels travel through the dam via a ramp to the right of the fish ladder and are counted by MyRWA staff and the the Massachusetts Division of Marine Fisheries.