The Mystic River Watershed Association (MyRWA) in partnership with the Massachusetts Division of Marine Fisheries estimated that 630,000 river herring migrated upstream to spawn at the Mystic Lakes this year – making it one of the largest herring migrations in the Commonwealth. Since 2012, MyRWA has been working with hundreds of volunteers to count river herring passing through the fish ladder at the Mystic Lakes Dam in Medford. In 2017, ninety trained citizen scientists counted fish at the Mystic Lakes Dam. Based on their observations, the Massachusetts Division of Marine Fisheries estimated this count as a 40% increase over last year.
“This has been an exciting year for herring! We are thrilled that the herring count has increased, and glad our volunteer monitoring program and our new underwater video monitoring program are engaging more people in the community – including local students – in the amazing river herring migration that this urban river supports. We will continue to partner with agencies and municipalities to improve water quality and habitat in the Mystic River watershed,” said Patrick Herron, Executive Director at MyRWA.
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 due to a variety of issues, including habitat loss. The installation of the fish ladder at the Mystic Lakes Dam in 2011 opened up 165 acres of additional habitat for the spawning herring. In 2012 – the first year of the Herring Monitoring Program – an estimated 198,932 herring entered Upper Mystic Lake. The run size is now more than 3 times that size, likely the result of adult fish returning to their native spawning grounds.
The Mystic River Watershed Association works each year to train a set of volunteers to perform visual counts at the fish ladder at the Mystic Lakes Dam, which is operated by the Massachusetts Department of Conservation and Recreation. Volunteers in the 2017 program logged 791 ten minute observations and counted 91,997 fish from April through June. The data are plugged into a sophisticated model developed by the Massachusetts Division of Marine Fisheries that yields the population estimate of 630,098 +/- 60,599 herring for 2017.
Thanks in part to the success of this program, a second fish ladder was installed in December 2016 in the Aberjona River, upstream of the Mystic Lakes. However, due to construction further upstream it was not functional this spring. Located at Center Falls Dam in Winchester Center, herring will soon be able to access Wedge Pond and potentially Horn Pond in Woburn, opening up many new acres of additional spawning and nursery habitat.
Additionally, MyRWA launched a new Herring Education Program this spring, partnering with six local schools to engage youth in this largely hidden annual migration. Through the installation of an underwater video camera at the Mystic Lakes fish ladder, the herring migration was broadcast into classrooms where students helped document the herring migration, explore data, and learn more about this important fish. MyRWA educators visited classrooms providing hands-on science and STEM education, in addition to hosting field trips to the fish ladder.
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.