4.14 3
Jim 2
Ron at fish ladder
The queue at Middle Pond


Springtime in New England signals the return of river herring from salty offshore waters and bays as they begin their migration “runs” up rivers to spawn in freshwater streams and ponds. Millions of river herring once turned coastal rivers silver during this annual rite of spring. Historically, these runs provided food to Native Americans and early settlers, as well as boosting the economies of coastal communities that harvested and sold the herring.

Years of overfishing and by-catch, obstructions to fish passage (dams and culverts), habitat loss and degradation, and poor water quality led to a steady decline in river herring populations in the late 20th century. In response to this decrease, the state of Massachusetts imposed a moratorium on the commercial and recreational harvesting (except for Native Americans), sale, and possession of river herring in 2006.

What are River Herring?

River herring are diadromous fish that spend most of their adult lives in saltwater, returning to freshwater to spawn. The two species of river herring found along the east coast are the alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis). Alewives range from Nova Scotia through North Carolina, while bluebacks extend their range even further south to Florida. River herring travel in large schools and feed on zooplankton and phytoplankton. In turn, river herring are an important food source for commercially valuable fish like striped bass, bluefish, cod, and tuna, as well as other wildlife including birds, otters, seals, and whales.

Adult river herring spawn every four to five years. Triggered by warming water temperatures (10.5°C/51°F) and guided by smell, alewives begin the migration run first, followed by bluebacks. For the Marstons Mills River herring run, the fish travel offshore from Nantucket Sound, through the Three Bays estuary, up the Marstons Mills River via fish ladders at Mill Pond and Middle Pond, to their final spawning destinations in the river, Middle Pond, and Mystic Lake.

Female river herring release millions of eggs that are fertilized by the males with very few of these eggs surviving to hatch. One female can produce between 60,000 and 300,000 eggs. Alewives prefer to spawn in slow-moving streams and ponds with rock, gravel, or sandy bottoms, while bluebacks prefer faster moving streams. After spawning, most adult herring head back downstream to the ocean.

Hatching in less than a week, the young herring spend their first few months growing and feeding on phytoplankton and zooplankton in their freshwater habitat. Juvenile herring begin heading downstream in mid-summer through the fall, depending on food availability and water levels. Some juveniles will spend their first year in the estuary before heading out to sea to mature for three to four years until they are ready to migrate back to their natal spawning grounds. Click here for more information on herring species found in MA.

Herring Runs

Today, there are over 100 herring runs located in 48 towns in Massachusetts, with 41 of those runs located on Cape Cod. Many of these herring runs are sites where important river herring population data is collected for the Massachusetts Division of Fisheries and Wildlife (MA DMF). While some run sites use electronic fish counters to count herring, many sites rely on volunteers to visually count the herring and collect scientific data as they travel upriver during their spring migration. These visual herring counts begin on April 1st and are conducted daily through June. Click here to view 2022 count data for runs through MA.

BCWC river herring monitors count the fish as they migrate up the Marstons Mills River and through two fish ladders, one located at Mill Pond and one near Middle Pond in Marstons Mills. In addition, they also conduct a count at a fish ladder on Boat Cove Creek in West Barnstable. Monitors also collect data on weather and water conditions. The visual counts and data are sent to MA DMF, where fisheries scientists use the count data to calculate the estimated herring run size for each fish ladder.

The estimated run sizes provide important population data that help fisheries managers track and manage river herring stocks around the state. River herring are an indicator species of healthy coastal and aquatic ecosystems. Despite the moratorium, herring populations have not rebounded, and river herring face even more threats from the impacts of climate change.


Mill Pond Fish Ladder Herring Estimates

Year Total Number of Herring Counted Estimated Herring Run Size
2023 12,952 92,723
2022 5,608 50,961
2021 5,736 54,713
2020 No data No data
2019 4,521 35,092
2018 1,767 10,306
2017 5,251 36,148
2016 2,043 13,954
2015 3,667 23,840
2014 6,396 47,006
2013 8,117 56,987
2012 10,327 87,308
2011 53 428
2010 478 3,944
2009 1,332 10,668
2008 5,232 42,404
2007 1,741 13,862
2006 719 6,302


Middle Pond Fish Ladder Herring Estimates

Year Total Number of Herring Counted Estimated Herring Run Size
2023 6,382 55,926
2022 2,776 26,492
2021 2,077 18,851
2020 No Data No Data
2019 25,867
2018 5,567
2017 10,236


Boat Cove Creek Fish Ladder Herring Estimates

Year Estimated Herring Run Size
2023 0
2022 0
2021 12