River Herring Runs on Cape Cod

River herring runs on Cape Cod only happen once a year and are not to be missed! Nothing heralds spring quite like rushing brooks filled with silvery flashes of river herring heading upstream to spawn.

Two species, alewife, and blueback, are known collectively as river herring and are the stars of river herring runs on Cape Cod. These fish spend most of their lives in saltwater, swimming in large schools, feeding on plankton and trying to evade predators like striped bass, cod, tuna, bluefish, seals, whales, and dolphins. River herring venturing into freshwater only to spawn in streams and ponds.

Herring is anadromous, meaning they live most of their lives in salt water but return to fresh water to reproduce. The river herring runs on Cape Cod and the Islands are made up of fish that spend most of their lives in Cape Cod Bay, Nantucket Sound, Pleasant Bay, Vineyard Sound, Buzzards Bay, and the broader Atlantic.

The river herring runs on Cape Cod are a tradition not to be missed and a perfect way to celebrate spring. Enjoy watching the fish fight their way upstream, avoiding gulls and obstacles or get involved as a citizen scientist, collecting data by counting fish at one of the many fish ladders and other sites of river herring runs on Cape Cod.

The spring spawning run marks the turn of the seasons and has long drawn onlookers. The Wampanoag tribe traditionally caught the herring for food and bait, as did European settlers.

According to the U.S. Fish and Wildlife Service historical accounts report rivers turning silver with the sheer density of fish spawning each spring. Over the years river herring have been used for fertilizer, lobster bait, and as a food source.

These days visitors gather to watch the herring use fish ladders to navigate around dams, with volunteers counting the fish to monitor the population size, which has declined significantly in the last several decades.

If you’re looking to join the celebration of the river herring runs on Cape Cod, stop by the Plimoth Grist Mill Herring Run Celebration in Plymouth on April 23rd from ten to four. The event, put on by the Plimoth Patuxet Museums features fish scientists, art, and games for kids, all while the alewives swim past up Town Brook.

The river herring runs on Cape Cod begin in early April, depending on the water temperatures. Mature herring, usually 2-5 years old, depart from their schools in the open ocean, following their olfactory senses to the freshwater in which they were born. Alewives begin their trip upstream when the water temperatures reach 51℉, while Bluebacks wait until the water gets up to 57℉.

Throughout the upstream journey the fish face a gauntlet of predators waiting on the banks of the rivers. Gulls, herons, osprey, river otters and raccoons all wait for the spring herring runs as well, plucking the nutritious fish out of the waterways. The trip is not an easy one; the Association to Preserve Cape Cod notes that 90% of adult herring die while migrating. While herring don’t leap out of the water in the showy way that spawning salmon do, they can swim fast upstream, navigating strong currents, and can make the trip multiple times in their lives.

The river herring’s journey is made more difficult by man-made development including dams, culverts, polluted waters, and increasingly by warming water temperatures. Once the alewives and bluebacks navigate waterways to the pond or lake of their choice, the U.S. Fish and Wildlife Service notes that adult females can produce 60,000-300,000 eggs. The eggs hatch in 3-6 days, and the young fish (called fry) spend the summer in freshwater. In the fall, when they are 1 ½ to 2 ½ inches long they head out to sea to join the large schools of herring in the Atlantic. Of all the eggs laid, less than 1% make it back to spawn.

Herring are a crucial part of the fresh and saltwater ecosystems, as a key food source for a variety of recreationally and commercially significant fish species. They are also good indicators for the health of the whole coastal ecosystem. Both factors make the decline of herring populations and river herring runs on Cape Cod so concerning. The declines, gradual over the last century, and steep in the past few decades, are attributable to dams, development, pollution, and habitat degradation, as well as overfishing and bycatch offshore. Since 2005, there has been a moratorium on fishing for herring, commercially or recreationally in Massachusetts, with the exception of the Wampanoag tribe’s aboriginal fishing rights.

Conservation groups and municipalities have been working to stabilize and increase the population of river herring runs on Cape Cod through a number of initiatives. Improvements have been made by removing barriers to fish passage either by removing old dams, enlarging culverts, or adding fish ladders to help fish navigate around obstacles.

The Association to Preserve Cape Cod collaborates with volunteers and scientists to track the number of spawning herring each season. Volunteers help to collect data by counting the fish, either beside the fish ladders or streams, or virtually using underwater cameras. Counting herring is a fun way to get involved in the preservation of this important fish while enjoying the spring river herring runs on Cape Cod!

Some of the many great river herring runs on Cape Cod and the Islands:

• Stony Brook in Brewster is one of the most popular river herring runs on Cape Cod, enjoyed by spectators and seagulls alike. Spectators can enjoy the sight of fish navigating sloops and a series of weir-pool fishways built into the stream, avoiding the Lower Mill Pond dam. The stone baffles help fish combat the natural elevation change on their way to 386 acres of headwater ponds upstream. Improvements, including enlarging a culvert in 2010, have aimed to support the population, which has fluctuated in recent years. The Division of Marine Fisheries reported 11,000 fish in 2009. The count rose to 275,000 in 2015 but dropped to 20,000 in 2017.
• Herring River off of Depot Street in Harwich, the aptly named run has benefited from lots of restoration efforts aimed at supporting the river herring population. Set in the Bells Neck Conservation Area, the site features a fish ladder at the West trailhead and is connected to lots of area ponds. In 2015, 250,000 herring were counted in this migration. Along with the herring run, the 250-acre preserve offers three miles of walking trails and great views of a salt marsh. The West trailhead parking lot is closed until mid-June to protect the herring.
• Monument River on the north side of the Cape Cod Canal in Bourne sports one of the largest river herring runs in Massachusetts. The DMF reported 672,000 fish in 2000, up from their count of 91,000 in 1980. Visitors can view this run, and the Monument River fishway from Route 6/28 from the Army Corps of Engineers Station.
• Santuit River/Pond, Quashnet River/Johns Pond, and Mashpee River/Pond are the multiple river herring runs that can be found in Mashpee. The Santuit River run features a fish ladder to bypass a dam, leading to the wetlands of the Santuit Pond Preserve, the result of a 2013 joint restoration effort between the towns of Barnstable and Mashpee, as well as county, state, and federal agencies. The Quashnet River in Mashpee flows through undeveloped land and abandoned cranberry bogs from Waquoit Bay to Johns Pond. In addition to herring runs, the river supports American Eels and Brook Trout. The Mashpee River/Mashpee Pond run is located on Route 130 next to the Mashpee Wampanoag Indian Museum. It is one of the area’s largest herring runs with 350,000 fish in 2015, and 107,000 fish in 2017.
• Eastham Herring Run on Herring Brook Road is the route of choice for river herring returning to Bridge Pond, Herring Pond, and Great Pond. It can be found between Cole Rd. and Bridge Pond Drive. An improved culvert in 2013 made the route easier for fish: 2,000 passed through in 2016, and 5,000 in 2017.
• Wellfleet’s Herring River on Duck Harbor Road leads fish four miles through 1,100 acres of estuary to four ponds. An expanded tidegate increased the numbers from 12,000 in 2012 to 70,000 in 2015. Either walk from Duck Harbor Road or from Duck Harbor Beach to check out this river herring run.
• Coonamessett River in Falmouth was once one of the largest herring runs in New England, with millions of fish using it as a migratory route. Due to dams and other impediments, just 75,000 fish were counted in 2015. The three-mile river has recently undergone a significant restoration effort to support river herring and other species. The project, a collaboration between NOAA and the town of Falmouth, removed dams, turned inactive cranberry bogs back into wetlands, and worked to stabilize the banks of the river while adding public access trails and boardwalks. The project, completed in 2020, reopened 2.2 miles of river and rebuilt 56 acres of wetland habitat.
• Pilgrim Lake in Orleans features a fish ladder dating back to 1865. Located on Herringbrook Road, the ladder helps fish migrate through Pleasant Bay, Little Pleasant Bay, and into Lonnie’s Pond. It is also an eel migration route.
• Martha’s Vineyard the Wampanoag Tribe of Gay Head Natural Resource Department monitors the fish through an underwater herring cam. They’ve noted the fish returning later each season to Aquinnah Herring Creek, Squibnocket and Menemsha Ponds, and in diminished numbers. These declines are attributed to overfishing of herring offshore as well as too much nitrogen and sediment in the ponds.
• Nantucket, the manufactured Madaket Ditch linking the Hither Creek to Long Pond, dug by Wampanoags and English settlers in the 1660’s supports a run of alewives and eels. The Nantucket Historical Association notes that before the joint project there were no herring runs on the island.
• Additional river herring runs on Cape Cod and the Islands include Red Lily Pond in Barnstable, Red Brook in Bourne, Stillwater Pond in Chatham, Bound Brook and Scargo Lake in Dennis, Mill Creek in Sandwich, Tom Matthews Pond, Baxter Mill, and Long Pond in Yarmouth, and Lover’s Lake in Chatham.