Diminishing Returns
Mashpee herring returns (thousands of fish) by river system, from 2011 to 2023. Years with missing data indicate years of limited to no sampling. Data source: Association to Preserve Cape Cod (https://apcc.org).
Every spring the rivers in Mashpee are transformed by schools of silvery fish. The water flashes and churns as the fish fight their way upstream in a determined, annual pilgrimage to their natal waters. These are the river herring - two closely related species, the alewife and blueback herring. While the two species of river herring are nearly impossible to tell apart to the casual observer, blueback herring spawn in the flowing rivers while alewife require unimpeded access to freshwater ponds to spawn.
Here in Mashpee, we're fortunate to have three active herring runs. Stretching roughly four miles from Mashpee-Wakeby Pond to Popponesset Bay, the Mashpee River is the largest of the Mashpee herring runs, averaging hundreds of thousands of returning herring per year. The other two smaller herring runs are the Santuit River in the east and the Quashnet River to the west. The Mashpee and Santuit rivers flow into Popponesset Bay, while the Quashnet River flows from Johns Pond in the north, south to Waquoit Bay.
Map of the Town of Mashpee showing the location of the three herring runs (red). Starting in the west is the Quashnet River, followed by the Mashpee River, and Santuit River furthest to the east.
The arrival of the river herring is a significant ecological and cultural event here on Cape Cod. These fish provide a vital food source for larger fish, birds, and mammals such as the osprey, striped bass, and bluefish. Their presence signifies a healthy ecosystem and their annual migration is a testament to the resilience of nature. This spectacle has been a part of Cape Cod's natural history for millennia, but for the past few decades, a sense of worry has mingled with the awe inspired by the herring runs. Populations have dwindled, their numbers a shadow of what they once were.
A Cause for Concern: Threats to the Herring
The decline of river herring can be attributed to a number of human-caused factors. Dams, culverts, and failing fish ladders impede fish passage and block the herring's upstream journey. Runoff from roads and lawns carries pollutants that fouls their habitat, and inadequate wastewater treatment options on Cape Cod have failed to remove harmful nutrients from entering our fragile coastal ponds, streams, and estuaries. Development along waterways destroys spawning and nursery habitats, squeezing the herring into ever-smaller refuges. While there is no longer a directed fishery for river herring, they are still caught as bycatch in offshore commercial fisheries.
From Decline to Hope: How We Can Help the Herring
The good news is that there are ways to reverse this trend. Here in Mashpee, and across Cape Cod, communities are taking action. Efforts are underway to remove or modify barriers to migration, allowing the herring free passage upstream. Local initiatives are focusing on improving water quality by reducing pollution from runoff and advocating for better wastewater treatment practices. But the fight for healthy herring runs isn't just for scientists and policymakers. There's a role for everyone to play. Here are some ways you can be a part of the solution:
Support Herring-Friendly Practices: Advocate for local initiatives that improve water quality and remove migration barriers. Let your voice be heard at town meetings and by contacting your local representatives.
Volunteer for Stream Monitoring: Organizations across Cape Cod are looking for volunteers to help track herring populations and report water quality concerns. By lending a few hours of your time, you can contribute valuable data to conservation efforts.
Reduce Your Impact: Be mindful of your yard care practices. Opt for natural fertilizers and minimize the use of pesticides and herbicides to prevent harmful runoff from reaching waterways.
Spread the Word: Talk to your friends and neighbors about the importance of healthy herring runs. Raise awareness about the threats they face and the ongoing efforts to conserve them.
Colored pencil drawing of the alewife, Alosa pseudoharengus by Cape Cod artist Mike Palmer. Shop prints here.
A Legacy for the Future
The Mashpee herring runs are more than just natural spectacle; they’re a vital part of the Cape Cod ecosystem. Herring are a keystone species, meaning their health impacts the health of the entire food web. A robust herring population supports everything from eagles and osprey to recreational fisheries. By working together, we can ensure that this wonder continues to inspire awe for generations to come.
Take the time to witness the river herring run. Each of the three Mashpee herring runs can be viewed from the fish ladders installed near the pond outflows. It’s a family-friendly activity that allows you to connect with nature and appreciate the delicate balance of our coastal ecosystem. Herring run typically occurs between late March and mid-May, so plan your visit accordingly. By respecting the regulations and simply observing this natural wonder, you'll be contributing to the continued success of the Mashpee herring runs for generations to come.
