River Herring / Alewife Restoration


Restoring Alewife to the Concord River

Salmon is the dramatic king of fish restoration in the Merrimack River valley, but beginning in May 2000 a quiet revolution to overthrow the king began in the Concord River. A team of people from the U.S. Fish and Wildlife Service, the Massachusetts Riverways Program, and volunteers from groups like the Sudbury Valley Trustees (SVT) released 7,000 adult River Herring or alewife to the Concord River. 


Like salmon, alewife are anadromous fish. They breed in fresh water rivers then, after a period of juvenile growth, the young fish swim downriver to spend their adult life in the ocean. After about 3 to 5 years in the ocean the now mature alewife return to the river in which they were born. The native population of Concord River alewife became extinct in the 1800s when dams constructed across the Concord and Merrimack Rivers prevented the mature fish from getting back "home" to spawn. Alewife and all other anadromous fish will return only to the river in which they were born. The instinct is imprinted on the fish's brain when it is born. Since there were no detour signs constructed at the mouth of the Merrimack in the early 1800s -- "Caution: Dams Ahead - Detour to Spawn in the Connecticut River", alewife born in the Concord River couldn't return home and the native population died.

Making the Transfer

Netting some fish, around 7,000 adult alewife that become the seeds of the Concord River restoration can be transferred from the Nemasket River to lay their eggs and spawn in the upper reaches of the watershed. The young alewife that hatch from these eggs during spring become imprinted with the water of the Concord River as their home river. They spend the summer growing up in the Concord and during fall (late August through November) up to two million (2,000,000) juvenile alewife will migrate downstream to spend the next 3 to 5 years in the ocean. When it is time for these alewife to spawn, they will return to their birthplace in the Concord River. With the arrival of a successful transfer process, it will be the first time in over a century that alewife native to the Concord River will return spawn. The Concord River alewife will be back from extinction!

Ways to Help

You Can Help the Alewife Restoration - Volunteer Positions open according to Doug Smithwood of the U.S. Fish and Wildlife Service restoration of alewife to the Concord River has the potential of being one of the most successful and dramatic fish restoration projects in New England. But bringing a native population of alewife back from extinction is not an easy task.

The Fish and Wildlife Service (and the alewife) needs some help.

The Concord River in Lowell is a critical point to monitor the alewife's progress. Volunteers are needed to monitor the downstream migration of juvenile alewife past the Wamesit and Middlesex Falls. Some alewife also need to be collected in nets (provided by us) so the Fish and Wildlife Service can study them. In the spring volunteers will be needed to help transport new breeding stock from the Nemasket River to the Concord. If you are interested in helping or learning more about the Concord River alewife restoration, check the volunteer opportunities or
contact us at 978-934-0030.

*This program is currently on hiatus due to a moratorium on fish transfers and low fish counts, however, we would still like to know if you are interested.