For the first time in decades, Maine has observed a monumental return of over 20 million river herring, known locally as alewives, in its rivers following key dam removals and ecological recovery initiatives.
- 20 million alewives counted in 2025, highest in decades
- Dam removals since 1999 improved fish migration
- Alewives help transfer vital ocean nutrients inland
What happened
Maine’s rivers have seen a dramatic resurgence of river herring, also called alewives, with counts reaching over 20 million in 2025. This remarkable recovery comes after more than a century of decline caused by damming and overfishing. Until recently, alewives were illegal to harvest due to their dwindling numbers, but river restoration projects have reversed decades of population loss.
Since 1999, efforts focused on removing several large dams, most notably on the Penobscot River. These removals reopened historic spawning grounds, allowing alewives to migrate upstream as they naturally do. In addition, fish passages around remaining barriers improved accessibility. Combined with a fishing moratorium offshore declared in 2012, these measures led to a rebound unseen since the 18th century.
Why it feels good
The return of alewives is more than an environmental win; it reconnects Maine’s people with a treasured natural and cultural resource. Historically a staple food for indigenous tribes, colonial settlers, and local wildlife, alewives have been celebrated for centuries during annual festivals that honor their journey upriver. Their comeback symbolizes resilience and renewal for local communities.
Ecologically, alewives play a crucial role as a 'nutrient conveyor belt,' bringing minerals and proteins from the rich ocean ecosystem into freshwater and forest habitats. This nutrient transfer supports many species, including fish, birds, and mammals, and enriches the soil. The success story inspires hope for other restoration projects and highlights the benefits of working with nature.
What to enjoy or watch next
Celebrate the alewife run through local festivals in Maine, where communities welcome back this shimmering natural spectacle every year. These events provide a chance to learn about the fish’s ecological importance, local history, and conservation efforts that made the comeback possible.
Looking ahead, continued monitoring and dam management will be key to maintaining healthy alewife populations. Other regions facing similar challenges may follow Maine’s lead in dam removal and habitat restoration to revive native fish runs. Watching how this success influences broader river ecosystems promises exciting developments for environmental conservation.