Alewives

1600 CE - present

The alewife is a small, anadromous species of herring. Native to North America, it breeds in northern freshwater habitats before migrating to spend its adult life in the Atlantic Ocean. Alewifes are known by most for their invasion of the Great Lakes, entering through the Welland Canal and disrupting the food chain. In their native habitats, however, alewives are a keystone species of which the health of the ecosystem is largely dependent on. Once exceptionally abundant, the salty fish sustained humans, fed their livestock, and fertilized their crops. Populations began to suffer as early as the 17th century, when dam construction blocked their migratory routes and industry runoff polluted their waters. Fisheries continued to operate without at full speed until legislation was passed in an attempt to conserve what was left of the species. Although incredibly resilient, Alewife populations are presently at severe risk of collapse and efforts to revive native fish communities are underway.

Most Pressing Issues

Dam Construction

Alewives spawn in the northern waters of Newfoundland, and later swim as far as South Carolina as they mature. In their lifetime, they may return north as many as eight successive times to spawn themselves. Since the late 17th century, their migratory routes have been blocked by dam and mill construction. These structures threaten the safety of the small fish as they attempt to pass through. Populations have disappeared completely from waters with long time dam structures present. Newly constructed fish ladders give some hope to the future sustainability of alewife populations, allowing them to safely bypass the dams.

Toxic algae in the Great Lakes

Alewives entered the Great Lakes after the construction of the Welland Canal in 1931. By 1965, 90% of the weight of all fish present in the Great Lakes was made up of alewives, as reported by the Michigan Department of Natural Resources. This profusion, primarily in Lake Huron and Lake Michigan, disrupted the health of both deep water and shoreline ecosystems. Since the late 1960s, the water’s lack of nutrients and toxic algae blooms have caused extreme seasonal alewife die offs, with millions of fish washing ashore each summer. These occurrences presently continue, and truck loads of fish are carted to landfills yearly.

Absence from native waters

As Alewife migration routes have been blocked by dam construction, and shoreline industries have contributed to runoff pollution, the fish has been fully absent from some of its native waters. As a keystone species, other birds, mammals, and insects suffer from the absence of the alewife. Efforts are underway to reintroduce populations to notable waterways such as the Bronx and Hudson rivers. As dams are removed, ladders are constructed, and fish are transplanted by the hundreds, there is hope for alewives to once again thrive in their native waters, and support their dependent flora and fauna.

How you can help

The Bronx River Alliance

The Bronx River Alliance works to protect, improve, and restore the Bronx River corridor. They were key in the construction of a fish ladder at the historic dam at River Park and have made numerous efforts to restock the river’s Alewife population. The Alliance is supported by its members, volunteers, and donors.

The Mystic River Watershed Association

The Mystic River Watershed Association has worked to protect and restore the Mystic River since 1972. The association hosts a volunteer-run bucket brigade to hoist migratory Alewives over the Mystic River dam each year. Community members are encouraged to participate and learn about the remarkable species. The size of the annual run is in part accounted for by volunteers between the months of April and June. Recruitment begins in February, and all are welcome to apply.

Alewife Harvesters of Maine

Alewife Harvesters of Maine is composed of fishermen, conservationists, biologists, and environmental advocates focused on conserving and preserving Alewife populations. The organization works with harvesters to maintain and improve harvest plans in accordance with historic and new runs.