Maine's alewives return after dams come down

A river site that saw fewer than 800 migrating alewives 35 years ago counted 9 million last year after dam removals.

On Maine rivers where dams have been removed, alewife populations have rebounded sharply. At one site, fewer than 800 of the migrating fish came upriver roughly 35 years ago. Last year, the count reached 9 million. The town of Benton marked the recovery with its annual Alewife Festival in mid-May, held on the riverbank as the migration passed.

The change traces to clearing physical barriers. Alewives run from the sea into freshwater to spawn, and dams block that path. Removing or bypassing them reopens the route, and the fish return in numbers that build year over year. At Benton the festival included smoked alewife samples, fish-themed crafts, and fishermen netting the run below Benton Falls Dam. The excerpt describes the scale of this recovery as unmatched elsewhere on the Atlantic coast.

For the commons, this is a concrete case of an ecosystem repairing itself once a human obstacle is removed. Alewives feed larger fish, birds, and mammals, and a restored run strengthens the whole river food web and the fisheries that depend on it. It shows that recovery does not always require complex intervention; sometimes it requires taking something away.

What to watch is whether similar dam-removal efforts produce comparable results on other rivers. The account originally appeared in Inside Climate News, and the numbers here describe a single site rather than a coastwide trend.

Source: HumanProgress