Plimoth Grist Mill (Ashley Ryan)
By Ashley Ryan
Each year, herring make a remarkable journey from the ocean to freshwater along the East Coast, with peak migration occurring from March to June. This migration is called the herring run.
Before diving into the runs, it’s important to understand the fish. Professor Gilbert Newton, who teaches environmental science at 4Cs, explains that the term “river herring” refers to two species: the alewife and the blueback herring.
These herring spend most of their lives in the ocean but return to freshwater to spawn. “She’ll lay between 60,000 and 300,000 eggs per season,” Professor Newton said. Once the juveniles mature, they return to the ocean. This migration is part of their life cycle, similar to salmon.
Herring runs are especially popular in the Cape Cod area. “We have 20 sites on Cape Cod, across 11 towns, being monitored,” Newton said. At these sites, volunteers count the fish nine times a day, in 10-minute intervals.
A common feature in freshwater systems is the fish ladder, which helps herring migrate. “The structures are built to assist them,” Newton said, but several factors affect the runs. “Many of these herring runs have been blocked by trash and other barriers,” he noted.
Climate change is another challenge. “It’s a big issue for animals that require cold water,” Newton said.
Despite these challenges, Newton remains optimistic about the conservation of herring runs. “I think they’re doing well. We need to maintain awareness and hopefully more people will get involved in protecting the species.”
