Maine Spring Fish Runs: River Herring

On the Kennebec River, Damariscotta Mills and the Presumpscot River, usually in April and May. That timing comes from the Maine Department of Marine Resources. The day each year follows the water: the Maine Department of Marine Resources puts the river herring spawn at 55 to 68°F.

The Maine Department of Marine Resources gives 55 to 68°F for river herring in Maine. Water inside that range means the spawn can be on; within 5°F below it, the run is getting close.

Each run card follows the usual months its source gives. The spawn itself waits on the water, so a river thermometer read against the spawning temperature on the card settles it: more than 5°F below the spawning temperature is Not yet, within 5°F is Getting close, inside the range is On, and above it late in the run is Winding down.

No. The months are the usual window, and the water sets the day: a cold spring holds a run back, and a warm one brings it forward. In Maine, a reading at the river against the spawning temperature shows where the water stands.

River herring are alewives and blueback herring, small sea run fish that crowd up coastal streams and fish ladders.

Water temperature is the main signal: each species waits for its own range. Longer days bring fish toward the rivers, and a warm rain that raises and warms the water often starts a push upstream. Walleye go first in cold water; white bass, herring and shad follow as rivers warm.