Alewives, small migratory fish that play a crucial role in the food chain of many Maine waterways, will be discussed Thursday, May 12, at the Craig Brook National Fish Hatchery. Naomi Schalit of Maine Rivers will speak on the impact of alewives in the Orland River beginning at 7 p.m. Admission is free, and refreshments will be provided by Friends of the Craig Brook National Fish Hatchery. The hatchery is located 6 miles north of Bucksport and 13 miles south of Ellsworth on Route 1. For information, contact Bob Mushrall, president of Friends of Craig Brook NFH, at 469-2400.