Atlantic salmon (Salmo salar) from four Penobscot River, Maine, brood stocks (two wild and two captive) and two landlocked brood stocks (Grand Lake, Maine, and Lake George, New York) were evaluated in hatchery tests to measure differential performance characteristics. Each stock was received as eyed eggs and cultured under standardized rearing conditions through 16 months. Penobscot stocks did not differ in growth rate or time of smoltification but did differ in frequency of six of seven body abnormality traits. Domestication effects on postyearling weights and smolt ATPase levels were detected in Penobscot stocks. The Grand Lake landlocked stock had a higher growth rate after 245 d and was heavier than Penobscot stocks after 280 d (36%) and 480 d (58%). Although differences among the Penobscot stocks were small and generally nonsignificant, the presence of domestication effects on 17‐month weight and Na+ K+ ‐ATPase indicates that progeny from fish held in the hatchery for four generations exhibited different hatchery performance characteristics than progeny from sea‐run parents.
