Relation between Winter Temperature and Survival of Larval Atlantic Herring along the Maine Coast

Abstract

Abstract Larval Atlantic herring Clupea harengus, hatched mainly in late summer and autumn in Maine coastal waters, experienced relatively small temperature declines (1.8–3.1°C) during their autumn transport along the coast to two inshore overwintering locations in the early 1960s and in 1982. Larvae that reached the Sheepscot River estuary on the central Maine coast experienced rates of temperature decline from 0.04 to 0.23°C/d in the early winter of 13 years during the period 1965–1985. Winter larval survival rates were more variable at lower gradients of minimum temperature and declined to lower values at higher gradients. Age-frequency data indicated that the 1984 year-class approached metamorphosis earlier than the 1983 year-class, possibly due to accelerated growth in early spring. Minimum temperatures of 0°C or less were recorded in Boothbay Harbor during the overwintering period for nine year-classes; two of these year-classes were exposed to low temperatures (–1.1°C) that approached the lethal li...