Environmental and phenotypic factors affecting the reproductive cycle of Atlantic herring

Abstract

A simple technique based on seasonal changes in gonad weights was used to describe key events in the spawning and maturation cycle of spring-spawning herring in the north-west Atlantic. Analysis showed that there were quite large inter-annual variations in the timing and duration of the maturation and spawning periods. The initial maturation process, which begins in the fall, is controlled mainly by phenotypic factors related to the size composition and condition of the adult population. The final maturation process, which begins in the spring and whose trajectory determines spawning times, is cued by January sea temperatures. The results contradict the general opinion that herring have a relatively fixed spawning season that is restricted to a brief 4-6 week period. Rather, the plasticity in spawning and maturation cycles of spring-spawning herring suggests that herring recruitment may not be a passive affair but an adaptive process in which Atlantic herring modify their reproductive activities to match expected environmental conditions during larval emergence. © 1996 International Council for the Exploration of the Sea.