Reproduction and Ecology of the Hermaphroditic Cockle Clinocardium nuttallii (Bivalvia: Cardiidae) in Garrison Bay

Abstract

ABSTRACT: In this first description of the hermaphroditic reproductive cycle of the cockle Clinocar- djum nutlallii, male and female follicles are shown to develop in phase with each other The gametes of both sexes are spawned about the same time. The cockles In Garrison Bay spawn from Aprll to November, usually in the second year, but for a small segment of the stock there is the potent~al to spawn in the first year of life. Density, growth rate, patterns of mortality and other ecological factors are discussed in relation to the evolution of bisexual reproduction. The central driving forces toward bisexual reproduction are the combination of environmental unpredictability and predatory pressure. where no refuge in slze exists to guide the allocation of energy between reproduction and growth.