TEMPERATURE EFFECTS IN REPRODUCTION OF THE BAY SCALLOP, AEQUIPECTEN IRRADIANS LAMARCK

Abstract

The events in the reproductive period of a population of the bay scallops, A. irradians, collected at intervals from the field, were analyzed by determing the gonad index and the stage of oocyte development. The animals collected at intervals during the reproductive period were maintained at various temperatures in the laboratory, without food. Temperature effects on gonad growth and gamete development was determined at the time of 50% survival. Animals maintained at the beginning of gonad growth or in the neutral stage failed to develop gonads, After the animals had accumulated a certain amount of reserves and the oocytes were developing in the ovary, maintenance at 20[degree] C, 25[degree] C. and 30[degree] C resulted in rapid maturation and release of gametes. The temperatures at which spawning occurred, decreased the further the oocytes had developed towards maturity. The time required for spawning at these temperatures showed a direct relationship. It appears that the development of oocytes to maturity is a function of temperature within a range characteristic for this species, provided the gonads have accumulated already sufficient reserves to support their synthetic activities. The results of this study indicate that the events in the reproductive period of scallops are regulated to the period when food is most abundant and temperatures are favorable for gonad development.