ABSTRACT
Gamete maturation and spawning in bivalve mollusks are described in many papers, but much of the literature is concerned with gonad devel opment and reports on breeding periods. The breeding habits of marine invertebrates including bivalves are classified into three broad categories, namely, year-round breeders, winter breeders, and summer breeders (Giese and Pearse 1974). Eighty-five percent of mollusks are considered to be summer breeders. In bivalves, reproduction can be divided into three major phases: gonad development, spawning and fertilization, and development and growth. These phases, functioning continually in coor dination with seasonal environmental changes, produce the pattern chara cteristic of a species. The timing and duration of reproductive activity are determined by the interaction of the exogenous factors and endogenous ones (Lubet and Mann 1987).
