REPRODUCTIVE CYCLE AND CHANGES IN ASSOCIATED PARTS OF GONAD IN CRASSOSTREA (SACCOSTREA) GLOMERATA (GOULD) FROM THE COAST OF KARACHI

Abstract

A study of the reproductive cycle of Crassestrea (Saccostrea) glomerata
from the coast of Karachi is described for the years 1971-73. The species attains
maturity of gonad in majority of specimens in April, which is continued in fluctuating
manner through October. Active spawning continues from MaylJune to
November. Comparison among the different size groups shows that spawning in
youngest size group is very restricted, which may be attributed to abundance of
phagocytes throughout the year. No 'inactive phase' is observed but 'indifferent
phase' generally occurs in winter. Comparison with the same Sipecies of New
Zealand shows that the temperature range at which reproduction is carried out is
different from that of the latter locality, suggesting acclimatisation to different
temperature condition of the two areas. Glycogen granules were abundant in winter
which declined gradually reaching minimum value in May|June and this condition
remained in summer. In September, build of glycogen starts, which attained maximum
concentration in the body parts in winter (November through January). In
conclusion the observations on the reproductive cycle of the species from Karachi
shows a different pattern from those of temperate regions.