STUDY ON THE MORPHOMETRIC TRAITS AND BREEDING BIOLOGY OF Meretrix meretrix COLLECTED FROM MOHESHKHALI CHANNEL, COX’S BAZAR, BANGLADESH

Abstract

The potential local and international markets, suitable habitats and by-product use has made the Asian hard shell clam, Meretrix meretrix as one of the potential species that may enhance the blue economy of Bangladesh. The fundamental aspects of reproductive biology, biometric, and morphometric traits for this genus in the coastal waters of Bangladesh remain unexplored. Therefore, this study was conducted to delineate the morphometric traits and breeding biology, including the Gonadosomatic Index (GSI) and Condition Index (CI), of Asian hard clam M. meretrix. A total of 2267 samples were collected from Chowfaldandi canal, near the Moheskhali Channel, over a year (from December, 2021 to November, 2022) during full-moon cycle at low tide. The positive correlations were observed between shell length- total weight, shell height- total weight-shell-width (p< 0.001). These relationships suggested that specific morphometric traits were linked to clam growth patterns, where allometric growth patterns were observed (W= 0.046* L 1.63, b=2.021). The sex ratio male to female for this species was 1:1.66 (P > 0.001) determined through Welch F test. The gametogenesis cycles was observed through histology showed that spawning periods for males were from February to April 2022, and for females from March to May 2022.The gametogenesis cycles of male and female M. meretrix exhibited stages of development and maturation, with males showing a tendency to initiate gametogenesis earlier than females. GSI value reached its peak in November-December indicating initiation of spawning period and reached its lowest point in June-July, signifying a period of inactivity or rest. The highest condition index value was noted in March 2022 (5.44±2.05), while the lowest was recorded in May,2022(2.16±1.31). Interestingly a high CI value in July despite being associated with the resting phase, emphasizing that CI values are influenced by factors beyond reproductive changes, such as water parameters and environmental conditions. Overall, this comprehensive study sheds light on the morphometric traits, breeding biology, and reproductive cycles of Meretrix meretrix providing valuable insights into its life history and potential reproductive periods