Coastal Aquaculture and Mariculture

Unit 7- Molluscan resources

7.2. Bivalves
Bivalves belong to the phylum Mollusca. They include clams, mussels, edible oysters, pearl oysters and window pane oysters. Mostly, bivalves are collected for their meat and shell. Pearl fishing took place for the golden coloured pearls till 1961. When the pearl oyster beds became barren, pearl fishing became uneconomic and it did not take place since then. Meanwhile edible bivalves and ornamental shells gained popularity and their fishery improved. During 1995-99, the average quantity of edible bivalve products exported per annum have been estimated as 580 tonnes, worth Rs.26 million and 567 t of oyster shell powder valued at Rs.1.5 million. The bivalve resources are mostly underexploitated along the northwest and northeast coasts whereas overexploited along the southeast and southwest coasts.
Production trend
The average annual production of edible bivalves during 1996 to 2000 was estimated as 1.52 lakh tonnes, about 2.5 times more than the average landings during the period prior to 1996. A variety of clams, oysters, mussels and windowpane oysters are distributed along the Indian coastline. They are mostly collected by the local people. Clams and cockles form 73.8%, followed by oysters (12.5%), mussels (7.5%) and windowpane oysters (6.2%). The west coast accounts for 52.3% of the landing where the catch is utilized for both the meat and the shell. Among the maritime states, Andhra Pradesh is the top producer (70,705 t) followed by Kerala (58,763 t). The production levels in other states are negligible.
Commercially important bivalves of India