Improving Model of Hard Clam (Meretrix lyrata) Seed Nursing in the Coastal Area - Case Study in Tra Vinh Province, Mekong River Delta, Vietnam

摘要

The model of clam seed nursery in the coastal area of Tra Vinh province was carried out from June 2019 to February 2020 in the coastal dune and tidal flat in Thanh Dat Cooperative. The clam seed source is the natural seed harvested in the coast of Tra Vinh province with the goal of exploiting and using local resources to provide clam seeds for the cooperative clam farming. The model consists of two phases: the first phase of nursing is in ponds on the coastal dune and the second phase of nursing is on the tidal flat in natural condition. It indicates that during the first phase, the input of model used 50 kg clam grade I (150,000 ind./ kg) was released into the nursing ponds, the nursing pond with oxygen supplementation is a good facility resulting high survival rate of 62.8% in comparison to 43.5% in case of pond without oxygen supplementation. In October 2019, total 285 kg of grade II clams (15,000 ind./ kg) was obtained and released on 6,000 m~2 clam ground in Thanh Dat Cooperative. In February 2020, total 2.33 million clam individuals were harvested, it is about 3,880 kg clam seed with the size of 600 ind./ kg. The model of clam seed nursing in the tidal flat was completed with clam seed survival rate of 54.5%. All of clam seed is continued culturing to the commercial clam production on the same ground of Thanh Dat Cooperative.