Effective oyster farming experience

(Baonghean.vn) Estuary oysters (Crasostrea revularis) are bivalve mollusks with large, thick shells, and a wide variety of shell shapes, usually oval or triangular. Estuary oysters are valuable aquatic specialties, mainly consumed fresh, and prepared in many different ways such as grilled, stir-fried, hot pot, porridge, etc., which are nutritious dishes.

Previously, fishermen knew how to take advantage of riverbank stones and bridge culverts at estuaries to exploit natural oysters, oysters about 50-150 mm in size. In 2003, the Danish government's Subproject to Support the Development of Brackish Water Aquaculture (SUMA) built an oyster farming model in Dien Van as a "Hunger Eradication and Poverty Reduction" model for residents of coastal areas. Through actual production, oysters are no longer the target of "hunger eradication and poverty reduction" but when well invested, many households have become rich from oyster farming. Estuary oyster farming has now truly become a profession. To ensure effective oyster farming, in addition to complying with the requirements of farming techniques, farmers need to pay attention to some points in management, care, and selection of harvest time so that the product has good quality, high profits, but still protects long-term resources.

1. Regarding management and care: The management and care process includes thinning, preventing adverse environmental factors and eliminating pests.

+ Thinning: During the farming process, when the oysters are growing, the farmer must thin out the substrate chains to ensure food conditions for the oysters. After about 6 months of farming, the large oysters should be harvested to reduce the farming density so that the remaining oysters can grow quickly;

+ Environmental management of the farming ground: If the environmental conditions are not favorable, the farming line can be lowered deep or when the farming ground is contaminated or affected by floods, the oysters must be moved to another area with a better environment. Pay attention to the density and location of the oysters on the farming line. If there are many oysters attached to the upper layer of the farming line, it shows that the bottom has problems such as low oxygen, low pH or too thick bottom mud, a lot of algae, the bottom has a lot of toxic gases... it is necessary to clean the bottom, adjust the substrate to be sparse or move to another cleaner place;

+ Destroy pests: Oyster pests include organisms that compete for attachment, predators (starfish, fish...), borers, parasitic organisms and algae.

For the group of attached organisms: The most effective method is to expose the attached organisms to sunlight. The chemical method is to use 1-2% copper sulfate for 1 hour, however this method is labor-intensive and expensive. When applying biological methods, we must clearly understand the life cycle, ecological characteristics, especially the breeding season of the attached organisms to proactively collect seeds and avoid times when many attached organisms appear;

For carnivorous, boring creatures: Including chicken heart snails, pearl snails, spiny snails, red snails, crabs, crabs, clams, starfish, fish... For this group, the main prevention method is to pick them up by hand when the tide is low or use traps and apply the method of raising them on racks and rafts to limit pests from the bottom. In addition, it is possible to collect and remove the egg sacs of snails during their breeding season (July-September);

For parasitic organisms and algae: Periodically or when oysters are dirty, clean the oysters by using a brush to scrub the oysters to remove dirt, algae and attached organisms.

2. Regarding harvesting, linking quality with the market and protecting resources: When oysters are 6-8 months old, they can be harvested. The oyster harvest season is related to product quality. During the breeding season, when oysters are about 12 months old (also known as milk oysters), the oyster meat at that time has a fatty taste, fragrant smell, a lot of meat, beautiful color, moderate size, uniform size, attractive, neat and beautiful external shape, and a very high selling price. Therefore, to have a source of milk oysters to supply the market all year round, farmers must proactively source the seed to raise each month according to the progress of each month, planting once. Thus, for oysters, the best harvesting season is during the breeding season.

Duy Luan