Shifting of sea farming space

For many years, coastal aquaculture has been developing rapidly in our country, creating jobs for the local population, promoting socio-economic development and helping to increase the country’s export production. The coastal aquaculture systems are mainly small, household and rudimentary cage materials. The biodiversity in farms is also quite diverse, such as marine fish, lobsters, molluscs and algae.

The rapid development of coastal aquaculture has led to many consequences such as pollution, disease spread, narrow coastal area, and sometimes conflicts with other economic sectors such as tourism, calendar and real estate. In this context, expanding the space for marine aquaculture and moving farms away from the coast is one of the solutions identified.

Offshore mariculture is usually defined as 6 nautical miles or more from shore. In offshore waters, it is less affected by estuarine alluvium, rich and diverse plankton ecosystems, large space, stable depth, current, clarity, temperature, and salinity. certainly. However, the farms there will also be affected by waves and stronger winds than in the coastal areas.

Vietnam has a coastline of more than 3,260 km stretching from Quang Ninh to Ca Mau and Kien Giang, along with thousands of large and small islands in the sea, many ponds, bays, lagoons and lagoons suitable for marine aquaculture development are. Industry that not every country has. Vietnam’s exclusive marine economic zone is over 1 million square kilometers and accounts for about 30% of the East Sea area. According to a study by Nha Trang University, there are three favorable areas for offshore mariculture development namely Quang Ninh, Khanh Hoa and Kien Giang based on the criteria of environment, depth, current and degree of water availability. Salt water and, above all, there are islands that are sheltered from wind and storms.

New industry, many challenges

In our country, offshore marine culture has not yet been fully explored. This is a new industry not only for Vietnam but worldwide. Therefore, offshore mariculture needs more research and requires careful planning and comprehensive guidelines to ensure efficiency, safety and sustainability. Offshore marine ecosystems differ significantly from inshore ecosystems.

As offshore mariculture flourishes, ecosystems and marine life will be more or less impacted. In the long term, the impacts of mariculture on the marine environment, ecology and space are almost impossible to fully assess, as well as the potential risks, which are difficult to predict because we do not have enough data and we do not have enough data. Scientific pilot models.

Our country’s seas are regularly hit with high frequency by storms, winds and tropical depressions. The North Sea is affected by a long, cold winter, which has a negative impact on production. In the context of climate change, Vietnam is one of the most vulnerable countries. The number of large and extreme storms in the East Sea is increasing. The breeding period is long, with average marine fish 12-15 months/crop, lobster 18-20 months/crop, large investment capital, high production risk and incomplete marine aquaculture insurance, resulting in economic sectors involved in marine aquaculture being limited.

The development of offshore mariculture requires a completely new and systematic approach. The basic requirements include integrated infrastructure, logistics, human resources, seeds, feed, services and materials, national and international legal frameworks and socio-economic issues. Social and political, oceanographic, biological, ecological and technological criteria.

It is difficult to create a complete set of criteria because most of the factors are interactive and not fixed but interdependent. For example, the depth of sea level is related to the speed of ocean currents. In addition, the selection of suitable agricultural sites must comply with standards or depend on technology and species.

Climate change can affect ecological risks such as changes in migration, abundance and distribution of species. Therefore, these changes should also be included in the sets of criteria, standards and regulations for offshore mariculture.

Technically, cages, nets, buoys and mooring lines have to withstand harsh weather conditions, high waves and strong currents. Cage materials must be strong and reliable, inhibit algae growth, and be resistant to corrosion and fouling.

In an environment far from land, farmers are not always caged, especially during storms or tropical depressions. Therefore, most of the farmer’s daily tasks have to be replaced by machines that are controlled automatically and remotely, e.g. B. automatic feeding technology, automatic washing systems for net cleaning or management, care and harvesting measures by intelligent control systems.

The production of juvenile fish from sea fish is still limited in our country. The hatcheries mostly work on a small scale. The systems and technology are still outdated, the quality of the seed is not stable, and many breeding herds are threatened by inbreeding. The lack of concentrated seed production also affects the development of commercial agriculture on an industrial scale. Aquaculture workers lack scientific and technical knowledge and experience in managing and operating offshore farms.

Effects on ecosystems and the soil environment

Marine farm waste, such as leftover food, fish manure and household waste, disperses quickly in the aquatic environment or sinks just as quickly as pellets. This organically enriches the soil sediments around the farm. The benthic response to organic enrichment cannot be assessed.

Benthic animals that tolerate pollution are few in coastal waters, so the ability of benthic organisms to assimilate organic matter may be limited. Instead, the waste is decomposed by microorganisms, which leads to an increased oxygen demand and an accumulation of sulphide in the sediment. This can have a negative impact on benthic biodiversity.

Offshore mariculture is projected to thrive over the next few decades as coastal space reaches its limits and pollutes the environment or is prioritized for the development of other important industries. Are existing regulatory instruments suitable for the offshore industry or do they need to be updated and strengthened through some pilot schemes?

Are the current human resources in aquaculture sufficient for industrial farming in the open sea, or is retraining required? Standards and regulations for the establishment of offshore sea farms comply with national and international legal frameworks… these are issues that need to be discussed and considered.