The series on Sustainable Marine Aquaculture: Article 2 – Evaluating waste from lobster farming

Experimental lobster farming for waste assessment

In 2024, scientists from the Research Institute for Aquaculture No. 3 (RIA3) conducted controlled lobster farming experiments to evaluate waste output. According to Vo Thi Ngoc Tram, Deputy Director of the Central Region Environmental Monitoring and Aquatic Animal Health Center (a RIA3 subsidiary), lobsters, along with barramundi and oysters, are key species in South-Central Vietnam. These species were studied to assess waste generation during cage farming.

The experiment involved three setups, each replicated three times. The first used traditional methods, feeding lobsters trash fish. The second employed industrial feed developed by RIA3. The third served as a control, with no lobsters. Daily monitoring included water parameters (temperature, pH, salinity, etc.), and researchers collected feces and uneaten feed to calculate waste levels.

“We measured waste from two sources,” Tram explained. “Dissolved waste, such as total nitrogen and phosphorus, and undissolved organic waste, including leftover feed and feces. Calculations were based on feed conversion ratios, lobster growth rates, and harvest yields.”

After three months of commercial farming and two months of juvenile rearing, the study showed lobsters grew well with survival rates exceeding 80%. Preliminary data now offers insights into waste loads associated with lobster farming.

Determining waste loads to optimize farming density

South-Central Vietnam, with its bays, lagoons, and tidal flats, has significant potential for aquaculture. Over the past 30 years, marine farming of lobsters, fish, and oysters has flourished, boosting local economies and providing jobs. However, this growth has produced substantial waste, degrading water quality, especially in sheltered bays. Quantifying this waste remains a challenge.

In response, the Ministry of Agriculture and Rural Development (MARD) tasked RIA3 with evaluating pollution sources and waste loads from marine aquaculture in South-Central Vietnam and proposing management solutions. The study focuses on key species such as lobsters, barramundi, and oysters.

Researchers employed tank experiments to compare the environmental impact of industrial versus traditional feeds. This approach provided controlled data on waste emissions.

“Evaluating marine aquaculture’s environmental impact is complex due to open systems where water exchange and currents affect waste dispersal,” said Associate Professor Vo Van Nha, RIA3 Director. “By simulating real-world conditions in tanks, we could better estimate waste per unit area or biomass. While field results may vary, these findings form a critical baseline.”

According to Nha, assessing aquaculture waste is vital to determining suitable farming densities to prevent exceeding the environmental carrying capacity. The project, spanning 2023–2025, aims to establish science-based guidelines for sustainable aquaculture management.

Toward sustainable farming practices

Nguyen Trong Tung, Director of the Phu Yen Department of Agriculture and Rural Development, highlighted the importance of environmental monitoring and disease surveillance in concentrated farming areas. Annual assessments by RIA3, local agriculture, and environmental departments provide scientific data to evaluate the carrying capacity of aquaculture zones.

Additionally, Phu Yen’s aquaculture development plan for 2021–2025, with a vision to 2030, includes strategies based on environmental capacity evaluations. These efforts aim to balance economic benefits with ecological sustainability, ensuring long-term viability for Vietnam’s aquaculture sector.

VFM