Integrated multi-trophic aquaculture

IMTA cultured mussels (Mytilus edulis) in the Bay of Fundy Canada

IMTA in Freshwater Pond

Carp (Catla catla) produced in IMTA pond

Off-bottom snail grown on bamboo split in IMTA

Snail produced on pond bottom of IMTA

Integrated Multi-Trophic Aquaculture (IMTA) is an approach to aquaculture that involves cultivating species from different trophic levels in close proximity. In IMTA systems, the by-products (wastes) from one species are recycled to become inputs (fertilizers, food) for another. This method is designed to improve environmental sustainability, economic stability, and resource efficiency.

Overview

Integrated Multi-Trophic Aquaculture combines the farming of fish, shellfish, and marine plants in a way that mimics natural ecosystems. The concept is based on the principle of waste recycling. For example, the waste produced by fish (such as salmon) can be used to feed bivalves (such as mussels and oysters) and seaweeds (such as kelp). This not only helps in reducing the environmental impact of aquaculture but also increases the diversity of the output.

Components

The main components of an IMTA system include:

• Fed Aquaculture: This typically involves fish or shrimp that are fed with external food sources.
• Extractive Aquaculture:
  • Inorganic Extractive: This includes seaweeds and algae that absorb dissolved inorganic nutrients (e.g., nitrogen, phosphorus).
  • Organic Extractive: This involves filter feeders like mussels and oysters that consume particulate organic matter.

Benefits

The benefits of Integrated Multi-Trophic Aquaculture include:

• Environmental Sustainability: By mimicking natural ecosystems, IMTA can reduce the environmental footprint of aquaculture. It helps in nutrient recycling and reduces the accumulation of waste products.
• Economic Stability: Diversifying aquaculture production can provide economic stability for farmers. It can also create new market opportunities for a variety of aquaculture products.
• Resource Efficiency: IMTA promotes the efficient use of resources by converting waste from one species into inputs for another.

Challenges

Despite its benefits, IMTA faces several challenges:

• Complex Management: Managing multiple species with different environmental needs can be complex.
• Market Acceptance: There may be market resistance to new and unfamiliar products from IMTA systems.
• Regulatory Hurdles: Aquaculture regulations may not be adapted to support IMTA practices, making it difficult to implement on a large scale.

Examples

Some examples of IMTA systems include:

• Cultivating salmon with mussels and seaweed in coastal waters.
• Combining shrimp farming with tilapia, which can utilize the waste produced by shrimp.

Future Directions

Research and development in IMTA are focused on optimizing system designs, improving economic viability, and addressing regulatory and market challenges. There is also an increasing interest in applying IMTA principles in freshwater aquaculture systems.