WHAT IS CAGE CULTURE? A BEGINNER’S GUIDE TO AQUACULTURE IN MESH ENCLOSURES

147

Fish can be cultured in one of four systems: ponds, raceways, recirculating systems, or cages. A cage or net pen confines fish or shellfish within a mesh enclosure. By definition, a cage has a rigid frame on all sides, while a net pen has a rigid frame only around the top. However, the terms “cage” and “net pen” are often used interchangeably.

Cage culture employs existing water resources (ponds, rivers, estuaries, oceans) while confining fish in a mesh enclosure, making feeding, observation, and harvesting easier. The mesh allows water to flow freely, maintaining water quality and removing wastes.

The origins of cage culture trace back to fishermen using cages to accumulate fish for market. In Southeast Asia, the first true culture cages, made from wood or bamboo, emerged in the late 18th century. In the U.S., modern cage culture began in the 1950s with synthetic materials, and freshwater cage culture research followed in the 1960s. Today, freshwater cage culture is practiced on a limited scale in the southern U.S., offering alternative agricultural opportunities.

ADVANTAGES OF CAGE CULTURE

1. Resource Use Flexibility: Cage culture can utilize various water bodies, including ponds, rivers, and lakes, provided water quality and legal permissions are in place.
2. Low Initial Investment: Relative to pond construction, cage culture requires minimal infrastructure and investment, making it an accessible entry point.
3. Simplified Cultural Practices: Fish behavior can be easily observed, helping anticipate issues such as stress or disease.
4. Simplified Harvesting: Harvesting is straightforward by crowding fish in cages and using nets for removal.
5. Multi-Use of Water Resources: Cages do not hinder other uses of water bodies, such as recreation or irrigation.

DISADVANTAGES OF CAGE CULTURE

1. Complete Diets Needed: Caged fish depend entirely on nutritionally complete feeds, which must be fresh and properly stored.
2. Water Quality Problems: High densities and feeding rates can lead to reduced oxygen levels and increased ammonia near cages.
3. Disease Susceptibility: Crowded conditions and proximity to wild fish increase disease risks.
4. Vandalism and Poaching: Cages are vulnerable to unauthorized access and predation.
5. Limited Production: Cage culture typically yields fewer fish per acre than open-pond systems due to stress and water quality challenges.
6. Overwintering Issues: Warm-water fish in cages face high mortality during winter due to diseases.

SPECIES SELECTION FOR CAGE CULTURE Species suitable for cage culture must thrive in confined conditions, have known culture requirements, and access to appropriate feeds. Common species include hybrid striped bass, rainbow trout, carp, tilapia, channel catfish, and sunfish. Unsuitable species, like blue catfish, cannot tolerate necessary crowding levels.

CONSIDERATIONS BEFORE IMPLEMENTATION Producers should evaluate market demand, site suitability, water quality, construction and production costs, and legal requirements before adopting cage culture. Markets are often overlooked but play a critical role in determining success.

GUIDE TO SUCCESSFUL CAGE CULTURE

1. Site Selection and Water Quality: Choose sites with appropriate depth, flow, and water quality. Ensure legal permissions.
2. Cage Construction and Placement: Use durable materials for cages and strategically position them in the water body to optimize flow and accessibility.
3. Species Selection: Select species based on market demand, environmental conditions, and nutritional availability.
4. Feeding and Observation: Use high-quality feeds and monitor fish behavior closely to mitigate stress and disease.
5. Harvesting: Plan efficient harvesting techniques, including partial harvesting for niche markets.
6. Risk Management: Address potential risks like poaching, predation, and water quality degradation through strategic planning and regular monitoring.

FUTURE PROSPECTS OF CAGE CULTURE As wild-capture fisheries decline and aquaculture expands, niche markets for cage-cultured fish are growing. By leveraging underutilized water resources, cage culture can provide sustainable fish production opportunities. Careful planning, species selection, and management practices can enhance profitability and environmental sustainability.

For more information about aquaculture, follow FisheryNews