Pen-and-Cage-System

PEN AND CAGE CULTURE

Open systems allow for interactions between fish culture units and the environment, typically in publicly-owned water bodies, leading to more diverse ecological interactions compared to closed systems.

Site Selection

Reference: For guidance on site selection for cage systems, refer to the UNDP/FAO document (1989) on site selection criteria for marine finfish net cage culture in Asia. Access Document Here

Distinction Between Cage and Pen Culture

  • Cage Culture: Fully enclosed by mesh or netting. Provides a controlled environment for aquatic organisms while allowing water exchange, which helps maintain water quality and nutrient levels.

  • Pen Culture: The bottom is open to the natural substrate (lake or sea bottom). Offers different ecological interactions compared to cages and may allow fish to interact with the natural environment, potentially benefiting growth and health.

Classification of Cage Systems (Huguenin 1997)

  • Operating Characteristics: Surface, Submerged, Adjustable buoyancy for various fish species needs.

  • Location Types: Marine, Estuarine, Freshwater systems are designed to optimize conditions for specific species.

  • Supporting Methods: Fixed to the bottom (via pilings) or Floating cages, which offer flexibility in installation and maintenance.

  • Structural Types: Rigid structures with mesh or Flexible mesh-only systems. Rigid structures typically provide better protection against predators.

  • Access for Service: With or without catwalks; serviced by boat/barge, which is critical for maintaining cage systems.

  • Operational Parameters: Include biomass loading (intensive/extensive) strategies, species management tailored to local conditions, and environmental exposure that should be evaluated to ensure sustainability.

Cage System Characteristics (Beveridge 1996)

  • Cage Types: Fixed, Floating, Submersible vary depending on water conditions and species requirements.

  • Rotation Mechanisms: Rotating vs. non-rotating designs based on buoyancy can enhance the efficiency of space utilization and feeding access for fish.

  • Structure Design: Rigid vs. Flexible collars for supporting the netting, with flexible structures offering adaptability in varying water conditions.

Principal Components of a Fish Cage (Beveridge 1996)

  • Service System: Essential for maintenance and operation, including feeding systems and waste management.

  • Floating System: Designed for buoyancy; stability in water is crucial for preventing structural failure.

  • Mooring System: Anchors that secure cages in position against currents and waves, essential for maintaining the integrity of the setup.

  • Cage Bag: Where fish are contained, requiring materials that minimize injury and allow optimal water flow.

Mariculture Zones in the Philippines

Defined areas for breeding and growing fish in zonified marine cages. The concept is similar to industrial zones for efficient use of ocean space. Annual leasing is cost-effective compared to establishing independent facilities. As of now, there are 50 mariculture parks in operation, totaling 2,168 cages over 49,950 hectares. These zones help regulate fish farming activities and protect marine ecosystems.

Environmental Considerations in Cage Fish Farming

Cage farming can significantly impact water quality:

  • Can cause sediment deposition and waste build-up, affecting surrounding ecosystems.

  • Must consider the size of the cage relative to water body capacity to avoid ecological imbalance.

  • Feeding technology affecting sustainability includes the quantity, quality, and method (e.g., automatic feeders versus hand feeding).

Feeding and Aeration Practices in Cage Farming

  • Feed Management: Adjust feed quantity based on water temperature and fish condition to optimize growth. Use water-stable, acceptable feed types (dry/pellet) to reduce waste.

  • Aeration Strategies: Improve environmental conditions and encourage balance. Use submersible pumps to manage sediment under cages and ensure that dissolved oxygen levels remain sufficient for fish health.

Oyster Farming Techniques

  • Cage Systems: Utilizes rafts and baskets for oyster cultivation, which can enhance growth rates and survival by providing stable structures.

  • Harvest Methods: Raking from the ocean floor or rope harvesting, both of which can be adapted based on the specific environment and target species.

This structured note aims to cover all necessary information for understanding pen and cage culture, their operational parameters, environmental impacts, and specific techniques relevant to aquaculture, with a focus on enhancing detail and depth of information across all sections.