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Pond bird and snake netting (aquaculture biosecurity)

Pond bird and snake netting is the use of overhead and side netting around an aquaculture pond to exclude fish-eating birds, snakes, otters and other predators that cause stock loss and also serve as vectors for disease introduction. It is a core component of best-management-practice packages issued by ICAR-CIBA and ICAR-CIFA for shrimp and freshwater fish farming.

Principle

Fish-eating birds such as kingfishers, cormorants and egrets, and reptilian predators such as water snakes, can cause direct stock loss, transmit pathogens between water bodies, and lead to sub-lethal stress in fish and shrimp through repeated disturbance. Physical exclusion is the most reliable mitigation in pond systems.

Implementation

The standard practice strings nylon line grids and shade-net cloth overhead, typically a grid of monofilament lines spaced at intervals that prevent bird entry, plus close-mesh side netting (often green shade-net cloth) along the pond bunds. Indian shrimp and carp farmers commonly replace overhead nets between crop cycles to limit fouling and rebuild a clean structure for the next stocking. International aquaculture biosecurity literature and replicated studies in Germany and the USA report significant reductions in fish loss after net installation.

Adoption context

Overhead netting plus close-mesh side fencing is recommended in the CIBA shrimp (Vannamei Shrimp Farming) and CIFA carp (Carp Polyculture Pond) best-management-practice packages, and is particularly important for murrel (Murrel Korameenu Farming) where surface-breathing fish are highly exposed. The technique is normally combined with full pond drying between cycles using outlet engineering provided by sound pond construction (Fish Pond Construction).

Limitations

Netting requires regular replacement as ultraviolet exposure degrades the polymer, and storms or heavy rainfall can collapse poorly tensioned overhead grids. The system does not exclude tunnelling crabs or rodents; supplementary trapping or compacted dyke construction is required for these pests.

See also: Vannamei Shrimp Farming, Carp Polyculture Pond, Murrel Korameenu Farming, Fish Pond Construction, Shrimp Pond Aeration.

References

  1. Use netting to exclude fish-eating birds. Conservation Evidence.
  2. Biosecurity for Aquaculture Facilities. Center for Food Security and Public Health.
  3. Advice for managing predatory birds. Global Seafood Alliance.