Principles and practices of cage mooring

Abstract

Moorings are required to hold cages against the forces generated by wind, currents and waves and to allow the fish stocks and the cages and let the best chance of survival. In sheltered waters, requirements to moor a cage safely were minimal. This has changed dramatically with moves into coastal waters, and a potentially much higher wave climate. Mooring failures were common place in the early days of coastal farming, but a better understanding of the problems, and more sophisticated analysis has largely reduced these risks. Perhaps the most important point is to view the cage group, its nets and moorings, as a single system, whose components are mechanically linked. Their dynamic responses cannot be considered in isolation, each component affecting the other. Cage and mooring design is “site specific”, and careful and combined choice of cage type, nets and most specifically moorings, has a considerable bearing on the ability of fish stocks to survive in major storms, on exposed sites.