Navigating the future: Strategic management of a mobile aquaculture system with receding-horizon control

Abstract

The New Zealand-based Whakapohewa ki ahumoana Reimagining Aquaculture project (funded by the Ministry for Business, Innovation and Employment Endeavour Fund) lead by Plant & Food Research, is designing a mobile aquaculture system for finfish, towed by an autonomous vessel, powered by renewable energy sources. This work presents the vessel management strategy for this mobile aquaculture solution, inspired by receding-horizon control, which uses available weather forecasts to minimize the energy consumption by the autonomous vessel while maintaining an optimal flow speed through the fish enclosure such that the optimal biological conditions (e.g. swim speed) for the fish can be maintained. The simulations performed for a generalized salmonid fish species cultured in Tasman Bay, New Zealand show that the food storage capacity of the autonomous vessel is consistently a limiting factor at low swim speeds (≤ 0.4 m s−1), while energy capacity limits at higher swim speeds. The simulations highlight how such a strategy allows the system to successfully shelter from storms and by virtue of going further from its “safe haven” can maintain optimal conditions for the fish through the enclosure. We anticipate this work to be a starting point for more sophisticated management strategies considering engineering criteria, species specific requirements, and environmental parameters such as temperature and water quality that impact fish welfare explicitly.