Unique applications of automated vehicles in aquaculture STEVEN HALL1, RANDY R. PRICE, AMoL MuDGUNDI, NAVNEET MANDHANI, UMA NADIMPALLI AND LAURA GAUTHREAUX Aquaculture is a growing field and approximately a $300 million annual business in Louisiana alone (LSU Ag Center Research and Extension Service 2004). Autonomous vehicles are capable of independent operation and can be used for monitoring and control in a variety of applications. Applications of such vehicles in aquaculture have been documented more heavily in recent years (Hall et al. 2003a, b, c, 2004, 2005). They have been used for such applications as the reduction of bird predation, monitoring water quality parameters, for agricultural or military procedures or in industrial settings. Autonomous boats were designed and built for monitoring and managing aquacultural pond water and, potentially, for drinking water in urban reservoirs. These boats are solar powered and capable of gathering environmental information. Thus, autonomous boats can be used for monitoring water quality parameters or other functions without causing harm. One application is reducing predatory bird incursions in aquacultural ponds. Pelicans, for example, can consume 0.45 to 1.3 kg of fish per day and may arrive with hundreds per flock. Cormorants, anhingas, herons and egrets may also do significant damage. It is estimated that one egret can eat 150 g of fish per day, while a great heron can eat 300 g to 341 g per day (Littauer et al. 1997, Bomford 1990, Hoy et al. 1989). While poisons, sonic cannons, shooting and other methods have been used, many are environmentally unfriendly, fatal, costly or Instruments used for the design of the system. ineffective. An alternative is mobile, semi-autonomous vehicles capable of environmentally friendly operation. These are solar powered and, along with some simple algorithms encoded on micro devices enclosed in waterproof plastic boxes, have proven successful in operation over many hours (Hall et al. 2001, Hall andPrice 2003a, Hall and Price 2003b). Navigation systems tested thus far have included a simple mechanism for allowing the boat to do a random walk around the pond surface. This system has proven quite effective during several tests. Other navigation systems still in development include GPS driven and vision system driven systems. Further development is underway. Another application is water quality sensing and management. For example, dissolved oxygen (DO) plays a vital role for the survival and growth of fish species. Real-time monitoring of DO could help reduce losses in fish production by maintaining optimum water quality. To achieve this, autonomous boats were equipped with three dissolved oxygen sensors at depths of 30.48 cm, 60.96 cm, and 91.44 cm; four thermocouples and a data logger that acted as a central storage device (Hall et al. 2004, Hall et al. 2005). In aquaculture applications, DO concentrations can be controlled by using a radio frequency transmitter and receiver with a control unit to aerate the pond. This gave us the abilWORLD AQUACULTURE 45
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