Ranching acoustically conditioned fish using an automatic fishing machine

Fish ranching using acoustic conditioning and an automatic fishing machine was tested in a reservoir as an intermediate stage between laboratory studies and future application of sea-ranching technology in the open sea. A self-operated floating fishing machine was used. Fish were conditioned to associate an acoustic signal with food and then were released into the reservoir. Reinforcement of the conditioned response by periodic training was used to maintain the trained behavior. Fish were captured by calling them to the fishing machine using the acoustic signal and automatically closing a net around them. In one experiment, fish responses to the presence of the fishing machine, the acoustic signal and the food were tested. In another experiment, 65% and 13% of stocked common carp (Cyprinus carpio) and tilapia (Oreochromis hybrid) were recaptured, respectively, together with con- and hetero-specifics of the reservoir. The total number of carp captured exceeded the number of stocked carp (154%) in nine capture events over 3 months. The experiments highlight the importance of choosing a competitive species for sea-ranching applications to be successful. (C) 2011 Elsevier B.V. All rights reserved.