Development of a New Monitoring Methodology for Counting Bluefin Tuna in Net Pens

摘要

We have succeeded in the development of an aquaculture tuna counting system using a multi-transducer and pinger. This newly developed multi-transducer sonar system is based on counting the individual fish that have passed through “the sound curtain” consisting of 15 transducers (460 kHz). In addition, a pinger was used to clarify the behavior and swimming speed of the caged fish. As a result, it was found that all of the fish regularly swim in a concentric circle in the cage space, and the lap time in each lane 1m from the cage center for one round was estimated by a linear regression equation. The number of fish in each lane for one round could be calculated by multiplying this lap time and the number of fish that passed through “the sound curtain” per unit time. The total number of fish could then be calculated by summing the number of fish in each lane. The accuracy of this method verified by multiple actual tests was 2% or less and 1 fish. It was considered that this approach is effective for counting caged bluefin tuna with the objective of practical use.