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INSTRUMENTATION FOR AQUACULTURE


The Aqua-Scanner™ is being designed not only to count but also to SIZE catfish in shallow aquaculture ponds. Fish size information is extracted from the echo WIDTH and AMPLITUDE. The idea is that a longer (larger) fish will produce a longer echo than a shorter (smaller) fish when both are insonified at the same aspect angle.
However, the echo amplitude must also be analyzed to distinguish between an echo from a large fish head-on and a small fish broadside. This technique relies on the knowledge that, under normal conditions, catfish in commercial ponds are uniformly distributed and at low density, which based upon previous work, is a reasonable assumption. 

The echo record from a 4 lb catfish and a 1/3 lb catfish that shows even though the echo amplitudes are similar, the fish size can be distinguished by the echo width.