Application of Ultrasonic Waves to Detect Sealworms in Fish Tissue

---------------------------ABSTRACT----------------------------The potential of employing ultrasonic waves to detect sealworms embedded deep in the fish musculature was demonstrated. Images were made of sealworm-infested cod by using both the scanning laser acoustic microscopic technique, as well as the pulse-echo technique at 10 MHz, Also, attenuation of ultrasound in the frequency range from 1.0 to 12.25 MHz was studied in Atlantic cod {Gadiis morhua), haddock {Melanogrammus aeglefinus), ocean catfish {Anarhichas lu­ pus), and the parasitic sealworm {Phocanema decipiens). The differ­ ence in the attenuation of ultrasound in sealworms and in fish tissue increased as a function of frequency. The differences between ultra­ sonic properties (attenuation and backscatter) of fish tissue and sealworms was attributable to the high collagen content of the sealworms. The differences were sufficiently large at 10 MHz that sealworms could be detected in over 4 cm thickness of fish tissue.