Frequency modulation of the sounds produced by the AQUAmark 200® deterrent devices

Abstract

The AQUAmark 200® device is used to reduce the incidental by-catch of small cetaceans in fishing gear. Little information is known about the signal features of this system despite the fact that such knowledge is important to evaluate its efficiency. The AQUAmark 200 device emits eight different signals composed of one fundamental and several others harmonics with energy in the 5-160 kHz band. The mathematical equation of the temporal evolution of the frequency of each signal has been determined by the authors, and the resulting function has been used to build the six nonconstant evolutions.