Sounding out pests: the potential of hydroacoustics as a surveillance and compliance tool in aquatic biosecurity

Shipping is the main method for goods transportation, accounting for approximately 60% of all global trade. Biofouling of these shipping vessels is a critical pathway for the introduction of non-indigenous species (NIS) across the world’s oceans. In order to reduce the likelihood of NIS introductions, appropriate biosecurity mechanism need to be in place, including maintaining high standards in vessel hygiene, such as zero secondary biofouling. Development of methodologies that can accurately quantify vessel biofouling without impeding maritime operations, while simultaneously providing effective biosecurity for the marine environment and resources, and mitigation of introduced marine pests would be highly advantageous. This study tests such a methodology. We conduct a proof-of-concept study that uses hydroacoustics to quantify the biofouling on a vessel’s hull, using surrogates for a vessel hull and biofouling. Based on a simple off-the-shelf single beam echosounder, the method was able to visually detect and quantify various biofouling mimics (ranging in height from 10 to 200 mm in height) at a slow tow speed (0.5 m/s). The efficacy of the hydroacoustic method was influenced by the movement of the echosounder, with the discriminating capability reduced to the detection of only larger mimics as the speed of movement increased. With further development, the use of hydroacoustics could become a viable biosecurity surveillance option for the mitigation of introduced marine pest incursions.