Soundscapes in aquaculture systems

Abstract

Sound in aquaculture production systems remains poorly understood in terms of both biological effects and engineering possibilities. Open systems such as net pens and traditional ponds are increasingly being complemented by recirculating aquaculture systems (RAS). Each of these systems create soundscapes, which may have a significant effect on the high-value commercial species being farmed. The current study compared recordings of soundscapes from commercial net pens, earthen ponds, and concrete and high-density polyethylene RAS holding systems. Calibrated measurements of each acoustic habitat revealed the range and intensity of sound in each system type. Spectra of each type of holding system were overlaid with the hearing ranges and sensitivity levels of 4 commonly aquacultured fish, common carp Cyprinus carpio, European perch Perca fluviatilis, red sea bream Pagrus major and Atlantic salmon Salmo salar, and 1 crustacean, common prawn Palaemon serratus. The majority of ambient noise recorded in RAS systems and net pens fell within the 100 to 500 Hz range at or near fish hearing thresholds. While RAS systems are a markedly louder environment for species otherwise held in earthen ponds, the net pen environment clearly represents the most variable and loudest aquaculture holding system, reaching noise levels capable of eliciting a measurable physiological response in many species and revealing a likely source of chronic stress. The long-term stress response of culture animals and performance cost of inappropriate soundscapes remains undetermined. A precautionary approach and optimised system engineering is recommended to reduce the sound impact on culture animals to optimise growth performance.

The impact of aquaculture soundscapes on whiteleg shrimp Litopenaeus vannamei and Atlantic salmon Salmo salar

“…The recordings applied in the current study are variable, particularly the salmon farm recordings. It is probable that the shrimp RAS system recording is not only quieter but also markedly less variable than those used in previous exposure studies (Radford & Slater 2019). However, this resembles the actually occurring sounds in German shrimp production systems.…”

“…The sounds generated by both of these aquaculture systems was relatively quiet (128 and 127 dB re 1 µPa) when compared to other anthropogenic sources of sound (Radford & Slater 2019). For example, commercial ships have source levels ranging from 175 to 192 dB re 1 µPa 2 in the frequency band 20 to 1000 Hz (McKenna et al 2013) and pile-driving activity generates sound exceeding 170 dB re 1 µPa (Würsig et al 2000).…”

“…Full bandwidth (50 Hz to 24 kHz) sound pressure level (SPL) was adjusted to 128 dB re 1 µPa in treatment tanks and maintained for 8 wk. This level was selected to represent maximum root mean squared (RMS) levels measured at the shrimp farm over a 24 h period (Radford & Slater 2019). In control tanks, speakers were not connected to a sound-producing device and sound level in control tanks was, however, determined as for exposure tanks.…”

“…Anthropogenic sources of underwater sound are potentially high-impact stressors in aquaculture environments and cannot be avoided by cultured animals (Popper 2003). Soundscapes in aquaculture systems have been shown to exceed both the physiological and behaviourally determined hearing thresholds of numerous vertebrate and invertebrate aquaculture species (Bart et al 2001, Ladich & Fay 2013, Radford & Slater 2019. Despite this, the growth, immune and stress response of key species to sound exposure in various commercial aquaculture production systems remains poorly investigated.…”

“…The acoustic habitats prevailing in recirculating aquaculture systems (RAS) and sea pens are highly variable, and the majority of the sound energy falls within the 100 to 500 Hz range, at or above fish hearing thresholds (Bart et al 2001, Craven et al 2009, Radford & Slater, 2019. Radford & Slater (2019) showed that RAS and sea pen sound levels exceed the hearing thresholds of the commonly cultured fish common carp Cyprinus carpio (Popper 1972), Atlantic salmon Salmo salar (Hawkins & Johnstone 1978) and European perch Perca perca (Wolff 1967), while the sound levels of aquaculture pond systems exceed the hearing thresholds of common carp (Amoser & Ladich 2005). Effects of long-term exposure, relevant to outgrowing aquaculture are unknown.…”