New applications of hydroacoustic methods for monitoring shallow water aquatic ecosystems: the case of mussel culture grounds

Abstract

The development of acoustics tools and methods for monitoring anthropized ecosystems represents a new field for the application of acoustics. Monitoring such an environment was not possible with single vertical echo sounders, due to the fact that the artificial structures and the natural targets were not distinguishable. Monitoring data were collected along the French Mediterranean coastline, during five short surveys of mussel culture longline areas. Both the Reson Seabat 6012 multibeam sonar (455 kHz) and the Simrad SR 240 omnidirectional sonar (23.75 kHz) were used for target detection. The former tools allow accurate allocation of the different types of echoes to artefacts, fish schools and scattered fish. The school characteristics collected included morphological, geographical (GPS, school location), and behavioural (connections with the longlines). An acoustic survey undertaken with the same hardware near the study area allowed the comparison of fish schools and the TS distribution of individual fish in the open sea and in the mussel area. These data permitted us to evaluate the ecological impact of a mussel culture on the ecosystem, in a context of predation behaviour of fish on these longlines. Finally, the acoustic data revealed the configuration of each concession and the level of charge of each line. We discuss the applicability of this technology for in situ real time monitoring for joint management of such ecosystems. The information can allow littoral cooperative management or incorporating it into an ecosystem approach.

Vertical variability of wild fish assemblages around sea-cage fish farms: implications for management

“…They have been applied to describe fish communities around other mariculture structures (e.g. mussel longlines, Brehmer et al 2003), which indicates that the technique has potential. Ultra-sonic tags and active or passive tracking of individual fish to describe horizontal and vertical movements over scales of 100s to 1000s of metres and for weeks to months will also provide novel information (Cooke et al 2004).…”

Attraction to and Avoidance of instream Hydrokinetic Turbines by Freshwater Aquatic Organisms

“…For example, Mueller et al (2006) described the use of visual and acoustic cameras to determine fish presence, behavior, and habitat associations in rivers. Brehmer et al (2003) were able to monitor fish aggregations, fish behaviors, diel variations, and interactions with artificial structures (vertical longlines suspended between anchors and buoys) using multi-beam side scan sonar. De Leeuw et al (2007) reviewed techniques for assessing the fish communities of large floodplain rivers, including the use of both hydroacoustic methods and more traditional trawling and netting methods.…”

Factors affecting the distribution of fish during receding flood in lower Irtysh: effects of water level and diurnal cycle

“…the use of common hydroacoustic methods has also been associated with serious problems in shallow waters (Simmonds and MacLennan, 2005). Fortunately, recent advances in hydroacoustic technology allowed successful use of echosounders in many kinds of these environments (Knudsen and Saegrov, 2002;Lucas et al, 2002;Brehmer, 2003;Ta´trai et al, 2009).…”