Shelf-scale mapping of sound production by fishes in the eastern Gulf of Mexico, using autonomous glider technology

Abstract

Autonomous gliders are a relatively new technology for studying oceanography over large time and space scales. We integrated a hydrophone into the aft cowling of a glider and used it in a 1 wk, shelf-scale deployment on the West Florida Shelf to detect and map fish sounds in the ocean over a large spatial scale. In addition to red grouper and toadfish sounds, at least 3 unknown biological sounds suspected to be produced by fish were identified through manual analysis of the acoustic files. The biogeography of these fishes was identified by mapping the occurrence of sounds along the glider track. Sounds produced by red grouper and toadfish were detected throughout the day predominately in bottom depths > 40 m. Conversely, the 3 unknown biological sounds were detected exclusively at night over varying bottom depths. Glider technology provides a reliable and relatively inexpensive method to collect acoustic and environmental data over large spatial scales while maintaining a high rate of successful retrieval.

Mechanisms of Fish Sound Production

“…Based on anatomical data, i.e., the presence of sonic swimbladder muscles, only a small number of families (mostly ophidiids, macrourids, and possibly morids) produce sound in the deep ocean where it would be of maximal advantage (Marshall 1962) due to the absence of surface light and low population densities. Although whale sounds are commonly recorded in deep water, fish sounds have not been demonstrated conclusively (Mann and Jarvis 2004;Wall et al 2012Wall et al , 2013Wall et al , 2014 below some hundreds of meters. Quite likely, sounds are important for courtship and reproduction in deep water, but it is unlikely that females are homing in on male callers from great distances.…”

A Review of the Tools Used for Marine Monitoring in the UK: Combining Historic and Contemporary Methods with Modeling and Socioeconomics to Fulfill Legislative Needs and Scientific Ambitions

“…Such static recorders remain the most suitable method to monitor underwater noise for management purposes, given the requirement to track long-term trends and the relative expense of installing and maintaining cabled systems. Glider technology (Section Remotely Operated and Autonomous Vehicles) has been mooted as a possible solution to underwater noise monitoring, and has been applied in several demonstration projects (e.g., Matsumoto et al, 2011;Wall et al, 2012). While monitoring from mobile platforms such as gliders lacks the power to detect long-term temporal trends in noise levels, the spatial coverage has potential uses in ground-truthing modeled maps of noise levels over large areas.…”

Monterey Bay ambient noise profiles using underwater gliders

“…Gliders have been used for acoustic applications such as detecting low frequency sources (Howe and Boyd (2008)), whales (Moore et al (2007)) and fish sounds (Wall et al (2012)). The works by Howe and Boyd (2008) and Moore et al (2007) used internal hydrophones.…”

“…The works by Howe and Boyd (2008) and Moore et al (2007) used internal hydrophones. The work by Wall et al (2012) used external hydrophones, but to detect nearby fish sounds. For making accurate measurements of low intensity ambient noise sounds, moving platforms such as gliders contend with instrument and flow noise in the sounds recorded by the external hydrophone.…”