Trouble-shooting deployment and recovery options for various stationary passive acoustic monitoring devices in both shallow- and deep-water applications

Abstract

Deployment of any type of measuring device into the ocean, whether to shallow or deeper depths, is accompanied by the hope that this equipment and associated data will be recovered. The ocean is harsh on gear. Salt water corrodes. Currents, tides, surge, storms, and winds collaborate to increase the severity of the conditions that monitoring devices will endure. All ocean-related research has encountered the situations described in this paper. In collating the details of various deployment and recovery scenarios related to stationary passive acoustic monitoring use in the ocean, it is the intent of this paper to share trouble-shooting successes and failures to guide future work with this gear to monitor marine mammal, fish, and ambient (biologic and anthropogenic) sounds in the ocean-in both coastal and open waters.

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

“…Moored PAM systems can be effective but have greater risk of being lost, stolen or damaged, especially in highly active areas (Luczkovich et al 2008, Dudzinski et al 2009). In addition, the spatial coverage and suite of environmental and optical conditions measured concurrently by the glider provide detail of the ocean environment and acoustic scene that cannot be discerned from stationary PAM methods that record only sound (Rudnick et al 2004).…”

“…noise generated from wave action) and anthropogenic (e.g. vessel traffic) sources (Urick 1983, Mellinger et al 2007, Locascio & Mann 2008, Luczkovich et al 2008, Dudzinski et al 2009). PAM systems collect data in remote locations under potentially unsafe seas through out a 24 h period providing large datasets that are unobtainable using observer-based methods (Rountree et al 2006).…”

Using drifting passive echolocation loggers to study harbour porpoises in tidal-stream habitats

“…Strong directional currents in tidal streams make it difficult to maintain hydrophone arrays in the correct configuration and generally to safely manoeuvre the survey vessel. Fixed autonomous acoustic recorders require robust moorings to resist the current, adding to mooring weight, complexity and cost, and potentially requiring larger vessels to safely deploy and retrieve them (Dudzinski et al 2011). Furthermore, mooring deployment and retrieval may only be possible during brief periods of slack water.…”

A Review and Inventory of Fixed Autonomous Recorders for Passive Acoustic Monitoring of Marine Mammals

“…Additional requirements to keep large moorings in position, such as flotation and ballast, will make them even larger, thus requiring vessels with heavy lifting capabilities. Smaller moorings can be deployed by divers or from a small boat, and the lifting requirements can be minimized by handling individual components (i.e., flotation, data recording electronics, batteries, ballast, and release system) one at a time (Dudzinski et al, 2011). The increasing need for PAM in shallow water environments, where currents, winds, heavy vessel traffic, and other conflicting activities are a concern, will require more reliable moorings.…”