Applying Two Active Acoustic Technologies to Document Presence of Large Marine Animal Targets at a Marine Renewable Energy Site

Garrett Staines,Rachel Kocik,Haley A Viehman,Gayle Barbin Zydlewski

doi:10.3390/jmse8090704

Abstract

Coastal regions are highly used by humans. The growing marine renewable energy (MRE) industry will add to existing anthropogenic pressures in these regions. Regulatory bodies require animal risk assessment before new industrial activities can progress, and MRE is no exception. Preliminary data of marine mammal use of an MRE device deployment location could be informative to permitting. A combination of downlooking hydroacoustics using an echosounder and acoustic camera (imaging sonar) was used to provide a number of large targets (proxy for large fish and marine mammals) in an area of interest for MRE tidal turbine deployment in Western Passage, Maine, USA. Data were collected in May, June, August, and September of 2010 and 2011. Of the nine large targets confirmed to be animals, eight were porpoises and one was a shark. Few large targets were observed in May and June, with the majority (90%) being present in August and September of both years. The most large targets were observed when tidal current speed was less than 1 m·s−1. These data provide a preliminary assessment of large targets in a single location over sixteen 24-h surveys. The aforementioned methodology could be used for future pre- and post-installation assessments at MRE device deployment locations. Their use in concert with visual and passive acoustic monitoring can provide water depth usage by marine mammals, which is a metric that is difficult to assess with passive acoustic and visual techniques.

Highlights

The world’s coastal regions are areas of intense anthropogenic activity, such as housing, recreation, fishing, and energy collection. These activities result in effects on marine ecosystems that range from the direct extraction of natural resources to habitat modification
Having preliminary data for both fish and marine mammals in a region is crucial for permitting and regulatory decision-making associated with marine renewable energy (MRE) pilot projects
By searching out only backscatter of −30 dB re 1 m2 and greater, we reduced the DIDSON data processing requirement to a small fraction of its total

Summary

Introduction

The world’s coastal regions are areas of intense anthropogenic activity, such as housing, recreation, fishing, and energy collection These activities result in effects on marine ecosystems that range from the direct extraction of natural resources (e.g., fish and currents) to habitat modification. As the US attempts to harness renewable energy derived from the ocean, it will affect the marine ecosystem in different and unknown ways [1,3,4,5,6]. New uses such as this will require different permitting procedures

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Conclusion