Detection of Visual Signatures of Marine Mammals and Fish within Marine Renewable Energy Farms using Multibeam Imaging Sonar

Abstract

Techniques for marine monitoring have been greatly evolved over the past decades, making the acquisition of environmental data safer, more reliable and more efficient. On the other hand, the marine renewable energy sector has introduced dissimilar ways of exploring the oceans. Marine energy is mostly harvested in murky and high energetic places where conventional data acquisition techniques are impractical. This new frontier on marine operations brings the need for finding new techniques for environmental data acquisition, processing and analysis. Modern sonar systems, operating at high frequencies, can acquire detailed images of the underwater environment. Variables such as occurrence, size, class and behavior of a variety of aquatic species of fish, birds, and mammals that coexist within marine energy sites can be monitored using imaging sonar systems. Although sonar images can provide high levels of detail, in most of the cases they are still difficult to decipher. In order to facilitate the classification of targets using sonar images, this study introduces a framework of extracting visual features of marine animals that would serve as unique signatures. The acoustic visibility measure (AVM) is here introduced as technique of identification and classification of targets by comparing the observed size with a standard value. This information can be used to instruct algorithms and protocols in order to automate the identification and classification of underwater targets using imaging sonar systems. Using image processing algorithms embedded in Proviwer4 and FIJI software, this study found that acoustic images can be effectively used to classify cod, harbour and grey seals, and orcas through their size, shape and swimming behavior. The sonar images showed that cod occurred as bright, 0.9 m long, ellipsoidal targets shoaling in groups. Harbour seals occurred as bright torpedo-like fast moving targets, whereas grey seals occurred as bulky-ellipsoidal targets with serpentine movements. Orca or larger marine mammals occurred with relatively low visibility on the acoustic images compared to their body size, which measured between 4 m and 7 m. This framework provide a new window of performing qualitative and quantitative observations of underwater targets, and with further improvements, this method can be useful for environmental studies within marine renewable energy farms and for other purposes.

Study on the Classification Performance of Underwater Sonar Image Classification Based on Convolutional Neural Networks for Detecting a Submerged Human Body

“…The techniques of recognizing an object in turbid water and making a decision on the type of the object are essential factors for a diver or a submersible to support marine tasks [1,2].…”

“…For this reason, sonar sensors are mainly utilized in water [9,10]. However, even though a sonar sensor can give a plausible underwater image in the limitation, the quality of the sonar image varies greatly depending on the background of the target [1]. The readability of the sonar image is very different according to the target distance from the underwater floor or the incidence angle of the sonar sensor.…”

Evaluation of Co-Existence Options of Marine Renewable Energy Projects in Japan

“…Direct economic valuation and cost benefit analysis of ocean information is impractical [35]. Marine energy is mostly harvested in murky and high energetic places where conventional data acquisition techniques are impractical [36].…”

“…Aquaculture is one of the best co-location options; however, it depends on how fishing gears can be used with MRE structures. With the combination of reef effects and remote monitoring facilities (e.g., detection of fish within MRE farms[36]), aquaculture facilities combined with MRE farms seems to be an attractive solution.• Local tourism can be improved by having visible MRE projects as well as organizing boat excursions to the power farm areas. Reef effect creates an environment conducive for snorkeling and diving.•There should be a practical method of regulating the interactions to maintain the safety and efficiency of both industries.•Due to the nature of operations, such as travel planning, aquaculture facilities (specially seaweeds culture) and leisure facilities have the same characteristics that differ from typical large-scale fishing.…”

Spatial, Temporal and Spectral Multiresolution Analysis for the INTERSPEECH 2019 ComParE Challenge

“…Active monitoring devices are beginning to be tested. This involves emitting sound pulses into the water [17] and radio waves into the air (x-band marine radar) [18]. Detection is done by analyzing the wave reflected by the animal.…”