Hydroacoustic Technology Research Articles

Hydroacoustic method and GIS-Dashboard visualization for fish size in Banggai Sea Waters

Estimating fish stocks, including their distribution and density, plays a vital role in the management of capture fisheries. Hydroacoustic technology is widely utilized for fish stock estimation study. In September 2022, BRIN and IPB University conducted hydroacoustic data measurement in the Banggai Sea as part of the “Banggai Upwelling Dynamics Exploration and Experiment” to estimate fish stocks. Very large fish (>58 cm) has a density of 12,452 fish km-2. The spatial distribution of fish occurs in the eastern waters of Banggai Island and the northern waters of Taliabu Island. The most significant potential is the epipelagic layer (0 to -200 meters), with very small-sized fish having the highest density, followed by large-sized and small-sized fish. To summarize the analysis results of fish density distribution , a GIS-Dashboard is utilized. This online platform integrates various maps and charts, offering an engaging and easily understandable visualization of the information.

Модель синтезу гідроакустичних сигналів із використанням нейронних мереж

Underwater acoustics (also called hydroacoustics), which is associated with the study of the patterns of propagation of sound waves in water, is a driving force in the research and development of systems of hydroacoustic technologies and means of communication, monitoring and detection of surface and underwater objects of biological or artificial origin, study of marine resources and environments, noise measurement, etc. This kind of research requires the analysis of huge amounts of data, revealing non-obvious patterns and creating models for the mathematical description of physical phenomena, such as sound propagation in a medium with random characteristics and radiation from different sources, as well as radiation from sources with different apertures or sound scattering, etc. That is why, in order to create the latest technologies in this area, it is necessary to solve complex specialized problems of a fundamental and applied nature using machine learning algorithms and artificial intelligence. Neural networks are nonlinear systems that allow you to effectively classify data compared to mathematical and statistical methods, which are currently quite widely used. In this paper, the authors propose to use a pre-trained neural network for the analysis and classification of hydroacoustic signals. This procedure for distinguishing acoustic signals has a number of advantages, in particular, individual objects are divided into groups based on information about one or more characteristics inherent in these objects, and on the basis of a training sample of pre-labeled objects. Thus, the proposed model of signal synthesis using neural networks is characterized by increased informativeness of the characteristics of the propagation of hydroacoustic signals, which will have prospects in further practical implementation.

Multibeam echosounder backscatter strength analysis for seafloor sediment identification in Damar Besar Island Waters, Thousand Islands

The condition of the Indonesian territory surrounded by the ocean requires technology to obtain seabed information to support the development of social, economic, and security activities. One of the technologies that can be used is the multibeam echosounder (MBES) hydroacoustic technology. MBES can scan seabed in a wide range, resulting in bathymetric data and backscatter values. The value of backscatter can be used to identify seafloor sediments. This study compared backscatter intensity values obtained from the MBES survey to the previous study. After identifying the sediment, the data obtained are mapped to produce a sediment distribution map. The types of sediment identified in the Damar Besar Island Waters are fine silt, medium silt, coarsed silt, silty sand, muddy sand, clayed sand, very fine sand, and fine sand with a range of backscatter values from -34,92 to -19,04 dB. Fine sand sediments are nearby the northern island while muddy sands and silty sands are scattered away from the island.

Identifying attacks in the Russia-Ukraine conflict using seismic array data.

Seismometers are generally used by the research community to study local or distant earthquakes, but seismograms also contain critical observations from regional1,2 and global explosions3, which can be used to better understand conflicts and identify potential breaches of international law. Although seismic, infrasound and hydroacoustic technology is used by the International Monitoring System4 to monitor nuclear explosions as part of the Comprehensive Nuclear-Test-Ban Treaty, the detection and location of lower-yield military attacks requires a network of sensors much closer to the source of the explosions. Obtaining comprehensive and objective data that can be used to effectively monitor an active conflict zone therefore remains a substantial challenge. Here we show how seismic waves generated by explosions in northern Ukraine and recorded by a local network of seismometers can be used to automatically identify individual attacks in close to real time, providing an unprecedented view of an active conflict zone. Between February and November 2022, we observed more than 1,200 explosions from the Kyiv, Zhytomyr and Chernihiv provinces, providing accurate origin times, locations and magnitudes. We identify a range of seismoacoustic signals associated with various types of military attack, with the resulting catalogue of explosions far exceeding the number of publicly reported attacks. Our results demonstrate that seismic data can be an effective tool for objective monitoring of a continuing conflict, providing invaluable information about potential breaches of international law.

Assessment of Target Strength Value of Demersal Fish in Lancang Waters Using Simrad Single Beam Echosounder

Hydroacoustic technology is excellent at determining accurately and in near real-time the objects located near the seabed. Therefore, acoustic technology is widely recognized for fisheries resources mapping, including demersal fish. The objective of this study was to estimate the value of demersal fish target strength (TS) in the waters of Lancang Island, Kepulauan Seribu region. A Single Beam Echosounder Simrad EK-15 with a frequency of 200 kHz was employed for data collecting in the waters around Lancang Island. The integration layer width was set at 3 meters with a horizontal integration distance of 200 meters. The average target strength (TSc) values obtained from the integration cell ranged from -55.52 dB to -42 dB with an average of -50.30 dB. Furthermore, the seabed depth influenced the distribution of TSc values, with higher TSc values in deeper habitat locations.

Target strength of seahorse (Hippocampus kuda) based on presence dorsal and ventral aspect of brood pouch: a experiment hydroacoustic using artificial neural network

Hydroacoustic technology is a tool can be used to study the behavior of organisms. The target strength of an object is main key in hydroacoustic technology. The value of target strength is strongly influenced by level of hardness of object, in this case the seahorse has a different level of hardness between dorsal and ventral aspect. The unique of male seahorse that experiences pregnancy and keeps it’s baby in brood pouch until it hatches. This can be used as a difference between males and females based on value of target strength. Acoustic data recording using single beam scientific echosounder SIMRAD EK-15 and Sonar-4 processing software. The results showed that mean TS value of pregnant male seahorses (with brood pouch) was smaller than of female seahorses (without brood pouch), there were differences in structure composition and anatomy of the brood pouch which backscattering strength to decrease. The artificial neural network shows that there is a difference in response between seahorse (having a brood pouch/male) compared seahorse (without a brood pouch/female). The results showed that was a difference in dorsal aspect of 87.5% and ventral aspect of 98.6%. The results of this study can be used as key to distinguish sex of seahorses using the hydroacoustic method.

Relationship of Acoustic Volume Backscattering of Fish Aggregations and Density of Pelagic Fish in The Waters of Pulau Baai Bengkulu City

The waters of Pulau Baai are unique waters that are closed or protected which have small pelagic fish resources, used as pelagic fishing areas for local fishermen so that they can help the community's economy. One method that can be used to describe the distribution of pelagic fish density is the use of hydroacoustic technology. This study aims to analyze the value of acoustic backscattering (volume backscattering strength, SV) of pelagic fish and associated with the estimation of the density of pelagic fish in the waters of Pulau Baai, Bengkulu City, through in-situ acoustic measurements. The results showed that in the waters of Pulau Baai the highest average SV value was -50.47 dB, which was thought to have a fish density of 2.57 ind/m3 while for a low average SV with a value of -57.48 dB, it was assumed to have a density of 0.04 ind/m3. The density of pelagic fish is acoustically estimated at 26.47 ind/m3 in the water column of Pulau Baai. The SV value affects the estimated fish density by 69% and is categorized as having a high correlation and a positive correlation direction.

Spatial autocorrelation and heterogeneity of fish resources in the Xijiang River, Pearl River Basin, China

The Xijiang River, China, is a hotspot for fish biodiversity. Using hydroacoustic data collected from March to June 2016, the spatial autocorrelation and heterogeneity of fish resources were determined using geostatistical methods. We analysed the skewness, kurtosis and coefficient of variation for fish density along the river and also examined the spatial autocorrelation of these data using Moran’s I statistic. Fish density was low in most of the survey areas. Moran’s I values were all positive (z>1.96, p≤0.01), which indicates significant spatial autocorrelation; however, the degree of spatial aggregation varied among months. Hotspot analysis revealed strong local spatial autocorrelation and varying “hot” and “cold spots” in different months. The spatial heterogeneity and directional variation of fish densities were assessed using geostatistical methods and the best-fitting semivariogram was an exponential model. Spatial autocorrelation accounted for 56-75% of the variation in the model, which indicates that fish distribution in the Xijiang River has a clear spatial structure. The results show the applicability of acoustic methods to study the spatial autocorrelation and heterogeneity of fish resources in rivers and provide a reference for the management of fish stocks. Keywords: Fish resources; Hydroacoustic technology; Spatial autocorrelation; Variation characteristics; Xijiang River

Distributions of environmental parameters and Plankton’s volume backscattering strength at Yos Sudarso Bay, Jayapura, Indonesia

The present study combined the data of environmental parameters and plankton distribution using hydroacoustic technology with the purpose to map the horizontal and vertical distribution of plankton in Yos Sudarso Bay, Jayapura, Indonesia. Hydroacoustic data were processed using a threshold in the range of −90 dB to −70 dB which was used for plankton detection at a depth range of 5–100 m. The results of the current study showed that the surface temperature changed from 30 °C on the outside to 18 °C on the inside of the bay. Similarly, the salinity of the surface outside the bay was 36‰ while it was 18‰ inside the bay. The distribution of chlorophyll had also decreased, where the value outside the bay was 0.32 mg/m3 and inside the bay was 0.02 mg/m3. The horizontal distribution of the values of plankton's volume backscattering strength (Sv) had a range of −82 dB to −75 dB with an average of −76.63 dB. When the distribution of plankton's Sv was detected vertically, it showed that the value of plankton’s Sv decreased with increasing the water depth.

Differentiation of two swim bladdered fish species using next generation wideband hydroacoustics

Monitoring fish populations in large, deep water bodies by conventional capture methodologies requires intensive fishing effort and often causes mass mortality of fish. Thus, it can be difficult to collect sufficient data using capture methods for understanding fine scale community dynamics associated with issues such as climate change or species invasion. Hydroacoustic monitoring is an alternative, less invasive technology that can collect higher resolution data over large temporal and spatial scales. Monitoring multiple species with hydroacoustics, however, usually requires conventional sampling to provide species level information. The ability to identify the species identity of similar-sized individuals using only hydroacoustic data would greatly expand monitoring capabilities and further reduce the need for conventional sampling. In this study, wideband hydroacoustic technology was used in a mesocosm experiment to differentiate between free swimming, similar-sized individuals of two swim-bladdered species: whitefish (Coregonus wartmanni) and stickleback (Gasterosteus aculeatus). Individual targets were identified in echograms and variation in wideband acoustic responses among individuals, across different orientations, and between species was quantified and visually examined. Random forest classification was then used to classify individual targets of known species identity, and had an accuracy of 73.4% for the testing dataset. The results show that species can be identified with reasonable accuracy using wideband hydroacoustics. It is expected that further mesocosm and field studies will help determine capabilities and limitations for classifying additional species and monitoring fish communities. Hydroacoustic species differentiation may offer novel possibilities for fisheries managers and scientists, marking the next crucial step in non-invasive fish monitoring.

Bloom-forming toxic cyanobacterium Microcystis: Quantification and monitoring with a high-frequency echosounder

Harmful cyanobacterial blooms pose a serious environmental threat to freshwater lakes and reservoirs. Investigating the dynamics of toxic bloom-forming cyanobacterial genus Microcystis is a challenging task due to its huge spatiotemporal heterogeneity. The hydroacoustic technology allows for rapid scanning of the water column synoptically and has a significant potential for rapid, non-invasive in situ quantification of aquatic organisms. The aim of this work is to develop a reliable cost-effective method for the accurate quantification of the biomass (B) of gas-bearing cyanobacterium Microcystis in water bodies using a high-frequency scientific echosounder. First, we showed that gas-bearing Microcystis colonies are much stronger backscatterers than gas-free phytoplanktonic algae. Then, in the tank experiments, we found a strong logarithmic relationship between the volume backscattering coefficient (sv) and Microcystis B proxies, such as Microcystis-bound chlorophyll a (Chl aMicro) and particle volume concentration. The sv/B ratio remained unchanged over a wide range of B concentrations when the same source of Microcystis material was used. Our measurements in Lake Dianchi (China) also revealed strong logarithmic relationship between sv and Chl aMicro. The biomass-calibrated echosounder was used to study the diurnal variability of Microcystis B in the lake. We found a sharp increase in the cyanobacterium B and sv/Chl aMicro ratio near the water surface during the daytime and more uniform distribution of these parameters during the nighttime. We argue that the variations in B and sv/Chl aMicro ratio could be associated with temporal changes in thermal stratification and turbulent mixing. Our data suggest that the sv/Chl aMicro ratio positively correlates with (i) the percentage of larger colonies in population and/or (ii) the content of free gas in cells. The last properties allow Microcystis colonies to attain rapid floating, which enables them to concentrate at the water surface at conducive ambient conditions. The sv/Chl aMicro ratio can be a new important variable reflecting the ability of Microcystis colonies to migrate vertically. Monitoring of this ratio may help to determine the early warning threshold for Microcystis scum formation. The proposed acoustic technology for in situ quantification of Microcystis biomass can be a powerful tool for accurate monitoring and assessment of this cyanobacterium at high spatiotemporal resolution in water bodies.

Hydro-acoustic Survey and Edge-detection method in Investigation of a Passenger Vessel Accident in East Java, Indonesia

As an archipelagic country, the shipping sector in Indonesia becomes crucial in delivering goods inter-island, and due to increasing transportation demands. However, that industry encounters some challenges of the ocean environment that could lead to vessel accidents. An investigation into the accident is crucial since this is related to the properties, environment, and life disadvantages. The wrecks of sinking vessels also could harm the environment, providing an obstacle to the sea passage hence increasing the risk of a shipping operation. A proper and comprehensive investigation needs to be carried out to identify the factors that contribute to the accident, so then risk mitigation can be taken to prevent re-occurrence. In the case of missing foundered or sunken vessels, an underwater examination is a must, so the investigator understands the real condition of the vessel. Although diver and underwater robotic surveys are still prevalent in the investigation, these techniques have limitations due to visibility and location. By contrast, those limitations can be addressed using hydro-acoustic technologies, which are capable of providing high-resolution underwater images and digital elevation model (DEM) bathymetry. Thus, the use of these technologies is promising in-vessel accident investigation, both in-situ investigation, and post-processing analysis. This paper describes an examination of the use of side-scan sonar and multibeam echosounder in-vessel accident investigation. The use of slope feature and edge-detection technique are also investigated concerning the investigation. Results indicate that those acoustic systems can contribute to the inquiry effectively by portraying some underwater objects as the accident suspects. Besides, slope and edge detection methods also produce expectant outcomes to support underwater object detection and investigation.

DISTRIBUTION AND DENSITY OF DEMERSAL FISHES IN YOUTEFA BAY, PAPUA, INDONESIA: A STUDY USING HYDROACOUSTIC TECHNOLOGY

A study was conducted to estimate the distribution and density of demersal fish in Youtefa Bay, Papua, Indonesia, using hydroacoustic technology. The hydroacoustic survey was carried out using a single beam echosounder SIMRAD EK-15 which operates at a frequency of 200 kHz. The hydroacoustic data was processed using Echoview software with a threshold between -70.00 to -34.00 dB. Schooling fish were detected at a maximum distance of 3 m from the seabed, with average volume backscattering strength ranging between -60.13 and -42.01 dB. The demersal fish density in the Youtefa Bay ranged from 0.09 to 42.19 fish m-3 with an average density of 12.62 fish m-3. The schools of demersal fish were dominantly detected in the coastal waters of Enggros Village to Abe Pantai Village. The condition of substrate and water depth seems to influence the spatial and vertical distribution of demersal fish in the Youtefa Bay.

Distribution of Fish Target Strength in Malang Rapat Seawater of Bintan Island, Kepulauan Riau Province

Malang Rapat is an area located in east Bintan Island. As a part of coastal communities, fisheries were the primary sector for public revenue in Malang Rapat. A qualified method is needed to determine the abundance and distribution of fish were required. Hydroacoustic technology is one method to solve this problem. This research aimed was to determine the value of fish target strength and to determine the pattern of fish distribution behavior in Malang Rapat, Kepulauan Riau Province, on September 23 and 24, 2016, using scientific echosounder Simrad EK15. The result indicated that fish target strength in Malang Rapat was -60 dB to -42 dB. This value was useful to estimate the length of fish ranged from 3 cm to 31 cm. The highest mean target strength based on depth was -48 dB at 10 m in the daytime and -52 dB at 3 m in the nighttime. The abundance of fish was found at night, precisely 3 meters from the surface of the water. The highest frequency appearance target strength range from -60 dB to -58 dB with 3.94 to 4.95 cm estimated fish length.

Using a Down‐Looking Multifrequency ABS for Measuring Suspended Sediments in Rivers

AbstractIn the last decade, much progress has been made in continuously measuring suspended sediment concentration (SSC) in rivers using horizontal side‐looking Acoustic Doppler Current Profilers. However, these techniques do not provide information on the spatial variability of the suspension. In this study, we explore some new possibilities offered by the down‐looking deployment of a multifrequency acoustic backscatter system (ABS) in order to obtain information on the suspension throughout an entire river cross section. Two sites, with low and high levels of SSC, were investigated. The acoustic signal was processed using multifrequency inversion methods. Both water sample calibration data and modeling were used for retrieving the acoustic properties of the suspended particles. At the low SSC site ( 30 mg/L), we successfully inverted the acoustic signal, except in some areas of high acoustic backscatter close to the surface that were probably generated by air microbubbles. At the high SSC site ( 10 g/L), estimates of both fine and sand SSCs throughout the river cross section were successfully obtained, except in some areas close to the bottom where the acoustic signal was totally attenuated due to distance and high concentration of fine sediments. This work confirms the capacity of hydroacoustic technology for providing spatial information on river suspensions.

PENERAPAN TEKNOLOGI HIDROAKUSTIK DI BIDANG ILMU DAN TEKNOLOGI KELAUTAN

APPLICATION OF FIELD HYDROACOUSTIC TECHNOLOGY FOR MARINE SCIENCE AND TECHNOLOGY Utilization hydroacoustic methods in recent years have become increasingly effective for estimating the abundance of marine fish, especially fish stocks, where is impossible to do with conventional methods approach. Widely hydroacoustic technology has been used to map and classify the content of the resource base of waters and benthic animals that are on the bottom, type of substrate and benthic biota. Target Strength (TS) is the most important factor in the detection and prediction of fish stocks by using hydroacoustic. The TS is a measure that can describe the ability of a target to reflect sound waves that come about it. In the propagation of sound waves, the amount of energy per second will be flowing through the unit certain area perpendicular to the direction of propagation. The amount of energy per second crossing a certain area of the unit refers to as the intensity of the wave. The system of detection and measurement of underwater involves three components, namely medium, targets, and equipment. Sonar equation is built based on the similarity or balance between the parts of the received signal, the desired (called signal) and the unwanted parts (referred noise or noise), depending on the specific sonar functions are applied.

Identification of Coral Reef Conditions Using Hydro-Acoustic Technology in Giligenting Island, Sumenep Regency Indonesia

Coral reefs are one of the major ecosystems in the coastal region with high biodiversity and resource level. As productive ecosystems with high economic and ecological potential, the existence of coral reef ecosystems must be sustainably managed. One of the areas with high diversity of coral reefs is Giligenting Island located in Sumenep regency. This research was conducted by taking primary data in the form of tidal data, bathymetry data and Side Scan Sonar recordings. From the primary data and then processed until produces 3 dimensional model of seabed features that are then interpreted and analyzed to obtain information about healthy or damaged coral reefs, using underwater geo-tagged photos to validate. The 3-dimensional model has a maximum depth of 7.667 meters and 1.403 meters at minimum depth with an area of 100,536.097 m2. From the interpretation of Side Scan Sonar acoustic images it is found the area of sand feature is 30.79%; the area of mud feature equal to 29.94%; the healthy coral covering 35.75% of the survey area, consisting 10.09% of coral reef barrier reef feature, and 25.66% of small coral reef feature; and 3.52% of damaged coral reef feature from total 43,527.110 m2 Side Scan Sonar survey area.

Correlation of consumer grade hydroacoustic signature to submersed plant biomass

Invasive macrophytes, such as non-native Hydrilla verticillata, negatively affect lentic systems of the Southeastern United States by impeding recreational activities and power generation as well as disrupting intrinsic ecological function. Expenditures associated with aquatic weed management include costs accompanied with monitoring, mapping, and implementing control measures. Traditional biomass sampling techniques have been widely utilized to assess the extent and abundance of submersed aquatic vegetation (SAV) incursions, but often require significant labor inputs which limits repeatability, the scale of sampling, and the rapidness of processing. Advances in consumer available hydroacoustic technology and data post-processing platforms offer the opportunity to estimate SAV biomass at scale with reduced labor and economic requirements. Research was conducted at two North Carolina reservoirs to compare acoustically derived cloud-based biovolume estimations from an over-the-counter echosounder, to in situ hydrilla biomass measurements. Temporal patterns, spatial developments, and hydrilla biomass prediction models are presented. Biomass and biovolume measurements were positively correlated at both the Shearon Harris and Roanoke Rapids study locations. The most robust predictive equation employed generalized additive models (GAMs) from the Shearon Harris dataset which, described environmental parameters with the lowest error and greatest agreement compared to other verified models. Each biovolume to biomass relationship supported the initial hypothesis that as biovolume increases, SAV biomass increases in a positive, non-linear trend. Implications from this study may prove useful for comparing seasonal growth patterns, littoral occupancy, and herbicide treatment effects on a spatiotemporal level.

Hydroacoustics as a tool to examine the effects of Marine Protected Areas and habitat type on marine fish communities

Hydroacoustic technologies are widely used in fisheries research but few studies have used them to examine the effects of Marine Protected Areas (MPAs). We evaluate the efficacy of hydroacoustics to examine the effects of closure to fishing and habitat type on fish populations in the Cabo Pulmo National Park (CPNP), Mexico, and compare these methods to Underwater Visual Censuses (UVC). Fish density, biomass and size were all significantly higher inside the CPNP (299%, 144% and 52% respectively) than outside in non-MPA control areas. These values were much higher when only accounting for the reefs within the CPNP (4715%, 6970% and 97% respectively) highlighting the importance of both habitat complexity and protection from fishing for fish populations. Acoustic estimates of fish biomass over reef-specific sites did not differ significantly from those estimated using UVC data, although acoustic densities were less due to higher numbers of small fish recorded by UVC. There is thus considerable merit in nesting UVC surveys, also providing species information, within hydroacoustic surveys. This study is a valuable starting point in demonstrating the utility of hydroacoustics to assess the effects of coastal MPAs on fish populations, something that has been underutilised in MPA design, formation and management.

Anomalous properties of water and their influence on hydroacoustic technologies

Was investigate the effect anomalous properties of seawater on the characteristics of sound in it. And conversely, acoustic waves of different frequency range -on the physical properties of water that forming, Very long phenomenon of sound in the ocean. Sonar technology used for navigation and for other tasks that require an understanding of the physical principles underlying the phenomena forming the main underwater sound channel and very long propagation in the marine environment. This was considered possible cause some anomalous properties of water, conducted a critical analysis of the characteristics of the marine environment, which affect the transfer of sound energy in it. It is shown that the temperature, salinity and pressure used in the calculation of the speed of sound in water by known formulas affect not directly but indirectly, through the formation of certain structures in the aquatic environment (mono-, nano- and supramolecular), which define those " abnormal "features of sound that recorded experimentally. Negative anomaly absorption of sound energy at low frequencies can be created on condition synchronization in space and time effects of changes in the structure of water while passing acoustic wave with the properties of the phenomenon itself (sound). The theory of Very long sound distribution should also take into account the effect of resonance, as a mechanism to reinforce a sound signal by coherent vibration process in the marine environment. At first sight, this may be due to coincidence acoustic wave periods and the period of natural oscillations compressibility of sea water.