Survey Vessel Research Articles

Submarine canyons as key habitats to preserve Risso’s dolphin (Grampus griseus) populations in the northwestern Mediterranean Sea

This paper summarises the occurrence of Risso’s dolphin (Grampus griseus) over 12 years (2009 to 2021) in the northwestern Mediterranean. The study was conducted off the central coast of Catalonia (NE Spain) in an area covering 8,026 km2 and featuring a system of submarine canyons. The habitat is suitable for a wide diversity of species, including deep-diving cetaceans. In addition, a different dataset from other projects was included to compare distances to the coast from different periods. A visual effort of 8,756 km was carried out with the recording of 17 Risso’s dolphin sightings. The relative mean density of Risso’s dolphin was 0.0078 individuals/km2 (SD 0.1, n = 17), and the densities were higher in the southern canyons than in the northern canyons. Furthermore, the distance to the coast and the depth of any sighting were compared by gathering data from different periods and surveys (first period 1985–2014; second period 2016–2021) with 34 sightings analysed. Significant differences were found related to the distance to the coast, showing a displacement of the animals to more pelagic areas between periods. The spatial distribution of Risso’s dolphins was investigated by applying a generalized additive model based on sighting data collected during standardized vessel surveys. Four predictive variables were considered, taking into account the local physiographical features. The model showed that the spatial distribution of Risso’s dolphin in the area was related to the slope and slope variation. The species showed preferences for offshore areas as significant differences were obtained in terms of the distance of sightings to the coast. This paper provides new insights into the distribution of Risso’s dolphin in the central western Mediterranean Sea and identifies the submarine canyons of northern Catalonia as an essential habitat for the species.

Coastal Bathymetric Sounding in Very Shallow Water Using USV: Study of Public Beach in Gdynia, Poland.

The bathymetric surveys executed with a use of small survey vessels in limited water areas, including offshore areas, require precise determination of the geospatial coordinates of the seabed which is a synthesis of, among others, determining the position coordinates and measuring the depth. Inclination of the seabed and the declining depth make manoeuvring of the sounding vessel, e.g., a hydrographic motorboat or Unmanned Survey Vehicle (USV), in shallow water impossible. Therefore, it is important to determine the minimal depth for the survey resulting from the draught of the sounding vessel and the limits of the sounding area. The boundaries also result from the dimensions of the sounding vessel, its manoeuvring parameters and local water level. Type of the echosounder used in the bathymetric survey is a decisive factor for the sounding profile planning and the distances between them and the survey vessel for the possibility performing the measurements in shallow water. Electronic Navigational Chart (ENC) was used to determine the water area's boundaries, and the safety contours were determined on the basis of the built Digital Sea Bottom Model (DSBM). The safety contour, together with the vessel's dimensions, its manoeuvring parameters and the hydrometeorological conditions, limit the offshore area in which the measurement can be performed. A method of determining boundaries of the survey performed by a USV equipped with SingleBeam EchoSounder (SBES) on survey lines perpendicular to the coastal line are presented in the paper in order to cover the water area with the highest amount of measurement data, with the USV's navigational safety taken into consideration. The measurements executed on the municipal beach served verification of the DSBM.

Experiment and numerical simulation study on resistance performance of the shallow-water seismic survey vessel

In this paper, a new type of shallow-water seismic survey vessel is proposed to solve the problem that the traditional seismic survey vessels cannot satisfy the requirements of the shallow-water marine resources exploration. To reveal the influence of shallow water effect on resistance and flow field, this research is to obtain the resistance and shallow-water characteristics of this shallow-water seismic survey vessel through ship model experiments and numerical methods. Firstly, the ship model experiment predicted the resistance at different speeds in shallow water and obtained the benchmark data to validate numerical methods. Then, the CFD methods were used to calculate the resistance of the ship in deep and shallow water. The numerical results are in good agreement with the experimental results. Finally, this paper provided details of the distribution of wave, pressure and flow fields at different water depth conditions in order to explain the causes of increased resistance in shallow water, providing a reference for the shallow-water seismic survey vessel design.

Sperm whale distribution and seasonal density in the Faroe Shetland Channel

Results from previous surveys suggest that an area of the northeast Atlantic, the Faroe Shetland Channel, is important for cetaceans. This study utilised passive acoustic survey techniques to evaluate the density of sperm whales in the Channel. Two-week surveys were carried out during oceanographic cruises in May and October 2001, and May 2002. A two hydrophone array was towed behind the vessel throughout the majority of the survey routes and was monitored by a two-person team and by software designed to automatically detect and measure bearings to whales. Distances of individual sperm whales from the trackline were determined using target motion analysis. Standard line transect techniques were applied to calculate the density of whales during surveys. The effects of sea conditions and survey vessel on the ability to detect whales were tested; the encounter rate and effective stripwidth (esw) were estimated independently for each sea state and for each of the vessels. A total of 79 individual whales were detected, and their distances from the trackline were calculated. As a probable result of insufficient sample size and a small effects size, neither the esw nor the encounter rates varied significantly with sea state or between the two survey vessels. The density of sperm whales during each of the surveys was estimated to be 2.05, 0.52 and 1.75 whales per 1,000km2 for the May 2001, October 2001 and May 2002 surveys respectively. Sperm whales were distributed across the majority of the Faroe Shetland Channel. This study has provided the basis for meaningful hypothesis generation in future studies and to gain a better understanding of the factors underlying the spatial and temporal distribution patterns of sperm whales in this area; data on oceanographic, biological and anthropogenic determinants should now be examined.

The estimation of the detection function and g(0) for shortbeaked common dolphins (Delphinus delphis), using doubleplatform data collected during the NASS-95 Faroese survey

This paper examines the data for common dolphins collected during a general double-platform line transect cetacean survey carried out in waters around the Faroe Islands in 1995 (from southeastern Iceland to western Ireland) in order to determine the extent to which a correction factor can be estimated to account for animals missed on the trackline and for responsive movement towards the vessel. A major assumption of conventional distance-based methods is that all objects at zero distance from the line are detected (i.e. g(0)=1). If this assumption is violated the estimated density and hence abundance will be negatively biased. It also assumes that animals do not respond to the survey vessel before they are detected by the observers. If the animals are attracted to the vessel, for example, this will result in a positively biassed estimate. The g(0) estimate was obtained using the method of Borchers et al. (1998). Visual inspection of the data suggested that the dolphins were attracted to the vessel and this was accounted for following the Buckland and Turnock (1992) approach. Coefficients of variation (CVs) and confidence intervals (CIs) were estimated using a non-parametric bootstrap procedure. During the survey, almost 1,700 n.miles were sailed on primary research effort. There were 153 common dolphin sightings including 52 duplicates. The chosen model for the detection function incorporated perpendicular distance, group size and Beaufort sea state. The resulting estimate of g(0) was 0.7961 (CV=0.14). Density estimates obtained under an assumption of no responsive movement are almost six times higher than when it is taken into account, highlighting the importance of collecting appropriate data to allow analysis of this potential problem in cetacean surveys.

Laser-induced breakdown spectroscopy instrument and spectral analysis for deep-ocean Fe-Mn crusts

IntroductionMarine ferromanganese crusts are potentially important metal resources.The deep-ocean research and survey ships often need to carry out rapid chemical element component analysis of mineral resources, so as to plan for the geological resource exploration mission.MethodsThe laser-induced breakdown spectroscopy can obtain the spectrum of chemical elements by the plasma excited by high-energy laser irradiation on the surface of the sample. A laser induced breakdown spectroscopy optical system for the detection of deepocean ferromanganese crusts is designed and built, which can meet the requirements of near-insitu chemical component detection of deep-ocean mineral resources on ocean-going survey ships.ResultsHyperspectral data of Fe-Mn crusts are carried out by the Laser-induced breakdown spectroscopy (LIBS) system during a deep-sea exploration mission at a depth of 2,490 m in the South China Sea. The experimental parameters of laser energy and spectral acquisition delay are optimized to improve the spectral measurement accuracy. Based on the calibration-free method, the significant spectral features of the chemical elements Fe and Mn were obtained through proper alignment with the National Institute of Standards and Technology (NIST) chemical element spectral library.DiscussionThe LIBS instrument can be placed on board long-range survey vessels in the future to provide a fast, convenient, accurate, and economical detection method for deep-ocean resource exploration.

Opportunistic Offshore Sighting of a Tricolored Bat (Perimyotis subflavus)

During a marine mammal vessel survey, a single Perimyotis subflavus (Tricolored Bat) was sighted 103.5 km off the coast of North Carolina. While we cannot determine whether the bat flew unaided from the mainland or stowed away on a ship, this is likely the furthest offshore sighting for the species. The possibility of Tricolored Bats flying offshore could have implications for wind-energy programs or other offshore industries.

A note on cetaceans off Kiribati and Tuvalu from a research cruise in October 2010

This paper summarises the results of a sighting survey conducted around the Gilbert Islands (Kiribati) and Tuvalu Islands (Tuvalu) in the central Pacific Ocean between 3 and 17 October 2010. This was the first systematic collection of cetacean sighting data in this region. The main objective of the survey was to investigate the occurrence and distribution of cetaceans around Kiribati and Tuvalu. In addition biopsy samples were obtained to investigate the species identity of Bryde’s-whale-like baleen whales through genetic analyses and to assess feeding ecology of cetaceans in the survey area through the examination of fatty acids. The survey was carried out using a sighting survey vessel, which covered a total of 1,012 n.miles (≈1,875km). A total of 24 schools (640 individuals) of cetaceans was sighted: three schools (five individuals) of Bryde’s-whale-like baleen whales, one school (nine individuals) of sperm whales (Physeter macrocephalus), one school (six individuals) of killer whales (Orcinus orca), one school (14 individuals) of short finned pilot whales (Globicephala macrorhynchus), one school (two individuals) of false killer whales (Pseudorca crassidens), eight schools (483 individuals) of spinner dolphins (Stenella longirostris), and one school (70 individuals) of striped dolphins (Stenella coeruleoalba). Mitochondrial DNA (mtDNA) analyses based on the biopsy samples identified two of the Bryde’s-whale-like whales sighted, as of the putative species Balaenoptera brydei. Compositions of fatty acids of Bryde’s and killer whales are presented. The survey provided new information on the distribution and fatty-acid composition of cetaceans around Kiribati and Tuvalu.

Carbon Footprint of An Offshore Survey by Oil and Gas Service Provider Company

The rapid development of global economy has leaded to climate change issues. The greenhouse gases including carbon dioxide have driven the issues of climate change and become one of the concerns confronting human society. An offshore survey project that carried out by a service provider company in oil and gas industry was chosen for the carbon footprint estimation during the project’s operation in this study. The major objective of this study is to calculate the carbon footprint of the above-mentioned project in terms of CO2, eq and use it as a benchmark or reference for the company, as well as to create an Excel Tool that can be used as a carbon footprint calculator. Greenhouse Gas Protocol methodology is to generate the framework for the project in this study. There have three unavoidable sources: fuel combustion by survey vessel, transportation involved and water consumption during the operation of the project. The emission factors approach is used in this study to quantify the emission of GHGs from the project. Emission factor values will be obtained from the published report that revised by Federal Register of Legislation in 2020. The carbon footprint of the project was calculated to be 130.44 tons of CO2, eq. Scope 1 accounted for 96.05% of the carbon footprint, which comprised fuel combusted by survey vessel.

Upwellings, canyons and whales: An important winter habitat for balaenopterid whales off Mauritania, northwest Africa

The aim of this study was to identify critical habitats for baleen whales in the Mauritanian upwelling zone using data collected from a platform of opportunity: a 60 day geophysical survey approximately 100km southwest of Cap Blanc, Mauritania in winter (2012/13). The bathymetry of the 5,500km2 study area was complex, including parts of the Cap Timiris Canyon system. Large whales, including sei and blue whales, accounted for 70% of the 238 cetacean sightings. Species identification was often problematic, especially in the case of balaenopterid whales, so data for all whales of this genus were pooled for the estimation of abundance and distribution. Spatial modelling was applied to estimate abundance and to plot a predicted density map of balaenopterid whales. Depth and the chlorophyll-a concentration when at its peak (in the previous September) were significant predictors of whale density. Point abundance in the study area was estimated at 272 whales (95% CI 265–279) and density was highest in the depth range 500–2,250m near to the canyon system (6.18 whales/100km2 , 95% CI 6.03–6.51). Steep seabed topography created by canyons running off the shelf edge, together with the strong upwelling system, probably create optimal habitats for the euphausiid prey of sei and blue whales. Sei whales were observed skim-feeding at dawn or dusk on seven occasions; in one sighting an aggregation of 18 skim-feeding sei whales were observed. The high density of these baleen whale species in such a highly productive area and direct observation of feeding behaviour in sei whales, provides evidence of feeding during the winter breeding season, when they have previously been presumed to feed less. This study demonstrates the potential value of collecting further data on seismic survey vessels and would improve understanding of cetacean ecology in remote and under-explored regions.

Joint spatiotemporal models to predict seabird densities at sea

IntroductionSeabirds are abundant, conspicuous members of marine ecosystems worldwide. Synthesis of distribution data compiled over time is required to address regional management issues and understand ecosystem change. Major challenges when estimating seabird densities at sea arise from variability in dispersion of the birds, sampling effort over time and space, and differences in bird detection rates associated with survey vessel type.MethodsUsing a novel approach for modeling seabirds at sea, we applied joint dynamic species distribution models (JDSDM) with a vector-autoregressive spatiotemporal framework to survey data collected over nearly five decades and archived in the North Pacific Pelagic Seabird Database. We produced monthly gridded density predictions and abundance estimates for 8 species groups (77% of all birds observed) within Cook Inlet, Alaska. JDSDMs included habitat covariates to inform density predictions in unsampled areas and accounted for changes in observed densities due to differing survey methods and decadal-scale variation in ocean conditions. ResultsThe best fit model provided a high level of explanatory power (86% of deviance explained). Abundance estimates were reasonably precise, and consistent with limited historical studies. Modeled densities identified seasonal variability in abundance with peak numbers of all species groups in July or August. Seabirds were largely absent from the study region in either fall (e.g., murrelets) or spring (e.g., puffins) months, or both periods (shearwaters).DiscussionOur results indicated that pelagic shearwaters (Ardenna spp.) and tufted puffin (Fratercula cirrhata) have declined over the past four decades and these taxa warrant further investigation into underlying mechanisms explaining these trends. JDSDMs provide a useful tool to estimate seabird distribution and seasonal trends that will facilitate risk assessments and planning in areas affected by human activities such as oil and gas development, shipping, and offshore wind and renewable energy.

The effects of seismic operations in UK waters: analysis of Marine Mammal Observer data

Sixteen years of information from observers on board seismic survey vessels in UK and adjacent waters have demonstrated the varied responses of marine mammals to seismic surveys. Most species showed some response to firing with ‘large arrays’ (airgun volume 500 cubic inches or more), but responses were less evident when "small arrays" (less than 500 cubic inches) were active. Several species/species groups responded proactively to the soft start procedure (where the level of firing is increased gradually) indicating that this can be an effective mitigation measure in reducing the risk of physiological damage. Despite the challenge in assigning ecological significance to the varied observed effects, the analyses in this study confirm that marine mammals are sensitive to noise from seismic surveys and therefore mitigation measures should continue to be applied to all seismic operations and such measures should cover all species.

Domain adapted probabilistic inspection using deep probabilistic segmentation

This paper introduces the concept of domain-adapted probabilistic segmentation for marine vessel classification. The evolution of corrosion is continuous and it is, therefore, impossible to acquire marine vessel inspection datasets representative of the entire active fleet. Additionally, human surveyors introduce high levels of subjectiveness in the classification process, resulting in potentially multiple equally valid but ambiguous classification results. Consequently, deterministic inspection is flawed. The goal of this paper is to address these challenges by using a probabilistic approach to segmentation while performing domain adaptation to align the feature space across the different stages of age degradation. We test a Probabilistic U-Net on both simulated images and images from real vessels and compare it against two novel probabilistic models. We have evaluated the models using both quantitative — energy distance as distribution similarity — and qualitative — feature reduction visualization — approaches. Our results indicate that the combination of probabilistic segmentation and domain adaption could potentially have a high impact on marine vessel surveys in the future.

Robert J. Walker: The History and Archaeology of a U.S. Coast Survey Steamship

Robert J. Walker: The History and Archaeology of a U.S. Coast Survey Steamship

Acoustic methods improve the detection of the endangered African manatee

The African manatee (Trichechus senegalensis) is an elusive, data-deficient, and endangered species which inhabits marine and freshwater systems throughout Western and Central Africa. A major challenge in understanding the species ecology and distribution is the difficulty in detecting it using traditional visual surveys. The recent invasion of Giant Salvinia (Salvinia molesta) at the most important site for the species in Cameroon further limits their detectability and may restrict their movements and habitat use. To investigate methods’ effectiveness in detecting African manatees, we conducted monthly vessel surveys from which visual point scans, 360° sonar scans, and passive acoustic monitoring were conducted simultaneously at ten locations and over 12 months in Lake Ossa, Cameroon. Manatee detection frequency was calculated for each method and the influence of some environmental conditions on the methods’ effectiveness and manatee detection likelihood was assessed by fitting a binary logistic regression to our data. Detection frequencies were significantly different between methods (p < 0.01) with passive acoustics being the most successful (24.17%; n = 120), followed by the 360° sonar scan (11.67%; n = 120), and the visual point scan (3.33%; n = 120). The likelihood of detecting manatees in Lake Ossa was significantly influenced by water depth (p = 0.02) and transparency (p < 0.01). It was more likely to detect manatees in shallower water depths and higher water transparency. Passive acoustic detections were more effective in uninvaded areas of the Lake. We recommend using passive acoustics to enhance African manatee detections in future surveys.

Augmented reality for crewed hydrographic surveys - How augmented reality can leverage water depth management in the port of Hamburg

For the process of hydrographic surveying, the skipper of the survey vessel needs a variety of real-time navigational and hydrographic information to navigate the vessel safely and precisely. The survey data is typically displayed on several monitors on board. As part of a research project, we are exploring the potential of augmented reality – a technology that can extend reality by overlaying it with computergenerated visualizations – to assist the skipper in hydrographic surveys. We report an overview of the technology itself, our proof of concept and several challenges we focus on to create a usable and valuable prototype system.

Assessment of the Effects of Sensors Misalignment of a Multi-Beam Hydrographic Survey

A hydrographic survey vessel shows three -dimensional movements (Roll, Pitch and Heave) misalignment with respect to the vessel reference unit (VRU) due to environmental effects, such as wind, current, other vessel wakes, etc. These motions if ignored, cause errors in measured depth and in the positioning of the sounding. Hence the need of a motion sensor and gyroscope. However, the alignment of the multi-beam sonar head to the motion sensor and gyro (Octant) is critical to the accuracy of the determined depths. It is not possible to install the sonar head in perfect alignment with the motion sensor and gyroscope to the accuracy required. The synchronization of the GPS time with the Motion sensor and gyro, the latency of the position, as reported by the GPS as well as the velocity of sound in water are important parameters to account for the misalignment of the motion senor and the multi beam sonar head; this is called the Patch Test. In view of this, a patch test was done to ascertain the mounting angles of EMB 2058 Multi-beam sonar with Octan V installed onboard a survey vessel (Bitam). The result of the Patch test gives a row, pitch and heading value of -1.242˚, -4.92˚, and -0.48˚respectively. The speed of sound in water as measured ranges from; 1531.47m/s to 1531.60m/s within a minimum cast depth of 0.49m and maximum cast depth of 16.00m. The statistical analysis gives and average error of 2.642cm/m2 which was within acceptable standard as define by the International Hydrographic Organization (IHO).

Determination of USV's Direction Using Satellite and Fluxgate Compasses and GNSS-RTK.

The measurement of a mobile object’s movement direction is performed by means of various analogue and digital devices, including both autonomous and non-autonomous ones. They represent different measuring qualities, dimensions, weights and tolerance to ambient disturbances. They allow measuring the course of heading and course over ground (COG) in sea navigation. They are used for the determination of motion vectors on the water’s surface and with respect to the sea bed, in integrated systems, DP and autopilots. Results of dynamic tests of three heading meters: electronic and satellite compasses, and Global Navigation Satellite Systems (GNSS) determining COG are presented in this paper. The measurements were conducted in good measuring conditions, in an open upper hemisphere for satellite receivers and at no or minimal disturbances of the magnetic field. Sensors were mounted on an unmanned survey vessel (USV) that was moving straight, performing quick turns and circulations. Each of them has some limitations with respect to its use in the water area in which a hydrographic sounding is to be performed; attention was paid to the possibility of using a given compass on board a small autonomous ship navigating automatically.

The Law of the Sea and PRC Gray-Zone Operations in the South China Sea

A growing number of incidents—particularly since 2009—highlight the South China Sea (SCS) as the preeminent venue for the People's Republic of China (PRC) maritime gray zone operations. “Gray zone operations” are, in essence, operations that are designed to exploit or create legal (and other) uncertainties for a military or strategic advantage. A prominent example is the way that China has used the so-called nine(ten)-dash line without fully explaining the legal basis for it. There are other examples, as well. China has deliberately cultivated uncertainty about the sovereign status of maritime militia vessels—and thus about whether and how the conduct of these vessels might be directly attributable to the PRC. It has harassed U.S. survey vessels seventy-five nautical miles (nm) south of Hainan Island in an effort to disrupt military survey operations that it claims are impermissible and has sunk a Philippine fishing vessel at Reed Bank in an effort to enforce Chinese claims to exclusive fisheries rights in this area. It has also asserted claims and enforcement rights in zones that clearly belong to other states—including actions against Indonesian fishing vessels in seas in the vicinity of the Natuna Islands, which are part of the Indonesian Exclusive Economic Zone (EEZ) (and Continental Shelf). And it has conducted operations on the basis of inapplicable maritime zone rights, such as by asserting a territorial sea and thus the right to control innocent passage around low-tide elevations with artificial installations built upon them—such as with Mischief Reef. The list goes on.

Design Evolution of CTV Vessels

When talking about the construction and operations/maintenance (O&M) of an offshore windfarm site it is critical the windfarm developer identify the important role that maritime vessels will play.There are a huge array of marine assets required in the process of developing and maintaining a windfarm, these include but are not limited to cable laying vessels, construction jack-up vessels, accommodation ships, survey vessels and for the purpose of this paper crew transfer vessels (CTVs).Offshore infrastructure including the wind turbines themselves and offshore substations need to be maintained during their lifetime for the system to be successful and for offshore windfarms the sole means of access to the offshore infrastructure is via a vessel. As a result, access to the wind turbines need to be possible throughout the year in a variety of weather and seastate conditions.For this reason, a very specific vessel type, designed specifically for this purpose is required to provide the maximum possible range of access to the wind turbine maintenance technicians.Like any other you need the right tool for the job.The evolution in this industry depends not only on the designers but also engine and machinery manufacturers, classification societies, shipbuilders, operators and charterers to stay in front and to ensure the best solution is being offered in terms of economics, safety, reliability and environmental impact.In addition, in a renewable industry is important that all parts stay consistent with the industry goal, posing additional requirements and challenges to the design of the vessels of the future.This paper has been written to present the evolution and the future of the design of the CTV vessel, from the experience of a designer and the application worldwide of a technology developed in the birthplace of the offshore wind industry.