Video Surveys Research Articles

On the tracks of white sharks in the Mediterranean Sea

White sharks (Carcharodon carcharias) are among the most widespread, charismatic, and studied predators in the ocean. However, their conservation status is concerning in many ocean sectors, most notably the Mediterranean Sea, which hosts one of the least known and most endangered populations globally. Though they were historically abundant and widely distributed in the region, Mediterranean white sharks have declined to dangerously low abundance levels, impacted by centuries of coastal and, more recently, industrial fishing. The IUCN lists this species as Critically Endangered in the region, but information about its current abundance and ecology is scarce, hindering effective management and conservation. Here, we describe our initial effort to find and track the remaining Mediterranean white sharks and report what we have learned from these activities. In 2021-2023, we conducted three pilot expeditions in the Sicilian Channel, covering four major sites, collecting 159 eDNA samples, and carrying out 359 hrs of pelagic mid-water baited video surveys, 43 hours of deep-water benthic baited video surveys, and 111 hrs of fishing. Baited video surveys detected 42 species of bony fishes, elasmobranchs, marine mammals, and turtles. We detected white sharks at four sites from eDNA samples. Though we did not observe white sharks directly, these activities supported the identification of one of the last strongholds of this population in the region and started a multi-institutional white shark conservation program in the Mediterranean Sea, aiming to track the last white sharks in the region, estimate their abundance and extinction risk, characterize the species’ ecology and inform management and conservation.

A Proposed Method for Assessing the Spatio-Temporal Distribution of Carcharhinus melanopterus (Quoy and Gaimard, 1824) in Shallow Waters Using a UAV: A Study Conducted in Koh Tao, Thailand

In this study, we propose a method for assessing the temporal and spatial distribution of Carcharhinus melanopterus in shallow waters using unmanned aerial vehicles (UAVs). Aerial surveys were conducted in Tien Og Bay (Koh Tao, Thailand) thrice daily (morning, afternoon, evening) along a 360 m transect at a 30 m altitude. Environmental factors, including cloudiness, sea conditions, wind, tide, and anthropogenic disturbance, were recorded for each time slot. We developed a Python/AppleScript application to facilitate individual counting, correlating sightings with GPS data and measuring pixel-based length. Abundance varied significantly across time slots (p < 0.001), with a strong morning preference, and was influenced by tide (p = 0.040), favoring low tide. Additionally, abundance related to anthropogenic disturbance (p = 0.048), being higher when anthropogenic activity was absent. Spatial distribution analysis indicated time-related, sector-based abundance differences (p < 0.001). Pixel-based length was converted to Total Length, identifying juveniles. They exhibited a strong sector preference (p < 0.001) irrespective of the time of day. Juvenile abundance remained relatively stable throughout the day, constituting 94.1% of afternoon observations. Between 2020 and 2022, an underwater video survey was conducted to determine the sex ratio of the individuals. Only females and juveniles were sighted in the bay.

Differences in Megabenthos Communities in the Eastern and Western Parts of the Kara Sea Based on Video Observations

The first quantitative video survey of the benthic megafauna was carried out on a transect in the eastern part of the Kara Sea from the slope of the Voronin Trough to the upper shelf in the depth range from 1680 to 70 metres. The data were obtained using the TU-V “Videomodule” during the 89th cruise of the R/V “Akademik Mstislav Keldysh” in autumn 2022. It was shown that the megabenthos in this area differs significantly from that of the western part of the sea and Blagopoluchiya Bay (Novaya Zemlya). In the eastern part of the Kara Sea, echinoderms dominated, among which ophiuroids were in the first place, whereas in the western part of the sea and in the Blagopoluchiya Bay, the key component of the megafauna was the snow crab Chionoecetes opilio. Single adults of Ch. opilio were recorded for the first time at almost all stations in the eastern part of the sea, but, in contrast to the western area, the snow crab has not yet become dominant here and has not influenced the benthic communities.

Expressing Anger with Robot for Tackling the Onset of Robot Abuse

Service robots in public spaces can sometimes become victims of ‘abuse’, manifesting as persistent blocking of the robot’s path, physical violence such as pushing or pulling, or abusive language. This kind of abuse can be a serious obstacle to the deployment of robots. We studied the possibility of mitigating obstructive behaviour towards the robot, which is known to happen in the early stages of robot abuse, by having the robot express anger-like emotions. We identified and implemented three distinct anger behaviours: furious, quiet, and scolding anger. Through an online video survey, we confirmed that all three designed robot behaviours were perceived as expressions of anger. Finally, we ran an in-lab experiment with child participants to study the influence of the robot’s expressions of anger on children’s obstructive behaviours. The results show that ‘furious anger’ was effective in reducing the frequency of obstructions, whereas the other two anger types were not.

Community structure and environmental drivers of offshore hard-bottom reef fishes in the northern Gulf of Mexico

Abstract Understanding patterns in community structure in large marine ecosystems is necessary for advancing community- and ecosystem-based approaches to marine fisheries management. We analyzed data from a large-scale, fishery-independent video survey to quantify the structure of reef fish communities on offshore hard-bottom reef habitats in the northern Gulf of Mexico (nGOM). A novel aspect of this work is that all species visualized on videos were identified and enumerated over a 13-year period, which allowed for a comprehensive analysis of fish community structure. We observed a total of 243 fish species from 54 families and 14 orders. Species richness and biodiversity varied considerably across the nGOM and were highest in regions that harbor extensive coral reef habitat (south Florida, Louisiana-Texas shelf). Multivariate analyses identified 12 species assemblages, with important fishery species and species of concern (i.e. IUCN-listed) occurring in the largest identified assemblages. One assemblage composed mostly of large-bodied fishery species accounted for 45% by number and 89% by weight of all fish observed. Species assemblages were most strongly associated with depth, temperature, and substrate composition, with weaker associations with the amount of attached algae and vertical relief, while species richness was positively correlated with bottom water temperature. In general, large-scale bathymetric and hydrographic factors (e.g. depth, temperature) were more important than local topographic structure and biogenic habitat in structuring reef fish communities at the spatial scales (i.e.1000 km) considered here. Our results advance ecosystem-based approaches to fisheries management by providing a basis for incorporating multispecies spatial dynamics into the monitoring and assessment of hard-bottom reef fish communities in the nGOM.

Preliminary Validation of Measures of Experienced, Perceived, and Internalized Stigma Among Adults Who Are d/Deaf or Hard of Hearing in the United States and Ghana.

In this article, we examine the psychometric performance of 3 scales measuring experienced, perceived, and internalized d/Deaf or hard of hearing (d/DHH) stigma among adult (18 and older) populations of individuals who are d/DHH, including those who have been d/DHH since before they developed language (lifelong) and those who became d/DHH after they developed language (acquired) in the United States and Ghana. The preliminary validation study took place in the Greater Accra and Eastern regions of Ghana and across the United States. In the United States, all data were collected online via self-administered surveys in English. In Ghana, trained interviewers who are d/DHH and fluent in Ghanaian Sign Language conducted interviews with participants who are lifelong d/DHH using a video survey. Ghanaian participants with acquired d/DHH status were surveyed by trained hearing interviewers. We calculated polychoric correlation matrices between the measures to remove redundant and unrelated items and used exploratory factor analysis to create the final scales. We also tested the association between the factor scores and a simple summing method for calculating the scale. The study sample included people who have been d/DHH since before they developed language (Ghana: n = 171, United States n = 100) and people who became d/DHH after they developed language (Ghana: n = 174, United States: n = 219). The final experienced, perceived, and internalized scales included six, seven, and five items, respectively. All three scales performed well as unidimensional measures across all four samples. Across the four samples, the experienced, perceived, and internalized stigma scales yielded ordinal αs ranging from 0.725 to 0.947, 0.856 to 0.935, and 0.856 to 0.935, respectively. It would be acceptable to operationalize all stigma scales as sum-of-item scores. The scales performed well and appear to provide a valid means of measuring different types of stigma among diverse groups of people who are d/DHH. Future work should refine and validate these scales in additional contexts.

Is it worthy to use environmental DNA instead of scientific trawling or video survey to monitor taxa in soft-bottom habitats?

Non-extractive techniques such as video analysis are increasingly used by scientists to study marine communities instead of extractive methods such as trawling. Currently, environmental DNA (eDNA) analysis is seen as a revolutionary tool to study taxonomic diversity. We aimed to determine which method is the most appropriate to describe fish and commercial invertebrate diversity comparing bottom trawl hauls, video transects and seawater eDNA. Our results reveal that video detected the lowest number of taxa and trawling the highest. eDNA analysis is powerful to describe marine bony fish communities, but some taxa of importance for the ecosystem such as elasmobranchs, crustaceans or molluscs are poorly detected. This may be due to several factors such as marker specificity, incomplete reference gene databases or low DNA release in the environment. For now, the various methods provide different information and none is exhaustive enough to be used alone for biodiversity characterisation.

Aerial Video Surveys and Spatial Prioritization Reveal Conservation Opportunities for Endangered Dugongs in New Caledonia

ABSTRACT The dugong population of New Caledonia was recently assessed as endangered by the IUCN due to its low genetic diversity, its limited number of mature individuals and the continuing threats from poaching, collisions, incidental capture and seagrass degradation. No‐take marine protected areas (MPAs) implemented in critical dugong habitats may efficiently safeguard the remaining population by directly or indirectly reducing these threats. The goal of the present study was to develop scenarios of MPAs targeting dugongs in New Caledonia, focusing on the central west coast where they are known to aggregate during austral winter. We combined 7 h of video surveys from a light airplane and habitat modelling to derive regional predictions of dugong density. We then used these predictions to (1) assess the proportion of dugong population abundance protected by existing no‐take MPAs and (2) develop spatial prioritization scenarios based on explicit dugong abundance targets. We found that existing no‐take MPAs only protect 11% of the estimated dugong population in the study region, leaving most dugong hotspots unprotected. For the same protected area coverage, prioritization based on abundance would allow protecting nearly five times more dugong individuals. Given the endangered status of the population, a 70% abundance prioritization scenario is warranted, requiring the expansion of existing MPAs toward reef passes and shallow nearshore areas where dugong abundance is the highest. Our study offers an opportunity for dynamic spatial management through the implementation of a seasonal closure strictly restricting human activities in areas where dugongs aggregate in winter.

Fine-scale spatial distribution of a fish community in artificial reefs investigated using an underwater drone and environmental DNA analysis

Although artificial reef (AR) effect evaluation is useful for planning the installation of high-rise ARs and their management, few studies have investigated them quantitatively. The fine-scale 2-dimensional fish distribution in ARs was estimated regarding current fields and vertical structures of 2 high-rise ARs (20 and 30 m high at 62 and 72 m depths, respectively) in Tateyama Bay, central Japan, using underwater drone recordings with vertical line transects and environmental DNA (eDNA) metabarcoding. The species detected by video surveys (21 taxa were identified to species, and 1 to genus) were fewer than by eDNA analysis (103 species and 6 genera), especially for pelagic, small-sized, and cryptic fish. Video surveys revealed that demersal fish increased with decreasing horizontal distance from the AR surface within 20 m, and the richness and total fish density were significantly higher upstream of the ARs. Conversely, the fish eDNA concentration showed different patterns, with significantly higher concentrations downstream of the ARs. The richness peaked at horizontal AR surfaces (e.g. reef top), but density of the dominant species peaked near the bottom by video survey. In comparison, eDNA analysis indicated lower richness and higher eDNA concentration of the dominant species at the reef top. Such discrepancies may be explained by the influence of eDNA transport or its specific behavior or buoyancy. Video surveys revealed the growth stage and sex information of 4 species from their morphology, which is not possible using eDNA analysis. This study shows that the advantages of each evaluation method can complement each other.

Wellbore salt-deposition risk prediction of underground gas storage combining numerical modeling and machine learning methodology

Strengthening the construction of underground gas storage (UGS) is significant for securing national energy and achieving carbon neutrality. However, salt deposition occurs in the wellbore affecting the safety of UGS seriously. How to predict the salt-deposition risk in UGS wells accurately and quickly is still challenging. This work aims at establishing a fast and convenient framework of wellbore salt-deposition risk prediction in UGS wells. Firstly, the influence of the production parameters on wellbore salt-deposition is analyzed by an in-house simulator. Further, an intelligent diagnostic model of salt-deposition risk is proposed based on the machine learning algorithm. The effect of salt deposition on reservoir is analyzed by reservoir salt-deposition simulation model. Finally, downhole video survey is used to validate the modeling accuracy of diagnostic model. Results indicate that the contribution ratio of daily gas production and water-gas-ratio to wellbore salt deposition is 3:2. After the salt deposition, the reduction in water saturation and the permeability of near wellbore areas are 77.14 % and 98.91 %. The modeling accuracy of diagnostic model is 97 %, which is applied in the Y UGS successfully. The proposed framework can predict the salt-deposition risk of UGS wells in real time to help engineers control salt clogging issues.

An underwater imagery identification guide for shallow, mesophotic and deep-sea benthos in Maldives.

During the 2022 Nekton Maldives Mission, we deployed a variety of platforms (snorkelling, remotely-operated vehicles and manned submersibles) to conduct video surveys of the biodiversity and composition of shallow (< 30 m), mesophotic (30-150 m) and deep-sea (> 150 m) benthos found in the Maldives' central and southern atolls. In total, ~ 80 hrs of stereo-video footage were collected during the benthic transect surveys, which were subsequently processed using annotation software in order to evaluate benthic biodiversity and community composition. Here, we present a photographic guide for the visual, in situ identification of reef benthos encountered, including corals, sponges and other invertebrates that inhabit Maldives' nearshore habitats. We hope that this identification guide will aid future imagery-based surveys or observations of organisms during fieldwork. A total of 283 morphotypes were identified, including those belonging to Octocorallia (61), Scleractinia (57), Porifera (38), Asteroidea (22), Antipatharia (15), Decapoda (13), Hydrozoa (12), Holothuroidea (10), Actiniaria (9), Echinoidea (8), Annelida (6), Chlorophyta (5), Gastropoda (4), Bivalvia (4), Ascidiacea (3), Crinoidea (3), Bryozoa (2), Cyanobacteria (2), Zoantharia (2), Cephalopoda (1), Ceriantharia (1), Corallimorpharia (1), Ctenophora (1), Ophiuroidea (1), Rhodophyta (1) and to an unknown category (1). Out of these, we identified 40 to species level, 120 to genus, 47 to family, 14 to order and suborder, 58 to class and subclass, two to phylum and one was of unknown phylum. This represents the first attempt to catalogue the mesophotic and deep-sea benthic megafaunal diversity in the Maldives using underwater imagery.

Risk assessment and the use of personal protective equipment in an emergency department: Differing perspectives of emergency and infection control clinicians. A video-vignette survey

The use of personal protective equipment (PPE) in emergency departments (EDs) is an important defense during infectious disease emergencies. However, what counts as appropriate PPE in EDs is contentious and inconsistently implemented in practice. An online scenario-based video survey was distributed through purposive sampling, and completed by 270 ED and infection prevention and control clinicians in Australia. A descriptive content analysis was performed on the data, and differences between groups were tested using Fisher exact test. Participants agreed that most items were required in both scenarios. Eye protection, mask use, and hand hygiene frequency were more contentious. Physicians were more likely than nurses, and ED clinicians more likely than infection prevention and control clinicians, to regard items or actions as optional rather than essential. Many ED clinicians, particularly physicians, regarded sequences as too time-consuming to be practical in a busy ED. Our findings likely reflect differences in professional roles, competing priorities, and risks, and highlight important contextual characteristics of EDs, such as diagnostic uncertainty, equipment inaccessibility, and resource constraints. To be feasible, practicable, and thereby effective, PPE guidance in the ED must be designed collaboratively with frontline ED staff, and reflects the complexities of their practice.

Incorporating environmental factors is critical for determining conservation baselines for relative abundance of sharks on coral reefs

Populations of sharks, including those inhabiting coral reefs, have experienced dramatic global declines. Setting appropriate targets for restoring reef shark populations requires estimates of expected relative abundances in the absence of intense fishing. It is therefore important to identify factors that drive the carrying capacity of sharks in relatively intact reef systems and to determine whether expected shark abundance varies according to easy to assess variables. These variables could then be used by managers for setting restoration targets, or prioritizing resource allocation, for particular areas in the absence of detailed data. French Polynesia, the world’s largest shark sanctuary, provides a model system for addressing this question. We used baited remote underwater video surveys to assess relative abundance of sharks on 35 reefs across the broad geographic range of French Polynesia. Boosted regression tree models revealed that relative abundance of sharks varied significantly with island geomorphology. Overall, relative shark abundances at high islands were nearly 3 times lower than on atolls, and among atoll geomorphology types, open atolls had abundances nearly 20% higher than closed atolls. Island group, temperature, and net primary productivity had more limited effects. Human pressure (measured as market gravity) was not a significant factor. Although species-specific patterns varied, our findings suggest that environmental factors, particularly island geomorphology, should be taken into account when setting shark abundance recovery targets. Using this easy to assess factor can facilitate the allocation of conservation effort and improve assessments of species recovery efforts for islands in the Indo-Pacific region.

Stereo-video landers can rapidly assess marine fish diversity and community assemblages

Climate change and anthropogenic stressors affect the distribution, abundance, and diversity of fish communities across the world. To understand rapidly changing biotic communities, resource managers need a method to quickly and efficiently document temporal and spatial changes in community assemblages across various spatial scales. In this study, we describe the use of new video lander tools to survey fish communities in rocky marine habitats on the continental shelf and slope in California, USA. We evaluate how fish diversity metrics determined by video surveys vary among geographically distinct areas. Our results demonstrate that species diversity, evenness, and richness vary spatially across the coast. Furthermore, community assemblages differ at both broad and fine spatial scales because of differences among habitats. Length frequencies and densities of species in this study were similar to those reported in previous studies. As community assemblages and biodiversity metrics shift in response to changing stressors, it is increasingly important to develop tools and methodologies to detect and rapidly monitor these changes.

Environmental DNA metabarcoding for the detection of the silverlip pearl oyster (Pinctada maxima) offshore of Eighty Mile Beach in northwest Australia

Effective fishery management relies on accurate knowledge of the spatial distribution of stocks of target species to efficiently focus fishing efforts. However, the distribution and abundance of species such as the silverlip pearl oyster (Pinctada maxima) can be difficult to determine with traditional survey methods since populations are patchy, often occur in low densities, and individuals can be quite cryptic, living partially buried in sediment. Environmental DNA is increasingly used to survey marine species and has proven to be particularly useful in detecting rare or elusive organisms. Here, we compared the presence of silverlip pearl oysters detected via eDNA metabarcoding to traditional towed video surveys offshore of Eighty Mile Beach, northwest Australia. Seawater samples were collected at the end of towed video transects and sites were categorised into shallow (<40 m depth) or deep (40 m +) groups. We applied an oyster-specific 16S metabarcoding assay as well as a universal 18S assay to identify potential indicator taxa associated with the presence of pearl oysters. Using the 16S assay, we detected silverlip pearl oysters at three of the 12 sites sampled, and found that eDNA records generally matched towed video transect data, with both survey methods detecting the target species predominantly in inshore waters at depths <40 m. Our results indicate that metabarcoding of seawater eDNA can be applied to detect cryptic species of commercial importance but highlight limitations around detecting organisms at very low abundances.

The fish–mangrove link is context dependent: Tidal regime and reef proximity determine the ecological role of tropical mangroves

AbstractTropical mangroves are known to support fish production, but natural variability in the link between mangrove habitats and fish populations undermines our ability to manage, conserve and restore this ecological relationship. This is largely due to undefined context‐dependence in the use of mangroves by fish. We collected a spatially extensive dataset of 494 mangrove fish assemblages using standardised Remote Underwater Video surveys of mangrove edge habitats from five environmentally heterogenous regions in the Indo‐Pacific. We used machine learning methods to define contextual limits of the use of mangroves by reportedly mangrove‐affiliated fish. We found that tidal range and proximity to coral reefs were the most important contextual predictors of the use of mangroves by most taxa. We established data‐driven threshold values for important contextual predictors of the use of mangroves by fish, offering new insights into the variable role played by tropical mangroves in supporting fish life histories. Where mangroves occur as part of reef seascapes in regions with limited tidal range (&lt;1.5 m), they appear to serve an important juvenile habitat function for a wide spectrum of reef fish. In regions with substantially larger tidal ranges, mangroves appear to only support certain reef species with coastal life histories. Coastal and estuary fish were able to use mangroves in a wide variety of non‐reef contexts. We demonstrate that key thresholds in environmental context can govern the functional role of mangroves, with strong implications for the role of other habitats in coastal seascapes.

Nature-based solutions for coastal protection in sheltered and exposed coastal waters: integrated monitoring program for baseline ecological structure and functioning assessment

Nature-based solutions, such as shellfish reefs, can support natural coastal defence and be a potential solution for climate-resilient shorelines in the future. In the Belgian Part of the North Sea, the “Coastbusters” projects aim to develop nature-based coastal protection by favouring subtidal mussel bed establishment on the seafloor through typical longline aquaculture techniques. Mussel beds are dependent on environmental conditions, and both influence the physical and biogeochemical features in a soft-sediment environment. Therefore, a comprehensive ecological monitoring program is essential to assess the success of future mussel bed development and its influence on the surrounding ecosystem. For establishing a monitoring baseline of the two experimental areas, a combination of conventional benthic assessment methods (grab sampling and granulometry) and non-invasive techniques (sediment profile imaging and transect diving video surveys) were utilised. Although mussel reefs did not yet develop by the time of this study, clear differences in ecological and sedimentological characteristics were found between two experimental areas (sheltered and exposed), subjected to slightly different hydrodynamic conditions. The one sheltered by coastal sandbanks was dominated by fine-muddy sand, higher species richness, biomass, and higher biological activity (burrows, fauna, and biological beds) as observed by all methods in one or another way. Moreover, functional diversity indices revealed a higher partitioning of the total available resources, suggesting more complex ecological processes in the sheltered area. Conversely, the area more exposed to the open sea was dominated by more sandy sediments, and fewer organisms were found. The combination of those different monitoring tools provides an integrated, complementary view, from different perspectives, on the biological, physical and functional characteristics of the study areas.

A Quasi-Experimental Intervention Trial to Test the Efficacy of a Human Trafficking Awareness Campaign: The Blue Campaign

ABSTRACT In the United States, several government and non-governmental organizations are implementing human trafficking awareness campaigns. This study aimed to test the effectiveness of specific videos developed as part of the Blue Campaign (BC), a U.S. Department of Homeland Security initiative focused on increasing awareness about human trafficking among first responders. We implemented a quasi-experimental study design with a pre-post intervention questionnaire and a control group, using an organic-sampling-survey method. The study was conducted between September 18–22, 2021. The data were gathered from 2,006 first responders using the online survey platform Pollfish, with three awareness videos embedded in an online survey instrument. Questions related to the content of each video were incorporated in the survey tool using a pre-post video survey design. Our findings indicate that the BC videos we examined are effective in improving general awareness about human trafficking based on the specific knowledge outcomes included in the survey. Our study did not test for the accuracy of the content of the videos or for actions undertaken by first responders based on the knowledge acquired. This study is aligned with the UN Sustainable Goal of promoting just, peaceful, and inclusive societies.

The vertical distribution of fish on two offshore oil platforms

Knowledge of platform ecology is necessary to best inform decommissioning practice. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however, the utility of this video for ecological assessments remains unclear. Archival ROV video surveys at the Wandoo oil platforms on Australia’s North West Shelf was evaluated for its utility, with only 4.9% of imagery usable for standardised ecological studies. Based on the subset of usable ROV video, the influence of depth and structural complexity on attributes of the fish assemblage on the Wandoo oil platforms was examined. Vertical ROV transects on three vertical shafts on the Wandoo platforms were stratified into 10 m depth strata from 0 to 50 m, with 111 fish taxa from 25 families identified and counted across all depth strata. At both platforms, taxonomic richness and abundance was significantly highest in shallow regions and declined with depth. Small reef fish were predominantly associated with structurally complex habitat in shallow regions (&amp;lt;22 m), whilst large demersal species dominated below 32 m. Future decommissioning policy in Australia should consider the vertical fish distributions and the importance of shallow sections of platforms. Finally, the dearth of usable video was due to the haphazard method of collection and it is recommended that future surveys should be conducted according to scientific standards to ensure greater utility of the video for both industry use and scientific research.

Low diversity and abundance of predatory fishes in a peripheral coral reef ecosystem.

Semi-enclosed seas are often associated with elevated local threats and distinct biogeographic patterns among marine fishes, but our understanding of how fish assemblage dynamics vary in relation to relatively small semi-enclosed seas (e.g., the Gulf of Aqaba) remains limited. Baited remote underwater video surveys (n = 111) were conducted across ~300 km of coral reef habitats in the Gulf of Aqaba and the northern Red Sea. A total of 55 predatory fish species were detected, with less than half of all species (n = 23) observed in both basins. Relative abundance patterns between the Gulf of Aqaba and the northern Red Sea were variable among taxa, but nearly twice as many predatory fish were observed per unit of effort in the northern Red Sea. In general, assemblages in both basins were dominated by three taxa (Epinephelinae, Carangidae, and Lethrinidae). Large-bodied and threatened species were recorded at very low abundances. Multivariate analysis revealed distinct assemblage structuring of coral reef predators between the Gulf of Aqaba and the northern Red Sea. Most of the species driving these differences were recorded in both basins, but occurred at varying levels of abundance. Environmental factors were largely unsuccessful in explaining variation in assemblage structuring. These findings indicate that biological assemblages in the Gulf of Aqaba are more distinct than previously reported and that reef fish assemblage structuring can occur even within a relatively small semi-enclosed sea. Despite inter-basin assemblage structuring, the overall low abundance of vulnerable fish species is suggestive of overexploitation in both the Gulf of Aqaba and the northern Red Sea of Saudi Arabia. As the region surveyed is currently undergoing large-scale coastal development, the results presented herein aim to guide spatial management and recovery plans for these coral reef systems in relation to this development.