Search

Shark depredation, whereby hooked fish are partially or completely consumed before they can be retrieved, occurs globally in commercial and recreational fisheries. Depredation can damage fishing gear, injure sharks, cause additional mortality to targeted fish species and result in economic losses to fishers. Knowledge of the mechanisms behind depredation is limited. We used a 13 yr dataset of fishery-dependent commercial daily logbook data for the Mackerel Managed Fishery in Western Australia, which covers 15° of latitude and 10000 km of coastline, to quantify how fishing effort and environmental variables influence depredation. We found that shark depredation rates were relatively low in comparison with previous studies and varied across the 3 management zones of the fishery, with 1.7% of hooked fish being depredated in the northern Zone 1, 2.5% in the central Zone 2 and 5.7% in the southern Zone 3. Generalized additive mixed models found that measures of commercial fishing activity and a proxy for recreational fishing effort (distance from town centre) were positively correlated with shark depredation across Zones 1 and 2. Depredation rates increased during the 13 yr period in Zones 2 and 3, and were higher at dawn and dusk, suggesting crepuscular feeding in Zone 1. This study provides one of the first quantitative assessments of shark depredation in a commercial fishery in Western Australia, and for a trolling fishery globally. The results demonstrate a correlation between fishing effort and depredation, suggesting greater fishing effort in a concentrated area may change shark behaviour, leading to high rates of depredation.

Offshore Oil and Gas (O&G) infrastructure affords structurally complex hard substrata in otherwise featurless areas of the seafloor. Opportunistically collected industrial ROV imagery was used to investigate the colonization of a petroleum platform in the North Sea 1–2 years following installation. Compared to pre-construction communities and pioneering colonizers, we documented 48 additional taxa, including a rare sighting of a pompano (Trachinotus ovatus). The second wave of motile colonizers presented greater diversity than the pioneering community. Occurrence of species became more even over the 2 years following installation, with species occurring in more comparable abundances. No on-jacket sessile taxa were recorded during first-wave investigations; however, 17 sessile species were detected after 1 year (decreasing to 16 after 2). Motile species were found to favour structurally complex sections of the jacket (e.g. mudmat), while sessile organisms favoured exposed elements. Evidence of on-jacket reproduction was found for two commercially important invertebrate species - common whelk (Buccinum undatum) and European squid (Loligo vulgaris). Moreover, abundance of larvae-producing species experience an 8.5-fold increase over a 2-year period compared to baseline communities. These findings may have implications for decommissioning and resource-management strategies, suggesting that a case-by-case reviewing approach should be favoured over the most common “one size fits all”.

In recent years, video footage obtained from routine industry surveys using remotely operated vehicles (ROVs) has been used to assess fish assemblages associated with offshore oil and gas infrastructure. However, as industry moves towards using autonomous underwater vehicles (AUVs), it is important to understand how such a change may affect assessments of fish assemblages and whether these data collected from AUVs can be directly compared to those collected from historic and future ROV footage. In an extremely rare opportunity, we compare fish assemblages surveyed by an industrial ROV and an industrial hybrid-AUV (H-AUV) along the same 2,060-m section of subsea pipeline, at the same time of day, within 1 day of each other. A total of 206 transects, each 20 m in length, were analyzed, recording 406 fish from 10 species. The H-AUV recorded all 10 fish species, while the ROV recorded seven. Mean species richness was ~4% higher for H-AUV, and mean abundance was ~21% higher for ROV; these differences can be considered negligible. Multivariate analysis revealed nonsignificant differences in species composition between survey methods. This result suggests that future surveys of fish at this pipeline using a similar H-AUV can yield comparable results to ROV and, as such, facilitate comparison to historical ROV imagery. Future surveys of pipelines with AUV should consider adding extra lighting and high-definition cameras onto booms similar to those operating on ROVs, which will provide a useful field of view into pipeline spans and make it easier to identify fish. Our study provides insight into the utility and comparability of industry ROV and AUV pipeline inspection footage for the assessment of fish assemblages associated with subsea pipelines, which is used to inform policies and practices on the installation and decommissioning of subsea infrastructure.

Offshore platforms, subsea pipelines, wells and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. Although structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes remains unclear. Here, we review the current state of knowledge on the role of O&G infrastructure in maintaining, altering or enhancing ecological connectivity with natural marine habitats. There is a paucity of studies on the subject with only 33 papers specifically targeting connectivity and O&G structures, although other studies provide important related information. Evidence for O&G structures facilitating vertical and horizontal seascape connectivity exists for larvae and mobile adult invertebrates, fish and megafauna; including threatened and commercially important species. The degree to which these structures represent a beneficial or detrimental net impact remains unclear, is complex and ultimately needs more research to determine the extent to which natural connectivity networks are conserved, enhanced or disrupted. We discuss the potential impacts of different decommissioning approaches on seascape connectivity and identify, through expert elicitation, critical knowledge gaps that, if addressed, may further inform decision making for the life cycle of O&G infrastructure, with relevance for other industries (e.g. renewables). The most highly ranked critical knowledge gap was a need to understand how O&G structures modify and influence the movement patterns of mobile species and dispersal stages of sessile marine species. Understanding how different decommissioning options affect species survival and movement was also highly ranked, as was understanding the extent to which O&G structures contribute to extending species distributions by providing rest stops, foraging habitat, and stepping stones. These questions could be addressed with further dedicated studies of animal movement in relation to structures using telemetry, molecular techniques and movement models. Our review and these priority questions provide a roadmap for advancing research needed to support evidence-based decision making for decommissioning O&G infrastructure.

Inherent differences between baited remote video versus diver-operated video survey methodologies may influence their ability to detect effects of fishing. Here the ability of no-take zones (NTZs) to provide protection for legal-sized fish from targeted species within the Ningaloo Marine Park (NMP) was assessed using both baited remote underwater stereo-video (stereo-BRUV) and diver operated stereo-video (stereo-DOV). The relative abundance of legal-sized individuals of three recreationally targeted fish species, spangled emperor Lethrinus nebulosus, chinaman cod Epinephelus rivulatus and goldspotted trevally Carangoides fulvoguttatus, were examined using both methodologies inside and outside six NTZs across the NMP. Stereo-BRUVs found positive effects of protection on the relative abundance of legal-size C. fulvoguttatus and L. nebulosus in NTZs. Stereo-DOVs, however, did not detect any differences in relative abundances and sizes of these species between areas opened and closed to fishing. These contrasting results suggest that choice of sampling methodology can influence interpretations of the ability of NTZs to provide adequate levels of protection for target species. Thus it is suggested to further investigate the ability of stereo-BRUVs and stereo-DOVs to observe differences in the abundance of targeted species inside and outside of NTZs for the long-term monitoring of the NMP.

Over 1400 km of oil and gas pipeline infrastructure exists within the boundaries of the Pilbara Trap Managed Fishery (PTMF) operating on the North West Shelf of Australia. Some of this infrastructure has reached the end of its operational life and requires decommissioning. Location and speed data collected from 2008 to 2018 using vessel monitoring systems onboard all trap fishing vessels (n = 3) operating in the PTMF were used to understand how fishing activity near pipelines has changed through time, and to identify the best predictive variables to explain hours spent fishing km−2 week−1. The proportion of fishing activity within 200 m of a pipeline increased over the survey decade and averaged 4.2% across all years. Hours spent fishing km−2 within 200 m of any pipeline was found to be 8.0 h km−2, ~ 11.4 times more than that recorded, on average, for the remaining area of the PTMF (0.7 h km−2), and ~ 4.6 times more than the western portion of the PTMP (1.7 h km−2) where all pipeline infrastructure exists. Fishing activity within 1 km of pipelines increased after their installation, and hence time since installation was the best predictor of fishing. This study demonstrated that trap fishers in the PTMF allocate a small proportion of their time targeting pipeline infrastructure, with the area close to a pipeline experiencing a relatively greater magnitude of fishing than that elsewhere in the PTMF. As such, the results of this study provide decision makers with an understanding of the intrinsic value of this infrastructure to trap fishers.

International audience; Few studies assess the effects of recreational fishing in isolation from commercial fishing. We used meta-analysis to synthesise 4444 samples from 30 years (1987–2017) of fish surveys inside and outside a large network of highly protected reserves in the Ningaloo Marine Park, Western Australia, where the major fishing activity is recreational. Data were collected by different agencies, using varied survey designs and sampling methods. We contrasted the relative abundance and biomass of target and non-target fish groups between fished and reserve locations. We considered the influence of, and possible interactions between, seven additional variables: age and size of reserve, one of two reserve network configurations, reef habitat type, recreational fishing activity, shore-based fishing regulations and survey method. Taxa responded differently: the abundance and biomass inside reserves relative to outside was higher for targeted lethrinids, while other targeted (and non-targeted) fish groups were indistinguishable. Reef habitat was important for explaining lethrinid response to protection, and this factor interacted with reserve size, such that larger reserves were demonstrably more effective in the back reef and lagoon habitats. There was little evidence of changes in relative abundance and biomass of fishes with reserve age, or after rezoning and expansion of the reserve network. Our study demonstrates the complexities in quantifying fishing effects, highlighting some of the key factors and interactions that likely underlie the varied results in reserve assessments that should be considered in future reserve design and assessment.

This work was carried out under animal ethics approval from The University of Western Australia (approval number F 18979). We thank Terry Maxwell and Robert Perrett, the skippers of 'Osso Blue' and 'Blue Horizon', respectively, for their assistance with collection of video footage, and for providing detailed information on shark interactions with fishing vessels. Thanks also to the deckhands of these vessels and to all of the recreational fishers who assisted with collection of video footage. We also thank Rory McAuley from the Western Australia Department of Primary Industries and Regional Development, for shark identification. Todd Bond and Michael Taylor from The University of Western Australia and Glenn Moore from the Western Australia Museum assisted with teleost fish identification. Two anonymous reviewers helped improve the manuscript. The research was financially supported by the Jock Clough Marine Foundation and the Western Australia Government's Recreational Fishing Initiatives Fund (project number 2016/08), which was administered by the Department of Primary Industries and Regional Development and Recfishwest. J. D. M. was funded by the Australian Federal Government and The University of Western Australia, through an Australian Postgraduate Award and an International Research Training Program (RTP) Stipend Scholarship, respectively.

Scientists, industry and regulators are seeking to understand the influence of oil and gas infrastructure in our oceans to mitigate its impacts and maximise environmental benefits. This project equipped a standard work-class ROV with a light-weight stereo-video camera system to collect high definition imagery of fish and habitats formed by marine growth associated with Woodside Energy's Goodwyn Alpha Platform jacket (GWA) 138 km offshore of Dampier, north-west Australia. ROV video surveys were rapidly performed by industry on four faces of the GWA jacket, from the surface to the seabed at 130 m, yielding 1 h and 14 min of imagery. The stereo-video cameras continued to film during standard ROV operations collecting a further 150 h of HD imagery, used to build a comprehensive fish species list. A total of 8676 individual fish from at least 57 species and 20 families, with an estimated combined mass of 8719 kg, were recorded from the vertical transects of four faces of the jacket. An additional 43 fish species from 21 families were recorded via rapid assessment of a subset of the additional, standard ROV operations imagery. The jacket was characterised by abundant Caranx sexfasciatus (bigeye trevally), Pseudanthias spp. (basslets), Heniochus diphreutes (schooling bannerfish), Labridae sp. (wrasse) and Acanthurus spp. (surgeonfish). Several fish important to the demersal scalefish fishery in the region were observed, including: Lutjanus argentimaculatus (mangrove jack), Lutjanus erythropterus (crimson snapper), Lutjanus malabaricus (saddletail snapper), Lutjanus russellii (Moses' snapper). Eleven broad marine growth types were observed with encrusting/enveloping species (brown algae, filamentous mat, coralline algae, calcite) and hard corals (Tubastrea sp.) present in the greatest coverage. Both marine growth and fish assemblages changed markedly with depth. The addition of a lightweight stereo-video system to an industrial ROV and the allocation of short amounts of time for rapid vertical surveys provided important information on the ecology of an oil and gas platform jacket. Future industrial ROV campaigns should consider utilising this approach to gather scientific information that may have value in the context of decommissioning comparative assessments and, more generally, improves our understanding of the impact of oil and gas infrastructure in our oceans.

Understanding the ecology of oil and gas infrastructure in our oceans is required to inform decommissioning such that environmental impacts are minimised, and benefits maximised. This study equipped an industrial remotely operated vehicle (ROV) with a stereo-video system and collected seven hours of high-definition imagery of two platform jackets, for assessments of benthic (type, density, complexity) and fish assemblages (richness, abundance, length) present. Harriet Alpha (25 m depth) and Gibson/South Plato (8 m depth) are located ca. 120 km offshore of north-west Australia, adjacent to Varanus Island. Twenty-one ‘classes’ of benthic biota were observed in high density, with little bare structure on either platform. Encrusting sponges (average 19% cover per virtual quadrat), barnacles (17%) and sponges (16%) were common on Gibson/South Plato while encrusting sponges (16%) and macroalgae (18%) were ubiquitous on quadrats on Harriet Alpha. The sun coral Tubastraea faulkneri was common on Harriet Alpha (38% of quadrats), though coverage was low (

Marine fisheries in coastal ecosystems in many areas of the world have historically removed large-bodied individuals, potentially impairing ecosystem functioning and the long-term sustainability of fish populations. Reporting on size-based indicators that link to food-web structure can contribute to ecosystem-based management, but the application of these indicators over large (cross-ecosystem) geographical scales has been limited to either fisheries-dependent catch data or diver-based methods restricted to shallow waters (20 m) that can misrepresent the abundance of large-bodied fished species. We obtained data on the body-size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo-video (stereo-BRUV). Sampling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No-take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal-size fishes typically declined as human impact increased. Our large-scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no-take marine reserves in protecting large-bodied fishes across a broad range of species and ecosystem configurations.Las pesquerías marinas de los ecosistemas costeros en muchas áreas del mundo históricamente han removido a individuos de gran tamaño, potencialmente perjudicando el funcionamiento ambiental y la sostenibilidad a largo plazo de las poblaciones de peces. Los reportes sobre los indicadores basados en el tamaño que se vinculan con la estructura de la red alimenticia pueden contribuir al manejo basado en el ecosistema, aunque la aplicación de estos indicadores a grandes (inter-ecosistemas) escalas geográficas ha estado limitada a datos de captura dependientes de las pesquerías o métodos basados en el buceo restringidos a aguas someras (20 m), lo cual puede representar erróneamente la abundancia de peces de gran tamaño capturados para la pesca. Obtuvimos los datos de la estructura del tamaño corporal de 82 teleósteos marinos demersales focalizados por razones recreativas o comerciales tomados de 2,904 despliegues de video estéreo subacuático remoto con cebo (stereo-BRUV, en inglés). El muestreo se realizó hasta los 50 metros de profundidad y abarcó aproximadamente 10,000 km del talud continental de Australia. El relieve marino, la profundidad del agua y la gravedad humana (es decir, un indicador de los impactos humanos) fueron los pronosticadores más sólidos de la probabilidad de incidencia de los peces de gran tamaño y de la abundancia de peces por encima del tamaño legal mínimo de captura. Las reservas marinas de protección total tienen un efecto positivo sobre la abundancia de los peces que están por encima del tamaño legal, aunque el efecto varió según el grupo de especies. Como contraste, los peces de tamaño sublegal fueron pronosticados de mejor manera usando gradientes de la temperatura de la superficie marina (media y varianza). En las áreas con un impacto humano reducido, los peces de gran tamaño corporal tenían hasta tres veces mayor probabilidad de aparecer y los peces de tamaño legal eran aproximadamente cinco veces más abundantes. Para los grupos de especies conspicuas con afinidades contrastantes de hábitat, ambiente y biogeografía, la abundancia de peces de tamaño legal normalmente declinó conforme aumentó el impacto humano. Nuestros análisis cuantitativos a gran escala resaltan la importancia conjunta que tienen la complejidad marina, las regiones con una huella humana reducida y las reservas marinas de protección total para la protección de los peces de gran tamaño corporal en una extensa gama de especies y configuraciones ecosistémicas. Efectos de la Huella Humana y los Factores Biofísicos sobre la Estructura del Tamaño Corporal de Especies Marinas Capturadas para la Pesca.

Marine reserves are a key tool for the conservation of marine biodiversity, yet only ~2.5% of the world's oceans are protected. The integration of marine reserves into connected networks representing all habitats has been encouraged by international agreements, yet the benefits of this design has not been tested empirically. Australia has one of the largest systems of marine reserves, providing a rare opportunity to assess how connectivity influences conservation success. An Australia‐wide dataset was collected using baited remote underwater video systems deployed across a depth range from 0 to 100 m to assess the effectiveness of marine reserves for protecting teleosts subject to commercial and recreational fishing. A meta‐analytical comparison of 73 fished species within 91 marine reserves found that, on average, marine reserves had 28% greater abundance and 53% greater biomass of fished species compared to adjacent areas open to fishing. However, benefits of protection were not observed across all reserves (heterogeneity), so full subsets generalized additive modelling was used to consider factors that influence marine reserve effectiveness, including distance‐based and ecological metrics of connectivity among reserves. Our results suggest that increased connectivity and depth improve the aforementioned marine reserve benefits and that these factors should be considered to optimize such benefits over time. We provide important guidance on factors to consider when implementing marine reserves for the purpose of increasing the abundance and size of fished species, given the expected increase in coverage globally. We show that marine reserves that are highly protected (no‐take) and designed to optimize connectivity, size and depth range can provide an effective conservation strategy for fished species in temperate and tropical waters within an overarching marine biodiversity conservation framework., An Australia‐wide dataset was collected using baited remote underwater video systems deployed across a depth range from 0 to 100 m to assess the effectiveness of marine reserves for protecting fished species. A meta‐analytical comparison of 73 fished species within 91 marine reserves found that, on average, marine reserves had 28% greater abundance and 53% greater biomass of fished species compared to adjacent areas open to fishing. We show that marine reserves that are highly protected (no‐take) and designed to optimize connectivity, size and depth range can provide an effective conservation strategy for fished species in temperate and tropical waters.

Made available in DSpace on 2021-06-25T12:19:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-24 Australian Government's National Environmental Science Program Australian Research Data Commons GorgonBarrow Island Gorgon Barrow Island Net Conservation Benefits Fund Baited remote underwater stereo-video systems (stereo-BRUVs) are a popular tool to sample demersal fish assemblages and gather data on their relative abundance and body size structure in a robust, cost-effective and non-invasive manner. Given the rapid uptake of the method, subtle differences have emerged in the way stereo-BRUVs are deployed and how the resulting imagery is annotated. These disparities limit the interoperability of datasets obtained across studies, preventing broadscale insights into the dynamics of ecological systems. We provide the first globally accepted guide for using stereo-BRUVs to survey demersal fish assemblages and associated benthic habitats. Information on stereo-BRUVs design, camera settings, field operations and image annotation are outlined. Additionally, we provide links to protocols for data validation, archiving and sharing. Globally, the use of stereo-BRUVs is spreading rapidly. We provide a standardized protocol that will reduce methodological variation among researchers and encourage the use of Findable, Accessible, Interoperable and Reusable workflows to increase the ability to synthesize global datasets and answer a broad suite of ecological questions. Univ Western Australia, UWA Oceans Inst, Perth, WA, Australia Univ Western Australia, Sch Biol Sci, Perth, WA, Australia Dept Biodivers Conservat & Attract, Marine Sci Program, Biodivers & Conservat Sci, Kensington, WA, Australia Curtin Univ, Sch Mol & Life Sci, Perth, WA, Australia Univ Tasmania, Inst Marine & Antarctic Studies, Hobart, Tas, Australia Silliman Univ, Angelo King Ctr Res & Environm Management, Dumaguete, Philippines NOAA Inouye Reg Ctr, NOAA Fisheries, Pacific Isl Fisheries Sci Ctr, Sci Operat Div, Honolulu, HI USA Univ Hawaii Manoa, Joint Inst Marine & Atmospher Res, Honolulu, HI 96822 USA South African Inst Aquat Biodivers, Grahamstown, South Africa Rhodes Univ, Dept Zool & Entomol, Grahamstown, South Africa Univ St Andrews, Ctr Res Ecol & Environm Modelling, Sch Math & Stat, St Andrews, Fife, Scotland Indian Ocean Marine Res Ctr, Australian Inst Marine Sci, Perth, WA, Australia Australian Inst Marine Sci, Townsville, Qld, Australia Govt Western Australia, Western Australian Fisheries & Marine Res Labs, Dept Primary Ind & Reg Dev, North Beach, WA, Australia NSW Dept Primary Ind, Fisheries Res, Taylors Beach, NSW, Australia Dept Environm & Water, Marine Sci Program, Sci & Corp Serv Div, Adelaide, SA, Australia Flinders Univ S Australia, Southern Shark Ecol Grp, Coll Sci & Engn, Bedford Pk, SA, Australia Deakin Univ, Sch Life & Environm Sci, Ctr Integrat Ecol, Warrnambool, Vic, Australia NSW Dept Primary Ind, Fisheries Res, Huskisson, NSW, Australia Coral Reef Res Fdn, Koror, Palau NSW Dept Primary Ind, Fisheries Res, Coffs Harbour, NSW, Australia Ctr Environm Fisheries & Aquaculture Sci, Lowestoft, Suffolk, England Sao Paulo State Univ, Elasmobranch Res Lab, Inst Biosci, Sao Vicente, SP, Brazil Massey Univ, Sch Nat & Computat Sci, Auckland, New Zealand Sao Paulo State Univ, Elasmobranch Res Lab, Inst Biosci, Sao Vicente, SP, Brazil

In 2011, the enigma of "mystery circles," small but complex underwater structures first observed by divers from southern Japan in 1995, was solved when a new species of pufferfish, white-spotted pufferfish (Torquigener albomaculosus Matsuura 2014), was identified as the responsible agent. To date these circles have been described only from Japan, where they are formed on a sandy seafloor in water depths less than 30 m. A survey of oil field infrastructure on the North West Shelf of Western Australia in 2018 using a remotely operated vehicle and hybrid autonomous underwater vehicle (HAUV) recorded a high-resolution video and bathymetric data of 21 circular formations with similar features to those described in Japan. The circles display dimensions and morphology like those described from Japan, but were observed in water depths between 129 and 137 m. The HAUV also recorded high-resolution photographs which captured a Torquigener sp. fish in the immediate vicinity of the circles. An additional circle and Torquigener sp. were observed in images collected by baited remote underwater stereo-video in a nearby location in 129 m depth. These circles are the first to be found in Australia. The pufferfish species responsible cannot be identified from images collected. Such a discovery not only generates intrigue and wonder among scientists and the general public but also provides an insight into the reproductive behaviour and evolution of pufferfish globally.

Nocturnal studies of fish assemblages are relatively rare, particularly at depths greater than 100 m, despite the relevance of diel shifts in habitat usage to fisheries management. This study assesses fish diversity and abundance from remotely operated vehicle (ROV) video recordings that were collected by industry during the day and at night in the course of a subsea pipeline survey, at 130 m depth. A total of 34,862 fish from 41 species and 25 families were recorded along the 23 km of pipeline. The pipeline was characterised by a high abundance of commercially important snapper (Lutjanidae) and grouper (Epinephelidae) species. The fish assemblage sampled along the pipeline during the day differed markedly to that sampled at night time. Several ubiquitous predatory species, e.g. Epinephelus areolatus, Lutjanus quinquelineatus, Lutjanus russellii, where present during the day but not at night, likely moving off the pipeline to feed in nearby habitats. Structurally complex mesophotic epibenthic habitat forming invertebrates were observed on the pipeline including; mesophotic corals, crinoids (featherstars), gorgonocephalids (basket stars), hydroids, true anemones and sponges, but elsewhere in the region, historical trawling effort is thought to have removed such organisms and extensively modified the original habitat. These complex epibenthic habitats were considered to be important to commercial target species and the modification or loss of these habitats is thought to have negatively impacted the valuable commercial fisheries in the region. This study suggests pipelines can offer a significant epibenthic habitat and refuge for fish, potentially comparable to the historical habitats lost to trawling. Fish diversity and abundance was observed to be consistently greater where a gap/crevice existed beneath the pipeline and many species were frequently observed in conjunction with the complex invertebrate matrix above the pipeline, under spanning sections beneath the pipeline and at the pipeline-sediment interface, regardless of time of day. Further dietary analysis, spatially explicit fisheries modelling and off-pipeline surveys on the natural seafloor are required to further investigate the ecological value of pipelines and its influence in fish behaviour. The study builds knowledge of mesophotic coastal fish ecology and will help to inform discussions regarding the ecological and fisheries implications of decommissioning and the removal of subsea infrastructure.

Shark depredation, where a shark partially or completely consumes an animal caught by fishing gear before it can be retrieved to the fishing vessel, occurs in commercial and recreational fisheries worldwide, causing a range of negative biological and economic impacts. Despite this, it remains relatively understudied compared to other fisheries issues. This is the first review of the literature relating to shark depredation, which also includes an overview of the potential mechanisms underlying its occurrence and options for mitigation. Furthermore, this review highlights key research gaps that remain to be investigated, thereby providing impetus for future research. In total, 61 studies have been published between 1955 and 2018, which include information on shark depredation. These studies recorded quantitative rates of depredation between 0.9 and 26% in commercial and recreational fisheries and during research fishing, identified 27 shark species from seven families that were responsible for depredation and discussed potential factors influencing its occurrence. Information from research into bycatch mitigation and the testing of shark deterrent approaches and technologies is also presented, in the context of applying these approaches to the reduction of shark depredation. This review presents an holistic overview of shark depredation in fisheries globally and, in doing so, provides a central resource for fisheries researchers and managers focusing on this topic to stimulate further collaborative research on this important fisheries issue.

When production ceases, offshore oil and gas wells are taken out of service which involves safely plugging, abandoning and usually removing most of the associated subsea equipment. This process must consider impacts to marine ecosystems to meet regulatory requirement and for best environmental practice. However, there is a paucity of information globally on the ecosystem value of these structures, despite the many thousands that are installed throughout our oceans. This study provides the first assessment of fish assemblages and habitats formed by colonising invertebrates on oil and gas wellheads and associated infrastructure in depths of 78–825 m on the north west shelf of Western Australia. Video footage was obtained from Remotely Operated Vehicles deployed by industry on 25 wellhead structures, with six surveyed in each of four distinct depth zones: 78–85 m, 125–135 m, 350–395 m and 490–550 m, and one in 825 m depth. A total of 7278 individual fish from 60 species and 35 families were observed. Commercially important lutjanid (snapper) and epinephelid (grouper) species were common and most abundant on well infrastructure to depths of 135 m, but were absent in depths > 350 m. An as yet unidentified species of roughy, recorded here as Gephyroberyx sp. was the most common fish species observed on well infrastructure in depths > 350 m. Two speckled swellsharks (Cephaloscyllium speccum), believed to be endemic to north-west Australia, were observed for the first time in situ. Numerous fish species were observed at depths beyond their known limits and two IUCN vulnerable species were recorded: the grey nurse shark (Carcharias taurus; 135 m depth) and the round ribbontail ray (Taeniura meyeni; 78 m depth). Fish assemblages and colonising invertebrate habitats present on wellheads and associated infrastructure were strongly influenced by depth, age and height of the structures. Older, taller wellheads in depths 100 m, or about wellheads as a type of subsea structure, this study demonstrates the ecological value of ROV footage obtained during industry operations and is indicative of the importance of subsea oil and gas infrastructure as a habitat for fish, and potentially as structures with value to fisheries.

This study was funded by the Chevron-operated Wheatstone Project's State Environmental Offsets Program and administered by the Department of Biodiversity, Conservation and Attractions. The Wheatstone Project is a joint venture between Australian subsidiaries of Chevron, Kuwait Foreign Petroleum Exploration Company (KUFPEC), Woodside Petroleum Limited and Kyushu Electric Power Company, together with PE Wheatstone Pty Ltd (part owned by TEPCO). Funding support was also received from the Gorgon Barrow Island Net Conservation Benefits Fund, which is administered by the Department of Biodiversity, Conservation and Attractions. Thank you to Helen Chedzey and Mark Broomhall from the Remote Sensing and Satellite Research Group at Curtin University for generating and providing the remotely sensed total suspended solids data for this study.

The authors thank all of the recreational fishers interviewed throughout the boat ramp surveys, without whom the study would not have been possible. Gratitude is also extended to the Department of Biodiversity Conservation and Attractions, Government of Western Australia, for supplying boat ramp visitation data, and to the US National Oceanic and Atmospheric Administration for providing SST data for this study. Peter Barnes from the Department of Biodiversity Conservation and Attractions provided local support and information relating to the fishery and the Ningaloo Marine Park. Thanks also go to Claire Smallwood and Karina Ryan from The Department of Primary Industries and Regional Development, Government of Western Australia, for their advice on boat ramp survey design. Brett Molony and Stephen Newman from the Department of Primary Industries and Regional Development also provided important background information on the recreational and commercial fisheries in this region, as well as useful feedback on the manuscript. Matias Braccini is thanked for offering guidance on the statistical analysis conducted in this study. Matt Gillett and Leyland Campbell from Recfishwest provided information on recreational fishing in Western Australia. Lastly, the authors thank Rory McAuley, Alastair Harry and Hannah Zilles from The Department of Primary Industries and Regional Development, Government of Western Australia, as well as 3 other anonymous reviewers, for providing feedback on the manuscript. This study was funded by the Australian Federal Government and The University of Western Australia, through an International Postgraduate Research Scholarship and Australian Postgraduate Award for J.D.M, with additional funding also received from the Jock Clough Marine Foundation.

Baited remote underwater stereo-video systems (stereo-BRUVs) are commonly used to sample fish assemblages across areas of differing fish densities with little consideration of how intraspecific and interspecific behaviours may influence estimates of abundance and body-size distribution. To investigate these potential biases, the current study compared the abundances and body-size distributions of seven target carnivorous species and six lower trophic level non-target species, across sites with high and low densities of large-bodied target species, using Stereo-BRUVs. Samples were collected inside and outside of an area closed to fishing at the Houtman Abrolhos Islands, Western Australia. Densities of large-bodied target species were found to be higher inside the closed fishery area, compared to similar areas outside. The presence of large-bodied target species did not appear to influence the body-size distribution of conspecifics, or the abundance and body-size distribution of small-bodied non-target species throughout the deployments. The abundance of large-bodied target species was found to peak earlier in deployments within the closed area than the areas open to fishing. This difference may be due to the higher relative density with the closed area, which may result in shorter arrival times as fish move towards the baited video, and/or to behavioural differences, as fish within the closed area may approach the baited video more readily. This potential behavioural difference between areas closed and open to fishing has important implications for duration of baited video sampling times, and we suggest that shorter deployments times (

Dredging can have significant impacts on benthic marine organisms through mechanisms such as sedimentation and reduction in light availability as a result of increased suspension of sediments. Phototrophic marine organisms and those with limited mobility are particularly at risk from the effects of dredging. The potential impacts of dredging on benthic species depend on biological processes including feeding mechanism, mobility, life history characteristics (LHCs), stage of development and environmental conditions. Environmental windows (EWs) are a management technique in which dredging activities are permitted during specific periods throughout the year; avoiding periods of increased vulnerability for particular organisms in specific locations. In this review we identify these critical ecological processes for temperate and tropical marine benthic organisms; and examine if EWs could be used to mitigate dredging impacts using Western Australia (WA) as a case study. We examined LHCs for a range of marine taxa and identified, where possible, their vulnerability to dredging. Large gaps in knowledge exist for the timing of LHCs for major species of marine invertebrates, seagrasses and macroalgae, increasing uncertainty around their vulnerability to an increase in suspended sediments or light attenuation. We conclude that there is currently insufficient scientific basis to justify the adoption of generic EWs for dredging operations in WA for any group of organisms other than corals and possibly for temperate seagrasses. This is due to; 1) the temporal and spatial variation in the timing of known critical life history stages of different species; and 2) our current level of knowledge and understanding of the critical life history stages and characteristics for most taxa and for most areas being largely inadequate to justify any meaningful EW selection. As such, we suggest that EWs are only considered on a case-by-case basis to protect ecologically or economically important species for which sufficient location-specific information is available, with consideration of probable exposures associated with a given mode of dredging.

Dredging can have significant impacts on aquatic environments, but the direct effects on fish have not been critically evaluated. Here, a meta-analysis following a conservative approach is used to understand how dredging-related stressors, including suspended sediment, contaminated sediment, hydraulic entrainment and underwater noise, directly influence the effect size and the response elicited in fish across all aquatic ecosystems and all life-history stages. This is followed by an in-depth review summarizing the effects of each dredging-related stressor on fish. Across all dredging-related stressors, studies that reported fish mortality had significantly higher effect sizes than those that describe physiological responses, although indicators of dredge impacts should endeavour to detect effects before excessive mortality occurs. Studies examining the effects of contaminated sediment also had significantly higher effect sizes than studies on clean sediment alone or noise, suggesting additive or synergistic impacts from dredging-related stressors. The early life stages such as eggs and larvae were most likely to suffer lethal impacts, while behavioural effects were more likely to occur in adult catadromous fishes. Both suspended sediment concentration and duration of exposure greatly influenced the type of fish response observed, with both higher concentrations and longer exposure durations associated with fish mortality. The review highlights the need for in situ studies on the effects of dredging on fish which consider the interactive effects of multiple dredging-related stressors and their impact on sensitive species of ecological and fisheries value. This information will improve the management of dredging projects and ultimately minimize their impacts on fish.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Fishing has had a profound impact on global reef shark populations, and the absence or presence of sharks is strongly correlated with national socio-economic conditions and reef governance. Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status(1,2). Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats(3). Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.

Artificial illumination is required when sampling with baited remote underwater video systems (BRUVS) in the lower mesophotic zone beyond ~ 90 m depth, yet little is known of how the choice of lighting influences fish assemblages and affects survey results in this zone. Here we use BRUVS equipped with the commonly used GoPro action camera to compare the composition and abundance of diurnal fish assemblages sampled under artificial Royal blue (~ 450 nm), Deep red (~ 660 nm) and natural day white light (~ 5600 K) in the lower mesophotic zone of the north-west shelf of Australia (19° 14.724′S 117° 20.286′E). No significant differences were detected in the fish assemblage composition or the number of species when surveyed using blue, red or white light at our study location. A greater mean total abundance of fish was observed using red light compared with white and blue light, however, individual species showed varied responses to the different light colours. When using consumer-grade action cameras such as GoPros, white light was shown to be far superior in image quality (and therefore ease of fish identification) compared to red and blue light. We recommend sampling diurnal mesophotic fish assemblages using a wavelength of light based on the survey objectives and the capabilities of the camera selected.

Baited remote underwater stereo-video systems (BRUVs) are being adopted globally as a sampling method for surveying fish assemblages. The literature demonstrates that researchers are using different deployment times, rarely with justification for the time chosen. We aimed to determine the optimal deployment time of BRUVs to sample reef fish assemblages in temperate, sub-tropical and tropical locations along the west coast of Australia. Observations of fish species richness and abundance were compared between deployment periods of 0–15, 15–30, 30–45 and 45–60 min duration. Within the subtropical and tropical locations there was no significant difference in the composition of the fish assemblage beyond 15–30 and 30–45 min respectively, suggesting 30 and 45 min would be suitable. Whereas within the warm temperate location, fish assemblages differed across all deployment periods with at least 60 min required to best characterise the fish assemblage. Most species (60–71%) and individuals (50–75%) were observed within 15 min at all locations and trends in the arrival times of individual species proved to be variable and species-specific. Critically, some larger-bodied target species continued to arrive in high proportions up to 45–60 min at all locations. Despite differences in optimal deployment durations between locations, we recommend that 60 min of imagery be collected as the cost of collecting, storing and annotating the extra imagery is minimal in comparison to the full costs of a program or recollecting imagery. Researchers may choose to analyse the first 30 or 45 min of imagery if sampling subtropical or tropical fish assemblages, yet the full 60 min is available should there be a need for standardised soak times to address questions involving spatial and temporal data collected by different users.

Many marine fish populations have declined due to the individual or cumulative impacts of increasing water temperatures, ocean acidification, overfishing and other human-induced impacts such as land run-off, dredging and habitat alteration. Some solutions may be offered by ecosystem-based fisheries and conservation management. However, understanding their effectiveness relies on the availability of good quality data on the size distributions and abundance of fish populations and assemblages, collected at appropriate temporal and spatial scales. Since the early 2000s, baited remote underwater video systems (BRUVs) have become a popular tool for collecting data on fish assemblages across a range of depths and habitats. In Australia, this technique has been adopted by many different agencies and institutions, creating a unique opportunity to compile a continental-scale synthesis of fish data using a standardised sampling technique. Key Australian researchers and managers were invited to contribute to a synthesis workshop on baited underwater video in Albany, Western Australia between the 4th and 8th of February 2018. Data from 19,939 BRUVs deployments, collected between 2000 and 2017 around Australia, were compiled using GlobalArchive (globalarchive.org). The workshop identified and prioritised several key research themes that would contribute to the conservation and sustainable management of focal species and broad assemblages. Our goal is to describe where and when the data were collected, the type of equipment used and how the imagery was analysed. We also discuss the types of questions that can be addressed by analysing these standardised datasets and the potential benefits to conservation and fisheries management.

The value of subsea pipelines as habitat for fish and benthic species is being considered, particularly by the oil and gas industry as they look to decommission seafloor infrastructure reaching the end of production. We investigated fish and benthic communities along a ca.345 km section of offshore pipeline in remote northern Australia to compare pipeline communities with those in surrounding areas and provide context for decommissioning risk assessments. We surveyed pipeline and adjacent natural seabed ecosystems at five locations on the continental shelf using remote video technology to quantify fish and benthic communities and modelled predicted fish communities across the study locations. We found that the pipeline supported turfing and low-relief biota (e.g. coralline algae, ascidians, bryozoans, small/encrusting sponges and soft coral or mixed filter feeder communities) with cover >75%. Pipeline benthic communities differed from those in adjacent ecosystems. Within 6 km of the pipeline, the seabed was predominantly sand/silt with only sparse biota; natural hard substrate (e.g. shoal features within 3 km of the pipeline) supported diverse coral and filter feeder communities (average 10–25% cover). Fish abundance and assemblage composition on the pipeline also differed from those in surrounding high- and low-complexity habitats. This difference was driven by high abundance and biomass of commercially important fish species near the pipeline and sand-affiliated species elsewhere. Our study provides important new insights into the marine communities associated with a subsea pipeline in northern Australia; with this artificial habitat observed to support a subset of species known to inhabit the area, but effectively representing a unique assemblage within the region.

Information for monitoring marine communities is increasingly collected using digital imagery and there is a need to understand how data collected using different methods compare. This study investigated the comparability of benthic data collected by downward facing diver operated stereo-video (DOV) with a forward facing stereo-DOV typically used in fish surveys. Data sets were collected by both methods from the same transect along which the benthos visible in each method was identified by taxonomy, growth form or substratum class. Analyses indicated that 77% of taxa were identified by both methods however, forward facing-DOV recorded 35 genera and downward-DOV 43 genera and there were significant (p

Habitat complexity is known to influence the structure of fish assemblages. A number of techniques have previously been used to measure complexity, including quantitative in-situ methods, that can be time consuming and labour intensive, and more rapid semi-quantitative visual scoring methods. This study investigated the utility of a novel method for estimating complexity, whereby habitat height was measured using stereo photogrammetry from diver operated stereo-video, traditionally used to sample fish assemblages. This ‘stereo-height’ method was compared to established in-situ and visual scoring techniques and found to produce similar estimates of complexity. To determine how relevant the proposed method is for assessing ecological relationships, it was then used in conjunction with visual scoring of relief and point-intercept samples of benthic composition to model fish-habitat associations in the Pilbara region of Western Australia. Visual scores of relief were marginally stronger predictors of fish assemblage parameters and functional groups than the stereo-height measurements, providing support for the visual scoring approach. The only exception was for corallivorous fishes, which were more strongly correlated with stereo-height measurements. This study has presented a method for assessing habitat complexity using video imagery that is both comparable to traditional in-situ techniques and useful for investigating fish-habitat relationships. We suggest that future studies interested in collecting habitat complexity data from new or existing stereo-video samples use both the stereo-height and visual scoring methods presented here. Together these methods enable studies to rapidly and effectively assess fish-habitat relationships across a range of habitats without the need for in-situ methods or solely relying on field observers trained in visual scoring techniques. This article is protected by copyright. All rights reserved.

Knowledge of the factors that influence spatial patterns in fish abundance, distribution and diversity are essential for informing fisheries and conservation management. The present study was conducted in the nearshore Pilbara bioregion of north-western Australia where the dynamic marine environment is characterised by large embayments, numerous islands and islets, coexisting with globally significant petrochemical and mineral industries. Within Western Australia, this nearshore bioregion has high biodiversity and is considered to play an essential role in the recruitment of species of commercial importance. To better inform future investigations into both ecological processes and planning scenarios for management, a rapid assessment of the distribution, abundance and associations with nearshore habitats of fishes across the region was conducted. Baited remote underwater stereo-video systems (stereo-BRUVs) were used to simultaneously sample the fish assemblage and habitat composition. Generalised additive mixed models (GAMMs) were used to determine whether the abundance of fishes were related to habitat and a range of environmental variables (visibility, depth, distance to 30 m and 200 m depth isobars, boat ramps and the nearest large embayment (Exmouth Gulf). A diverse fish assemblage comprising 343 species from 58 families was recorded. The abundance and distribution patterns of fishery-target species and of the five most common and abundant species and families were linked positively with areas of high relief, hard coral cover, reef and macroalgae and negatively with the distance to the nearest oceanic waters (200 m depth isobar). This study provides information that can contribute to future marine spatial planning scenarios for management of the Pilbara using a unique, analytical approach that has broad application in biogeography.

Sediment transport-induced changes to the embedment of three 26 km long sections of subsea pipeline are analysed and subsequently explained using model scale experiments. Rather than the scour and scour-induced sinking and sagging traditionally thought to dominate post-lay pipeline spanning and embedment change, the change for these pipelines is shown to be caused by sedimentation. The pipelines traverse a range of metocean and soil conditions; the variation in embedment correlates well with the variation in metocean conditions, with most change occurring in an area where multidirectional high-velocity short-duration flows associated with internal waves propagate at near-perpendicular angles to the pipeline. To understand the mechanism driving these changes, a series of model scale tests in O-tube flumes have been completed under flow conditions mimicking those recorded in the field. Good agreement is found between the field and laboratory results, both in terms of the process timescale and the post-sedimentation profile. The consistency of the embedment changes between the pipelines, their correlation with metocean conditions, and the ability to replicate these changes in model scale tests suggests that such changes can be accounted for in more effective pipeline design. Spans are relatively rare along the pipelines but where they do occur fish rather than scour are shown to be the principal agent of span formation.

An assessment to remove, partially remove, leave in situ or repurpose oil and gas infrastructure at end of field life can be more robust if it uses rigorous, relevant and accurate data. We used industry remotely operated vehicle (ROV) video, specialised high-definition stereo-video systems and partnered with industry to enhance future ROV campaigns for the collection of scientific data from infrastructure. Data from 17 pipelines and 51 wells were analysed to report on patterns in fish species richness and abundance in Australia’s north, north-west and south-east regions. This represents the largest synthesised data set on marine communities for pipelines and wells, globally. We observed 401 fish species, 350 along pipelines and 113 on well infrastructure. Potential new fish species, critically endangered species, unique behaviours and diverse communities were discovered around pipeline and well infrastructure. Predicting the environmental consequences of different decommissioning options relies on a region-specific understanding of the ecological communities that are associated with these structures. We showcase marine research from around Australia that will inform local decommissioning and contribute to a more comprehensive global understanding of the impact of subsea infrastructure in our oceans.

Artificial reefs are frequently installed to provide additional habitat that enhances recreational activities such as diving and fishing. This study assessed changes to habitats, macroinvertebrates and fish after installation of an artificial reef, deployed to influence the marine community and create a more appealing dive trial at Port Coogee, Western Australia. This was achieved by comparing the communities at three control sites to the impact site (artificial reef) before installation and at increased time intervals after installation (3, 11 and 20 months). Across the sampling period and at the impacted site the cover of brown turfing algae increased significantly by 87%. Relative to previous monitoring 18 new species of macroinvertebrate and on average 138 more individuals were detected during post reef surveys. Both the species richness and abundance of fish tended to increase at all sites over the duration of the survey. Although this result was not significant, the final sampling period detected 14 more species and on average 31 more individuals than the previous sampling period. The colonisation of these structures and the progression of the marine community at this site provides valuable insight into the potential function of engineered artificial reefs.

Baited video systems have been widely used to assess the relative abundance and diversity of sharks in locations around the world, however they provide limited information on behaviour. We developed and pilot tested a novel experimental approach to investigate whether repeated deployments of baited video systems in the same location could generate quantitative data on shark behavioural patterns, in the context of shark depredation (where sharks consume hooked fish). Specifically, we sought to test whether repeated exposure to boats and food in the same location would lead to a change in the arrival time and first feeding time of sharks, over a short timescale. We used the Ningaloo Marine Park (NMP) in Western Australia, a location where higher shark depredation rates have been identified in consistently fished areas, as a case study. A modified Baited Remote Underwater Video (BRUV) system was repeatedly deployed at two fished sites and two sites within a no-take marine reserve in the NMP, over six consecutive days, to mimic repeated recreational fishing and the availability of hooked fish for sharks to depredate. This approach was designed to investigate and disentangle the potential role of changes in behaviour versus variation in shark abundance, as a mechanism for how and why shark depredation can occur. Here, we report preliminary results from this methodological approach, where time of arrival and time of first feeding declined markedly in the fished site over 6 days of BRUV deployments, compared to the control site in the no-take marine reserve. A greater number of individuals from four carcharhinid species were observed at the fished site, compared to only three individuals from two species in the no-take marine reserve. The preliminary results from pilot testing of this novel experimental approach suggest that, with further modifications to identify individual sharks, and a greater spatial and temporal replication of sampling, it may be possible to identify behavioural changes occurring in sharks in the context of shark depredation. Understanding this mechanism can bring important benefits for fishers and managers, as it can lead to modifications in fishing methods designed at reducing the occurrence of behavioural changes in sharks, and thus mitigating shark depredation.

Knowledge of marine ecosystems that grow and reside on and around subsea oil and gas infrastructure is required to understand impacts of this offshore industry on the marine environment and inform decommissioning decisions. This study used baited remote underwater stereo-video systems (stereo-BRUVs) to compare species richness, fish abundance and size along 42.3 km of subsea pipeline and in adjacent areas of varying habitats. The pipeline is laid in an onshore-offshore direction enabling surveys to encompass a range of depths from 9 m nearshore out to 140 m depth offshore. Surveys off the pipeline were performed across this depth range and in an array of natural habitats (sand, macroalgae, coral reef) between 1 km and 40 km distance from the pipeline. A total of 14,953 fish were observed comprising 240 species (131 on the pipeline and 225 off-pipeline) and 59 families (39 on the pipeline and 56 off-pipeline) and the length of 8,610 fish were measured. The fish assemblage on and off the pipeline was similar in depths of

© 2018 For thousands of years humankind has sought to explore our oceans. Evidence of this early intrigue dates back to 130,000 BCE, but the advent of remotely operated vehicles (ROVs) in the 1950s introduced technology that has had significant impact on ocean exploration. Today, ROVs play a critical role in both military (e.g. retrieving torpedoes and mines) and salvage operations (e.g. locating historic shipwrecks such as the RMS Titanic), and are crucial for oil and gas (O&G) exploration and operations. Industrial ROVs collect millions of observations of our oceans each year, fueling scientific discoveries. Herein, we assembled a group of international ROV experts from both academia and industry to reflect on these discoveries and, more importantly, to identify key questions relating to our oceans that can be supported using industry ROVs. From a long list, we narrowed down to the 10 most important questions in ocean science that we feel can be supported (whole or in part) by increasing access to industry ROVs, and collaborations with the companies that use them. The questions covered opportunity (e.g. what is the resource value of the oceans?) to the impacts of global change (e.g. which marine ecosystems are most sensitive to anthropogenic impact?). Looking ahead, we provide recommendations for how data collected by ROVs can be maximised by higher levels of collaboration between academia and industry, resulting in win-win outcomes. What is clear from this work is that the potential of industrial ROV technology in unravelling the mysteries of our oceans is only just beginning to be realised. This is particularly important as the oceans are subject to increasing impacts from global change and industrial exploitation. The coming decades will represent an important time for scientists to partner with industry that use ROVs in order to make the most of these ‘eyes in the sea’.

As offshore oil and gas infrastructure reaches the end of its operational life, owners and regulators will question the best options available to decommission it, with decisions requiring information about the potential ecological value of these structures and the environmental impact of their removal. Using a combination of existing industrial underwater Remotely Operated Vehicle video data and marine scientific remote stereo-video surveys, we describe and compare the fish assemblage on pipelines with those on the adjacent natural seafloor of the North West Shelf of Western Australia. Using these video observations of commercially important fish species on pipelines we were able to summarise the potential monetary value of commercial fish found on pipelines to commercial fisheries. Greater numbers of fish were observed on pipelines, compared with that seen on adjacent seafloor areas, and the monetary value of the fish found on the pipelines was estimated to be ca. six times greater than that of fish in surrounding areas lacking subsea infrastructure. Pipeline spans had high fish abundance, with fish appearing to utilise these spans as refuges. These results, together with allied assessments of marine growth on pipelines, suggest over the course of their operating lives, pipelines gain ecological and fishery value, enhancing the diversity and abundance of fish (including important commercial species) which can be translated to a monetary value for commercial fisheries. With an extensive array of pipeline infrastructure spread across the North West Shelf of Western Australia, knowledge of the ecological and fisheries value of subsea infrastructure is imperative to understanding the environmental and economical consequences of removing infrastructure as part of decommissioning. Where pipelines add value to marine biodiversity and fisheries in Western Australia, engineers and ecologists can work towards quantifying this value and preserving it – and potentially also enhancing it – via novel evidence-based abandonment strategies.

Natural fluctuations in the abundance and length of targeted fish are often disrupted by acute environmental changes and anthropogenic impacts, particularly fishing pressure. Long-term assessments of targeted fish populations inside and outside areas closed to fishing are often necessary to elucidate these effects, yet few of these studies extend over long time periods. We assessed trends in the abundance and length of six targeted fish species in areas open and closed to fishing on seven occasions spanning a 9-year period (2005–2010 and 2013) at the Houtman Abrolhos Islands, Western Australia. Shallow (8–12 m) and deep (22–26 m) coral-dominated reef sites were sampled across four geographically separated island groups using baited remote underwater stereo-video (stereo-BRUV). Between 2005 and 2010, populations of Lethrinus miniatus, Lethrinus nebulosus, Plectropomus leopardus, and Chrysophrys auratus became increasingly dominated by larger individuals, potentially indicative of an ageing population. Between 2010 and 2013, however, there was a significant increase in the proportion of smaller L. miniatus, L. nebulosus, and P. leopardus in both open and closed areas, reflecting increased recruitment perhaps due to changing environmental conditions associated with a marine heat wave anomaly. This recruitment pulse was not observed for the other species in this study (Chr. auratus, Choerodon rubescens, and Glaucosoma hebraicum). Lethrinus miniatus, L. nebulosus, Chr. auratus, and P. leopardus were larger in closed areas relative to open areas; however, they were not more abundant. These complex responses to protection also varied across sampling years for certain species (e.g., P. leopardus). Monitoring changes over the long-term in areas open and closed to fishing provides a sound basis for separating environmental variability from that associated with fishing mortality, which is crucial for optimising fisheries management.

Expansion of demersal fisheries into the deep sea has driven a need for methods to provide information on the status of deepwater fish assemblages, especially for vulnerable species. For this purpose, we compared co-located sampling by baited longlines and baited remote underwater video systems (BRUVs) off southeastern Australia and found these techniques observed different elements of the continental slope fish assemblage, but were complementary for monitoring needs. Of the 94 species surveyed in total, only 32% were common to both survey techniques, with BRUVs sampling fewer species, with 51 species detected compared with 73 species captured by longlines. Species detected exclusively by BRUVs (21 spp) included those not vulnerable to longline hooks, and those with large-body size—including several chondrichthyans. One group of chondrichthyans, gulper sharks (Centrophorus) were the focus of this study because they are listed as conservation dependent under Australia’s Environmental Protection and Biodiversity Conservation Act, and are subject to a management plan that requires their recovery to be monitored. Very few gulper sharks were observed by BRUVs (n=10). Longlines captured 773 gulper sharks suggesting this technique provides a more effective means of sampling. However, most longline caught sharks were either dead or in poor condition on capture, further depleting this vulnerable species. BRUVs are non-lethal, but a high sampling intensity is likely to be needed to detect changes in gulper shark abundance within typical management timeframes (years).

Information on the potential ecological value of offshore oil and gas infrastructure is required as it reaches the end of its operational life and decisions must be made regarding the best practice option for decommissioning. This study uses baited remote underwater stereo-video systems to assess fish assemblages along an offshore subsea pipeline and in adjacent natural seabed habitats at ∼140 m depth on the North West Shelf of Western Australia. A total of 955 fish from 40 species and 25 families were recorded. Species richness was, on average 25% higher on the pipeline (6.48 ± 0.37 SE) than off (4.81 ± 0.28 SE) while relative abundance of fish was nearly double on the pipeline (20.38 ± 2.81 SE) than in adjacent natural habitats (10.97 ± 1.02 SE). The pipeline was characterised by large, commercially important species known to associate with complex epibenthic habitat and, as such, possessed a biomass of commercial fish ca 7.5 × higher and catch value ca. 8.6 × ($65.11 ± $11.14 SE) than in adjacent natural habitats ($7.57 ± $2.41 SE). This study has added to the knowledge of fish assemblage associations with subsea infrastructure and provides a greater understanding of the ecological and fisheries implications of decommissioning, helping to better inform decision-making on the fate of infrastructure.

Subsea pipelines have been installed in all major hydrocarbon basins across the globe to support the offshore Oil & Gas (O&G) industry. These artificial structures provide hard substratum that can be colonised and utilised by sessile and mobile organisms. The present study utilises industry-collected remotely operated vehicle (ROV) video to assess fish species richness and abundance, and marine growth type, extent and complexity along sections of a subsea gas pipeline, in 56–82 m depth, that traverses the Australian Commonwealth Montebello Marine Park (MMP). A total of 7493 fish from 81 species and 33 families were recorded from 606 analysed 10 m transects spaced across sections of the pipeline. Of these 81 species, 27 are considered fishery-target species in the Pilbara Demersal Scalefish fishery (PDSF), with select commercial fishing activities permitted with authorisation within the Marine Park. A moderate abundance (175) of sub-adult red emperor (Lutjanus sebae), a fishery-indicator species, were observed along the pipeline. Eleven different categories of marine growth habitat were observed, with the pipeline possessing quite uniform coverage of encrusting marine growth (coralline algae, bryozoans, ascidians, etc.) with patchy occurrences of more structurally complex sponges and black/octocoral forms. Fish species richness and abundance of the commercially targeted Moses’ snapper (Lutjanus russellii) were correlated positively with increasing cover of sponges. The pipeline itself had very few spans and was never more than fractionally buried. Despite the somewhat homogenous habitats, depths, and position of the pipeline relative to the seafloor, presence of a field joint indent had a positive influence on the abundance of some common and commercially important fish species. This study demonstrates the ecological value of ROV footage obtained during industry inspection operations that were conducted for reasons unrelated to the determination of ecological information. The pipeline offers a corridor of hard bottom habitat within a marine park that facilitates epibiotic growth and the presence of reef-associated species in a region characterised by sandy sediments. Results indicate the potential importance of subsea O&G infrastructure as a habitat for fish, and in consequence, potentially also as structures with value to fisheries.

The offshore hydrocarbon basins of the world and their neighbouring countries are faced with an immense decommissioning challenge. Uncertainties in regulation and costs, coupled with limited environmental data, stifle consideration and support for alternative options to full removal. In separate regions, scientists and industry are forming partnerships and commencing research that advances understanding of regional and ecosystem-scale processes, including the habitat value of oil and gas infrastructure. With similar decommissioning-related marine research priorities being identified globally, a more coordinated approach to such research is needed: a global decommissioning marine research network and taskforce. This taskforce would not only be highly cost-effective, but it would also enable consistent approaches to science and management of the marine environment and secure protection and conservation of global marine resources. This network and taskforce would bring together leading scientists and experts in the oil and gas industry to develop an international research program that will significantly advance our understanding of the consequences to ecosystems as a result of decommissioning, as well as identify the differences and commonalities in environment–infrastructure interactions across different geographical regions. The outcomes would support sustainable installation and decommissioning practices worldwide and ensure that policies adhere to international agreements on environmental protection.