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The authors acknowledge the financial support of Woodside Energy Ltd., operator of permit WA33P, on behalf of the Browse joint venture in the conduct of this research. We wish to thank the Master and crew of RV Solander and staff from ERM (Environmental Resources Management) for support during the field surveys. EC was supported by the ARC Industrial Transformation Research Hub for Offshore Floating Facilities which is funded by the Australian Research Council, Woodside Energy, Shell, Bureau Veritas and Lloyds Register (Grant No. IH140100012). We thank M. Hatch (Woodside) for providing comments on the draft of this manuscript.

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.

Species with specialized resource use can display strong spatial heterogeneity in abundance according to the availability of their preferred habitats. If these preferences shift with ontogeny, then a wide range of habitats may need to be protected in order to support both adult populations and their replenishment. We explored whether microhabitat selectivity interacts with habitat availability to provide an effective suite of indicators for regional fish abundance and replenishment, using offshore rocky reefs in south-eastern Australia as a case study. We examined generalized additive mixed models (GAMMs) in a full subsets approach to infer the best predictors for adult and juvenile fish density in four diverse families (Labridae, Odacidae, Pomacentridae, Serranidae), based on rapid underwater visual surveys across transects (⿼500 m 2 ), wave exposures (0.3⿿1 km), and sites (0.3⿿48 km). We then examined whether these regional fish-habitat models aligned with the microhabitat electivity of individuals (at scale of 2 ). Microhabitat selection by reef fishes at the local scale underpinned the most effective habitat indicators for regional heterogeneity in fish abundance, and pointed to critical nursery habitats that support hotspots of juvenile recruitment. Strong species-habitat relationships, such as these, can be combined with broad-scale habitat mapping to assess the potential carrying capacity of focal areas, spatial management zone placements, and nursery habitats that warrant special protection. A number of emerging threats to these key habitat types indicates an urgent need for habitat-based protection and monitoring as a key part of holistic marine ecosystem conservation and management.

A major limitation to fully integrated ecosystem based fishery management approaches is a lack of information on the spatial distribution of marine species and the environmental conditions shaping these distributions. This is particularly problematic for deep-water species that are hard to sample and are data poor. The past decade has seen the rapid development of a suite of advanced species distribution, or ecological niche, modelling approaches developed specifically to support efficient and targeted management. However, model performance can vary significantly and the appropriateness of which methods are best for a given application remains questionable. Species distribution models were developed for three commercially valuable Hawaiian deep-water eteline snappers: Etelis coruscans (Onaga), Etelis carbunculus (Ehu) and Pristipomoides filamentosus (Opakapaka). Distributional data for these species was relatively sparse. To identify the best method, model performance and distributional accuracy was assessed and compared using three approaches: Generalised Additive Models (GAM), Boosted Regression Trees (BRT) and Maximum Entropy (MaxEnt). Independent spatial validation data found MaxEnt consistently provided better model performance with ‘good’ model predictions (AUC =>0.8). Each species was influenced by a unique combination of environmental conditions, with depth, terrain (slope) and substrate (low lying unconsolidated sediments), being the three most important in shaping their distributions. Sustainable fisheries management, marine spatial planning and environmental decision support systems rely on an understanding species distribution patterns and habitat linkages. This study demonstrates that predictive species distribution modelling approaches can be used to accurately model and map sparse species distribution data across marine landscapes. The approach used herein was found to be an accurate tool to delineate species distributions and associated habitat linkages, account for species-specific differences and support sustainable ecosystem-based management.

Climate change is transforming the structure of biological communities through the geographic extension and contraction of species’ ranges. Range edges are naturally dynamic, and shifts in the location of range edges occur at different rates and are driven by different mechanisms. This leads to challenges when seeking to generalize responses among taxa and across systems. We focus on warming-related range shifts in marine systems to describe extensions and contractions as stages. Range extensions occur as a sequence of (1) arrival, (2) population increase, and (3) persistence. By contrast, range contractions occur progressively as (1) performance decline, (2) population decrease and (3) local extinction. This stage-based framework can be broadly applied to geographic shifts in any species, life-history stage, or population subset. Ideally the probability of transitioning through progressive range shift stages could be estimated from empirical understanding of the various factors influencing range shift rates. Nevertheless, abundance and occupancy data at the spatial resolution required to quantify range shifts are often unavailable and we suggest the pragmatic solution of considering observations of range shifts within a confidence framework incorporating the type, amount and quality of data. We use case studies to illustrate how diverse evidence sources can be used to stage range extensions and contractions and assign confidence that an observed range shift stage has been reached. We then evaluate the utility of trait-based risk (invasion) and vulnerability (extinction) frameworks for application in a range shift context and find inadequacies, indicating an important area for development. We further consider factors that influence rates of extension and contraction of range edges in marine habitats. Finally, we suggest approaches required to increase our capacity to observe and predict geographic range shifts under climate change.

Trade-offs between the costs and benefits of growth are thought to be mediated by behaviour, whereby rapid growth is associated with greater predation mortality because of increased foraging effort. We tested this hypothesis by collecting young Pomacentrus amboinensis using light traps and settling them onto patch reefs where their behaviour and survivorship were monitored for 24 h. One month later, individuals of the same cohort were collected from shallow reefs and released onto patch reefs where their behaviour and survivorship were monitored for 6 days. At settlement young fish suffered high (60% in 24 h) mortality that preferentially removed larger, faster-growing individuals. However, we could find no evidence that foraging behaviour contributed to this selective mortality. In contrast, 1 month later the same cohort underwent negative size-selective mortality where the smallest, slower-growing fish were preferentially removed by predators. Larger fish spent more time foraging, were more aggressive, swam greater distances and chased more fish than smaller individuals. Thus, consistent individual differences in behaviour contributed to patterns of mortality, but in a way that involved no apparent trade-off with growth. For P. amboinensis, consistent variation in growth may be maintained by spatial and temporal differences in the selective regime within the reef environment.

Broad-scale mapping of marine benthos is required for marine resource management and conservation. This study combines textural derivatives based on bathymetry from multibeam hydroacoustics with underwater video observations to model and map sessile biota between 10- and 60-m water depth over 35 km2 in Point Addis Marine National Park (MNP), Vic., Australia. Classification tree models and maps were developed for macroalgae (all types, mixed red algae, Ecklonia, and rhodoliths) and sessile invertebrates (all types, sponges, and ascidians). Model accuracy was tested on 25% of the video observation dataset reserved from modelling. Models fit well for most macroalgae categories (correct classification rates of 67–84%), but are not as good for sessile invertebrate classes (correct classification rates of 57–62%). The poor fit of the sessile invertebrate models may be the combined result of grouping organisms with different environmental requirements and the effect of false absences recorded during video interpretation due to poor image quality. Probability maps, binary single-class maps, and multi-class maps supply spatially explicit, detailed information on the distribution of sessile benthic biota within the MNP and provide information at a landscape-scale for ecological investigations and marine management.