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As the global environmental crisis grows in scale and complexity, conservation professionals and policymakers are increasingly called upon to make decisions despite high levels of uncertainty, limited resources, and insufficient data. Global efforts to protect biodiversity in areas beyond national jurisdiction require substantial international cooperation and negotiation, both of which are characterized by unpredictability and high levels of uncertainty. Here we build on recent studies to adapt forecasting techniques from the fields of hazard prediction, risk assessment, and intelligence analysis to forecast the likelihood of marine protected area (MPA) designation in the Southern Ocean. We used two questionnaires, feedback, and a discussion round in a Delphi-style format expert elicitation to obtain forecasts, and collected data on specific biophysical, socioeconomic, geopolitical, and scientific factors to assess how they shape and influence these forecasts. We found that areas further north along the Western Antarctic Peninsula were considered to be less likely to be designated than areas further south, and that geopolitical factors, such as global politics or events, and socioeconomic factors, such as the presence of fisheries, were the key determinants of whether an area was predicted to be more or less likely to be designated as an MPA. Forecasting techniques can be used to inform protected area design, negotiation, and implementation in highly politicized situations where data is lacking by aiding with spatial prioritization, targeting scarce resources, and predicting the success of various spatial arrangements, interventions, or courses of action.

International audience; The sustainable mitigation of human–wildlife conflicts has become a major societaland environmental challenge globally. Among these conflicts, large marine predatorsfeeding on fisheries catches, a behaviour termed “depredation,” has emerged concomitantlywith the expansion of the world’s fisheries. Depredation poses threatsto both the socio-economic viability of fisheries and species conservation, stressingthe need for mitigation. This review synthesizes the extent and socio-ecologicalimpacts of depredation by sharks and marine mammals across the world, and thevarious approaches used to minimize it. Depredation was reported in 214 fisheriesbetween 1979 and 2019 (70% post-2000) and affected fleets from 44 countries, inall sectors (commercial, artisanal and recreational), and in all major fishing techniques(nets, traps and hook-and-lines). A total of 68 predator species were involved in depredation(20 odontocetes, 21 pinnipeds and 27 sharks), and most (73%) were subjectto either by-catch and/or retaliatory killing from fishers when interacting with gear.Impacts on fishers were primarily associated with catch losses and gear damage butoften lacked assessments. Deterrence was a major mitigation approach but also theleast effective. Gear modifications or behavioural adaptation by fishers were morepromising. This review highlights the need for improved monitoring, and interdisciplinaryand integrated research to quantify the determinants and impacts of depredationin the socio-ecological dimension. More importantly, as the conflict is likely toescalate, efforts directed towards changing perceptions and integrating knowledgethrough adaptive co-management are raised as key directions towards coexistencebetween fisheries and large marine predators.

International audience; Marine predators feeding on fisheries catches directly on the fishing gear, a behaviour termed “depredation”, has emerged as a major human-wildlife conflict globally, often resulting in substantial socio-economic and ecological impacts. This study investigated the extent of this conflict in commercial Patagonian toothfish (Dissostichus eleginoides) fisheries across subantarctic waters where both killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) feed on toothfish caught on longline hooks. Using long-term datasets from six major fishing areas, from southern Chile to the Indian Ocean sector of the Southern Ocean, statistical models were developed to quantify the catch removals due to whale depredation interactions. The results indicated that these removals were large, totalling more than 6600 t of toothfish between 2009 and 2016 with an annual mean of 837 t [95% CI 480–1195 t], comprised of 317 t [232–403 t] and 518 t [247–790 t] removed by killer whales and sperm whales, respectively. Catch removals greatly varied between areas, with the largest estimates found at Crozet, where on average 279 t [179–379 t] of toothfish per year, equivalent to 30% [21–37%] of the total catches. Together, these findings provide metrics to assess the impacts of depredation interactions on the fishing industry, whale populations, fish stocks and associated ecosystems. With an estimated $15 M USD worth of fish depredated every year, this study highlights the large geographic scale and economic significance of the depredation issue and its potential to compromise the viability of some toothfish fisheries which are the primary socio-economic activity in subantarctic regions.

This study investigated maturation and spawning of Patagonian toothfish Dissostichus eleginoides in the Heard Island and McDonald Islands (HIMI) fishery on the Kerguelen Plateau in the Indian Sector of the Southern Ocean based on gonads and otoliths collected between 2004 and 2015 and using histological analyses and calibration of macroscopic staging criteria. Dissostichus eleginoides at HIMI spawn throughout the austral late autumn and winter months of May-August and spawning activity is concentrated on slopes along the west and south of the plateau around HIMI at depths of 1500-1900 m. Comparison between histological analyses and macroscopic gonad staging indicated that many fish that had spawned, as indicated by the presence of post-ovulatory follicles, returned to a resting stage which was macroscopically indistinguishable from maturing fish. Furthermore, the occurrence of females of all size classes with low gonado-somatic index and low macroscopic gonad stage during the spawning season suggested that a proportion of mature females did not spawn every year. Age-at-maturity estimates, based on the assumption that fish of macroscopic stages >=2 were mature, decreased between the 2004-2009 and 2010-2015 periods for both sexes. The magnitude of this temporal variation in age at maturity, however, varied between gear types and fishing depths and variable sampling regimes probably influenced these variations. This study highlights the importance of correct interpretation of macroscopic gonad stages and understanding the influence of fishery operations on estimations of life-history parameters.

Aim: Quantifying biological assemblages and their environment is a fundamental, yet statistically challenging task in conservation ecology. Here, we use a recently developed approach called Regions of Common Profile (RCP) to quantify and map the distribution of demersal fish assemblages in an ecologically significant region of the Southern Ocean to (1) gain ecological and management insights and (2) evaluate the utility of the new method for ecoregionalization. Location: Northern Kerguelen Plateau, Subantarctic Islands, Southern Ocean. Methods: The RCP approach is a multispecies, model‐based approach that can overcome many limitations of traditional distance‐based approaches. It simultaneously groups sites with a similar composition of species and describes the patterns of variation in assemblages using environmental data, allowing the prediction of assemblages across the study region. We apply RCP to a unique dataset of demersal fish occurrences across the northern Kerguelen Plateau to model and map the distribution of assemblages and examine the representativeness of the Heard Island and McDonald Island marine reserve. Results: We demonstrate that the RCP approach allows a direct and quantitative interpretation of the composition of assemblages as well as their environment. Further, the model reasonably predicts the occurrence of individual species across the plateau as well as the species composition of sites. We distinguish and map seven assemblages defined by depth, surface temperature and chlorophyll a. Shallow‐water assemblages contain a high proportion of endemic species, while deep‐water assemblages contain more cosmopolitan species. With the exception of one deep‐water assemblage, assemblages were well represented within the current Heard and McDonald Islands marine reserve. Main conclusions: The RCP is a valuable tool for classifying biological regions with a range of ecological and conservation management applications. Our results extend current ecological and biogeographic knowledge for the northern Kerguelen Plateau, and maps of the distribution of assemblages will be useful for ongoing spatial management.

Three species of skate, Bathyraja eatonii , B. irrasa and B. murrayi, are commonly taken as incidental by-catch in Patagonian toothfish ( Dissostichus eleginoides ) longline and trawl fisheries, and the mackerel icefish ( Champsocephalus gunnari ) trawl fishery on the Kerguelen Plateau (KP) in the southern Indian Ocean. Data from fishery observations for 1997–2014 shows that the three skates were widely distributed across the Kerguelen Plateau, showing different spatial distributions, linked mainly with depth. Off Heard Island and McDonald Islands (HIMI), in the southern part of the KP, B. eatonii and B. irrasa were most abundant to the north and northwest of Heard Island, out to the edge of the Australian Exclusive Economic Zone (EEZ), and were caught down to depths of 1790 m and 2059 m respectively. The smallest species, B. murrayi , occurred mainly in the shallower waters down to 550 m, and was most abundant to the north and northeast, close to Heard Island. Around Kerguelen Islands, in the northern part of the KP, skates were most abundant between the 500 m and 1000 m contours circling and extending from the islands. Catch rates were modelled using zero-inflated GAMs and GLMs. The catch rates of skates from the trawl fisheries in the Australian EEZ surrounding Heard Island and McDonald Islands have shown little evidence of depletion on the main trawl fishing grounds, although there is evidence of a decrease in the average total length of B. eatonii . The marine reserves and the conservation measures employed by the Commission for the Conservation of Antarctic Marine Living Resources in the HIMI fisheries, appear to provide effective protection for the skates, at least in the shallower waters where the trawl fisheries operate. B. irrasa taken in the deeper waters where longline fishing occurs have shown a slight decline in catch rate over the years of the HIMI fishery. Although all skates are returned to the water from this fishery, survival rates are unknown and careful monitoring should continue to assess the status of these stocks. There appears to be little change in the abundance of the skate species at Kerguelen in the time period. This study provides the first review of skate by-catch across both the HIMI and Kerguelen fisheries. Ongoing monitoring of species specific by-catch levels and further research to determine the important life history parameters of these species are required, particularly for B. irrasa which is taken in both trawl and longline fisheries.

Understanding patterns of oceanic transport and their role in population connectivity, particularly for the early life stages of marine organisms, has important implications for population biology and management. Various approaches have been used to observe and model larval transport and recruitment in marine environments. In the Southern Ocean, these approaches are presented with particular challenges due to logistical difficulties in accessing and sampling remote, open water or deep-sea environments. In this study, we examine the use of remotely-sensed sea surface height data (AVISO) – which is now easily accessible and available for more than 20 years – to model transport and dispersion of eggs and early larval stages of Patagonian toothfish on the Kerguelen Plateau in the Indian Sector of the Southern Ocean. We compare simulated transport patterns from AVISO with those calculated from an ocean reanalysis product (Southern Ocean State Estimate; SOSE), and draw conclusions on likely patterns of connectivity between spawning regions and regions that offer suitable habitat for juvenile fish. The results of our study suggested regions with successful spawning that are consistent with those observed by the fishery and describe inter-annual differences in simulated connectivity between spawning and recruitment habitats.

Satellite telemetry data was used to predict at sea spatial usage of five top order and meso-predators; Antarctic fur seals ( Arctocephalus gazella ), macaroni penguins ( Eudyptes chrysolophus ), king penguins ( Aptenodytes patagonicus ), black browed albatross ( Diomedea melanophrys ), and light mantled albatross ( Phoebetria palpebrata ). All were tagged at Heard Island in the Southern Ocean over a single summer season collecting over 5000 tracking days for 178 individuals. We aimed to predict areas of likely high foraging value from tracking environmental data and also to quantify overlap in foraging range between species. Hidden Markov models were used to differentiate between bouts of Area Restricted Search (ARS) assumed to be associated with areas of higher foraging value, and transit behaviours. Oceanographic and distance metrics associated with ARS activity were then used to calculate a habitat electivity index. A combined bootstrap/Monte Carlo scheme was employed to propagate uncertainty from the Hidden Markov models into the habitat prediction scheme. Distinct differences were predicted in the spatial distribution of foraging locations in different species, reflecting different dispersive abilities and foraging strategy. The extent of usage and foraging distribution was largely contained within Australian the Economic Exclusion Zone (EEZ). In comparison, the smaller Australian Commonwealth Marine Protected Areas (MPAs) contained

The Patagonian toothfish, Dissostichus eleginoides, is a valuable fishery species and has a discontinuous distribution across the Southern Ocean. Identification of the genetic stock structure of toothfish would allow evaluation of the suitability of the spatial scale at which fisheries management operates. Genetic subdivision seems likely given the species distribution. Population genetics studies of this species have been performed; however, they have been limited by sample size, spatial coverage and/or the type of markers investigated. As a potential solution, we developed methods for extracting toothfish DNA from otoliths that are available in large numbers from collections held at several research institutes. Genetic differentiation between the three oceanic sectors was investigated. Four mitochondrial and four nuclear markers with multiple single nucleotide polymorphisms were sequenced by high throughput sequencing for samples from six locations. Genetic differentiation was found between three sectors with nuclear markers. However, only the Pacific sector was differentiated from other sectors with mitochondrial markers. This study demonstrates the usefulness of otolith DNA as a means of increasing sample sizes for population genetics research of fish. Additionally, the combination of nuclear and mitochondrial markers may allow insight into how the observed differences in movements between male and female toothfish impact population structure.

As Antarctic fish species experience increasing anthropogenic pressures there is a growing need to characterise the structure and function of their populations and understand how they may respond to changes in their environment. We integrated fishery-dependent and environmental data from years 2003–2017 to investigate the distribution of Antarctic toothfish Dissostichus mawsoni along a c. 3000 nm expanse of the shelf and slope along East Antarctica (30–150 °E). Spatially-explicit generalised additive mixed models were used to characterise the environmental drivers of relative abundance, mean individual weight, maturity-stage composition and sex ratio. Antarctic toothfish were not randomly distributed across the region, and spatial variations were characterised by complex relationships involving topography, temperature, salinity and sea ice. In particular, catch rates were highest at depths between 1000–1700 m. Mean weight and the proportion of fish that were mature both increased with depth and decreased with bottom temperature. Model predictions were also used to develop hypotheses relating to population function, including the location of nursery and spawning areas. This characterisation of the population can facilitate evaluation of fishing impacts in East Antarctica, and improve our understanding of the role of toothfish in Antarctic and Southern Ocean ecosystems.

The emergence of longline fishing around the world has been concomitant with an increase in depredation-interactions by odontocete whales (removal of fish caught on hooks), resulting in substantial socio-economic and ecological impacts. The extent, trends and underlying mechanisms driving these interactions remain poorly known. Using long-term (2003–2017) datasets from seven major Patagonian toothfish (Dissostichus eleginoides) longline fisheries, this study assessed the levels and inter-annual trends of sperm whale (Physeter macrocephalus) and/or killer whale (Orcinus orca) interactions as proportions of fishing time (days) and fishing area (spatial cells). The role of fishing patterns in explaining between-fisheries variations of probabilities of odontocete interactions was investigated. While interaction levels remained globally stable since the early 2000s, they varied greatly between fisheries from 0 to >50% of the fishing days and area. Interaction probabilities were influenced by the seasonal concentration of fishing effort, size of fishing areas, density of vessels, their mobility and the depth at which they operated. The results suggest that between-fisheries variations of interaction probabilities are largely explained by the extent to which vessels provide whales with opportunities for interactions. Determining the natural distribution of whales will, therefore, allow fishers to implement better strategies of spatio-temporal avoidance of depredation.

Length frequency data (LFD) are an important input to integrated stock assessments, and statistical tests for variables that significantly influence the length distribution of fish can assist in the definition of effort strata, typically denoted as fisheries or sub-fisheries, in order to account for important systematic differences due to availability and/or gear-specific selectivity of size classes. Here, a nonparametric model of the probability density function of lengths is described which, instead of fitting to LFD directly, is fitted to the set of length quantiles for a pre-determined set of corresponding probabilities p (in this instance 0.05, 0.1–0.9 in 0.1 increments, and 0.95). These length quantile data (LQD) can be constructed with individual hauls as sampling units or after pooling hauls to sampling units defined by combinations of covariates such as gear type, spatial block, depth strata, or the sex of sampled fish. The length quantiles are modelled as a Gaussian response variable using a Generalised Additive Mixed Model (GAMM) with smoothing splines fitted for each combination of the covariates (i.e. gear type, depth strata and sex). Graphical presentation of the fitted splines along with standard error of difference bounds were used to investigate where differences were significant in order to assist in the optimal definition of sub-fisheries. The model has the advantage of greater generality and sensitivity in detecting differences compared to modelling a single quantile such as the median. In addition, fitting splines allows flexible and parsimonious modelling of length distributions of any shape. The model is demonstrated using LQD from commercial fishing for Patagonian toothfish at Heard Island.

International audience; Antarctic coastal polynyas are persistent open water areas in the sea ice zone, and regions of high biological productivity thought to be important foraging habitat for marine predators. This study quantified southern elephant seal (Mirounga leonina) habitat use within and around the polynyas of the Prydz Bay region (63˚E– 88˚E) in East Antarctica, and examined the bio-physical characteristics structuring polynyas as foraging habitat. Output from a cli-matological regional ocean model was used to provide context for in situ temperature-salin-ity vertical profiles collected by tagged elephant seals and to characterise the physical properties structuring polynyas. Biological properties were explored using remotely-sensed surface chlorophyll (Chl-a) and, qualitatively, historical fish assemblage data. Spatially gridded residence time of seals was examined in relation to habitat characteristics using generalized additive mixed models. The results showed clear polynya usage during early autumn and increasingly concentrated usage during early winter. Bathymetry, Chl-a, surface net heat flux (representing polynya location), and bottom temperature were identified as significant bio-physical predictors of the spatio-temporal habitat usage. The findings from this study confirm that the most important marine habitats for juvenile male southern elephant seals within Prydz Bay region are polynyas. A hypothesis exists regarding the seasonal evolution of primary productivity, coupling from surface to subsurface productivity and supporting elevated rates of secondary production in the upper water column during summer autumn. An advancement to this hypothesis is proposed here, whereby this bio-physical coupling is likely to extend throughout the water column as it becomes fully convected during autumn-winter, to also promote pelagic-benthic linkages important for benthic foraging within polynyas.

Humans have devised fishing technologies that compete with marine predators for fish resources world-wide. One such fishery for the Patagonian toothfish (Dissostichus eleginoides) has developed interactions with a range of predators, some of which are marine mammals capable of diving to extreme depths for extended periods. A deep-sea camera system deployed within a toothfish fishery operating in the Southern Ocean acquired the first-ever video footage of an extreme-diver, the southern elephant seal (Mirounga leonina), depredating catch from longlines set at depths in excess of 1000m. The interactions recorded were non-lethal, however independent fisheries observer reports confirm elephant seal-longline interactions can be lethal. The seals behaviour of depredating catch at depth during the line soak-period differs to other surface-breathing species and thus presents a unique challenge to mitigate their by-catch. Deployments of deep-sea cameras on exploratory fishing gear prior to licencing and permit approvals would gather valuable information regarding the nature of interactions between deep diving/dwelling marine species and longline fisheries operating at bathypelagic depths. Furthermore, the positive identification by sex and age class of species interacting with commercial fisheries would assist in formulating management plans and mitigation strategies founded on species-specific life-history strategies.

Size and sex specific habitat preferences are common in animal populations and can have important implications for sound spatial management of harvested species. Patagonian toothfish (Dissostichus eleginoides) is a commercially exploited fish species characterised by its longevity (>50 yo) and its extremely broad distribution in depths ranging from 10 m to 2500 m on most of the Plateaux, banks and seamounts of the Southern Ocean. As many bentho-pelagic fish species, Patagonian toothfish exhibits sexual dimorphism and ontogenetic habitat shift towards deeper waters as they grow. In this study, we modelled the spatial structure of Patagonian toothfish population (median total length and sex composition) in a data-rich area, the Kerguelen Plateau (Southern Indian Ocean), to better understand the ecological drivers of their distributional patterns and inform current and future fishery management strategies. We applied spatially-explicit statistical models to quantify and predict the effects of the complex topography of the Kerguelen Plateau in structuring the spatial distribution of Patagonian toothfish total length and sex ratio, while controlling for gear selectivity and season. Model predictions showed that juvenile toothfish live in shallow regions (shelf and banks) and move downward progressively up to 600 m while they grow. Between 600 m and 1200 m, the downward movement stops and fish settle at their preferred depths. While in this depth range, fish are ∼75 cm long and most vulnerable to fisheries. As they approach maturity large fish move downward to deep-sea habitats (from 1200 m to >2300 m) and head towards the spawning grounds on the western side of the plateau and around Skiff Bank. Importantly, the sex ratio was not evenly distributed across the Plateau; prediction maps revealed a higher proportion of females in the South whereas a strong male-bias sex ratio (70%) occurred in the North-West. Large-scale prediction maps derived from our models assisted in developing hypotheses regarding ecological drivers of Patagonian toothfish habitat-use and movement across different life stages and sex. Such hypotheses are crucial to inform management strategies of this multijurisdictional fishery (France and Australia) at the spatial and temporal scales over which natural processes and fishery extend.

McLeod, D. J., Hobday, A. J., Lyle, J. M., and Welsford, D. C. 2012. A prey-related shift in abundance of small pelagic fish in eastern Tasmania? – ICES Journal of Marine Science, 69: 953–960. Shifts in the relative abundance of small pelagic fish species have signalled a change in the ocean environment in a number of locations. Here we show that the replacement of jack mackerel, Trachurus declivis, with redbait, Emmelichthys nitidus, as the dominant small pelagic species from eastern Tasmania, following a period of high fishing pressure on jack mackerel, is consistent with altered zooplankton communities and long-term climate change. Stomach contents analysis and morphology measurements were conducted on both species to determine if they were functionally equivalent with regard to zooplankton prey. Diet varied between species and with fish size. Krill (Nyctiphanes australis) was consumed by both species, with redbait feeding more heavily on small copepods. The diet overlap and morphometric characteristics indicated that these species are not equivalent with regard to prey and therefore changes in prey availability may have contributed to the observed shifts in relative abundance. The continued poleward extension of the East Australian Current is expected to favour small warm-water copepods; thus, redbait may have an advantage over jack mackerel due to prey preferences. An increase in relative abundance of redbait has decreased effort in surface fisheries and may impact on surface-feeding higher predators in this region.

Integrated assessments that use catch-at-age or abundance-at-age data for model calibration require an ageing error matrix as input in order to account for imprecision in age determinations from counts of annual growth rings in otoliths. A new method of estimating the ageing error matrix is described and demonstrated using repeat readings by 4 readers of a set of 203 reference otoliths from Patagonian toothfish ( Dissostichus eleginoides ). Errors were defined as the nearest integer value deviations, denoted as integer errors (IEs), from the mean age for an individual otolith. Frequencies of random IEs, treated as classes, depend on the readability score of the otolith and its average age and were modelled in two stages. In the first stage the frequency of the absolute value of IE, the AIE, considered as 0, 1, 2, 3, 4, 5+ year classes for each of 4 readability classes and 7 age classes for ages up to 28 years were modelled using continuation ratios in order to predict proportions in AIE classes. Proportion in the AIE 1 year error class decreased relative to the zero class as readability improved but increased with age. To model any asymmetry in IEs, a binomial/logistic model of the proportion of non-zero IEs that were negative was fitted. The construction of the ageing error matrix combines the modelled probabilities for AIE and negative IE while incorporating logical constraints. This approach differs from those used previously by accounting for the readability of otoliths and any asymmetry in signed integer ageing errors.

Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill (Euphausia superba).

The apparently intense selective differentials imposed by many fisheries may drive the rapid evolution of growth rates. In a widely-cited laboratory experiment, Conover & Munch (2002; Science 297:94-96) found considerable evolutionary change in the size of harvested fish over 4 generations. Their empirical model has since been used to estimate the impact of fishery-driven evolution on fishery sustainability. Using a mathematical, individual-based model (IBM) that simulates that experiment, we showed that the selection imposed in the Conover & Munch (2002) model is unrealistically strong when compared to harvest rates in wild fisheries. We inferred the evolutionary change that could be expected over the timescale used by Conover & Munch (2002), had they simulated more realistic harvest regimes, and found that the magnitude in their original experiment was 2.5 to 5 times greater. However, over evolutionary timescales of 30 generations and with realistic fishing pressure, the results of Conover & Munch (2002) are comparable to wild fisheries. This simulation result provides support for the use of empirical models to predict the impacts of fishery-driven evolution on yields and sustainability. Future models should consider the timing of fishing events, the trade-off between size, maturation and growth, and density-dependent effects for a comprehensive analysis of the consequences of fishery-driven evolution.

The early life-stages of Notolabrus fucicola and N. tetricus are described and illustrated. Developmental stages examined included eggs and yolk-sac larvae reared in aquaria and post-settlement juveniles collected from artificial habitats in the coastal waters of eastern Tasmania, Australia. Larvae were similar to other labrids previously described. Species-specific characters were only evident after settlement, and with the development of scales at c. 15 mm standard length. A molecular assay, based on restriction fragment length polymorphism (RFLP), enabled the discrimination of all five of the closely-related wrasses in the genera Notolabrus, Pseudolabrus, Dotalabrus, and Pictilabrus found on the east coast of Tasmania. This study constitutes the first description of the early life-stages of Notolabrus spp. from temperate Australia.

Sixty-four post-larvae of the King George whiting Sillaginodes punctata were tested in swimming chambers, against one of five flow-through velocities (2, 4, 6, 8 or 10 cm s -1 ) for up to a maximum of 120 min. Fish were determined by regression to have an FV 50 (50% fatigue velocity) of 6.0cm s -1 . No fish survived the full 120 min at 10 cm s -1 . Sixteen individuals were tested in a swimming chamber against a flow-through velocity of 6 cm s -1 and allowed to swim to exhaustion. Fish swam between 25 and 538 min with a peak at c. 6-8 h. Total swimming time was not correlated with standard length of fish although the size range examined was narrow. Relative to recent studies on the swimming abilities of late-stage larvae of reef fishes, this study indicates that post-larval King George whiting are weak swimmers. The weak swimming ability of post-larval King George whiting is consistent with studies showing passive dispersal and recruitment of this species.

International audience; Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea-ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This paper reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea-ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms, but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed. This article is protected by copyright. All rights reserved.

Vertically stratified sampling was undertaken for pre-settlement K n g George whiting Sillaglnodespunctata at 1 site in 1995 and 4 sites in 1996, in Port Phillip Bay, Australia. In 1995, 3 depth strata were sampled: surface, 2.5-3.0 m, and 5.0-5.5 m, in a total water depth of 7 to 8 m. Samphng was conducted on 17 dates and encon~passed all combinations of day and night, and ebb and flood tide. A total of 3, or in one case 4, replicate samples were taken at each depth. On 4 occasions a smaller zooplankton net was deployed at the same time as the ichthyoplankton net. Pre-settlement S. punctata showed 'reverse' &urnal vertical migration, with concentration near the surface during the day and diffusion through the water column at night. A much weaker tidal migration was also detected, with larvae slightly higher in the water column on flood tides. Pre-settlement S. punctata only fed in daylight and zooplankton taxa that were eaten did not show vertical stratification during daytime. In 1996. 4 sites were sampled at a minimum of 10 m depth, and an additional depth stratum, 7.5-8.0 m, was sampled. Smaller numbers of larvae were collected in 1996 compared with 1995. All larvae collected in daytlme were in the surface stratum, whilst at mght larvae were spread through the water column. Although diurnal vertical migration was not a response to prey migrations, daytime ascent of larvae may have occurred to find adequate light levels for visual predation. The generality of tidal migration is unclear, and may have been a result of local factors. Both diurnal and tidal migration would be expected to strongly influence transport of pre-settlement S. punctata to seagrass beds in Port Phillip Bay.

Although three species of the genus Macrourus are recognized in the Southern Ocean, DNA sequencing of the mitochondrial COI gene revealed four well-supported clades. These barcode data suggest the presence of an undescribed species, a conclusion supported by meristic and morphometric examination of specimens. Fil: Smith, P. J.. National Institute of Water and Atmospheric Research; Nueva Zelanda Fil: Steinke, D.. University of Guelph; Canadá Fil: McMillan, P. J.. National Institute of Water and Atmospheric Research; Nueva Zelanda Fil: Stewart, A. L.. Museum of New Zealand Te Papa Tongarewa; Nueva Zelanda Fil: McVeagh, S. M.. Museum of New Zealand Te Papa Tongarewa; Nueva Zelanda Fil: Díaz de Astarloa, Juan Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Welsford, D.. Australian Antarctic Division; Australia Fil: Ward, R. D.. CSIRO Marine and Atmospheric Research; Australia

Juvenile giant crabs (Pseudocarcinus gigas), sourced from laboratory-reared larvae, were ongrown through to the 7th crab stage over 2 years to allow identification of specimens collected for ecological studies. Morphological development through these stages is described. Each stage up to Crab 5 can be distinguished by changes in morphology of the appendages, primarily the 3rd maxilliped and antennule. Growth of juveniles under laboratory conditions was also recorded, with mean size of juveniles reaching 24.5 mm carapace length, 737 days after hatch.

The age of Notolabrus fucicola from the east and southeast coasts of Tasmania was estimated from counts of opaque (transmitted light) growth zones in thin transverse sections of sagittal otoliths. The position of the first annulus was validated through the otolith radii of known-age juveniles. Marginal increment analysis was performed by examining the growing edge of otoliths over 2 years. This showed that opaque zones were formed annually and were consistently deposited from late September to early December (spring season), which is coincident with annual increases in somatic growth and water temperature during this season. A criterion was developed to ensure accurate age estimation for individuals sampled during the time of year when deposition of opaque material was incomplete or not apparent. The maximum age estimated was 20 years and the relationship between fork length and age was described by the von Bertalanffy growth function (L∞ = 368 mm, K = 0.116 and t0 = –1.87 for males and L∞ = 385.7 mm, K = 0.109 and t0 = –1.96 for females). The clarity of increment structure and rigorous validation protocol that was adopted minimised the risks associated with using marginal increment analysis to validate the periodicity of increment formation and it provided robust age and growth estimates for N. fucicola in Tasmanian waters.

Notolabrus fucicola and N. tetricus larvae were reared in the laboratory at a constant temperature of 11°C; both species hatched after 4 days. Mortality was high throughout the post-hatching stage, with no N. tetricus surviving beyond 24 hours post-hatching. Notolabrus fucicola late yolk sac larvae showed no clear incremental structure in their sagittal otoliths up to 9 days post-hatch. The radius of the sagittae of these late yolk sac larvae corresponded with the radius of a non-incremental region around the primordium of sagittae taken from post-settlement juveniles of both species captured in the wild. Therefore, it is likely that the first increment is formed at or near yolk sac absorption in these species. Post-settlement juveniles of both species were exposed to oxytetracycline (OTC) and held in aquaria for up to 33 days. Post-OTC increment counts showed that increments were formed daily in the sagittae of both species.

Krill forms an important part of the diet of many Antarctic fish species. An understanding of the role of fish as krill predators in the Southern Ocean is critical to understanding how changes in fish abundance, such as through fishing or environmental change, are likely to impact on the food webs in the region. First attempts to estimate the krill and pelagic food consumption by Antarctic demersal fish in the low Antarctic were made in the late 1970s/early 1980s. Those estimates were constrained by a paucity of biomass estimates and the mostly qualitative nature of food studies. Food consumption estimates were extended to the mesopelagic realm and the high-Antarctic Zone in the late 1980s and early 1990s when these areas were exploited commercially for Electrona carlsbergi. Currently, the best estimates of annual krill consumption by fish are 23 000 000–29 000 000 tonnes of krill and other pelagic prey taken annually by demersal fish in the 1980s in the whole Southern Ocean, and 5 000 000–32 000 000 tonnes taken by mesopelagic fish in the Atlantic sector of the Southern Ocean. It is clear from this review that fish are important predators of krill, in particular the larger myctophids and some channichthyids and nototheniids, and that the importance of krill in fish diets varies substantially both with time and location on various scales, as well as with the availability of alternate prey in the different regions in the Southern Ocean. Ecosystem models therefore need to account for their role. However, several key areas of uncertainty exist, which need to be considered in ecosystem and food-web models for the Southern Ocean. For instance, no robust estimates of food consumption by mesopelagic fish can be provided for the vast areas of the Indian and Pacific Ocean sectors, or for several of the most abundant myctophid species in the Atlantic sector, due to the paucity of relevant studies in these regions. Where biomass estimates do exist, such as in the Atlantic sector, there can be a lack of precision in trawl and hydroacoustic surveys. Studies that adequately capture the seasonal variation in consumption rates and changing importance of krill in the diet of fish are also rare. Furthermore, the effects of large changes in abundance and community structure of fishes brought about by industrial fishing need to be considered when evaluating patterns that have emerged in Southern Ocean ecosystems in the course of the 20th century. As a first step towards a modelling approach to include fish in krill-based food-web models, it is suggested to incorporate data on Champsocephalus gunnari from the western Atlantic sector and Dissostichus mawsoni from the Ross Sea into modelling approaches within the CCAMLR Ecosystem Monitoring Program. Both species are important predators of krill (C. gunnari) and fish (D. mawsoni) in turn form key prey for top predators in each region.

International audience; Ecoregionalisation is a process that aims to identifyareas with distinct biological content and associatedenvironmental conditions. It improves on manytraditional approaches to regionalisation by explicitlyincorporating biological data into classifications.Ecoregionalisations are useful for improving our ecologicalunderstanding of marine ecosystems and forinforming spatial management. This includes providinginformation to aid in defining and prioritising areas forconservation, evaluating current spatial managementarrangements, targeting monitoring efforts and managinghuman activities (e.g. Grant et al., 2006; Douglass etal., 2014). The Kerguelen Plateau is a highly productiveregion of the southern Indian Ocean that supports lucrativedemersal fisheries (Duhamel and Welsford, 2011).It is subject to spatial management in the form of marineprotected areas (MPAs) with varying levels of protection(Commonwealth of Australia, 2014; Koubbi et al.,2016). Recently two ecoregionalisations have been independentlygenerated for the northern Kerguelen Plateau;one for benthic invertebrates (Martin et al., 2018) andanother for demersal fish (Hill et al., 2017). Here weconduct a preliminary analysis examining the congruencebetween these ecoregionalisations that representdifferent components of the demersal ecosystem.