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The proceedings present the findings from two workshops in Bogor Indonesia in 2019 to provide participants with training in management strategy evaluation for fisheries and apply the MERA framework to evaluate seven data-limited fisheries in Indonesia. These fisheries were chosen because of their fisheries or conservation significance and covered a diversity of species with very different life-history strategies - blue swimmer crabs, scalloped spiny lobster, hammerhead sharks, red-bellied yellowtail fusilier, skipjack tuna, leopard coral grouper and humpback red snapper. The Proceedings summarise the current information on biology, fisheries and management measures for each fished species. They then apply the Method Evaluation and Risk Assessment Tool to consider different management options including those based on catch, effort, size and area closures. These findings were used to inform discussions on identifying potential future management options for the fisheries.

We genetically characterised larval and adult specimens of species of Echinocephalus Molin, 1858 (Gnathostomatidae) collected from various hosts found within Australian waters. Adult specimens of Echinocephalus were collected from a dasyatid stingray [Pastinachus ater (Macleay); n = 2] from Moreton Bay, Queensland and larvae from a hydrophiine sea snake [Hydrophis peronii (Duméril); n = 3] from Cape York Peninsula, Queensland, from an octopus (Octopus djinda Amor & Hart; n = 3) from Fremantle, Western Australia and from a lucinid bivalve [Codakia paytenorum (Iredale); n = 5] from Heron Island, Queensland Australia. All nematode samples were identified morphologically and genetically characterised using the small subunit nuclear ribosomal DNA (SSU). Some morphological differences were identified between previous studies of Echinocephalus spp. and those observed herein but the significance of these differences remains unresolved. Molecular phylogenetic analyses revealed that larval Echinocephalus sp. from H. peronii and C. paytenorum in Australia were very similar (with strong nodal support) to larval Echinocephalus sp. infecting two fish species from Egypt, Saurida undosquamis (Richardson) (Synodontidae) and Pagrus pagrus (Linnaeus) (Sparidae). The SSU sequences of larval Echinocephalus sp. from O. djinda and adults from P. ater formed a well-supported clade with that of adult E. overstreeti Deardorff and Ko, 1983 from the Port Jackson shark, Heterodontus portusjacksoni (Meyer), as well as that of the larval Echinocephalus sp., from the common carp (Cyprinus carpio Linnaeus) from Egypt. This study extends the intermediate host range of Echinocephalus larvae by including a sea snake for the first time. Findings of this study highlight the importance of genetic characterisation of larval and adult specimens of Echinocephalus spp. to resolve the current difficulties in the taxonomy of this genus.

This study investigates the distribution, abundance, and foraging ecology of Caspian Terns, Hydroprogne caspia, during 5 months of their non-breeding season, in the Peel-Harvey Estuary, south-western Australia. Observations were carried out at 20 sites around the estuary and 6 main areas (13 sites) where terns were abundant. Terns were observed every hour over 5h time-blocks in the morning, midday, and afternoon, and the number of birds, number of birds foraging and time spent foraging were recorded for 10min on the hour. From the 760h of observation, a single overnight roosting site was identified in November, where a maximum of 147 birds were counted in February, after which time the roosting site appeared to shift. The total number of terns, foragers and proportion of time foraging varied amongst the six areas and foraging activity differed amongst times of day. Two areas, both characterised by large, sandy spits adjacent to shallow water, one adjacent to a river mouth and one near an ocean channel, were particularly important for terns and their foraging. Foraging activity was higher in the morning than at other times of day. Although salinity, air temperature, water temperature and wind speed were correlated with the total terns, foragers and proportion of time foraging, the correlations accounted for <25% of the total variation explained. The results of this study provide information for evaluating the use of Caspian Terns as bio-indicators of the Peel-Harvey Estuary and highlights the importance of this system during the non-breeding period.

Marine ranching has been proposed as a promising solution to manage the depleted coastal fishery ecosystem in recent decades across China. Marine ranching integrates the practices of artificial habitat-based with aquaculture-based enhancement. Assessing the ecological carrying capacity of target species for enhancement is a precondition for determining the optimal numbers for release, particularly for those species whose habitat restrictions have been eliminated through the construction of artificial habitats in the marine ranch. A responsible approach to stock enhancement aims not only to increase total yield and stock abundance but also to consider any potential effects on ecosystem structure and function. A time-dynamic, ecosystem model was constructed using Ecopath with Ecosim for the Laizhou Bay (Bohai Sea) marine ranching ecosystem in the nearshore waters of northern China. Two sedentary target species with potential for stock enhancement, i.e., the carnivorous red snail Rapana venosa and the detritivorous sea cucumber Apostichopus japonicus, were selected to simulate and estimate their ecological carrying capacities and project their overall effects on the ecosystem. Ecological carrying capacity was defined as the maximum standing stocks of the target species that would not cause “unacceptable” impacts on the ecosystem function and resilience, i.e., not cause any other group’s biomass to fall below 10% of its original biomass. The ecological carrying capacities estimated for R. venosa and A. japonicus were 623.46 and 200.57 t·km−2, respectively, corresponding to 7.8 and 5.0 times higher than their current standing stocks. Simulations of R. venosa enhancement showed distinct effects of increased target species abundance on other functional groups and ecosystem properties. An increase in red snail biomass caused negative impacts on the biomass of most other functional groups and ecosystem indicators, such as Finn’s cycling index, transfer efficiency, and Kempto

Fisheries stock status is generally based on time series catch and effort data sourced from independent surveys and the fishery. These methods are often expensive and can be limited temporally and spatially. Alternative methods include the use of local fisher knowledge (LFK) to identify observed changes in catch. The blue swimmer crab (Portunus armatus) supports a small-scale commercial fishery and one of the most popular recreational fisheries in south-western Australia. Previous studies identified concerns from recreational fishers over its long-term sustainability. To understand if fishers’ perceptions of change provide useful information on actual changes in the fisheries, a triangulation approach was used to assess changes in size and abundance of crabs in two estuaries (Peel-Harvey and Swan-Canning). Three types of data were used: (i) fisher recollections from 1940s to 2010s, including face-to-face interviews and online surveys; (ii) historical records from newspaper articles from 1900 to 2000; and (iii) quantitative data on size between 2006/07 and 2018/19. Results identified: (i) crabs were smaller in the Peel-Harvey, a consistent difference identified in all data sources; (ii) crab size was perceived to have decreased in the Peel-Harvey; (iii) inter-generational differences in fishers’ perceptions regarding size changes over time; and (iv) historical evidence of persistent fishers’ concerns and perceptions of changes in the fishery and wider environment. These findings are evidence of a likely decline in the average size of crabs in south-western Australia over the last century, particularly in the Peel-Harvey, and demonstrate that LFK may be a valuable source of information particularly when other data sources are lacking.

Human-caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of individuals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3–8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating accept

Insights into the food habits of predators are essential for maintaining healthy predator populations and the functioning of ecosystems. Stomach content and stable isotope analyses were used to investigate the foraging habits of an apex predator, the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in south-western Australia. A total of 2,594 prey items from 26 families were identified from the stomachs of 10 deceased stranded dolphins. Fish otoliths from stomach contents were used to identify fish to family or species level. Ninety-three percent of identified stomach contents were perciforme fishes, however, perciformes comprised only 30% of the catch during prey sampling. Gobiidae species, small fish generally <100 mm in total length, were the most prevalent family identified in dolphin stomachs, accounting for 82% of identified prey, yet Gobiidae accounted for 12.7% of the catch during prey sampling. For stable isotope analyses, tissue samples from 14 free-ranging dolphins were analyzed for nitrogen (δ15N) and carbon (δ13C) ratios. From stable isotope analyses and boat-based dolphin photo-identification surveys (n = 339, 2007–2011), results indicated niche differentiation between coastal and inshore (bay and estuarine habitat) dolphins. Carbon signatures showed that coastal dolphins had a more pelagic diet compared to a benthic diet observed in the inshore dolphins. Whereas, nitrogen signatures of inshore dolphins showed higher nitrogen levels than coastal dolphins, likely attributed to feeding on enriched prey typical of estuarian environments. Overall, these results indicated that bottlenose dolphins in the study area were selective foragers and that their foraging is specialized by the habitats most frequently used.

Documented cases of cetacean births in the wild are rare. While there are currently no direct observations of a complete humpback whale birth, they are one of the few large whale species where observers have been present during a birthing event. We compiled eye-witnessed accounts of all known humpback whale birthing events and found nine well-documented cases globally (three published and six “new” unpublished). In two-thirds of the accounts another “escort” whale was present and in close association with the birthing female, and of these, most cases involved multiple escorts (n = 4). We describe details of birthing events, including mother, neonate and escort(s)’ behavior, neonate appearance, and discuss reasons for escort presence during parturition. We note that immediately postpartum: (1) blood and/or placenta were not always apparent during above water observations, (2) females often (but not always) supported calves at the surface, (3) constant travel and tail slapping were typical neonate behaviors, (4) two cases of temporary calf abandonment (<10 min), and (5) evidence of shark scavenging (of placenta) and possible predation attempts (of neonate). Lastly, we suggest curled tail flukes as an additional trait for identifying neonates and note that fetal folds are not always evident in newborn humpback whales.

The fish faunas of eight estuaries along 130 km of the south coast of Western Australia were sampled seasonally for one year, during which Beaufort Inlet became markedly hypersaline (salinities up to 122 and > 100 for six months). These conditions were caused by a combination of low amounts of saline river flow, the bar of this shallow estuary remaining closed for 27 months and high rates of evaporation. Fish faunas in the nearshore, shallow and offshore, deeper waters of Beaufort Inlet were depauperate compared to nearby estuaries. The number of fish species declined as salinity increased, with the highly euryhaline, estuarine-resident atherinid Atherinosoma elongata being the only species to survive throughout the study. The cosmopolitan flathead mullet Mugil cephalus survived for the next longest period, living in salinities in excess of 100 for at least four months and in a maximum salinity of 122. This is the highest known salinity in which a marine-spawning fish species has been found globally. This finding provides support for the cryptic species complex hypothesis pertaining to M. cephalus and that individuals in south-western Australia may be a seperate species. The survival of these species for a relatively protracted time reflects the fact that they are euryhaline and have a suite of adaptations that allow them to occupy environments from freshwater to extreme hypersaline conditions. The longer occurrence of M. cephalus in the extreme salinities than Acanthopagrus butcheri and Aldrichetta forsteri, is likely also related to their primary diet of detritus, particulate organic matter and diatoms, all of which are abundant in Beaufort Inlet. In contrast, piscivorous and zoobenthivorous fish were depauperate and in low abundances, which may reflect limited food resources during hypersaline conditions, and/or more reduced euryhalinity by these species. Clearly, hypersalinity has a marked effect on the faunas and thus ecosystem functioning of estuaries, and wit

Small-scale fisheries (SSF) provide crucial contributions to livelihoods, food and nutrition security, and the well-being of coastal communities worldwide. In Indonesia, 2.5 million households are involved in SSF production, yet these households are characterised by high poverty rates and vulnerability due to declining ecosystem health and climatic change. In this study we applied the Sustainable Livelihoods Framework to analyse the characteristics and immediate and longer-term outcomes of 20 SSF livelihood-focused intervention programs implemented in coastal communities across the Indonesian Archipelago over the last two decades. Projects covered a wide range of spatial scales, funding providers and key participants. Factors supporting positive program outcomes included application of inclusive and holistic approaches to sustainable livelihoods, implemented and supported over appropriate time frames; use of participatory capacity development methodologies and locally-situated project facilitators; and collaborative engagement with local government, non-government organisations and private-sector actors. However, it was impossible to identify evidenced successes from a longer-term sustainability perspective. Short project timeframes, absence of baseline or monitoring data, pressure for satisfactory reports to donors, and limited post-project evaluation, together with invisibility of women’s work and non-commercial exchanges, affected the adequacy of assessments. Given the lack of post-project assessment among projects studied, a thorough review of longer-term project impacts is recommended, guided by the Sustainable Livelihoods Framework, to evaluate sustained improvements in livelihoods outcomes and environmental sustainability. This would support best-practice design and implementation of SSF livelihood-focused interventions, disseminated beyond academia, to influence policy and development to achieve socio-economic equity and environmental goals.

Identification of key drivers of population dynamics and prediction of rates of population recovery following stock decline are crucial aspects of fisheries management. The abundance of a blue swimmer crab population (Portunus armatus) in Cockburn Sound, Western Australia, which once supported the largest commercial fishery for this short-lived species in the State, declined markedly and has remained low despite two commercial fishery closures. This study employed state-space biomass dynamics models to explore evidence for potential factors contributing to the lack of stock recovery, including fishing pressure, changes in primary production (using chlorophyll-a as a proxy) and depensatory stock-recruitment dynamics. Likelihood ratio test results indicated better statistical fits for models with production functions modified to account for chlorophyll-a or both depensation and chlorophyll-a. Models incorporating both depensation and chlorophyll-a provided the most biologically-feasible results (e.g. estimated intrinsic increase, , not near zero) and the estimated biomass trajectories were less uncertain. For all models, estimated annual harvest rates peaked in the late 1990s, prior to the first major stock decline, and again in 2009−12, when the fishery was briefly re-opened with tight management restrictions. Results for models including both depensation and chlorophyll-a indicated that stock productivity is positively-related to chlorophyll-a. Thus, below-average chlorophyll-a concentrations in Cockburn Sound in recent years, in combination with some form(s) of depensation (e.g. associated with predation pressure), may be preventing stock recovery. Despite a sustained period of very limited recreational fishing and no commercial fishing, stock recovery appears highly uncertain under current environmental conditions. The results of this study highlight the value of incorporating environmental data and alternative stock-recruitment assumptions when fitting production

Simulated social facilitation techniques (e.g. decoys and call playbacks) are commonly used to attract seabirds to restored and artificially created nesting habitats. However, a lack of social stimuli and conspecific cueing at these habitats may limit the use of these sites, at least in the short term. Therefore, testing the effectiveness of simulated audio-visual cues for attracting gregarious birds is important for conservation planning. In this study, we (1) assessed whether call playback and decoys were associated with an increased likelihood of Australian fairy terns Sternula nereis nereis visiting potentially suitable nesting habitats; (2) tested their behavioral response to different cues; and (3) documented whether social facilitation had the potential to encourage colony establishment. A full cross-over study design consisting of all possible pairings of decoy and call playback treatments (control [no attractants], decoys, call playback, both decoys and playback), allocated as part of a random block design, was undertaken at 2 sites. Linear modeling suggested that call playback was important in explaining the time spent aerial prospecting as well as the maximum number of fairy terns aerial prospecting, although this only appeared to be the case for 1 of the 2 sites. Decoys, on the other hand, did not appear to have any effect on time spent aerial prospecting. The results from this study suggest that audio cues have the potential to encourage site selection by increasing social stimuli, but attractants may be required over several breeding seasons before colonies are established.

Portunid crabs contribute to significant commercial and recreational fisheries globally and are commonly fished in estuaries and/or marine embayments, which are amongst the most degraded of all aquatic ecosystems. Portunus armatus were collected seasonally between April and February from five locations across three systems in temperate south-western Australia. The dietary composition of crabs was quantified and compared between two estuaries (Peel-Harvey and Swan-Canning) and a sheltered marine embayment (Cockburn Sound) containing three distinct habitats: shallow seagrass, shallow sand and deep sand. Overall, crabs ingested large volumes of bivalves (both live organisms and dead shell), polychaetes, crustaceans (e.g., amphipods, small decapods), and smaller volumes of teleosts, echinoderms and plant material (seagrass, algae). Analysis of Similarities showed that dietary composition varied significantly among the five locations (two estuaries and three habitats within Cockburn Sound) and seasons, with greater location than seasonal differences in the two estuaries. Diets were most distinct in the Cockburn Sound seagrass due to greater volumes of decapods and teleosts and smaller volumes of bivalve shell consumed in this habitat. Crabs from both estuaries consumed greater quantities of bivalves than those from Cockburn Sound. Seasonal differences in both estuaries were greatest between summer and winter, with a more diverse range of prey and large quantities of bivalves ingested in summer, whereas small bivalves and bivalve shell in the Peel-Harvey and polychaetes and other crustaceans in the Swan-Canning, were consumed in greater quantities in winter. The summer diet in the Peel-Harvey Estuary in the current study was compared to that 20 years previous and with documented change in the benthic macroinvertebrate fauna. Currently, crabs consume smaller volumes of high-calorie prey, i.e., polychaetes, small bivalves and teleosts, and instead ingest greater proportions

Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.

Indonesia is an archipelagic nation, with over 13,466 islands within one of the largest exclusive economic zones (EEZs) in the world. Indonesian capture fisheries are among the most productive fisheries worldwide, with several fisheries in the top five by production globally. Statistics from the Food and Agriculture Organization of the United Nations (FAO) show that the overall production of fish products in Indonesia is second globally (FAO, 2020). Indonesian fisheries become even more significant when considering the number of livelihoods supported by small-scale fisheries...

The two workshops held in Bogor, Indonesia, synthesised information for seven data-limited fisheries in Indonesia and built an understanding of both evaluating management strategies for fisheries and how to apply the Method Evaluation and Risk Assessment package (MERA). As part of the process, new data assessments of fisheries were tabled, mainly using the length-based spawning potential ratio, which typically found very low stock levels. These findings are consistent with those reported to the Government of Indonesia on the status of stocks across the 11 Fisheries Management Areas (FMAs). For example, in 2011, 35% of stocks were assessed as fully exploited and 38% as overexploited, while in 2017, 39% were reported as fully exploited and 44% as overexploited (e.g. decision number 50/KEPMEN-KP/2017). The findings also highlight the need to better manage the fisheries and implement effective measures to rebuild stocks...

Indonesian capture fisheries are among the most productive fisheries worldwide; several feature in the five highest-producing fisheries globally. Statistics for 2018 from the Food and Agriculture Organization of the United Nations (FAO) show that the overall landings of marine fish in Indonesia rank a global second. Moreover, the importance of small-scale Indonesian fisheries is underscored by the number of livelihoods they support. These proceedings report the findings from two workshops held to consolidate the available information on and evaluate management strategies for seven data-limited fisheries in Indonesia. The work builds on previous Australia–Indonesia collaborations in marine fisheries research, including three projects conducted by the Australian Centre for International Agriculture Research (ACIAR): (1) Capacity development to monitor, analyse and report on Indonesian tuna fisheries; 2005–2010 (ACIAR Project FIS/2002/074), (2) Developing new assessment and policy frameworks for Indonesia’s marine fisheries, including the control and management of Illegal, Unregulated and Unreported Fishing (ACIAR Project FIS/2006/142), and (3) Developing research capacity for management of Indonesia’s pelagic fisheries resources (ACIAR Project FIS/2009/059)...

Fisheries enhancements are management approaches involving the use of aquaculture and habitat technologies (in the broadest sense) to enhance or restore fisheries. The technologies most commonly used include hatchery rearing and release of aquatic animals and provision of artificial structures such as artificial reefs. Both are associated with distinct fields of knowledge and communities of practice. Recent calls to expand and broaden the role of aquaculture and habitat enhancements in marine conservation and an increasingly integrated view of living marine resource management have led to an aspirational broadening of concepts in this area. The 10th William R and Lenore Mote Symposium and 6 th International Symposium on Stock Enhancement and Sea Ranching aimed to advance and integrate knowledge across enhancement technologies and practices. Substantial progress was noted in multiple technical areas such as understanding the potential and limitations for rearing organisms fit for release into the wild, and the design of artificial reefs to enhance local fish abundance. Crucial higher-level goals such as effectively enhancing or restoring fish abundance and fisheries at the stock level continue to receive insufficient attention across the enhancement sciences. Integration of enhancement strategies provides opportunities and challenges including a need to recognize, cross-discover, and engage other distinct areas of knowledge and communities of practice. A quick reference guide is provided to facilitate this process.

Vessel strike is recognized as a major modern threat to the recovery of large whale populations globally, but the issue is notoriously difficult to assess. Vessel strikes by large ships frequently go unnoticed, and those involving smaller vessels are rarely reported. Interpreting global patterns of vessel strikes is further hindered by underlying reporting biases caused by differences in countries’ research efforts, legislation, reporting structures and enforcement. This leaves global strike data “patchy” and typically scarce outside of developed countries, where resources are more limited. To explore this we investigated vessel strikes with large whales in the Eastern Tropical Pacific (ETP), a coastal region of ten developing countries where heavy shipping and high cetacean densities overlap. Although this is characteristic of vessel strike “hotspots” worldwide, only 11 ETP strike reports from just four countries (∼2% of total reports) existed in the International Whaling Commission’s Global Ship Strike Database (2010). This contrasts greatly with abundant reports from the neighboring state of California (United States), and the greater United States/Canadian west coast, making it a compelling case study for investigating underreporting. By reviewing online media databases and articles, peer review publications and requesting information from government agencies, scientists, and tourism companies, we compiled a regional ETP vessel strike database. We found over three times as many strike reports (n = 40), from twice as many countries (n = 8), identifying the geographic extent and severity of the threat, although likely still underestimating the true number of strikes. Reports were found from 1905 until 2017, showing that strikes are a regional, historic, and present threat to large whales. The humpback whale (Megaptera novaeangliae) was the most commonly hit species, and whale-watch industries involving small vessels in areas of high whale densities were recognized

This study investigates the distribution, abundance, and foraging ecology of Caspian Terns, Hydroprogne caspia, during 5 months of their non-breeding season, in the Peel-Harvey Estuary, south-western Australia. Observations were carried out at 20 sites around the estuary and 6 main areas (13 sites) where terns were abundant. Terns were observed every hour over 5 h time-blocks in the morning, midday, and afternoon, and the number of birds, number of birds foraging and time spent foraging were recorded for 10 min on the hour. From the 760 h of observation, a single overnight roosting site was identified in November, where a maximum of 147 birds were counted in February, after which time the roosting site appeared to shift. The total number of terns, foragers and proportion of time foraging varied amongst the six areas and foraging activity differed amongst times of day. Two areas, both characterised by large, sandy spits adjacent to shallow water, one adjacent to a river mouth and one near an ocean channel, were particularly important for terns and their foraging. Foraging activity was higher in the morning than at other times of day. Although salinity, air temperature, water temperature and wind speed were correlated with the total terns, foragers and proportion of time foraging, the correlations accounted for <25% of the total variation explained. The results of this study provide information for evaluating the use of Caspian Terns as bio-indicators of the Peel-Harvey Estuary and highlights the importance of this system during the non-breeding period.

Feeding studies provide important information about animals and the environments in which they live. Yet little is known about the diet of the Australian Fairy Tern Sternula nereis nereis, despite the species being listed as threatened (Vulnerable) and in need of research. This study investigated the dietary composition of this bill-loading seabird, at three colony sites of an inner shelf seascape (two marine and one estuarine) using non-invasive digital photography and direct observations (number of observations [n] = 9854). Small surface schooling, inshore spawning fishes were the most important prey at all sites. Blue Sprat Spratelloides robustus, hardyheads (Atherinidae spp.), and garfishes Hyporhamphus spp. dominated the diet, contributing 75% of all prey at each site. The abundance of these fishes, whose spawning period overlapped the Fairy Tern breeding season in south-western Australia (October to February), is likely an important factor influencing the location of Fairy Tern colonies. Multivariate statistical analyses showed that dietary composition differed significantly among colony sites, breeding seasons, between courtship and chick feeding, and time of day. Blue Sprat, Beaked Salmon Gonorynchus greyi, and flyingfishes (Exocoetidae spp.) were present in greater proportions at Rottnest Island and Penguin Island (marine sites) than at Point Walter (estuarine). In contrast, hardyheads, Tailor Pomatomus saltatrix, and Yelloweye Mullet Aldrichetta forsteri were more common at Point Walter. Garfishes were around twice as important at Penguin Island than the other sites. Differences in habitat and fish species assemblages at each site may explain the observed spatial trends in dietary composition, while environmental factors, e.g. sea surface temperature and freshwater discharge, and natural interannual variability may explain the observed temporal trends in diet. Fish donated for courtship were ∼21% (12 mm) longer than those provisioned to chicks and the comp

Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.

This research describes the breeding ecology, behaviour and substrate preferences of the Australian Fairy Tern, Sternula nereis nereis, in four colonies around Perth, Western Australia between 2018 and 2020. Extensive field observations, supported by a bird banding study and sunrise to sunset video recording were used at colony and roosting sites to determine the processes of mating, colony formation, egg-laying and incubation periods, post-hatching care and breeding success (fledglings per pair). At a colony in North Fremantle, the median nest spacing was 0.71 m (mean ± s.e. = 0.89 ± 0.05 m), which increased over time. Birds establishing nests within a week of the first eggs being laid selected sites with significantly higher percentage beach shell cover (73.5 ± 4.5%) than those laying later in the season (58.2 ± 7.9%) and on average, birds selected sites with higher shell cover (64.9 ± 2.8%, n = 114) than a random sample of sites within the colony (53.7 ± 4.4%, n = 44). Incubation periods ranged from 17 to 26 days (n = 86, mean = 21 ± 0.17 days). Incubation shift duration was highly variable, with both sexes contributing, almost equally to the care of the brood (mean = 1.27 ± 6.11 h). Chicks fledged 21–23 (mean = 22 ± 0.21, n = 10) days following hatching, with all banded juveniles leaving the colony site within 8 days of fledgling. The information gained from this research helps inform conservation strategies for this vulnerable species, where management interventions are frequently necessary to prevent population decline.

Sustainable natural resource management requires collaboration, adaptability and coordination between science, policy and stakeholders. Communication of scientific information through social networks is integral to effective governance. This study employed social network analysis to investigate information flow between stakeholders associated with the blue swimmer crab (Portunus armatus) fishery in the Peel-Harvey Estuary, south-western Australia. Although the fishery received Marine Stewardship Council certification in 2016, a preliminary study conducted between 2017 and 2018 revealed that fishers were concerned about its status and management. Consequently, 85 face-to-face interviews were conducted with commercial and recreational fishers, academics, government bodies, representatives of fishing organizations, non-governmental organizations, and tourism operators to understand the flow of information and the influence on perceptions of sustainability. The results showed that: (i) few individuals were key for sharing information within and between different organizations forming the fishery network and only two of the six groups (government bodies and the commercial fishing sector) were highly connected and appeared as key for information sharing; (ii) after the public awareness and tourism groups, academic groups were the second-least connected, despite having actively researched the Peel-Harvey Estuary and the P. armatus fishery for over 40 years; (iii) recreational fishers exchanged information mainly with other fishers and the state fisheries department; (iv) modes of communication used with the recreational fishing sector differed greatly between the fisheries department (i.e., mainly via phone/email) and the recreational fishing organization (i.e., strong online presence, social media, and phone/email); (v) issues of inclusiveness and representativeness were highlighted for some of the groups and organizations. This is the first study looking at information-s

The Carcharhinidae is one of the most at-risk shark families in the Indo-West Pacific (IWP), which is a global priority for the conservation of elasmobranchs. Of the 57 described species of carcharhinids, 43 are known from the IWP, where many are subject to high fishing pressure. Many of these species are also found outside this bioregion. Understanding the connectivity of individual species across their ranges is paramount to successful management of their fisheries. Studies of population genetic structure have been the mainstay for assessing connectivity. Here, we review 41 studies pertaining to the population genetic structure of 20 species of carcharhinid whose ranges include the IWP and for which relevant data are available. The genetic markers used range from microsatellite loci and small mitochondrial DNA sequences (375 to 4797 bp) to genomic analyses. Overall, the population genetic structure for these carcharhinids was varied but patterns emerged according to the lifestyle of the species, with the greatest structure shown by species that are highly habitat dependent and the least structure shown by oceanic species. Experimental designs of the underlying studies have, however, often been opportunistic with small sample sizes, few locations sampled and based on analysis of single mitochondrial regions and/or few microsatellite markers. The literature provides a basis for understanding the population genetic structure of IWP carcharhinids, but future research needs to focus on the application of population genomics and more robust experimental design so that population genetic structure can be quantified with higher certainty and resolution over finer spatial scales.

Small-scale fisheries (SSF) in southeast Asia contribute more food fish for human consumption than industrial fisheries and in Indonesia, employ almost 85% of the total fisheries employees. Grouper and snapper are commercially important species highly targeted, including by small-scale fishers. We estimate the spawning potential ratios (SPRs) of high-value species in a small-scale fishery in Saleh Bay (Plectropomus leopardus, Variola albimarginata and P. maculatus) and in the Timor Sea (Lutjanus gibbus, L. boutton and Epinephelus areolatus) from a larger scale fishery (Kupang) and a SSF (Rote), using length-frequency data, biological parameters and empirical equations and the length-based SPR methodology. Measuring programs collected 10,621 lengths frequency samples from six species over 12 months, with ¿ 800 recorded lengths for each species. The SPRs for all species were very low (0.02–0.12), except for E. areolatus (0.49) and ratios of fishing to natural mortalities (F/M) were high (1.8 – 9.3). The results from the length-based SPR model indicate that the fish are harvested below the size of maturity, except for E. areolatus. Further analysis indicated that the smaller E. areolatus landed in Rote is likely under-represented compared to that of E. areolatus landed in Kupang. The expanding landings of grouper and snapper on a broad-scale and low SPRs highlight the importance of seeking measures to rebuild these stocks. These estimates of SPR would be enhanced by detailed biological studies of these species to obtain local estimates of growth parameters and size at maturity, as well as the size-at-selectivity for different fishing gears.

Long-term monitoring data and models have been used to explore the efficacy of restocking an estuarine-resident teleost species. Juveniles of Acanthopagrus butcheri were cultured from broodstock from the Blackwood River Estuary in 2002 and their otoliths stained with alizarin complexone. 150,000 marked juveniles were released into the Blackwood River Estuary at three months old in early 2003, with the stain in their otoliths subsequently remaining visible during the following 16 years. Samples of A. butcheri were obtained annually from a commercial gill net fisher and at intervals by fishery-independent methods. Commercial catch per unit effort was positively related to freshwater discharge. Indices of year class strength, derived from annual age-frequency distributions and assuming length-dependent natural mortality, demonstrate that between 1993 and 2012, natural recruitment to the population was only strong in 1999 and 2008 and was not significantly related to freshwater flow. The number of wild stock A. butcheri ≥ minimum legal length (250 mm total length), comprising mainly the 1999 year class, were estimated to have declined sequentially to only ∼12,000 fish in 2010. The restocked fish contributed between 61 and 73 % to the total number of fish in the commercial catches between 2007 and 2010 and their numbers remained at > 10 % of their number at release until 2011. The contribution of the 2008 year class, of which ∼50 % had been estimated as derived from restocked fish, increased from 20 % of the commercial catch in 2012 to between 50 and 80 % between 2013 and 2018. A progressive decline in growth of year-class groups of wild stock fish, from 1970-1998 to 2008-2011, is considered to reflect the detrimental effects of hypoxia. Restocked fish grew less rapidly than younger and older year-class groups of wild stock fish, suggesting that the growth of cultured fish may have been compromised by hatchery processes. The large contributions made by restocked fish to

Fisheries management rights (FMRs), such as territorial use rights in fisheries (TURFs), are a promising approach for fisheries management that, if implemented on larger geographic scales, may be able to reduce the risk of fisheries decline, particularly for small-scale fisheries (SSF). SSF are significant throughout Asia, Africa and South America for millions of fishers and supporting the livelihoods of coastal communities. This research evaluates the potential of TURFs as a management tool in Indonesia and develops this into a concept of contemporary FMRs. In Indonesia, the adat communities, i.e. those communities where customary tenurial claims are still practiced, acknowledged under law and respected by migrant communities, have been able to implement TURFs. In Maluku and West Papua regions, TURFs (≈customary marine tenure or petuanan laut) are possible because tenure rights are recognized and confer the essential TURFs elements of exclusivity and security. We investigate the potential for scaling up TURFs by transforming petuanan laut that has enabled the successful implementation of sasi laut, a traditional measure to regulate the utilization of marine resources, into modern FMRs, especially for SSF. Elements of policy reform, the use of science-based fisheries management principles, and data-limited stock assessment methods to inform adaptive management are also considered. We discuss the adoption of FMRs into relevant law to allow the scaling up of TURFs throughout Indonesia. The FMRs are conceived as a privilege granted by government to an entity or group that comes with resource stewardship responsibilities and should be revocable if they are breached.

The gobiid Acentrogobius plflaumii, native to estuaries and coastal embayments in East Asia, has recently established a population in the warm-temperate Swan-Canning Estuary (SCE) in southwestern Australia. Data from 432 individuals demonstrated that although A. pflaumii was shown to live for 4 years, the age composition was dominated by 0+ and 1+ individuals. The maximum size of female (94 mm) and male (96 mm) A. pflaumii in the SCE is 33% larger than in its native habitat. Acentrogobius plflaumii grew rapidly, attaining a length of 65 mm, i.e. 84 and 87% of their ’s of 77.3 and 72.9 mm for females and males, respectively, within the first year of life. Gonadosomatic indices, trends in monthly gonadal development and histological examination of gonads indicate that, although peak spawning in the SCE occurs over a similar period and season as in South Korean waters, spawning is more protracted in the SCE. Two discrete modes in oocyte diameter frequencies indicate this species exhibits determinate fecundity. The protracted spawning period enables batches of eggs to be released periodically during favourable conditions. These biological traits are likely to have aided in the successful colonisation of this species in the SCE. Quantifying the phenotypic plasticity of this non-indigenous species may inform risk assessments and subsequent management plans to mitigate the effect of A. pflaumii in the SCE and predict the likelihood of it colonising other southwestern Australian estuaries.

The implications of plastic pollution, including microplastics, on marine ecosystems and species are increasingly seen as an environmental disaster. Yet few reports focus on filter-feeding megafauna in regions heavily impacted by plastic pollution, such as Indonesia in the Coral Triangle, a global marine biodiversity hotspot. Here, we evaluate plastic abundance and characterize debris from feeding grounds for manta rays Mobula alfredi and whale sharks Rhincodon typus in three coastal locations in Indonesia: Nusa Penida Marine Protected Area, Komodo National Park, and Pantai Bentar, East Java. A 200 μm plankton net was used to sample the top 0.5 m of the water column (‘trawl survey’) and floating plastics were assessed along ∼440 m long transects (‘visual survey’) during the Indonesian north-west (wet) and south-east (dry) monsoon seasons during 2016–2018. Microplastics were identified visually, measured and categorized from trawl samples, and larger floating plastics were counted and categorized visually from boats. Plastic abundance ranged widely from 0.04 to 0.90 pieces m–3 (trawl survey) and 210 to 40,844 pieces km–2 (visual survey). Results from linear models showed significant seasonal and location differences in estimated plastic abundance for trawl and visual surveys in Nusa Penida and Komodo. Plastic abundance was up to ∼ 44 times higher in the wet than the dry season, with the largest seasonal effect observed in Nusa Penida. Overall, small pieces < 5 mm (≥ 78%), films and fragments (> 50% combined) were the most prevalent plastics. Theoretical plastic ingestion rates were calculated using estimated filtration volumes of manta rays and whale sharks and the mean plastic abundance in their feeding grounds. Upper plastic ingestion estimates for manta rays were ∼63 and 25 pieces h–1 for Nusa Penida and Komodo locations, respectively, and ∼137 pieces h–1 for whale sharks in Java. Analysis of manta ray egested material confirmed plastic ingestion, the consequences

Fisher perceptions are a useful source of information that allows changes in stocks to be detected quickly and indicate the social acceptability of different management regulations. Yet traditionally, such information is rarely employed when developing management approaches. Face-to-face interviews were used to elicit recreational and commercial fishers’ perceptions of a crab (Portunus armatus) fishery in three south-western Australian estuaries. Differences in the perceived changes in the average size of crabs and fishing effort, reported concerns and supported solutions were detected among the recreational fishers utilizing the three estuaries and between recreational and commercial fishers in the Peel-Harvey Estuary. However, some common views were expressed by recreational and commercial fishers, with both sectors stating concerns over recreational fisher compliance and increased fishing and environmental pressures. While both sectors believed that reducing fishing and increasing compliance would benefit crab stocks, the mechanisms for achieving this differed. Recreational fishers favoured increasing the length of the seasonal closure, while commercial fishers favoured the introduction of a recreational shore-based fishing licence. These findings suggest that sector- and estuary-specific management rules may better facilitate the amelioration of pressures affecting individual estuaries and could contribute towards a more socially and biologically sustainable fishery.

In recent decades, there have been considerable efforts to enhance, diversify, or implement alternative livelihood activities in marginalized coastal communities, to ease reliance on deteriorating coastal resources, reduce poverty and improve well-being outcomes. To date, gender has been notably absent from the literature on small-scale fisheries and associated livelihood improvement programs, despite increasing evidence of the importance of gender equality and women’s empowerment in achieving such outcomes in other contexts. In this paper, drawing from an evaluation of the effectiveness of 20 livelihood development projects implemented in coastal communities in Indonesia since 1998, we report on how gender was considered in these projects. We assessed whether and how gender was included in project rationales, and how men and women were included in project activities. We found that, despite the women being reached by many project activities, particularly efforts to increase women’s productive capacity through training and group-based livelihoods enterprises, 40% of the projects had no discernible gender approach and only two of the 20 projects (10%) applied a gender transformative approach that sought to challenge local gender norms and gender relations and empower women beneficiaries. Our assessment suggests the need for greater understanding of the role of gender in reducing poverty and increasing well-being outcomes in coastal communities. Lessons from comparable agricultural settings suggest that this may be facilitated by locally situated gender social relations analysis, integration of gender throughout livelihood improvement project cycles, gendered capacity building activities and shared learning from the evaluation of the gendered outcomes of project activities.

This study describes nest desertion as a probable but previously undescribed anti-predator strategy for the Australian Fairy Tern Sternula nereis nereis. Deserted nests were observed at night for up to nine nights following the laying of the first eggs at a colony in southwestern Australia. Nocturnal nest desertion may provide the terns with a mechanism for assessing the occurrence of potential nest predators, maintaining reproductive synchrony, and reducing the total time a colony is detectable by predators. Additionally, temporary diurnal nest desertion for up to 80 minutes was observed following the predation of an adult tern. Diurnal nest desertion may be used to reduce the risk of adult mortality and, consequently, decrease colony visibility, thereby increasing reproductive success.

The deployment of artificial reefs to enhance the abundance of reef-associated species in the coastal waters of China occurs on a very large scale. However, the ability of these artificial structures to mimic natural habitats for fauna has not been evaluated. This study examined the benthic fish and macroinvertebrates assemblages (sampled using trap nets) of artificial reef complexes deployed in shallow, nearshore (9–11 m) and deeper, offshore waters (20–30 m) in the Lidao artificial reef zone (Yellow Sea, China) to determine whether they differed from assemblages on adjacent habitats: i.e. natural reefs in nearshore and bare substratum in offshore waters. It also investigated the extent of any temporal variation in these assemblages. A greater total number of taxa were identified in offshore than nearshore waters, but nearshore waters supported higher total mean numbers and biomass. No significant differences were detected in the characteristics of the benthic fish and macroinvertebrate fauna between artificial reefs and their corresponding natural habitats in both depths. Faunal composition in both depths showed strong patterns of temporal variation, mainly due to changes in the abundance of some transient fish species such as Conger myriaster and Pseudopleuronectes herzenstein, which matched seasonal patterns in water temperature and clarity. The similarity of community structure between nearshore artificial reefs and natural habitats implies that the artificial reefs are mimicking natural habitats, which facilitates functional connectivity. Thus, in the Lidao artificial reef zone, artificial reefs and natural habitats can be considered as integrated habitat management units. In the offshore waters, however, the lack of a difference in composition between habitats possibly reflects the observed sinking of the artificial reefs. This highlights the importance of detailed site assessments before the deployment of artificial reefs, particularly in silty sediments.

Gastric tract (crop and stomach) and stable isotope analyses (SIA) were used to evaluate the dietary composition of resident, commercially important Octopus aff. O. tetricus Gould, and its importance as a predator of Haliotis laevigata Donovan, on artificial abalone habitats. Taxonomic diversity and resolution of diet were higher in crops (13 taxa) than stomachs (10 taxa), with the latter dominated by unidentifiable material (%Volume = 74%). Crops contained mainly molluscs (~54%, including 31% abalone) and crustaceans (33%), suggesting octopus are important predators of abalone on the sea ranch. Dietary composition of crops did not differ with increasing octopus weight (<300 g, 300–999 g, ≥1,000 g wet weight), paralleling the findings of SIA and reflecting the high stocking densities of abalone that are able to be consumed by octopus of all sizes. The SIA also revealed that octopus occupy a mid‐trophic level, slightly below teleosts and loliginid squids.

Domestic cats have a cosmopolitan distribution, commonly residing in urban, suburban and peri-urban environments that are also critical for biodiversity conservation. This study describes the impact of a desexed, free-roaming cat on the behavior of a threatened coastal seabird, the Australian Fairy Tern, Sternula nereis nereis, in Mandurah, south-western Australia. Wildlife cameras and direct observations of cat incursions into the tern colony at night, decapitated carcasses of adult terns, dead, injured or missing tern chicks, and cat tracks and scats around the colony provided strong evidence of cat predation, which led to an initial change in nesting behavior and, ultimately, colony abandonment and the reproductive failure of 111 nests. The death of six breeding terns from the population was a considerable loss for this threatened species and had the potential to limit population growth. This study highlights the significant negative impacts of free-roaming cats on wildlife and the need for monitoring and controlling cats at sites managed for species conservation. It also provides strong evidence against the practice of trap-neuter-release programs and demonstrates that desexed cats can continue to negatively impact wildlife post-release directly through predation, but also indirectly through fundamental changes in prey behavior and a reduction in parental care.

Understanding fisher beliefs and attitudes towards specific management strategies can help inform and improve fisheries management, and thus stock sustainability. Previous studies highlight a lack of fisher awareness regarding environmental issues influencing the systems they utilise and the negative impacts of specific strategies, such as stock enhancement. Our study used a two-phase approach to first elicit and then measure the strength of common fishers’ beliefs and associated attitudes regarding stock enhancement. Specifically, this research focused on recreational fishers of an estuarine crab fishery (Portunus armatus) in south-western Australia. The results demonstrate that recreational fishers believe stock enhancement could have strong positive outcomes, but also recognise that this management strategy could lead to some negative outcomes, though the latter are perceived as less likely to happen. This contrasts with previous research on fisheries stocking and demonstrates the value of using the two-phase approach to clarify fishers’ perceptions of particular management approaches. To reduce fisher dissatisfaction with management actions, careful communication on the benefits and costs of stock enhancement is recommended. Our study highlights the significance of integrating social sciences into fisheries research, and the need to better understand fishing community beliefs to ensure effective management of the fishery.

Non-indigenous species are recognised as a significant threat to estuaries as they can negatively impact native fauna and ecosystem functioning. This study compared the abundance and distribution of the introduced gobiid, Acentrogobius pflaumii, with native gobiids in the shallow, nearshore and deeper, offshore waters of the Swan-Canning Estuary over 31 consecutive months and determined the influence of salinity and water temperature on the gobiid assemblage. Eight gobiid species were recorded (six native and two non-indigenous). Each species was present in offshore waters, with five also occurring in nearshore waters. The contribution of A. pflaumii to the gobiid fauna varied markedly between depths, not being recorded in the 1240 samples from nearshore waters, but representing almost half of all gobiids caught in offshore waters. The percentage contribution of this species to the total gobiid abundance declined with distance from the estuary mouth, from 96% in the most downstream region to only 0.4% in the uppermost. The overwhelming contributions of A. pflaumii in the lower estuary, which historically contained few gobiids, indicate that it has successfully exploited an unoccupied niche. Gobiid composition, in both depths, differed mainly among regions, with species partitioning themselves along the longitudinal axis of the estuary. In offshore waters, Favonigobius lateralis and A. pflaumii dominated the lower regions and Arenigobius bifrenatus, Favonigobius punctatus and Pseudogobius olorum the regions further upstream. The distributions of these species are influenced by salinity and, to a lesser extent, temperature. While there is spatial overlap between A. pflaumii and native gobiid species, its preference for deeper, more saline waters may limit the impact of this non-indigenous species.

Editorial Material

Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics and movements. We investigate the population structure and residency patterns of reef manta rays (Mobula alfredi) in the Nusa Penida Marine Protected Area (MPA). From photo-identification data logged by citizen scientists and trained observers (mantamatcher.org), we identified 624 reef manta rays from 5,913 sightings (January 2012–April 2018) based on their unique ventral coloration patterns. Year-round records were collected from two shallow (<20 m) reefs – Manta Bay (MB; n = 3,029 sightings) and Manta Point (MP; n = 3,058) – that are used frequently by tourism operators. Maximum likelihood techniques and a Markov movement analysis were used to model residency patterns and movement between these sites within the MPA. Manta rays at MB were predominantly male (64%, n = 261 individuals), with immature males (14%, n = 59) being sighted most frequently (39%, n = 1,170). In contrast, few immature individuals were sighted at MP (6%, n = 28), and they were sighted on few occasions (2%, n = 45), while mature female manta rays comprised 26% (n = 127) of the MP community and were the most frequently sighted (48%, n = 1,413). Lagged identification rates indicated high site fidelity at each location. However, 44% (n = 278) of individuals moved between the two sites and cumulative discovery curves showed a continued recruitment of individuals over the 6 years of the study. In addition, the behaviors displayed by the manta rays differed markedly between the two sites: MB appears to be a foraging ground, especially for juveniles, and potentially a nursery, while MP is used mainly for cleaning and courtship, indicating a social and reproductive site. Reproductive behavior coincided with the peak annual sightings in May. To prevent disturbance to this threatened species by tourism, regu

Many factors can affect growth, survival, reproduction, and fisheries productivity of estuarine species, including structural and physico-chemical habitats, and freshwater inflow to estuaries. Land-based activities can lead to poor catchment condition, and catchment-derived stressors can adversely impact estuarine systems. Using the Eastern School Prawn (Metapenaeus macleayi) in a south-eastern Australian estuary (Camden Haven Estuary) as a case study, we examine juvenile recruitment and fisheries productivity alongside a comprehensive suite of catchment-derived stressors, and interpret patterns in the context of existing studies of lethal and sub-lethal impacts of these stressors on penaeid prawns. Logged dissolved oxygen data indicated a moderate frequency of hypoxia throughout the system, with occasional periods of anoxia. Dissolved aluminium concentrations remained above the relevant marine water quality guideline for the majority of the study period, and concentrations tended to correlate with estuarine inflow. Hypoxia led to depressed prawn abundance, and both hypoxia and high estuary inflow led to decreased somatic condition in prawns. Long-term commercial catch negatively correlated with estuary inflow, which was the opposite of the expected pattern for the species. These patterns highlight the potential cumulative impacts of a complex array of catchment-derived stressors on an important exploited penaeid species. Similar patterns probably occur for prawn species across other floodplain estuaries across south-eastern Australia, and suggest a hitherto unquantified economic impact of degraded catchments through losses in fisheries productivity.

This study examined the occurrence of octopus across an abalone, Haliotis laevigata, Donovan, sea ranch in south‐western Australia, to understand how octopus may be impacting abalone production. Commercial divers removed 654 octopus and 17,666 empty abalone shells during regular, 2 to 4‐weekly surveys over 27 months. A negative binomial generalised linear model estimated a 78% increase in empty shells per artificial abalone habitat per day, when octopuses were present, after adjusting for location and season. Of the 408 shells examined for evidence of predation, 19% had a small, slightly ovoid hole consistent with those made by octopus. The mean (± 1 SE) length of shells with boreholes (70.3 ± 2.2 mm) was significantly longer than those without (59.8 ± 0.5 mm), and boreholes were concentrated over the adductor, respiratory organs and heart. This study provides important insights into the adaptable feeding regimes of octopus and their potential to impose strong top‐down controls on sea ranching operations.