Rapid dispersion of escaped meagre (Argyrosomus regius) from a coastal Mediterranean fish farm

Meagre (Argyrosomus regius) is an emerging species in aquaculture considered a locally absent species in the Western Mediterranean. Little is known about meagre escape incidents from farms. To evaluate escape impacts and develop mitigation measures, knowledge about the behaviour of escaped meagre is necessary. In this study, a rapid dispersion of escaped meagre was observed following a simulated escape incident in a coastal Mediterranean farm, using acoustic telemetry (acoustic tag: AT) and mark‐and‐recapture techniques (external tag: ET). A small proportion of AT meagre (22.7%) remained within the farm boundaries 24 h after the simulated escape. A total of 84 meagre (9.2%) were captured by local trammel netters nearby the farm facility within the first 48 h after escape. Only two AT individuals (15.3%) were detected by acoustic receivers located in coastal areas within 2 days after dispersal from the farm and eight ET meagre (0.8%) were recaptured along the shoreline during the first week. Two AT individuals (15.3%) were considered to be dead by predation few hours after escape. The rest of the AT individuals (N = 6, 46.2%) left the facility alive, and they were never detected by receivers nor reported back by fishermen. Thus, our results highlight the necessity of establishing escape mitigation strategies at Mediterranean fish farms, i.e. recapture programmes 24–48 h after the escape incident in collaboration with local fishermen, to diminish potential impacts related to meagre escapees.     

The importance of dietary HUFA for meagre larvae (Argyrosomus regius; Asso, 1801) and its relation with antioxidant vitamins E and C

Despite the interest of meagre (Argyrosomus regius) as a fast‐growing candidate for Mediterranean aquaculture diversification, there is a lack of information on nutrition along larval development. Importance of highly unsaturated fatty acids (HUFA) and the antioxidant vitamins E and vitamin C has not been investigated yet in this species. Six diets with two levels of HUFA (0.4% and 3% dw), two of vitamin E (1500 and 3000 mg kg^?1) and two of vitamin C (1800 and 3600 mg kg^?1) were fed to 15 dah meagre larvae. Larval growth in total length and dry body weight was significantly lowest in larvae fed diet 0.4/150/180 and showed few lipid droplets in enterocytes and hepatocytes and lower HUFA contents than the initial larvae. Increase in dietary HUFA up to 3%, significantly improved larval growth and lipid absorption and deposition. Besides, among fish fed 3% HUFA, increase in vitamin E and vitamin C significantly improved body weight, as well as total lipid, 22:6n‐3 and n‐3 fatty acids contents in the larvae. Thus, the results showed that 0.4% dietary HUFA is not enough to cover the essential fatty acid requirements of larval meagre and a high HUFA requirement in weaning diets is foreseen for this species. Besides, the results also pointed out the importance of dietary vitamin E and C to protect these essential fatty acids from oxidation, increase their contents in the larvae and promote growth, suggesting high vitamin E and C requirements in meagre larvae (higher than 1500 and 1800 mg kg^?1 for vitamin E and vitamin C respectively).     

Risk assessment of small‐scale reef fisheries off the Abrolhos Bank: Snappers and groupers under a multidimensional evaluation

In the Abrolhos Bank (Southwest Atlantic), multidimensional indicators were used in sustainability assessments of data‐poor reef fisheries. Potential impacts, risks and stocks vulnerabilities were evaluated based on biological, environmental, social and economic aspects by combining both adapted productivity and susceptibility analysis (PSA) and scale intensity consequence analysis (SICA). Data were obtained from local surveys with stakeholders and experts and from literature. A value chain map revealed final consumers at many locations and middleman presence. Vulnerability to overexploitation ranged from low (Cephalopholis fulva (L.), Lutjanus synagris (L.) and Ocyurus chrysurus (Bloch)) to moderate (Lutjanus jocu (Bloch & Schneider), Epinephelus morio (Val.) and Mycteroperca bonaci Poey). While moderate consequences of the catches were observed to C. fulva, major consequences were identified to the other five stocks. The main threat to coral reef habitats was found to be mining wastes. Poor governance may constrain fisheries sustainability in the region, while the empowerment of fishers in both governance and post‐harvest processes should enhance it.     

The global contribution of forage fish to marine fisheries and ecosystems

Forage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine ecosystems through a synthesis of 72 published Ecopath models from around the world. Three distinct contributions of forage fish were examined: (i) the ecological support service of forage fish to predators in marine ecosystems, (ii) the total catch and value of forage fisheries and (iii) the support service of forage fish to the catch and value of other commercially targeted predators. Forage fish use and value varied and exhibited patterns across latitudes and ecosystem types. Forage fish supported many kinds of predators, including fish, seabirds, marine mammals and squid. Overall, forage fish contribute a total of about $16.9 billion USD to global fisheries values annually, i.e. 20% of the global ex‐vessel catch values of all marine fisheries combined. While the global catch value of forage fisheries was $5.6 billion, fisheries supported by forage fish were more than twice as valuable ($11.3 billion). These estimates provide important information for evaluating the trade‐offs of various uses of forage fish across ecosystem types, latitudes and globally. We did not estimate a monetary value for supportive contributions of forage fish to recreational fisheries or to uses unrelated to fisheries, and thus the estimates of economic value reported herein understate the global value of forage fishes.     

Genetic population structure of marine fish: mismatch between biological and fisheries management units

An essential prerequisite of a sustainable fisheries management is the matching of biologically relevant processes and management action. In fisheries management and assessment, fish stocks are the fundamental biological unit, but the reasoning for the operational management unit is often indistinct and mismatches between the biology and the management action frequently occur. Despite the plethora of population genetic data on marine fishes, to date little or no use is made of the information, despite the fact that the detection of genetic differentiation may indicate reproductively distinct populations. Here, we discuss key aspects of genetic population differentiation in the context of their importance for fisheries management. Furthermore, we evaluate the population structure of all 32 managed marine fish species in the north‐east Atlantic and relate this structure to current management units and practice. Although a large number of studies on genetic population structure have been published in the last decades, data are still rare for most exploited species. The mismatch between genetic population structure and the current management units found for six species (Gadus morhua, Melanogrammus aeglefinus, Merlangius merlangus, Micromesistius poutassou, Merluccius merluccius and Clupea harengus), emphasizes the need for a revision of these units and questions the appropriateness of current management measures. The implementation of complex and dynamic population structures into novel and less static management procedures should be a primary task for future fisheries management approaches.     

Linking the biology and ecology of key herbivorous unicornfish to fisheries management in the Pacific

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Integrated ecological–economic fisheries models—Evaluation,review and challenges for implementation

Marine ecosystems evolve under many interconnected and area‐specific pressures. To fulfil society's intensifying and diversifying needs while ensuring ecologically sustainable development, more effective marine spatial planning and broader‐scope management of marine resources is necessary. Integrated ecological–economic fisheries models (IEEFMs) of marine systems are needed to evaluate impacts and sustainability of potential management actions and understand, and anticipate ecological, economic and social dynamics at a range of scales from local to national and regional. To make these models most effective, it is important to determine how model characteristics and methods of communicating results influence the model implementation, the nature of the advice that can be provided and the impact on decisions taken by managers. This article presents a global review and comparative evaluation of 35 IEEFMs applied to marine fisheries and marine ecosystem resources to identify the characteristics that determine their usefulness, effectiveness and implementation. The focus is on fully integrated models that allow for feedbacks between ecological and human processes although not all the models reviewed achieve that. Modellers must invest more time to make models user friendly and to participate in management fora where models and model results can be explained and discussed. Such involvement is beneficial to all parties, leading to improvement of mo‐dels and more effective implementation of advice, but demands substantial resources which must be built into the governance process. It takes time to develop effective processes for using IEEFMs requiring a long‐term commitment to integrating multidisciplinary modelling advice into management decision‐making.     

Towards resilient recreational fisheries on a global scale through improved understanding of fish and fisher behaviour

Despite recreational fisheries serving as a prime example of a coupled social–ecological system, much of the research on such fisheries has been monothematic in orientation and focused either on fisheries ecology or human dimensions. An attempt was made to break down some of the barriers to more interdisciplinary research on recreational fisheries at the 6^th World Recreational Fishing Conference. The overall conclusion was that future research and management efforts should increasingly focus on the feedbacks between the interacting human and ecological components of recreational fisheries. Doing so promises to improve understanding of how recreational fisheries respond to social–ecological change. In this context, the behaviour of both fishes and humans provides an important, yet often overlooked, integrator of the ecological and social components of recreational fisheries. A better understanding of the behavioural dynamics of recreational fishers as well as exploited fishes will help predict how recreational fisheries change, evolve, adapt and reorganise through time to maintain resilience and achieve sustainability on a global scale.     

Fish assemblages of the northern Argentine coastal system: spatial patterns and their temporal variations

The springtime spatial pattern of demersal fish assemblages in the northern Argentine coastal ecosystem (34°–41°S) and their relationships with environmental variables were investigated over 6 years (1981, 1983, 1994, 1995, 1998 and 1999). For each fish assemblage area for each year, we identified the most common species and those species that had the highest ability to discriminate it from adjacent assemblage areas. Within each area, species were considered as resident (common in all years) or facultative (contributing to less than 90% of similarity within any year). The analysis (detrended canonical correspondence analysis), conducted using species abundances (t nm^?2) and environmental data, indicated that six fish assemblage areas are consistently distinguishable. The fish assemblage areas correspond to inner, central and middle regions of the Río de la Plata estuary, and inner, central and middle regions of the coastal shelf. Spatial differences in the composition among areas were primarily due to changes in species composition rather than changes in relative abundance, and were primarily related to water mass characteristics. Salinity in the estuary and temperature on the shelf were more relevant to the spatial structuring of the fish community in each environment. The assemblage areas showed a remarkable degree of temporal persistence in species composition and geographical location. The facultative species contributed more to the species composition temporal dynamics than resident species. El Niño (La Niña) condition, associated with increase (decrease) of the Río de la Plata freshwater discharge, produced a movement of the estuarine assemblage areas to the coastal shelf (upriver). Under normal freshwater discharge conditions, the boundaries of the fish assemblages were relatively more stable.