Reviews in Fish Biology and Fisheries

Gillnets, which are frequently used in small-scale fisheries (SSF), raise concerns regarding bycatch and conservation. This study evaluates the context of use and the potential advantages of gillnets alone compared to mixed (gillnet and other gear) and other gears in multi-species freshwater SSF, based in analyses of 36,869 fishing events in four rivers in the Brazilian Amazon (Tapajós, Negro, Madeira and Xingu) and considering five indicators: catch per unit of effort (CPUE), fish value (average income per kg), diversity and composition of fish caught, and variance of catches. Gillnets were used in most (~ 61%) of fish landings in three of the studied rivers, and the frequency of use matches the observed advantages from gillnets in each river. Overall, the probability of gillnet use was statistically (P < 0.05) lower inside protected areas and higher when fishing in group, being also influenced by season. The highest advantages of using gillnets were to reduce variance (hence unpredictability) on the biomass of fish caught in the Tapajós River (L.Ratio = 9.59, P = 0.008), to increase CPUE (t (15220) = − 2.94, P = 0.005 and t (15230) = − 4.73, P < 0.001, compared to mixed and other gears, respectively) and to reduce variance (L.Ratio = 29.26, P < 0.001) in the Madeira River, and to catch more valuable fishes in the Xingu River (t (13160) = − 3.68, P < 0.001 and t (13160) = − 3.67, P < 0.001, compared to mixed and other gears), whereas in the Negro River, both gillnets and mixed gears increased CPUE (t (1073) = − 2.89, P = 0.004). The gillnets could also allow fishers to harvest a higher diversity of fish. However, mixed gears provided similar or better outcomes when compared to gillnets alone. These results can inform policies aiming to manage use of gillnets while considering fishers' needs in the Brazilian Amazon and other multispecies SSF.

Small-scale fisheries (SSF) account for much of the global fish catch, but data to assess them often do not exist, impeding assessments of their historical dynamics and status. Here, we propose an approach to assess 'data-less' SSF using local knowledge to produce data, life history theory to describe their historical multispecies dynamics, and length-based reference points to evaluate stock status. We demonstrate use of this approach in three data-less SSFs of the Congo Basin. Fishers' recalls of past fishing events indicated fish catch declined by 65-80% over the last half-century. Declines in and depletion of many historically important species reduced the diversity of exploited species, making the species composition of the catch more homogenous in recent years. Length-at-catch of 11 of the 12 most important species were below their respective lengths-at-maturity and optimal lengths (obtained from Fishbase) in recent years, indicating overfishing. The most overfished species were large-bodied and found in the Congo mainstem. These results show the approach can suitably assess data-less SSF. Fishers' knowledge produced data at a fraction of the cost and effort of collecting fisheries landings data. Historical and current data on fish catch, length-at-catch, and species diversity can inform management and restoration efforts to curb shifting baselines of these fisheries. Classification of stock status allows prioritizing management efforts. The approach is easy to apply and generates intuitive results, having potential to complement the toolkits of researchers and managers working in SSF and engage stakeholders in decision-making processes.

The bleak Alburnus alburnus is a medium body-size leuciscid fish that is naturally distributed across central European and western Asian fresh waters. However, during the last two decades A. alburnus has been widely introduced elsewhere in Europe and in northern Africa, mostly as a forage species for game fishes. Given its relatively recent history of invasion in non-native Eurasian waters, where it can become highly abundant, A. alburnus poses a serious risk to native communities where introduced. This study provides a review and meta-analysis of the biological traits of A. alburnus coupled with insights into its invasiveness. In its native range, A. alburnus has a moderate lifespan, inhabiting lakes or still waters in medium-to-large rivers, where it feeds mainly on zooplankton. However, non-native A. alburnus populations display high phenotypic plasticity in their biological attributes. Thus, growth, reproductive and/or dietary traits have adapted to local environmental conditions, with the species also invading lotic (stream) ecosystems. Feeding changes to benthic invertebrates, plant material and detritus when zooplankton is scarce. Such plasticity, including broad physiological tolerance, is likely to facilitate the species’ adaptation and invasion of new habitats in the near future.

Informal cross-border fish trade (ICBFT) is becoming predominant in many African nations and unfortunately there is little information on its magnitude at country level. To address this gap, this study was conducted in mainland Tanzania covering two border posts and one fishing village, to identify the nature, conditions and assess the weight and value of ICBFT in comparison to the available official data, so as to determine the Government revenue loss for the marine small pelagic fishery which is locally known as dagaa. Data was collected through participants observation, interviews and informal routes monitoring framework. Interview excerpt coding, social network analysis and quantification were used in data analysis. Findings revealed that the marine dagaa informal cross-border trade is being operated in a multifaceted setting, characterized by five aspects: network; key actors; social supports; informal cross-border trade routes; and informal transiting places, time and vehicles. Middlemen and Porters scored higher network centrality scores, implying that, they are the key actors in the ICBFT operation. Further, it was found that the marine dagaa ICBFT accounted for about 972.6 M. tons valued at US$1.8 million, which is 7.5 higher compared to official data between 2018 and 2019, resulting in approximately US$165,006 government revenue loss. Such findings are essential for assessing the total contribution of cross-border fish trade to the country's economy, and setting appropriate ICBFT management strategies to maximize benefits from the cross-border trade in the country for people’s well-being and the neighbouring countries.

A common goal among fisheries science professionals, stakeholders, and rights holders is to ensure the persistence and resilience of vibrant fish populations and sustainable, equitable fisheries in diverse aquatic ecosystems, from small headwater streams to offshore pelagic waters. Achieving this goal requires a complex intersection of science and management, and a recognition of the interconnections among people, place, and fish that govern these tightly coupled socioecological and sociotechnical systems. The World Fisheries Congress (WFC) convenes every four years and provides a unique global forum to debate and discuss threats, issues, and opportunities facing fish populations and fisheries. The 2021 WFC meeting, hosted remotely in Adelaide, Australia, marked the 30th year since the first meeting was held in Athens, Greece, and provided an opportunity to reflect on progress made in the past 30 years and provide guidance for the future. We assembled a diverse team of individuals involved with the Adelaide WFC and reflected on the major challenges that faced fish and fisheries over the past 30 years, discussed progress toward overcoming those challenges, and then used themes that emerged during the Congress to identify issues and opportunities to improve sustainability in the world's fisheries for the next 30 years. Key future needs and opportunities identified include: rethinking fisheries management systems and modelling approaches, modernizing and integrating assessment and information systems, being responsive and flexible in addressing persistent and emerging threats to fish and fisheries, mainstreaming the human dimension of fisheries, rethinking governance, policy and compliance, and achieving equity and inclusion in fisheries. We also identified a number of cross-cutting themes including better understanding the role of fish as nutrition in a hungry world, adapting to climate change, embracing transdisciplinarity, respecting Indigenous knowledge systems, thinking ahead with foresight science, and working together across scales. By reflecting on the past and thinking about the future, we aim to provide guidance for achieving our mutual goal of sustaining vibrant fish populations and sustainable fisheries that benefit all. We hope that this prospective thinking can serve as a guide to (i) assess progress towards achieving this lofty goal and (ii) refine our path with input from new and emerging voices and approaches in fisheries science, management, and stewardship.

The United Nations (UN) Decade of Ocean Science highlights a need to improve the way in which scientific results effectively inform action and policies regarding the ocean. Our research contributes to achieving this goal by identifying practical actions, barriers, stakeholder contributions and resources required to increase the sustainability of activities carried out in the context of artisanal fisheries to meet UN Sustainable Development Goals (SDG) and International Year of Artisanal Fisheries and Aquaculture (IYAFA) Global Action Plan (GAP) Pillar targets. We conducted a novel ‘social value chain analysis’ via a participatory workshop to elicit perspectives of value chain actors and fisheries stakeholders associated with two Spanish artisanal common octopus (Octopus vulgaris) fisheries (western Asturias—Marine Stewardship Council [MSC] certified, and Galicia—non-MSC certified) about their priorities regarding sustainable octopus production and commercialization. Our adapted Rapfish sustainability framework emphasised the importance of economic, environmental, ethical, institutional, social, and technological indicators to different actors across the value chain. We mapped participants’ shared sustainability priorities (e.g. integrated fisheries management, knowledge-based management, product traceability) to six Rapfish indicators, seven IYAFA Pillars and twelve SDGs to reveal how our results can inform ocean policy and actions. This identified how certification incentives and other cooperative approaches can facilitate environmental, economic and social sustainability (e.g. value-added products, price premiums for producers, gender inclusive organisations); support IYAFA priority outcomes (raised awareness, strengthened science-policy interface, empowered stakeholders, partnerships); and help to achieve UN SDG targets (e.g. SDG 14.b, SDG 17.17). The results can inform actors, stakeholders and policymakers about how different actors contribute to efforts to achieve the SDGs and how to manage priorities for sustainable actions within artisanal fisheries and their value chains. We recommend inclusive and equitable participatory knowledge transfer and governance platforms as part of the UN Decade of Ocean Science and beyond where participants can create theories of change towards sustainability involving the development of multi-sectoral ocean policies framed at the level of the value chain and supported by appropriate governance structures. Graphical Abstract

Australia’s fisheries have experience in responding individually to specific shocks to stock levels (for example, marine heatwaves, floods) and markets (for example, global financial crisis, food safety access barriers). The COVID-19 pandemic was, however, novel in triggering a series of systemic shocks and disruptions to the activities and operating conditions for all Australia’s commercial fisheries sectors including those of the research agencies that provide the information needed for their sustainable management. While these disruptions have a single root cause—the public health impacts and containment responses to the COVID-19 pandemic—their transmission and effects have been varied. We examine both the impacts on Australian fisheries triggered by measures introduced by governments both internationally and domestically in response to the COVID-19 pandemic outbreak, and the countermeasures introduced to support continuity in fisheries and aquaculture production and supply chains. Impacts on fisheries production are identified by comparing annual and monthly catch data for Australia’s commercial fisheries in 2020 with averages for the last 4–5 years. We combine this with a survey of the short-term disruption to and impacts on research organisations engaged in fisheries monitoring and assessment and the adaptive measures they deployed. The dominant impact identified was triggered by containment measures both within Australia and in export receiving countries which led to loss of export markets and domestic dine-in markets for live or fresh seafood. The most heavily impact fisheries included lobster and abalone (exported live) and specific finfishes (exported fresh or sold live domestically), which experienced short-term reductions in both production and price. At the same time, improved prices and demand for seafood sold into domestic retail channels were observed. The impacts observed were both a function of the disruptions due to the COVID-19 pandemic and the countermeasures and support programs introduced by various national and state-level governments across Australia to at least partly mitigate negative impacts on harvesting activities and supply chains. These included protecting fisheries activities from specific restrictive COVID-19 containment measures, pro-actively re-establishing freight links, supporting quota roll-overs, and introducing wage and businesses support packages. Fisheries research organisations were impacted to various degrees, largely determined by the extent to which their field monitoring activities were protected from specific restrictive COVID-19 containment measures by their state-level governments. Responses of these organisations included reducing fisheries dependent and independent data collection as required while developing strategies to continue to provide assessment services, including opportunistic innovations to harvest data from new data sources. Observed short run impacts of the COVID-19 pandemic outbreak has emphasised both the vulnerability of fisheries dependent on export markets, live or fresh markets, and long supply chains and the resilience of fisheries research programs. We suggest that further and more comprehensive analysis over a longer time period of the long-run impacts of subsequent waves of variants, extended pandemic containment measures, autonomous and planned adaptive responses would be beneficial for the development of more effective counter measures for when the next major external shock affects Australian fisheries.

Human-induced climate change is already apparent through warming temperatures, altered precipitation, and greater prevalence of extreme weather events (e.g., droughts and floods) all of which are anticipated to be exacerbated in the foreseeable future. Meanwhile, demand for hydropower generation is expected to increase and future hydropower developments will be important for mitigating climate change. Yet, climate change will affect the natural flow regimes, which will undoubtedly impact hydropower operations (e.g., storages and releases), and in turn the impact of altered hydropower operations on the discharge and consequence to fish that live in these regulated systems. Here, we synthesize the current knowledge of climate-induced alterations to hydropower operations and the expected impacts of altered hydropower operations on riverine fishes. We also consider what is needed to adapt to the way environmental threats will change over the typical 50–100 year lifespan of such facilities. Based on our synthesis, we anticipate the impact on native riverine fishes will increase in severity moving forward. Fortunately, we can take proactive measures to mitigate the adverse, yet synergistic, impacts of hydropower and climate change on aquatic ecosystems. Doing so will require extensive foresight, planning, and incorporating novel mitigation strategies into hydropower development. We also call for greater involvement of fisheries professionals in such processes to ensure that fish are not an afterthought. Failure to better consider how to future-proof hydropower in the context of climate change threatens not only fish populations but also the humans that depend on them for livelihoods, nutrition, and socio-cultural benefits. Graphical abstract

In the Northern Alboran Sea, artisanal small-scale fisheries using trammel nets suffer economic losses, and local fishermen see their way-oflife endangered, due to interactions with wildlife species such as alien species and dolphins. On the one hand, the alien seaweed Rugulopteryx okamurae, which was first recorded in the Alboran Sea in 2015, has undergone an intensive expansion in the subregion, monopolizing the available seabed, causing radical changes in the underwater seascape and clogging the trammel nets. On the other hand, the damage caused to the fishing nets by dolphin fish predation is an ancient problem worldwide, but it is intensifying in the last years. The main objective of this study is to understand the main environmental and technical conditions that favor damages of fishing trammel nets in the Alboran Sea, which entails an important loss of catchability, due to (i) the clogging of the artisanal fishing trammel nets by invasive seaweed, and (ii) the breaking of the nets by dolphin predation. Through close monitoring of fishermen in port, we obtained direct information of 548 sets. Our results indicate that approximately 30% of trammel sets suffered a damage due to unwanted interaction with alien seaweeds and dolphins. As seaweeds invasion is a global problem while dolphin-fishing gear interaction is more local, we concluded that only a large-scale management of exotic algae, together with the involvement of local fishermen, could solve the economic problems of this activity.

Small-scale fisheries play a critical role in food security and contribute to nearly half of reported global fish catches. However, the status of most small-scale fisheries stocks is still poor. In data-limited situations, length-based methods have been widely applied to estimate reference points and to understand stock status. This study applied three different length-based assessment methods (length-based indicators—LBI, length-based spawning potential ratio—LBSPR, and the length-based Bayesian biomass approach—LBB) to predict fisheries stock sustainability in the Azores. Overall, the three methods showed robustness for 15 out of 18 stocks assessed and agreed on their exploitation status. The results showed that 45% of the Azorean stocks were classified as sustainable stocks, 33% possible rebuilding/overfished and 22% overfishing/overfished stock status. Sensitivity analysis showed that biases on the source of initial life-history parameters, especially the asymptotic length (L∞) and the ratio of natural mortality and growth coefficient (M/k), have a stronger influence on the reference points of conservation of mature individuals (LBI), spawning potential ratio and fishing mortality (LBSPR) and the biomass relative to the maximum sustainable yield (LBB). Furthermore, sensitivity analysis indicated that, among the three methods, LBI is more robust. Our findings provide some management recommendations such as (1) catches and effort should be reduced; (2) minimum landing size should be increased; (3) minimum hook size should be increased, to be applied mainly for those stocks classified as possible rebuilding/overfished and overfishing/overfished stock status. Graphical abstract

Species specificity of taste preferences supposes the ability of fish to consume food with particular taste and thus minimize feeding competition while sympatry. However, the problem of the extent to which taste preferences can be related to trophic category and phylogeny of fish has not been yet resolved. We evaluated the taste preferences in Mozambique tilapia Oreochromis mossambicus for 37 substances (amino acids, sugars, basic taste substances) that we used earlier in experiments with the Nile tilapia O. niloticus. In O. mossambicus, taste attractive substances are the least numerous (4) and substances with an indifferent taste predominate (25). In O. niloticus, the numbers of taste attractive and indifferent substances are nearly equal (20 and 17), while substances with repulsive taste were not found. The difference between these facultative phytophagous fish is most noticeable for sugars palatability: in O. mossambicus none of the sugars have attractive taste, and 6 of them evoke aversive responses. In opposite, 9 of sugars have attractive taste, while others are indifferent, and none of sugars decrease ingestion of flavoured agar pellets in O. niloticus. Nevertheless, many substances are arranged in a similar order in the rows ranked by palatability for these fish. The patterns of feeding behavior are almost the same in tilapias. The study highlights that the phylogenetic proximity and similarity in the trophic category does not lead to the similarity of fish taste preferences. Most probably, feeding competition in the historical past is the main force that triggers the divergence in fish taste system functionality. Graphical abstract

Successful settlement and recruitment of reef fish are influenced by spatial and temporal processes and variables on distinct scales. Moreover, they require survival at various stages in different environments for species with a complex life cycle, as in the case of most reef fish. The variability in those processes can be explained by biotic and abiotic factors that affect pre and postsettlement stages. Despite the many benefits of marine protected areas (MPAs) for fish and fisheries, the positive effects of protected areas on the reproduction, settlement, and recruitment of reef fish are still unclear. The present study reviewed the biotic and abiotic factors that influence the settlement and recruitment of reef fish, especially regarding the role of MPAs in these processes. This bibliographic review shows that the larval settlement is shaped by the interaction of biological traits (e.g., life history) and environmental factors (e.g., temperature, currents), which are determinants of the life cycle and population structure of reef fish. The main contribution of MPAs to these processes is the export of eggs and larvae to adjacent regions. However, further research is needed on the issues of settlement and recruitment in the specific context of MPAs. The absence of studies on this topic, particularly how protection affects, directly and indirectly, recruitment variability and how this is reflected in the adult population, hinders MPAs objectives and seems to be a serious shortcoming in attempts to support future populations at ecologically adequate levels.

Understanding how elasmobranchs respond to stressors is imperative so that effective measures to reduce mortality be employed, whether in commercially captured animals or sharks and rays maintained in human care. Currently, reflex action mortality predictors (RAMPs) are the most reliable proxies to indicate an animal's condition state, commonly employed for both teleost and elasmobranchs. As our understanding of mortality predictors is evolving, is it necessary that traditional indicators be constantly reviewed and new proxies proposed, in order to improve the tools available for the best possible evaluation of a stressed individual. In this context, this review aimed to compile data on behavioral and visual proxies, along with the proposition of new proxies to guide professionals and assist them in identifying signs associated with alarming situations that might potentially result in the death of highly stressed individuals or sub-lethal effects at population level (migration, reproduction) that may seriously compromise the success of release measures.

Inland capture fisheries in rivers, wetlands, lakes, tanks, and dam reservoirs support millions of marginalized people in countries like India. While being a critical resource for many, fishing also has negative impacts on threatened wildlife, through net entanglement and mortality, and fishery-associated hunting or poaching activities. Also, both fishing and river wildlife have declined due to dams affecting river flows, water pollution, and other anthropogenic threats. A dominant approach to protect terrestrial wildlife in India has been the creation of Protected Areas (PAs) where human activities detrimental to wildlife, including fishing, are banned or significantly regulated. But PAs in India have been historically sited in and near dam reservoirs, where culture-based fisheries are often allowed. This triad of PAs, dams, and reservoir/river fisheries can lead to inequitable outcomes, tradeoffs, and conflicts between wildlife conservation and fishery-dependent livelihoods. Hence there is a need to understand factors leading to fishery-wildlife conservation conflicts across PAs. In this review paper, attribute data on ecotype, area, number of dams, fishing intensity levels, and conservation status were compiled for non-marine PAs across India to understand their broad correlations with fishery-conservation conflict intensity levels. Conflict intensity levels were correlated with PA area, PA conservation status, and fishing intensity, and with the number of dams associated with PAs. These results are discussed and specific institutional gaps and management limitations in India are identified, that need to be addressed to prevent negative fishing impacts on wildlife and secure human livelihoods dependent on fisheries.

Antarctic Toothfish are a circumpolar species which are targeted in multiple fisheries around Antarctica covering nine statistical areas within the Convention for the Conservation of Antarctic Marine Living Resources. Despite this, it is still unclear whether the species forms a single stock across its circumpolar distribution, shows a pattern of isolation by distance, or exhibits discrete stock structure between different regions. Recent genetics studies of Antarctic toothfish have shown connectivity between two areas (Ross Sea and Antarctic Peninsula), but earlier studies with smaller number of markers produced inconsistent results with regards to genetic connectivity between other geographic locations. Here we present a range-wide population genetic study of Antarctic toothfish using > 11,000 nuclear single nucleotide polymorphisms from 715 fish collected. Our results indicate that genetic diversity of the Antarctic toothfish is very low, with only 0.1% of genetic variability associated with geographic location. Multiple clustering methods, both supervised and unsupervised, indicated no distinct breeding populations. These results are consistent with current theories of egg and larval dispersal by the predominant Antarctic currents.

The term “data-limited fisheries” is a catch-all to generally describe situations lacking data to support a fully integrated stock assessment model. Data conditions range from data-void fisheries to those that reliably produce quantitative assessments. However, successful fishery assessment can also be limited by resources (e.g., time, money, capacity). The term “data-limited fisheries” is therefore too vague and incomplete to describe such wide-ranging conditions, and subsequent needs for management vary greatly according to each fishery’s context. Here, we acknowledge this relativity and identify a range of factors that can constrain the ability of analyses to inform management, by instead defining the state of being “data-limited” as a continuum along axes of data (e.g., type, quality, and quantity) and resources (e.g., time, funding, capacity). We introduce a tool (the DLMapper) to apply this approach and define where a fishery lies on this relativity spectrum of limitations (i.e. from no data and no resources to no constraints on data and resources). We also provide a ranking of guiding principles, as a function of the limiting conditions. This high-level guidance is meant to identify current actions to consider for overcoming issues associated with data and resource constraints given a specific “data-limited” condition. We apply this method to 20 different fisheries to demonstrate the approach. By more explicitly outlining the various conditions that create “data-limited situations” and linking these to broad guidance, we aim to contextualize and improve the communication of conditions, and identify effective opportunities to continue to develop and progress the science of “limited” stock assessment in support of fisheries management.

Fish drying is a traditional method of preserving and utilizing fish in India. Small-scale women processors play a dominant role in production and marketing of dried fish. This paper analyzes the changes in the profile of India’s fish processing industry over time focusing on the dried fish segment. We postulate that structural changes in fish production, including the rapid surge in aquaculture production, are closely linked to changes in fish processing and utilization in India. In particular, surge in demand for fishmeal and fish oil (FMFO) as an ingredient in aquaculture feeds has tilted fish utilization from direct human consumption towards feed. We pool data on India’s fish production, utilization, and trade to describe these changes and their implications through descriptive analysis and regression modeling. Results from the regression analysis show that the FMFO segment gains market share mostly at the expense of the dried fish segment.

Summary statement Socially induced sex change is orchestrated by a novel combination of genes and epigenetic factors that govern sex differentiation and cell fate. Approximately 500 fish species can change sex in adulthood. The molecular basis for this astonishing transformation remains broadly unknown. Genetic regulation of embryonic sex differentiation is well established in vertebrates but also appears influential in sequential hermaphrodites. Recent work indicates that epigenetic effects and genes regulating cell fate are also important drivers of sex change. Here we use the spotty wrasse to investigate gonadal sex change at a molecular level. While the expression of some sex differentiation genes (dmrt1, foxl2a, ctnnb1) in spotty wrasse follow established sex-biased patterns, others (sox9a, znrf3, rspo1) oppose typical vertebrate-models. We propose that gene neofunctionalisation due to teleost whole-genome duplication may explain these counter-intuitive expression profiles. Significant epigenetic reprogramming within the transitional spotty wrasse gonad is implied through the dynamic expression of methyltransferases and the chromatin-modifying Jumonji family genes, jarid2b and kdm6bb. Furthermore, our results show that fancl and pou5f3, two genes associated with either DNA repair pathways or stem cell pluripotency, are downregulated as sex change advances. This highlights genetic factors that may underlie a functional change of cell fate trajectory. Collectively, this work demonstrates the diversity of genetic pathways that are dynamically activated in a phased, sex-specific manner to co-ordinate vertebrate sex change.

Anguillid eels are near globally distributed catadromous fishes with marine spawning areas and inshore and inland growth areas in both lotic (rivers, estuaries) and lentic (lakes, ponds, lagoons) water bodies. As predators, anguillid eels play an important ecological role in both marine and freshwater systems, and several species are harvested commercially for food. However, some of the more widely distributed species have undergone severe declines in recruitment and their population status is now of significant concern. Given the multiple and lengthy migrations undertaken by anguillid eels, understanding of the drivers of movement is fundamental for species conservation and management. Yet, despite the importance of lentic systems to their ecology, most studies on anguillid eel movement have been conducted in lotic systems. Given that key influences on eel migration in lotic water bodies, such as fluctuations in flow and water temperature, may be minimised in lentic environments, the transferability of findings between lotic and lentic systems cannot be assumed. A systematic map was constructed to synthesise current knowledge on the extrinsic and intrinsic drivers of anguillid eel movement in lentic systems. The current state of knowledge of the drivers of eel movement in lentic systems is presented and compared to the relatively well-understood drivers of movement in lotic systems. We also discuss current knowledge gaps and limitations, and identify key future research requirements to inform the management and conservation of anguillid eels in understudied lentic systems. Graphical abstract

The growing focus on the blue economy is accelerating industrial fishing in many parts of the world. This intensification is affecting the livelihoods of small-scale fishers, processors, and traders by depleting local fishery resources, damaging fishing gears, putting fishers' lives at risk, and compromising market systems and value chain positions. In this article, we outline the experiences, perspectives, and narratives of the small-scale fishing actors in Ghana. Drawing on qualitative interview data, we examine the relationship between small-scale and industrial fisheries in Ghana using political ecology and sustainable livelihood approaches. We demonstrate how industrialised, capital-intensive fishing has disrupted the economic and social organisation of local fishing communities, affecting incomes, causing conflicts, social exclusion and disconnection, and compromising the social identity of women. These cumulative impacts and disruptions in Ghana's coastal communities have threatened the viability of small-scale fisheries, yet coastal fishing actors have few capabilities to adapt. We conclude by supporting recommendations to reduce the number and capacity of industrial vessels, strictly enforce spatial regulations, and ensure "blue justice" against marginalisation.

Historical information is needed to describe in a robust manner long-term changes in the distribution of organisms, although it is in general scarce or contained in non-scientific sources. Gazetteers (or geographical dictionaries) constitute a potential source of historical species records, which has not been accurately explored yet. The dictionary edited by Pascual Madoz between 1845 and 1850 extensively described the geography, population and socioeconomic aspects in Spain. The dictionary included abundant information on wild animals and plants, with a special focus on socioeconomically relevant species. Here, we present a database generated by collecting and georeferencing the mentions to freshwater fauna records in the Madoz, which includes 10,750 occurrence records of 39 freshwater-associated taxa from 5,472 localities. This database has been made public and usable (following FAIR criteria) in GBIF. Most of the records correspond to fish (10,201 records, 94.9% of total; 33 taxa), followed by crayfish (418 records, 3.9% of total; one species). Annelids (one taxon), amphibians (one taxon), reptiles (one taxon) and mammals (three species) sum up to 132 records (1.2% of total). The database presented here can be used to estimate the baseline ranges of many freshwater species, which should inform present-day management for the conservation and recovery of endangered species and freshwater communities. Graphical abstract

Despite its relevance, the economic contribution of small-scale fisheries to poverty alleviation is still poorly understood. This study investigates why some fishers perform economically better in fisheries than others under similar conditions and whether these variations in performance were due to individual adaptive strategies related to fishing technology and effort. A pairwise comparison between fishers’ income from the Brazilian equatorial region in 1994 and 2014 was performed while modeling individual changes related to the fishing activity (Generalized Linear Model, GLM) and the factors that would explain why fishers became richer or poorer over time (Proportional odds model). Fisher’s geographical region, the use of motorized boats and the adoption of hookah compressors explained income in 1994, whereas having larger boats and fishing with hook and line explained it in 2014. Fishers were slightly more likely to gain income if they changed their type of boat. Some fishers are trapped in poverty, and the changes they made were either not enough to leave this condition or made it worse. Escaping poverty traps in fisheries may require efforts beyond those available to the individuals, especially as stocks become increasingly overfished. Graphical Abstract

Seafood is an important source of protein and micronutrients, but fishery stocks are increasingly under pressure from both legitimate and illegitimate fishing practices. Sustainable management of our oceans is a global responsibility, aligning with United Nations Sustainable Development Goal 14, Life Below Water. In a post-COVID-19 world, there is an opportunity to build back better, where locally sourced food via transparent supply chains are ever-more important. This article summarises emerging research of two innovative case studies in detecting and validating seafood provenance; and using alternative supply chains to minimise the opportunity for seafood fraud in a post-COVID-19 world.

Besides modern and exogenous knowledge, traditional and Indigenous knowledge of local communities are also needed for proper management and conservation of marine resources. This study aimed at assessing the knowledge of Indigenous Turkmen fishers of Gorgan Gulf which is a conservation priority coastal ecosystem in Caspian Sea, Iran. To do so, an in-field participatory research was done in five villages adjacent to Gorgan Gulf in 2020 using semi-structured interviews and focused group discussion with 48 knowledgeable Turkmen fishers through snowball sampling method. The result showed that Turkmen fishers carried extensive body of knowledge about fish species, their characteristics (size, weight, morphology, behavior), traditional fishing calendar and factors affecting it (including fish spawning time, weather condition, wind types), fishing location, orientation and navigation in fishing, fishing tools and equipment and methods of net placement. Turkmen fishers also described how the quantity, quality and diversity of fish has drastically decreased over time and they mentioned six main reasons for that including exchange of paddling and rowing boats for motor boats; adoption of galvanized nets which replaced cotton nets; decreased possibility and condition of spawning; degradation of shore habitats and decline in fish food leading to fish migration; destruction of small lakes and wetlands adjacent to Caspian Sea and overfishing. In conclusion, considering the role of small-scale fishers in human well-being and food security, their Indigenous and local knowledge must be taken into consideration for natural resources management and conservation. Graphical abstract

Policy decisions should be guided by the relative degree of risk of error and bias and strength of evidence of the efficacy of alternative management interventions. This study describes the benefits and limitations of applying a sequential evidence hierarchy to evaluate alternative fisheries bycatch management strategies. Fisheries bycatch is an obstacle to global food and livelihood security and is a main anthropogenic threat to several threatened species. Independent synthesis of all accumulated information is a fundamental principle for developing transparent , evidence-informed regional conservation policy. Meta-analytic syntheses produce the most robust and generalizable findings that are optimal for guiding regional bycatch management. Otherwise, given too few studies to support robust meta-syntheses, decisions should rely on qualitative syntheses of accumulated studies. Bycatch mitigation methods with findings only available from studies with relatively weak forms of evidence, or lacking any evidence, should only be considered as a precautionary approach when more certain alternatives are unavailable. Strictly applying a hierarchical approach on study evidence to make policy decisions, however, risks ignoring potentially important findings derived from studies using methods low on an evidence hierarchy. Instead, in making bycatch management policies, authorities should account for all accumulated evidence and the implications of different approaches for testing different hypotheses. Fisheries bycatch policy guided, but not bounded, by a sequential evidence hierarchy promises to achieve ecological and socioeconomic objectives.

Cephalopod beaks are essential for prey acquisition and fragmentation during feeding. Thus, it is expected that ecological pressures affect cephalopod beak shape. From a practical perspective, these structures are also used to identify gut contents of marine megafauna, such as toothed whales, sharks, seabirds, and large pelagic fishes. Here, we investigated the relative importance of ecological pressures and phylogenetic relatedness in the evolution of beak shape using a wide range of Mediterranean cephalopod species. Phylogenetic analyses based on complete mitogenomes and nuclear ribosomal genes provided a well-supported phylogeny among the 18 included cephalopods. Geometric morphometric and stable isotope methods were implemented to describe interspecific beak shape and trophic niche variability, respectively. Phylogenetic signal was detected in the shape of both parts of the beak (upper and lower). However, lower beak shape was more distinct among closely related species, in line with the empirical notion that lower beak morphology is more useful as an identification tool in cephalopods. Interestingly, no association between beak shape and trophic niche (stable isotope values) was found. These results suggest that the evolution of cephalopod beak shape as quantified here is mainly driven by phylogenetic relationships, while feeding habits play a minor role. Graphical abstract

Understanding the drivers behind fluctuations in fish populations remains a key objective in fishery science. Our predictive capacity to explain these fluctuations is still relatively low, due to the amalgam of interacting bottom-up and top-down factors, which vary across time and space among and within populations. Gaining a mechanistic understanding of these recruitment drivers requires a holistic approach, combining field, experimental and modelling efforts. Here, we use the Western Baltic Spring-Spawning (WBSS) herring ( Clupea harengus ) to exemplify the power of this holistic approach and the high complexity of the recruitment drivers (and their interactions). Since the early 2000s, low recruitment levels have promoted intense research on this stock. Our literature synthesis suggests that the major drivers are habitat compression of the spawning beds (due to eutrophication and coastal modification mainly) and warming, which indirectly leads to changes in spawning phenology, prey abundance and predation pressure. Other factors include increased intensity of extreme climate events and new predators in the system. Four main knowledge gaps were identified related to life-cycle migration and habitat use, population structure and demographics, life-stage specific impact of multi-stressors, and predator–prey interactions. Specific research topics within these areas are proposed, as well as the priority to support a sustainable management of the stock. Given that the Baltic Sea is severely impacted by warming, eutrophication and altered precipitation, WBSS herring could be a harbinger of potential effects of changing environmental drivers to the recruitment of small pelagic fishes in other coastal areas in the world. Graphical abstract

The Arabian/Persian Gulf (‘Gulf’ hereafter) is bordered by eight countries that consider fishery as their most important renewable resource. This includes artisanal fisheries, which are a major contributor to seafood production and fishers’ livelihoods. Despite the importance of the artisanal sector, in-depth studies examining aspects—like total and country-specific production trends, used fishing gears and main threats—remain limited. Inadequate knowledge about such fundamental aspects could jeopardize the sustainability of fisheries and muddle policymaking. Here, we provide a comprehensive account of artisanal fisheries in the Gulf. Specifically, we examined: (i) magnitude of the artisanal sector, (ii) types of fishing gears used, (iii) exploited functional groups, and (iv) threats to and opportunities for sustainable artisanal fisheries. We show that around 71% of the Gulf total catch is produced by artisanal fisheries, and this trend is growing. The dominating fishing gears are gillnets, traps, and lines—collectively accounting for 72% of the total catch. Among these fishing gears, gillnets alone account for a third of the production. Most of the artisanal catch comprises medium to large fish that are demersal, pelagic, and reef-associated. Fisheries are primarily based on gear restrictions, minimum size of capture, seasonal closures, and spatial restrictions. However, weak enforcement is a core issue for the effectiveness of management regulations. Mismanaged fisheries, coastal development, and climate change are primary threats facing fish abundance and essential fish habitats. Engaging artisanal fishers in management and preserving habitats can contribute toward sustainable artisanal fisheries in the Gulf.

Here we propose a framework and agenda for nutrition-sensitive governance (NSG) of fisheries that rethink dominant paradigms of fisheries governance and propose measures to incorporate nutrition-related objectives into fisheries governance. Fish, rich in micronutrients, have potential for improving the nutritional status of coastal and riparian communities, particularly in the Global South where inadequate nutrition is prevalent. Yet, the potential for fish to alleviate malnutrition remains limited to policy documents and high-level government commitments. We propose an agenda for NSG in the Global South grounded in three main pillars: 1-extending the boundaries of fisheries governance, 2-integrating multiple forms of knowledge, and 3-prioritizing domestic and local needs; each of these pillars links different levels of governance starting at the level of conceptualization and images connected to what fisheries are and should do, to a more policy-oriented level with hands-on recommendations, through an intermediate level that links the two. Overall, we propose a concept and agenda for NSG grounded in a human-centred approach to fisheries governance with social sciences playing a crucial role in unearthing the nodes of power that limit access and agency of poor and vulnerable (fishing) communities to the nutritional benefits of fish. In doing so, we critically analyze dominant fisheries governance agendas (‘Blue Economy’, ‘Blue Growth’) through the lens of food and nutrition security and anchor these debates to the objective of getting the right nutrients to those who need them most

The Lancang-Mekong River, the largest river in Southeast Asia, supports high biodiversity of fish but has also suffered from intensive human- and nature-induced stressors for decades, and it is feared that this trend will continue in coming decades. Although the river has received wide attention from researchers, spatiotemporal trends in fish diversity and production and of environmental stressors within the catchment remain unclear. Also, an overview of current knowledge for catchment-scale sustainable management is lacking. This study analysed research publications related to Mekong fishes and threats, and identified knowledge gaps and limitations in current research. We found an increasing trend in studies on fish and/or environmental stressors, but that some research themes, including dam construction, pollution, infectious disease, and salinization, vary across regions. In general, research foci were determined by geographical location, fish diversity, and environmental stressors in each region. For fish-related studies, research in the Upper and Middle Lancang-Mekong regions was mostly related to the conservation of wild fish populations and communities, while in the Mekong Delta, a large proportion of studies were related to fish farming. For studies related to environmental stressors, current research foci were mainly on persistent threats, including flow modification, pollution, habitat degradation, and overexploitation. However, coverage of some newly emerging threats, such as microplastic pollution and harmful algal blooms were lacking. This study helps provide a better understanding of factors impacting the Lancang-Mekong River and its fish communities, and provides a basis for future research, management, and conservation actions. Graphical abstract

methods used, as well as the outcome or objectives targeted for each method. In addition to summarizing the use of complementary methods and their outcomes, we discuss how they supplement acoustic telemetry and other tracking approaches. Our review shows that using additional methods to support telem-etry data helps expand the breadth of research questions that can be addressed regarding the complex and assorted factors influencing movement patterns. Doing so enables greater value in movement ecology research and adjacent fields such as population dynamics, physiology, trophic ecology, reproduction, and health and survival, to underpin management decisions. This review serves as a primer and guide for bolstering data collection and multidisciplinary Abstract Tracking the movements of aquatic animals is a primary means of understanding movement ecology and interactions with human activities such as fisheries. Despite the diverse spatiotemporal scales that various underwater tracking tools (e.g., acoustic, satellite, PIT, radio, archival telemetry) enable, there are still limitations associated with their application and ability to address diverse research questions. In many cases, supplementary methods are used to complement tracking approaches either to overcome such limitations or to optimize the data that can be collected in a study. In this review, we synthesize relevant literature between 2010 and 2019 to evaluate the different types of complementary methods used with one of the main approaches for tracking fishes-acoustic telemetry. We categorize broad and specific

Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these recent advances and provides strategic guidance for researchers aiming to characterise the occurrence of depredation, identify the shark species responsible, and test deterrent and management approaches to reduce its impacts. Specifically, the review covers the application of social science approaches, as well as advances in video camera and genetic methods for identifying depredating species. The practicalities and considerations for testing magnetic, electrical, and acoustic deterrent devices are discussed in light of recent research. Key concepts for the management of shark depredation are reviewed, with recommendations made to guide future research and policy development. Specific management responses to address shark depredation are lacking, and this review emphasizes that a “silver bullet” approach for mitigating depredation does not yet exist. Rather, future efforts to manage shark depredation must rely on a diverse range of integrated approaches involving those in the fishery (fishers, scientists and fishery managers), social scientists, educators, and other stakeholders.

Anadromous fish challenge human jurisdictions and are exposed to cumulative pressures originating in the marine, freshwater, and terrestrial realms. Here, a detailed questionnaire survey to anadromous fishers (river Mondego, n = 35; international river Minho/Miño, n = 38) assesses and compares perceptions on sustainability and management for important small-scale estuarine and inland fisheries in the NW Iberian Peninsula. There are differences in the governance and fisheries management of the two systems, but exploitation patterns are similar. Revenue importance of fishing, professional exclusivity, and geographic mobility in the last two generations significantly decline upstream in both rivers. The intangible “contact with nature” is the most valued dimension of fishing, common across rivers and longitudinal position. A long tradition in the fishing profession and a strong generational continuity are still detected, especially in the river Minho, but there are signs of diminishing likelihood of hand-over to younger generations. Fishers detect environmental degradation (e.g., perceptions of increase in exotic species and pollution in both rivers, increase in siltation in the river Minho) and overexploitation (perception of decrease in allis shad abundance in the river Minho and increase in sea lamprey poaching in the river Mondego) that will require reactive governance under external drivers that intensify such problems. Better communication, to clarify and improve fishery rules, and more deliberation, to legitimize fisheries management and increase its capacity to contribute towards integrated approaches at the level of watersheds, are locally explored solutions that can have global relevance. Graphical abstract

Animals need to move between different habitats to successfully complete their life cycle. Anthropogenic activities and infrastructure impact animal movement, especially in the aquatic realm, due to habitat alteration (including fragmentation), pollution, overexploitation, the spread of invasive alien species and climate change. Gaining knowledge on the complex phenomenon of fish movement is essential to understand the diverse ways in which anthropogenic activities may influence the spatial ecology of fish, which can inform management. The four main methods to study fish movement are through observation and interception, electronic tracking, otolith chemistry and environmental DNA. We discuss the strengths and shortcomings of these methods and suggest effective management can be aided by combining these and other methods. Often the weaknesses of one technique can be met by the strengths of the others. Also, cross-boundary collaboration is essential for the successful management of fish that move over jurisdictional boundaries to complete their life cycle. Data analyses on interdisciplinary datasets obtained at spatial scales relevant to the movement ecology of a given population can yield a more holistic understanding of fish movement. This knowledge may help for the appropriate selection of cost-efficient, evidence-based and effective management actions that balance the needs of fishes and human activities. Graphical abstract

Marine megafauna are critical for marine ecosystem health and their removal can cause food webs to collapse. Methods to reduce marine megafauna mortality can result in conflict between scientists, conservationists, fishers and fisheries management due to real or perceived effects on target catch, income and food security. Sensory deterrents have been used in attempts to mitigate bycatch and retain target catch quantity and quality. Here, we completed a systematic review of 116 papers, plus 25 literature reviews published between 1991 and 2022, to investigate potential for sensory deterrents to mitigate bycatch across four marine megafauna taxonomic groups (marine mammals, sea turtles, seabirds and elasmobranchs). Lights on gillnets are the only technology so far to result in significant bycatch reductions across all four taxonomic groups. It is difficult to make generalisations about the efficacy of sensory deterrents and their ability to deliver consistent bycatch reductions. The efficacy of each method is context dependent, varying with species, fishery and environmental characteristics. Further research is recommended for field studies assessing bycatch mitigation in all sensory deterrents, including combinations of deterrents, to assess effects on target and non-target species. The associated issues of habituation, habitat exclusion and foraging around fishing gear are important, although reducing mortality of vulnerable species should remain the highest priority for conservation and preserving ecosystems that fishers depend on. Multiple complementary measures will be required to achieve consistent bycatch reduction targets in many fisheries, of which sensory deterrents could play some part if implemented appropriately.

Small island developing states (SIDS) are highly dependent on coastal marine resources. Artisanal fishers in SIDS currently face multiple stressors related to global environmental change. Considering Mauritius (South Western Indian Ocean) as a case study, this paper characterizes artisanal fishers in SIDS and assesses their perception of global change using the Local Ecological Knowledge (LEK) approach. A semi-structured survey method was used to interview 247 fishers from all around the country. Artisanal fishers used multiple fishing areas and gears, with half of the fishers using Fish Aggregating Devices (FADs). Six main groups of fishers were identified according to their fishing strategies, which reflected different target species in their reported catches. The majority of fishers reported lower fish abundances and fewer species now compared to 10 to 15 years ago. All groups of fishers observed environmental change over the same period. Such ecological knowledge highlights the exposure of fishers to stressors induced by environmental change. The characterization of the groups of fishers and their fishing strategies will be useful to better evaluate adaptation strategies and support management measures to face global environmental change. Graphical Abstract

Understanding the emerging roles of non-coding RNAs (ncRNAs) in the regulation of the physiology of aquaculture animals raises the possibility of potential applications of ncRNAs for the advancement of aquaculture. Long non-coding RNA (lncRNA), like other ncRNAs do not encode proteins. However, by interacting directly with RNAs, DNAs or proteins lncRNAs participate in the regulation of target genes at the transcriptional, post-transcriptional and epigenetic levels. A number of studies have shown that lncRNAs play a key role in multiple aspects of animal physiology, including reproduction, development, growth, metabolism, stress response, immunity and rhythmicity. However, application of lncRNAs knowledge to aquaculture is still limited and dispersed. This review updated the status of lncRNAs research and suggested future directions that may contribute to development of potential applications of lncRNAs to the improvement of farmed aquatic animals.

We implement a newly developed framework, expressed as a mathematical model that we solve numerically, for understanding environmental sex determination in populations with consistent trends in abundance. Though broadly applicable, the analysis here focuses on the steadily declining North Atlantic eel populations. This enables us to show how the eco-evolutionary dynamics of eels reflect sex-specific and habitat-specific relationships among demographic features. When increasing stress levels resulting from Human-Induced Rapid Environmental Change are imposed on these populations, they become increasingly vulnerable to highly biased sex ratios. Our analysis is both prescriptive (identifying the key components and the priorities for deepening our understanding of them) and predictive (indicating expected qualitative patterns to be tested in future work). Priorities include establishing sex ratios and age/sex structure by habitat, measuring the magnitude and effects of social and individual stress levels, estimating effects of fishing pressure, and investigating reproduction in the Sargasso Sea. Key predictions address expected biases and trends in sex ratios, habitats more likely to be population sources (e.g. river basins) or sinks (e.g. estuary), expected trends in bimaturism (sex-specific maturation times), implications of the relative speed of adaptation and of environmental deterioration, and fitness responses to stress levels, early-stage mortality, and female demographic parameters.

Increasing the knowledge of approaches to estimate the status of data-limited stocks is of crucial importance since the vast majority of stocks are data-limited, i.e., there is not enough data to conduct a fully integrated statistical catch-at-age or at-length assessment. Among the different data-limited methods, surplus production models (SPMs) are usually considered the most complete data-limited assessment methods since they are the only method that provides a full stock assessment. Due to high interest in the application of SPMs for assessing data-limited stocks, our contribution focuses on providing a practical review of these models and their corresponding characteristics. Additionally, we review the use of the surplus production concept in the “known biomass production models”, highlighting their potential through examples of relevant applications. After a general introduction to the formulation of SPMs, their framework and features, this review focuses on the SPMs most frequently applied by well-known marine research organisations: ASPIC (a stock-production model incorporating covariates), SPiCT (surplus-production model in continuous time) and JABBA (just another Bayesian biomass assessment). For each model, we provide details of its formulation and main features, in addition to evaluating the quality and characteristics of the available software. Based on this information, our comparative study highlights the advantages and disadvantages of each of the three SPMs. The conclusion provides recommendations for their use in the assessment of data-limited stocks, facilitating a decision about whether SPMs constitute an appropriate tool for guidance on and assessment of specific stocks. Finally, we evaluate which of the SPMs considered in this paper should be applied.

Two nektonic squid species, Illex argentinus in the Southwest Atlantic and Dosidicus gigas in the Eastern Pacific, are amongst the largest commercial cephalopod resources; presently comprising from one third to almost one half of the global cephalopod catch. These squids are straddling stocks exploited during their ontogenetic migrations both within exclusive economic zones of coastal States and in adjacent high seas. At present, fisheries of these squids lack an agreement to undertake comprehensive international stock assessments and management, resulting in minimal data exchanges among coastal States and those fishing in the high seas. In the high seas, there is little to no regulation and control of fishing activities, with very limited information on catch and effort. However, the high seas have been very important for commercial exploitation of both species, with annual averages of 45% of the total I. argentinus catch and 30–40% of the total D. gigas catch over the last decade. With uncontrolled harvest in the high seas, and without any unified international regulation, these straddling squid resources are highly vulnerable to overfishing; especially during years of poor recruitment and low abundance. Recent dramatic increases of fishing pressure pose a significant threat to the sustainability of these globally important squid resources. A proposal to reduce the risk of squid stocks depletion would be the establishment of a multi-national advisory forum to explicitly monitor stocks, coordinate assessment of population dynamics, and provide management recommendations for cephalopod fisheries around the world.

Billfish species (families Istiophoridae and Xiphiidae) are caught in artisanal, recreational, and commercial fisheries throughout the Western Indian Ocean region. However, data and information on the interactions among these fisheries and the ecology of billfish in the WIO are not well understood. Using an in-depth analysis of peer-reviewed articles, grey literature, observation studies, and authors' insider knowledge, we summarize the current state of knowledge on billfish fisheries in 10 countries. To describe historical and current trends, we examined fisheries statistics from governmental and non-governmental agencies, sportfishing clubs' reports, diaries of sportfishing captains, and the catch and effort databases of the Indian Ocean Tuna Commission. We highlight two key points. First, billfish fisheries in the Western Indian Ocean are highly diverse, comprising two distinct segments-coastal and oceanic. However, data are poor for most countries with significant gaps in information especially for sport and artisanal fisheries. Second, the evidence assembled showed that billfish species have immense social, cultural, and economic value. Swordfish are targeted by both large-scale and semi-industrial fisheries, while other billfish species, particularly marlin, are highly sought after by sport fisheries in most countries. Our paper provides a comprehensive review of billfish fisheries and available information in the context of the WIO underscoring the need to strengthen data collection and reporting, citizen science, and collaborative sustainable development and management of billfish. Supplementary information: The online version contains supplementary material available at 10.1007/s11160-022-09725-8.

Marine population modeling, which underpins the scientific advice to support fisheries interventions, is an active research field with recent advancements to address modern challenges (e.g., climate change) and enduring issues (e.g., data limitations). Based on discussions during the ‘Land of Plenty’ session at the 2021 World Fisheries Congress, we synthesize current challenges, recent advances, and interdisciplinary developments in biological fisheries models (i.e., data-limited, stock assessment, spatial, ecosystem, and climate), management strategy evaluation, and the scientific advice that bridges the science-policy interface. Our review demonstrates that proliferation of interdisciplinary research teams and enhanced data collection protocols have enabled increased integration of spatiotemporal, ecosystem, and socioeconomic dimensions in many fisheries models. However, not all management systems have the resources to implement model-based advice, while protocols for sharing confidential data are lacking and impeding research advances. We recommend that management and modeling frameworks continue to adopt participatory co-management approaches that emphasize wider inclusion of local knowledge and stakeholder input to fill knowledge gaps and promote information sharing. Moreover, fisheries management, by which we mean the end-to-end process of data collection, scientific analysis, and implementation of evidence-informed management actions, must integrate improved communication, engagement, and capacity building, while incorporating feedback loops at each stage. Increasing application of management strategy evaluation is viewed as a critical unifying component, which will bridge fisheries modeling disciplines, aid management decision-making, and better incorporate the array of stakeholders, thereby leading to a more proactive, pragmatic, transparent, and inclusive management framework–ensuring better informed decisions in an uncertain world.

Smartphones are increasingly the most common type of mobile phone used throughout the world, offering users the ability to browse the internet and access mobile applications. Smartphones are also often equipped with high definition digital cameras, accelerometers, gyroscopes, and GPS. They can, therefore, facilitate the collection and dissemination of data, often through purpose designed applications (apps). As a result, numerous apps have been developed for use in wild capture fisheries. These apps have been designed for a number of purposes including for data collection, providing information to fishers, being linked to value chains and post-harvest practices and for uses linked to employment, legislation and safety. These apps are used across the world from large commercialized fisheries to small scale fisheries. In the latter, apps have the potential to bridge a technology gap, possibly replicating the functions of multiple pieces of hardware such as are used on larger vessels. This paper presents results from a narrative literature review to provide a synthesis of smart phone apps currently available for use by commercial fishers. 84 smartphone apps were identified as being currently available for use in commercial wild capture fisheries throughout the world. Smartphone apps were available for a number of uses but they were predominantly used for data collection and reporting. While this review provides an important overview of the extent of app use in commercial wild capture fisheries there remains potential for future work to improve understanding of how beneficial app use is and what it is that encourages app use and determines an app as being 'successful'. Supplementary information: The online version contains supplementary material available at 10.1007/s11160-022-09727-6.

The practice of seine fishing for vendace (Coregonus albula) has continued as an unbroken tradition in Lake Puruvesi in eastern Finland since 1300 AD. While fishing methods have evolved, the fishery still relies heavily on the traditional knowledge of practitioners, which is passed along from generation to generation. Traditional knowledge of weather patterns, the fish themselves, and other components of the lake ecosystem have allowed fishers to maintain an economically viable fishery without depleting fish stocks. Lake Puruvesi and its traditional seine fishery represent a stronghold of Finnish fishing culture and traditional ecological knowledge. In recent years, local observations by fishers have identified threats to the lake ecosystem and the fishery, including eutrophication, climate change-related threats to fish, and climate-related disruption of fishing practices. This paper explores the unique ecological, social, and economic characteristics that have allowed the fishery to remain sustainable. We discuss the role of traditional knowledge in maintaining the fishery and we use a socio-ecological framework to broadly assess the value of the fishery. We also consider threats facing the fish and fishery and discuss approaches taken by fishers to address those threats.

Disentangling the causes and consequences of ontogenetic niche shifts has been a pivotal challenge in ecology, aiming to enhance the understanding of biological processes that function at the individual, population, and community levels. Studies on ontogenetic dietary shifts have traditionally focused on short time scales, mostly including sampling covering just one or a few consecutive years, thus neglecting possible aspects of temporal variation and ecosystem stability that can only be revealed on long-term scales. We address ontogenetic dietary shifts of two fish predators in an intraguild system (Arctic charr and brown trout) using a long-term dataset spanning 20 consecutive years. Our study revealed distinct ontogenetic niche shifts of the two intraguild predators and demonstrated that these patterns were stable over time, suggesting large stability in prey acquisition and resource partitioning despite changes in their abundances and relative species composition. Some interannual variation was observed, but this was primarily due to sampling bias from low observation numbers for some ontogenetic stages, reflecting a common methodical challenge for ontogenetic niche shift studies. The persistent patterns in the trophic ontogeny of intraguild predators likely facilitate population and community stability by reducing inter- and/or intraspecific competition, thereby having important consequences for ecosystem functioning and resilience. Our study provides a strong rationale for performing ontogenetic niche shift studies over several consecutive years, enabling important insights into temporal variation, enhancement of observation numbers by merging data from multiple years, and the facilitation of a less intrusive sampling scheme for more vulnerable populations.

The incidental or target capture of sea turtles by small–scale fisheries (SSF) has been receiving increasing attention in recent years due to its high impact. Here, we evaluated the impact of the SSF on sea turtles in Cabo Verde, which hosts the largest rookery of the endangered Eastern Atlantic loggerhead turtle (Caretta caretta) population. This is the most comprehensive study evaluating the impact of SSF on sea turtles in the Cabo Verde Archipelago involving more than 85% of boats and more than 20% of the fishermen registered in the archipelago. Between the years of 2011 and 2014, 763 artisanal fishermen were interviewed at all the main ports and fishing communities of seven islands. Artisanal fishermen reported a mean annual capture of 1.5 turtles per boat indicating that a minimum of 1675 sea turtles could be landed per year in this fishing sector alone, with 65% in Santiago Island (which host the country’s capital, Praia). Most captures (95.7%) occurred from May to September and coincided with the loggerhead turtle nesting season. These results suggest a severe impact of the SSF on adult loggerheads turtles in Cabo Verde as well as green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) juvenile turtles. To mitigate this impact, measures such as revising the current legislation for fisheries, the supervision and control of landings, especially in the most remote ports of the Archipelago, the regulation of the SSF during the nesting season around the main nesting areas, awareness–raising campaigns, sustainable activities, and alternative sources of income in fishing communities are recommended.

Coral reef fishes often exhibit specific or restricted depth distributions, but the factors (biotic or abiotic) that influence patterns of depth use are largely unknown. Given inherent biological gradients with depth (i.e. light, nutrients, habitat, temperature), it is expected that fishes may exploit certain depths within their environment to seek out more favourable conditions. This study used baited remote underwater video (BRUV) systems to document variation in the taxonomic and functional (trophic and size) structure of a fish assemblage along a shallow to upper-mesophotic depth gradient (13–71 m) at a submerged, offshore shoal in the northern Great Barrier Reef. BRUVs were deployed during two separate time periods (February and August 2017), to separately examine patterns of depth use. Both the relative abundance and diversity of reef fishes declined with depth, and there were pronounced differences in the taxonomic and functional structure of the fish assemblage across the depth gradient. In shallow habitats (< 30 m), the fish assemblage was dominated by herbivores, detritivores, planktivores and sessile invertivores, whereas the fish assemblage in deeper habitats (> 30 m) was dominated by piscivores and mobile invertivores. Depth and habitat type were also strong predictors for important fisheries species such as coral trout (Plectropomus spp.), emperors (Lethrinus spp.) and trevallies (Carangid spp.). We found limited evidence of temporal changes in depth and habitat use by fishes (including fisheries target species), although recorded temperatures were 4 °C higher in February 2017 compared to August 2017.