Sustainable Fisheries Dynamics

Small-scale fisheries constitute the backbone of coastal livelihoods in Indonesia, yet comprehensive socio-economic data remain limited for effective management. This study characterizes the operational and socioeconomic patterns of multi-gear artisanal fisheries in the Pangandaran coastal waters of West Java, Indonesia. A cross-sectional survey of 136 fishers across 14 coastal communities was conducted using structured questionnaires covering socio-demographic characteristics, fishing operations, and catch composition. Complete economic data were available for 125 fishermen, while multivariate analyses used n = 105 due to listwise deletion of cases with missing predictor variables. Fishermen averaged 46.9 years of age with 25.8 ± 11.6 years of fishing experience. Mean monthly income was IDR 5.80 million (SD = 7.51, 95% CI: 4.47–7.13 million, approximately USD 387). Gillnet was the dominant fishing gear (73.5% of fishermen), followed by hook-and-line (14.7%). A total of 57 fish species were recorded, dominated by hairtail Trichiurus spp. (61.0% occurrence). Statistical analyses revealed weak relationships between conventional demographic and operational variables and income. Although crew number showed a statistically significant association with income (p = 0.039), its effect size was small, and the overall regression model was not significant, with very low explanatory power (R² = 0.038). These results indicate that income variability is largely driven by unmeasured and context-specific factors rather than observable fishing characteristics. These findings provide baseline socio-economic data essential for developing community-specific management interventions in Pangandaran waters. Full article

Brown trout (Salmo trutta) populations at the southern edge of the species’ distribution are increasingly exposed to interacting climatic, biotic, genetic, and anthropogenic pressures. This study provides an integrative assessment of the drivers of variation in brown trout density, biomass, and size structure across six Mediterranean river basins in Catalonia (NE Iberian Peninsula), based on long-term standardized electrofishing surveys (2016–2025; 88 sites). Generalized linear mixed models revealed that mean summer temperature, genetic introgression from hatchery-derived Atlantic lineages, and the density of introduced fish species were the most consistent negative predictors of total density, biomass, and juvenile abundance (<120 mm FL). Hydrological and nutrient variables showed comparatively weak or non-significant effects relative to thermal and biotic predictors. Fishing regulations significantly influenced the biomass and density of larger trout (>220 mm FL), with lower values in harvest-allowed sections, whereas total density was less responsive to regulation. These findings indicate that Mediterranean brown trout populations are primarily constrained by thermal conditions, genetic integrity, and biological invasions, with implications for conservation and fishery management under ongoing climate warming. Full article

To assess the status of Coilia nasus resources in the Yangtze River Estuary and support evaluation of fishing ban effectiveness, this study integrated fishery resource survey data and environmental variables collected from 2023 to 2025. A generalized additive model (GAM) was applied to examine post-ban recovery patterns of C. nasus and the environmental drivers shaping its spatiotemporal distribution. The results revealed pronounced seasonal variation in biomass, with autumn (November) values significantly higher than those in spring and summer. Biomass peaked in autumn 2024, forming a persistent and highly concentrated aggregation. Spatial analyses further indicated that high-biomass areas were consistently distributed within the brackish-water mixing zone of the outer estuary, corresponding to migratory pathways and foraging requirements of the species. GAM results demonstrated that the spatiotemporal distribution of C. nasus was jointly regulated by multiple environmental factors. In spring, temperature, depth, transparency, pH, dissolved oxygen (DO), and chlorophyll-a (Chl-a) exerted significant effects; in summer, salinity and pH were the dominant drivers; and in autumn, temperature, pH, salinity, DO, ammonium (NH₄⁺–N), nitrate (NO₃⁻–N), and phosphate (PO₄³⁻–P) showed significant influences. This study provides scientific evidence to support the management of C. nasus resources, particularly in the brackish-water mixing zone of the outer Yangtze River Estuary, and to improve evaluation of fishing-ban effectiveness. Full article

Extreme natural disasters raise a fundamental question for biologically rigid food production systems: does post-disaster productivity recovery stem from technological change or from adaptive reorganization within existing constraints? In inland aquaculture, where biological processes, fixed production cycles, and capital requirements severely limit short-run technological upgrading, this distinction is particularly critical. Using two post-earthquake time points (2023 and 2025), the analysis documents productivity and efficiency patterns rather than causal recovery trajectories. Accordingly, the analysis is explicitly descriptive and does not attempt to identify causal recovery mechanisms or long-run productivity dynamics. Adaptive efficiency is not directly measured in this study; rather, the term is used as an interpretative construct to describe efficiency changes that are consistent with adaptive behavior under post-disaster constraints. This study examines productivity patterns observed during the post-earthquake period in inland trout aquaculture following the 6 February 2023 earthquake in Eastern Türkiye, with a particular focus on adaptive efficiency as a recovery-consistent mechanism. Using a balanced panel of 290 inland trout farms observed during the immediate post-earthquake adjustment period (2023) and a subsequent recovery phase (2025), the analysis integrates bias-corrected Data Envelopment Analysis, Malmquist productivity decomposition, and resilience-oriented truncated regression. Recovery dynamics are examined conditional on farm survival, allowing within-farm adaptive adjustment to be distinguished from exit-driven selection effects. The results indicate that productivity recovery was driven predominantly by improvements in technical efficiency, while technological change remained close to unity across provinces, suggesting short-run production frontier stability. This pattern is consistent with delayed or constrained investment behavior under heightened uncertainty rather than with technological stagnation. This interpretation is not unique and should be read as one plausible mechanism among several, rather than as a definitive explanation of observed frontier stability. Farms primarily restored performance through operational reorganization, input coordination, and scale adjustment within existing biological and technological constraints, rather than through innovation. Second-stage results further show that the coefficient on access to liquidity is positive, while higher mortality rates and greater distance to markets are systematically associated with weaker post-disaster adjustment. Overall, the findings indicate that short- to medium-term productivity patterns in biologically rigid inland aquaculture systems are governed primarily by efficiency changes consistent with adaptive efficiency rather than technological change. From a policy perspective, post-disaster aquaculture recovery strategies should prioritize liquidity support, biological continuity, and operational stability over premature technology-push interventions. The analysis is based on two post-disaster observation points (2023 and 2025), which allows identification of short- to medium-term recovery-consistent patterns but does not permit causal or long-run inference. Full article

Investigating the impact of factor mobility (FM) on the economic efficiency of marine fisheries (EEMF) holds scientific reference value for promoting the high-quality development of the marine fisheries economy in China’s coastal regions. This study is based on panel data from 11 coastal provinces and municipalities in China, covering the period from 2008 to 2023. Utilizing Tobit models and mediation effect models, it empirically analyzes the direct and indirect impacts of FM on the EEMF, as well as the regional heterogeneity of these effects. Research findings indicate that (1) the level of FM and the EEMF in coastal regions both exhibit fluctuating upward trends, although regional variations exist across different provinces. (2) FM in coastal regions enhances the EEMF. For every additional unit of FM, the EEMF increases by 0.0825 units. (3) Technological innovation levels and industrial structure upgrading serve as key pathways through which FM influences the EEMF, acting as mediating variables. (4) This impact exhibits regional heterogeneity, with the Eastern Marine Economic Circle being the most significantly affected. The research findings expand the scope of studies on FM and the EEMF, providing practical advice for promoting the optimal allocation of factors in coastal regions and enhancing EEMF development. Full article

Global fishery resources are under increasing pressure from environmental change and institutional constraints. China’s seasonal fishing moratorium has contributed to resource recovery but has also created income and employment challenges for small-scale fishers. This study examines how livelihood capital structures shape annual livelihood portfolios under predictable closure constraints, using three representative fishing communities in Guangdong Province as case studies. A combination of data augmentation, regression analysis, and agent-based simulation was applied to analyze the relationships between capital endowments and behavioral responses. Results show that environmental and financial capital significantly increase the likelihood of maintaining capture as the primary livelihood, while psychological capital stabilizes decisions under uncertainty. Physical capital and social networks exhibit more variable effects, reflecting differentiated adaptive capacities. Simulations further reveal threshold effects and diminishing marginal returns in capital accumulation, with heterogeneous temporal impacts across capital types. Theoretically, the study extends the Sustainable Livelihoods Approach by incorporating environmental and psychological capital, thereby enriching the understanding of capital mechanisms in fisheries. Overall, the findings advance knowledge of how small-scale fishers adapt under institutional constraints and provide practical insights for policies aimed at aligning livelihood security with the sustainable use of marine resources. Full article

White croaker (Pennahia argentata) is an ecologically and economically relevant fish species targeted by demersal trawls using diamond-mesh codends at fishing grounds in China, Japan, and Korea. However, the stock has been overexploited, and the capture of undersized individuals is of concern. Further, diamond-mesh codends are known to have varying mesh shape due to the fact that the opening angle in them varies along the codend and during the fishing process. Therefore, to fully understand the effect of mesh size and opening angle on the size selectivity of white croaker, experimental fishing trials and fall-through trials were conducted. By combining the results from these trials, a model was constructed to predict the effect of mesh size and mesh opening angle on size selectivity of white croaker. The predicted size selectivity results for white croaker fitted well with those from the sea trial experiments, which enabled us to use the model established to predict the size selectivity of diamond-mesh codends with a mesh size ranging from 15 to 90 mm and the effect on the exploitation pattern of the species in the fishery by changing the codend mesh size. Full article

Round scad (Decapterus maruadsi) and jack mackerel (Trachurus japonicus) are economically significant pelagic species widely distributed in the northern South China Sea (SCS), with overlapping habitats and life history stages. To examine the distribution patterns of round scad and jack mackerel and their responses to environmental variables, we conducted a preliminary analysis using catch and environmental data from four seasonal surveys around Hainan Island. Three species distribution models—generalized linear models (GLM), generalized additive models (GAM), and random forests (RF)—were applied to quantify species–environment relationships. Explanatory variables included both biotic and abiotic factors: temperature, salinity, water depth, sea surface chlorophyll a concentration (SSC), phytoplankton abundance, and zooplankton abundance. The results revealed pronounced spatial heterogeneity in the high-density areas of both species. Among the models, GAM consistently explained a higher proportion of deviance in the observed distributions. Further analysis showed that round scad and jack mackerel responded differently to environmental gradients such as water depth and temperature, although their responses to varying plankton concentrations were largely consistent. Specifically, round scad are typically found in waters at depths ranging from 0 to 50 m, whereas jack mackerel tend to inhabit depths exceeding 100 m. In response to high plankton abundance, both species exhibit a notable increase in resource availability when plankton levels surpass 3. These findings indicate distinct spatial niches and suggest potential competition in feeding ecology between the two species. Overall, the study enhances understanding of the spatial dynamics of key commercial species in the northern SCS and provides valuable insights for sustainable fisheries management and conservation planning. Full article

In the dynamic and increasingly threatened marine environment, understanding the full spatial ecology of species like the reef manta ray (Mobula alfredi) is crucial for effective conservation. While typically considered a shallow-water species, reef manta rays in New Caledonia were investigated to explore their vertical habitat use. This study utilized satellite telemetry data from 19 tagged individuals, with three tags providing sufficiently high-resolution information on dive behaviour, to describe and quantify three-dimensional movements. We found that New Caledonian reef manta rays exhibit outstanding deep-diving capabilities, with all individuals diving below 300 m and one reaching 672 m. These deep dives occurred regularly, averaging one every 4.8 days, which is notably more frequent than in other studied populations. Dive profile analysis revealed a mixture of foraging and exploratory behaviors, supporting the hypothesis that these deep excursions are driven by the search for demersal or mesopelagic food resources. Our findings highlight the ecological plasticity of M. alfredi and demonstrate that their habitat use extends far beyond the coastal, shallow waters previously assumed, a critical consideration for developing comprehensive and effective marine protected areas. Full article

Artificial light has been shown to enhance the fishing efficiency of fishing gear by attracting marine organisms. This study introduces a novel approach by incorporating noctilucent materials into crab pots and evaluates their effects on catch performance. Based on the crab pots commonly used on the coast, four types of crab pots were tested: ordinary crab pots (Con-pot), ordinary crab pots equipped with noctilucent sticks (Exp-pot 1), crab pots equipped with noctilucent nets (Exp-pot 2), and crab pots equipped with both noctilucent nets and sticks (Exp-pot 3). The results showed that the noctilucent material exhibits 6 h persistent emission in darkness after just 10 min of solar charging. Exp-pot 3 could significantly enhance fishing efficiency, which increased by 63.84% compared to the Con-pot. The proportion of crabs in Exp-pot 3 was the highest (86.35%), and the individual weight of crabs in Exp-pot 3 was the heaviest (61.5 g), which was 38.30% heavier than that in the Con-pot. Notably, Exp-pots 2 and 3 demonstrated superior selectivity with higher W₅₀ values (53.01 g and 54.49 g), narrower SRs (33.04–72.98 g and 32.95–76.03 g), effectively balancing target catch retention with undersized crab release, indicated that noctilucent nets exhibited stronger weight selectivity for crabs compared to noctilucent sticks. These results demonstrate that functional materials have broad potential applications in fishing gear, which could enhance the catch efficiency and individual size of crab caught. Full article

The National Institute of Fisheries Science in Korea is developing marine mammal bycatch reduction devices (BRDs) for midwater trawl gear. In this study, we tested two BRD-type guide nets (inclined net panel) with 30° and 45° tilt angles to prevent marine mammals from reaching the codend and facilitating their escape from the net. Fishing operations were conducted along the east and south coasts of South Korea, and cameras were installed in front of the BRDs to monitor their performance. The catch loss of herring with the 30° guide net was 13% and 11% in number and weight. The catch loss of hairtail was 53% and 51% in number and weight with the 30° guide net. Mackerel showed a 97% catch loss in number and weight with the 45° guide net. The 30° guide net resulted in lower catch loss for rudderfish and jack mackerel compared to the 45° guide net. The jellyfish discard rate of the BRD was 5% and 7% in number and weight with the 30° guide net and 12% and 11% with the 45° guide net, indicating that the 30° guide net was more effective at discarding jellyfish. Mesh selectivity was not strongly related to target species body length. Full article