Search Results (1,582)

Salinity is a key environmental survival factor for all aquatic organisms, especially migratory species. The masu salmon (Oncorhynchus masou) is a representative migratory fish species. Following the freshwater parr stage, anadromous masu salmon briefly inhabit brackish water and transition before migrating to the ocean. To demonstrate the physiological responses of masu salmon (length: 8 ± 0.5 cm, water temperature: 10 ± 0.5 °C) to variations in salinity, we carried out three gradual transfer experiments (gradual daily increases direct transfer experiment of 3.2 (D10), 1.6 (D20), and 1.1 (D30) ppt until reaching 32 ppt) and one (immediate transfer to 32 ppt on day 0) as domestication regimens for masu salmon. The results indicated the following: (1) In the gradual transfer experiment group, growth performance, along with ion and hormone indicators, suggested that the D30 treatment group of anadromous masu salmon exhibited a high level of adaptability. (2) In the direct transfer experiment, in addition to the activity of antioxidant enzymes, both ion concentrations and hormone indicators returned to a stable state within 7 days. Our findings provide a scientific protocol for salinity regulation during the artificial propagation of masu salmon and establish critical acclimation parameters for land-based recirculating aquaculture systems aimed at marine salmonid farming, thereby highlighting their practical value. Full article

Soil organic carbon (SOC) is a major component of the global carbon cycle. This study aimed to: (i) monitor five decades’ land use/land cover (LULC) changes in the northern Nile delta using Landsat imagery; (ii) quantify baseline SOC stocks (SOCs) in 2021; (iii) project SOCs and potential SOC sequestration (PSOCS) to 2100 under four SSP2-4.5 climate scenarios using RothC model; and (iv) evaluate uncertainty in SOCs and PSOCS projections using the Monte Carlo approach. Sixty soil samples were collected during the winter and summer seasons of 2018/2019 (30 per season). Agricultural land expanded from 12% in 1972 to 35% in 2021, while fish farms, established in the 1990s, accounted for 24% of the area by 2021. SOCs varied across LULC types and seasons. Between 13 and 28% of agricultural land exceeding 7 Mg C ha⁻¹ in summer and winter, respectively. Barren land and sabkha were characterized by low SOCs (<3 Mg C ha⁻¹). Model predictions indicate that mean SOCs will increase from 5.83 (2021) to 6.16 (mid-century), followed by a decline to 5.96 Mg C ha⁻¹ by 2100. Estimated PSOCS range from 0.13 to 0.32 Mg C ha⁻¹. Monte Carlo uncertainty analysis yielded median SOCs between 6.01 and 6.27 Mg C ha⁻¹ and median PSOCS between 0.18 and 0.44 Mg C ha⁻¹, reflecting moderate projection uncertainty. Full article

To reduce pressure on capture fisheries, sustainable aquaculture must decrease its dependency on fish meal and fish oil. Microalgae are a promising substitute due to their complete nutritional profile and low-footprint production process. This study examined the use of the cyanobacterium Limnospira maxima (commercially known as Spirulina) as a partial substitute for fish meal in feed for juvenile Nile tilapia (Oreochromis niloticus). We developed isoproteic (36%) and isoenergetic (3000 kcal kg⁻¹) fish feed formulations containing 0% (control), 10%, 20%, 30%, or 40% L. maxima dry biomass. The experimental diets were then fed to 360 juvenile O. niloticus (1.32 ± 0.35 g) for 85 days using a randomized experimental design. The hepatic, intestinal, and muscle (fillet) tissues of the fish were collected for morphophysiological, fatty acid, and proteomic analyses. The intestinal coefficient, number of intestinal villi, villus height, and hepatosomatic index were essentially the same for all treatments (p > 0.05). Treatments containing 20–30% L. maxima exhibited a higher degree of unsaturation and better dietary fat quality. A greater abundance of the enzymes SOD, GSR, PRX1, and PLD3 in the experimental groups indicated higher antioxidant activity, whereas a greater abundance of acyl-CoA dehydrogenases indicated better use of fatty acids as an energy source. These trends were more evident in the 20–30% inclusion range. Thus, adding L. maxima to fish feed improves farming performance, fish health, and product quality. The results encourage the use of microalgae to promote more sustainable aquaculture. Full article

In healthy ecosystems, large raptors such as the White-tailed Eagle perform the essential roles of predators, bioindicators, and umbrella species. Despite their importance, many species of raptors are globally endangered, and similarly, in the Republic of Moldova, 13 species of diurnal birds of prey went extinct in the last 7 decades. The White-tailed Eagle (Haliaeetus albicilla) is the only example of a raptor that has regionally made a demographic and distributional comeback after decades of absence. Following this comeback, a national monitoring scheme during 2014–2025, including a nest counting survey in 2022–2024, has been implemented to understand what the current national situation of the species is and its ecological preferences and threats, together with the fundamental ecological context that allowed the breeding population to adapt to an ever-changing landscape. Field research conducted over 12 years confirmed the breeding of eight pairs, with data indicating a minimum of 19–23 nesting pairs. Pairs generally avoid human-dominated landscapes, preferring higher coverage of wetlands and forests, but current data suggests frequent occupancy of suboptimal territories and increasing tolerance towards human activity and infrastructure. Although currently small, the breeding population experiences high breeding success with no negative outcomes recorded. However, droughts and forestry activities in the proximity of the nests potentially reduced and delayed breeding success. Current forestry and fish farming practices increase the vulnerability of the few known breeding pairs to habitat degradation, poaching, and deforestation. To improve the conservation status of this endangered raptor in the Republic of Moldova, as close as possible to Least Concern status, it is crucial to implement multi-purpose buffer zones around active nests during the breeding season and to further survey the breeding population and assess any demographic trends. Full article

Aquatic pollution threatens biodiversity, disrupts ecological balance, and poses risks to communities dependent on freshwater resources. Aquaculture ponds are especially susceptible, as contaminants directly influence both ecosystem stability and the safety of fish for human consumption. With the rapid growth of pond-based aquaculture, accurate modeling of pollutant dynamics is essential. This study analyzes pollution in a system of n interconnected ponds, assuming a clean water source, constant volume, and steady pollutant inflow and outflow. A previous model based on ordinary differential equations is solved using matrices, eigenvalues, eigenvectors, and generalized eigenvectors. A generalized fractional model is then developed employing the Caputo–Liouville derivative. Unlike classical models, fractional models account for memory effects and anomalous diffusion, providing a more realistic description of pollutant behavior. Analytical solutions are derived to track pollutant variation across ponds, and a comparison of the two formulations is presented. The results enhance understanding of pollution transport in aquaculture systems and offer insights for sustainable water quality management in fish farming. Full article

In recirculating aquaculture systems, fish detection is an essential component for maintaining effective farming operations. The availability of high-quality fish datasets is limited because of the richness of fish species, and the annotation of large-scale data, which is used to train models, is often labor-intensive and time-consuming. The presence of different fish species across batches introduces further challenges for consistent detection performance. This work introduces a few-shot learning approach for fish detection, utilizing a customized dataset as novel classes and the Fish4Knowledge dataset for base classes, thereby establishing a framework that enhances adaptability in data-scarce scenarios. Within the model architecture, multi-scale feature extraction is enhanced through an attention mechanism, which is integrated as a dedicated module to strengthen representation learning, thus enhancing the model’s capability to differentiate visually similar fish species. Two distinct customized fish datasets are employed to evaluate the robustness of the proposed method. Experimental results show that the proposed model performs competitively against TFA, Meta-RCNN, and VFA. In the base-training phase, it achieves a mAP of 0.775, slightly surpassing VFA, while in the 1-shot, 5-shot, and 10-shot fine-tuning settings, it obtains mAP values of 0.152, 0.247, and 0.265, respectively. A similar trend is observed on a subset of black fish, with mAP scores of 0.169, 0.253, and 0.286 in the corresponding few-shot settings. These results indicate that the proposed approach can maintain relatively stable detection accuracy and adaptability across different fish batches, offering a practical solution for fish detection tasks in aquaculture when annotated data is scarce. To further demonstrate the efficacy and practical utility of the proposed methodology, a case study in fish farming confirms that the enhanced model achieves consistent and precise detection across diverse fish species, even when trained with limited annotated data. Full article

The enclave villages of Lake Malawi National Park (LMNP) are human settlements within a World Natural Heritage landscape. While social heterogeneity has been widely discussed in social–ecological systems (SES) scholarship, ethnic diversity has often remained analytically implicit. This study makes ethnic diversity central to analysis by examining how it shapes livelihoods, resource use, and governance across enclave villages. Drawing on an integrated household survey, key informant interviews, and extended field observations, and informed by collaboration theory, the SES framework, and scholarship on social differentiation, the analysis shows that ethnic diversity facilitates exchanges of fishing techniques, farming skills, ecological knowledge, and market linkages, producing plural and seasonally adaptive livelihood portfolios. Households routinely combine fishing, agriculture, tourism, petty trade, and forest use, contributing to diversified resource use. However, pressures on fish stocks, forest resources, and agricultural land highlight the need for more inclusive co-management. Emerging community-based institutions and collaborative initiatives increasingly facilitate coordination, rule-making, and shared stewardship. Overall, the findings identify practical and conceptual entry points through which ethnic diversity, ecological knowledge, and adaptive livelihoods can jointly support more resilient and inclusive pathways for sustainability at the crossroads of resource-dependent livelihoods and conservation, offering insights for socially diverse human–nature landscapes. Full article

The rapid expansion of offshore wind energy in Korea has raised concerns among coastal fishing communities about potential changes in fish assemblages. We conducted a summer 2022 survey at the Tamra Offshore Wind Farm (Jeju, Korea), comparing turbine-adjacent and reference sites using diver-operated video (DOV), direct capture, and stereo-baited remote underwater video (stereo-BRUV). Across methods, 23 fish species were identified, and stereo-BRUV detected the highest species richness. In stereo-BRUV analysis, the observed fish species and relative abundance metrics were higher in turbine-adjacent sites than reference site, including greater MaxN (maximum number of individuals observed in a single video frame) and Max spp. (maximum number of species observed in a single video frame). Most individuals measured from stereo imagery were 15–25 cm in total length (TL). For dominant taxa, TL distributions derived from stereo-BRUV were comparable to those measured from captured specimens, supporting the practical use of stereo-BRUV for size–structure characterization. Epifaunal assemblages on turbine jackets exhibited higher density and biomass than the reference site and showed clear vertical stratification (upper/mid > bottom). Diet items in captured fish overlapped with dominant jacket epifauna, consistent with a potential trophic linkage. Overall, stereo-BRUV can be used as a non-destructive and auditable approach for documenting fish assemblages around wind-farm structures. Because sampling was limited in spatial and temporal replication, the observed patterns should be interpreted as exploratory and hypothesis-generating for future synchronized and replicated monitoring. Full article

This study was conducted to explore the impacts of L-carnitine (CAR) on growth performance, antioxidant capacity, hepatic lipid deposition and fatty acid β-oxidation in farmed fish fed a high-fat diet (HFD). A total of 150 juvenile tiger puffer (15.23 ± 0.01 g) were randomly assigned into six tanks (three tanks each group) and fed with a control diet (HFD, 16% lipid) and a HFD supplemented with 1.5% CAR for eight weeks, respectively. The results indicated that the growth performance and the most proximate compositions were not influenced by dietary CAR. However, compared to the control group, the hepatosomatic index and crude lipid content in the liver were significantly reduced in the CAR group, indicating that CAR performed a lipid-lowering effect in tiger puffer. Serum lipid profiles remained stable, implying that the cholesterol metabolism was not influenced by dietary CAR. Furthermore, dietary CAR activated fatty acid β-oxidation (FAO) in both the mitochondria and peroxisomes and drove lipolysis and fatty acid intracellular transport to supply sufficient substrates for FAO, manifested by the activation of related genes, proteins and enzyme activity. Additionally, CAR lowered hepatic MDA levels, indicating improved antioxidant capacity. In conclusion, CAR shows potential as a lipid-lowering feed additive for marine fish under high-fat dietary conditions. Full article

Accurate feeding-state monitoring is essential for improving feeding management, reducing feed waste, and supporting water quality and fish welfare in aquaculture. However, existing vision-based methods often rely on subjective labels or computationally expensive temporal models, which limits practical on-farm deployment. Here, we propose an objective, edge-deployable framework for motion-driven feeding-state quantification and binary feeding/non-feeding recognition from top-view videos. The framework integrates frame-pair dense optical-flow encoding with a lightweight network (EfficientFeedingNet) to enable real-time deployment. Using an optical-flow-derived motion-intensity signal (V-Value), we automatically delineate feeding-response intervals and construct a perception-based dataset (Perceptual Dataset) with reproducible binary labels, alongside an observer-labeled Intuitive Dataset. Across representative backbones, models trained on the Perceptual Dataset achieve >90% test accuracy and improve over the Intuitive Dataset by 13.13–18.46 percentage points. The proposed EfficientFeedingNet attains 96.53% test accuracy while remaining lightweight for edge deployment; on a Jetson Orin NX, it runs at 7.0 ms per image (143.24 fps). Overall, the proposed framework provides a practical basis for timely, data-driven feeding decisions in precision aquaculture. Full article

Antimicrobial resistance in bacteria associated with aquaculture, such as Edwardsiella spp., represents an emerging challenge because of their relevance to fish health and their potential impact on animal, environmental, and human health. In this study, we primarily investigated the antimicrobial susceptibility profiles of Edwardsiella anguillarum isolated from farmed Nile tilapia (Oreochromis niloticus) in Brazil. Based on our findings, herein, we propose provisional local epidemiological cut-off values (pECVs) using the normalized resistance interpretation method, with data for Edwardsiella tarda included as an exploratory context. Fifty isolates (31 E. anguillarum and 19 E. tarda) collected between 2017 and 2025 were tested against 28 antibacterial agents using the disk diffusion method. Based on the pECVs, isolates were classified as wild type (WT) or non-WT (NWT), and the multiple antibiotic resistance (MAR) index was calculated. Most E. anguillarum isolates remained susceptible to several classes, although NWT and multidrug-resistant profiles were detected with a MAR index of 0.68, suggesting selective pressure in intensive tilapia farming systems. These findings support the use of local, species-specific pECVs for resistance surveillance in aquaculture, highlighting the importance of continuous antimicrobial resistance monitoring in aquaculture from a One Health perspective. Full article

The study aimed to assess the influence of two packaging methods (under vacuum, VP vs. air, AP) on the quality of fish balls from carp (Cyprinus carpio) stored at +4 °C up to 14 days after preparation. The air-packed and vacuum-packed fish balls were analyzed for physicochemical parameters, microbiological status, and sensory characteristics. The packaging method and storage time interaction significantly (p < 0.05) affected the acid value (AV) and peroxide value (PV), as well as the thiobarbituric acid reactive substance index (TBARS), with lower values of these parameters observed in vacuum-packed samples at 7 d (AV, PV, TBARS), 9 d (TBARS), 12 d (PV) and 14 d (TBARS) of storage. Moreover, vacuum packaging helped maintain a beneficial oil absorption and pH, and partially slowed down the occurrence of undesirable changes in color, i.e., the decrease in redness of semi-raw fish balls or increase in yellowness of deep-fried products. Based on the overall quality values, the air-packed fish balls were sensory acceptable for up to 9 days, while the vacuum-packed fish balls were acceptable up to 12 d. The bacterial counts (total viable counts—TVC, psychrotrophic bacterial counts—PBC, total staphylococcal counts—TSC, sulfite-producing bacteria counts—SPBC, and lactic acid bacteria counts—LABC) increased during storage. Although the rate and pattern of growth varied depending on the packaging, fish balls maintained the recommended microbiological quality throughout the entire storage period. The VP method inhibited the growth of TVC, PBC, TSC, and SPBC relative to the AP method, while the VP method showed a higher increase in LABC. The results indicated that vacuum packaging appears to be an effective approach to prolong the shelf life of fish balls made from carp. Additionally, developing this convenient food product could be a valuable strategy to enhance consumer acceptance and promote the use of widely farmed carp species. Full article

Siberian sturgeon (Acipenser baerii Brandt, 1869), characterized by its rapid mass accumulation and high survival rate under industrial breeding conditions, is one of the most promising aquacultural species. This research aimed to study the growth and development of farmed Siberian sturgeon (Acipenser baerii Brandt, 1869) to improve breeding programs. This research was conducted at the Federal Research Center for Animal Husbandry named after Academy Member L.K. Ernst and focused on the Lena population broodstock of Siberian sturgeon of the April 2022 generation (n = 98), grown in a recirculating aquaculture system (RAS). The experiment took into account body weight (W, g) and eleven morphological measurements: L—absolute length (cm); LR—fish body length increase (cm/day); l—commercial length (cm); L2—fork length (cm); HL—head length (cm); PV—pectoventral distance (cm); VA—ventroanal distance (cm); pl1—peduncle length (cm); H—body height (cm); h—peduncle height (cm); SC—body thickness (cm); GC—body circumference (cm); and Cc—peduncle circumference (cm). These measurements were taken from the same sample of fish at five different time points, all belonging to the same generation and approximately the same age. Measurements were taken every 3 to 9 months: 1 y (group G1), 1 y. 5 m. (group G2), 2 y. 2 m. (group G3), 2 y. 5 m. (group G4), 3 y. 2 m. (group G5), and 3 y. 5 m. (group G6). To evaluate the rate of growth and development, relative speed of growth (SGR) and relative speed of lengthening (SLR) during the observation period were determined. To characterize the fish’s exterior, we evaluated Fulton’s condition factor (KF) and the leanness index (Q). With increasing age, there was a significant (p < 0.01) decline in both SGR (from 0.454 to 0.065 g%/day) and SLR (from 0.132 to 0.028 cm%/day), which reflects changes in the fish’s physiological processes tied to the transition from the growth phase to the puberty phase. Relatively large variability was observed in body weight (C_v = 19.7–30.4%) compared to morphological measurements (C_v = 5.7–14.9%). Correlations between morphological measurements and the body weight of the fish varied from low to high (r = 0.22–0.97). Equations that allow for very precise (coefficient of determination R² = 0.800–0.933) estimation of the fish’s body weight based on morphological measurements were developed. The most preferable predictors were measurements of H (R² = 0.931), SC (R² = 0.933), and L2 (R² = 0.930). These morphological measurements are promising candidates for future development of contactless live weight detection using computer vision and machine learning algorithms. The study of live weight conjugacy at different ages showed that the best time to use this measurement to select fish for reproduction is at the age of 2 y. 2 m. or older. Acquired data can be used for the development and improvement of programs for the selection and breeding of Siberian sturgeon grown in a recirculating aquaculture system. Full article

As global aquaculture continues to expand, there is increasing interest in sustainable and non-invasive tools for monitoring fish growth. Nile tilapia (Oreochromis niloticus) is one of the most farmed species worldwide. Its biomass estimation often relies on manual sampling or stereo-camera systems limited by water turbidity. This study establishes a robust relationship between lateral target strength (TS) and the total length (TL) and weight (W) of Nile tilapia using a cost-effective 201 kHz single-beam echosounder. Measurements were conducted with free-swimming fish in a controlled pond environment (TL range, 13–44 cm). The results show a strong linear correlation between acoustic and biometric data. Specifically, the relationship for mean TS was defined as TS_mean = 20.4log(TL) − 68.8 (R² = 0.93) and TS_mean = 6.3log(W) − 55.4 (R² = 0.96), proving the system’s accuracy for biomass estimation. Furthermore, the Method of Fundamental Solutions (MFS) was employed for numerical validation based on X-ray morphometry of the swim bladder. Very good agreement was observed between experimental data and numerical simulations, reinforcing the validity of the acoustic models despite the inherent complexity of biological targets. These findings demonstrate that calibrated single-beam acoustic systems provide a viable, non-intrusive tool for real-time monitoring in aquaculture ponds. Full article

The transition toward sustainable and circular bioeconomies in Agriculture 4.0 demands fertilization strategies that reduce environmental impacts while maintaining agronomic productivity. This article presents a structured narrative review of peer-reviewed literature integrating evidence across waste management, soil science, food safety, and regulatory frameworks to evaluate the potential of seafood processing byproducts including fish offal, shellfish residues, and aquaculture effluents as nutrient-rich fertilizers. These materials provide nitrogen, phosphorus, calcium, and essential micronutrients and may contribute to nutrient recycling within precision and resource-efficient agricultural systems. Evidence from diverse cropping contexts indicates that seafood waste-derived fertilizers can improve crop yield, nutrient use efficiency, and soil biological activity under site-specific conditions. Biological processing methods, including composting, enzymatic hydrolysis, and fermentation, are examined for their roles in enhancing nutrient bioavailability and reducing undesirable constituents. Particular emphasis is placed on food safety considerations, including heavy metals, persistent organic pollutants, antimicrobial resistance, pathogens, and microplastics, with discussion of speciation-based risk assessment and mitigation strategies such as thermal treatment, microbial screening, and compliance with international standards. Regulatory fragmentation, economic feasibility, and lifecycle environmental implications are also critically assessed. Emerging digital tools, including Internet of Things (IoT)-enabled nutrient monitoring and artificial intelligence (AI)-assisted compost optimization, are discussed as enabling technologies for integrating seafood-derived biofertilizers into smart farming systems. Overall, this interdisciplinary synthesis highlights the potential contribution of seafood waste valorization to circular nutrient management, environmental stewardship, and sustainable food production. Full article