Search Results (84)

The effects of household cooking on mercury speciation in whole small pelagic fish remain insufficiently understood. To address this gap, total mercury (T-Hg), methylmercury (MeHg), and Hg(II) were determined in wet whole-fish homogenates, including viscera, of sardines and sprats before and after boiling, steaming, baking, and frying. T-Hg was determined by AMA-254 and mercury species by HPLC-ICP-MS; results were expressed on wet-weight (ww), dry-weight (dw), and 100 g reference-portion bases. Frying yielded the highest dry matter, underscoring moisture-related differences among reporting bases. T-Hg concentrations ranged from 0.0518 to 0.1322 µg/g dw and MeHg from 0.0273 to 0.0624 µg/g dw. MeHg was detected in all samples, whereas Hg(II) exceeded the method detection limit only in baked and steamed sardines. MeHg amounts per 100 g ranged from 1.38 to 2.35 µg in sardines and from 0.95 to 1.79 µg in sprats. Within the tested batch, no treatment consistently reduced T-Hg or MeHg across both species. By combining analysis of the complete fish matrix with direct mercury speciation and multiple reporting bases, this study provides a food-relevant framework for interpreting mercury in processed small pelagic fish. Full article

Small pelagic fishes play a crucial role in structuring marine food webs, yet their trophic flexibility and feeding interactions remain poorly understood in highly dynamic, nutrient-rich systems such as upwelling regions. This study combines bulk stable isotope analysis (δ¹³C and δ¹⁵N), compound-specific nitrogen isotope analysis of amino acids (CSIA-AA), and fatty acid (FA) profiles to assess feeding patterns and trophic overlap among four planktivorous species in the North Iberian shelf (Galicia and the Cantabrian Sea). The combined trophic indicators reveal clear niche partitioning between clupeids (sardine and anchovy) and scombrids (mackerel and chub mackerel), with the latter exhibiting higher CSIA-AA-derived trophic positions and distinct FA composition. Our analysis further shows that fatty acid biomarkers are essential for resolving finer-scale differences within each group, driven by variable contributions of phytoplankton and zooplankton to species diets. Although all species shared resources within the same food web, isotopic baselines indicate a decoupling between carbon and nitrogen pathways. For sardine, we compared neutral and polar lipid fractions with the total lipid extract in terms of FA composition and key dietary markers. Our results suggest that separating lipid fractions can improve dietary resolution, especially when lipid content is low. Overall, our findings highlight the value of integrating classical and emerging biochemical tracers to better resolve trophic dynamics in coexisting planktivorous fishes. Full article

Long-term changes in land-use and water quality degradation are key pressures on riverine ecosystems, yet their effects on the functional structure of fish assemblages remain insufficiently quantified. We conducted a decadal assessment of fish assemblages in four rivers experiencing rapid land-use transformation in Guangxi, China—the Zuojiang (ZY), Youjiang (YJ), Yujiang (YuJ), and Guijiang (GJ) rivers. Species-level functional traits describing body shape, vertical habitat position, feeding guild, trophic level, and maximum total length were used to calculate multiple functional diversity indices related to environmental variables using redundancy analysis and random forest models. Over the decade from 2013 to 2023, impervious surface and bare land increased significantly, while forest, shrubland, and grassland declined, coinciding with marked deterioration in water quality, including higher chlorophyll-a and lower dissolved oxygen concentrations (p < 0.05). Fish abundance and species richness decreased, and formerly dominant benthic cyprinids and loaches were replaced by tolerant and invasive taxa such as Oreochromis niloticus and Tilapia zillii. NMDS and PERMANOVA indicated a significant shift in community composition between 2013 and 2023 (R² = 0.14, p < 0.001), with fish assemblages shifting toward small-bodied, pelagic, omnivorous, and laterally compressed species. Functional richness declined, whereas functional evenness and functional dispersion increased, indicating functional simplification and homogenization. Multivariate and machine learning models consistently identified increasing impervious cover and declining dissolved oxygen as the strongest predictors of these changes. Our results demonstrate that land-use intensification and water quality deterioration are associated with reduced functional integrity in Guangxi rivers and highlight the value of trait-based indicators for monitoring and managing biodiversity in rapidly urbanizing catchments. Full article

Charal (Chirostoma spp.) is a small pelagic fish of high nutritional and economic importance in central Mexico. However, its high moisture content and rapid post-harvest deterioration result in substantial losses in artisanal fisheries. Solar drying represents a sustainable preservation alternative, particularly in regions with limited access to refrigeration. This study investigates the drying kinetics of whole charal under field-realistic mild-to-moderate solar drying scenarios, including forced convection, natural convection, and open-air exposure. Experimental drying curves were modeled using classical thin-layer formulations, and neural network models were evaluated as complementary one-step-ahead predictors of experimental moisture ratio. Among the evaluated thin-layer models, the Modified Page formulation consistently provided the most reliable empirical description of the drying curves, with coefficients of determination greater than 0.97. An ablation-style comparison of ANN, CNN, LSTM, and CNN-LSTM architectures showed that the CNN model achieved the highest global predictive accuracy in the present dataset, with R² = 0.987 and MSE = 4.3 × 10⁻⁴. Because the dataset contained a limited number of independent drying curves, the deep-learning results are interpreted as exploratory and complementary to thin-layer modeling rather than as a replacement for classical empirical models. The proposed framework may support future drying-endpoint estimation and decision-support tools for artisanal fish processing, provided that additional validation is performed with standardized sample masses, environmental covariates, and product-quality indicators. Full article

Small pelagic fishes are essential for artisanal fisheries and food security in São Tomé and Príncipe, yet biological information required for stock assessment remains scarce. This study examined the population dynamics and life-history traits of Caranx crysos, Euthynnus alletteratus, Hemiramphus balao, and Cheilopogon melanurus using 9052 specimens collected from artisanal landings between 2023 and 2025. C. melanurus (35.2%) and H. balao (34.0%) dominated the sampled catches, followed by C. crysos (18.1%) and E. alletteratus (12.7%). Standardized CPUE series modelled using GAMs revealed significant temporal and seasonal variation in relative abundance, with contrasting species-specific trends. Length–weight relationships revealed negative allometric growth in three of the four species examined (75%), with b values ranging from 2.50 to 3.19, while Fulton’s condition factor differed significantly among species (Kruskal–Wallis χ² = 6702.7, p < 0.001). Sex-ratio analyses showed significant deviations from parity in C. crysos and C. melanurus, whereas E. alletteratus and H. balao remained balanced. Gonadosomatic index and maturity-stage distributions indicated year-round reproductive activity with distinct spawning peaks. Length at first maturity (L50) ranged from 30.2 cm to 38.8 cm among species. Growth parameters estimated from length-frequency data using the von Bertalanffy Growth Function fitted through ELEFAN_GA in TropFishR yielded L∞ values of 43.9–68.4 cm and K values of 0.065–0.336 yr⁻¹. Growth performance index (φ′) ranged from 2.48 to 2.99, corresponding to theoretical longevities of 8.9–46.3 years. Length-based cohort analysis indicated biomass concentration in intermediate size classes and increasing fishing mortality towards larger individuals. Exploitation rates revealed contrasting fishing pressures among species, while sensitivity analyses identified growth and mortality parameters as the main sources of uncertainty. These findings provide the first integrated biological baseline for the assessment and management of small pelagic resources in São Tomé and Príncipe. Full article

Fish Aggregating Devices (FADs), traditionally used to attract and concentrate fish, can also serve as effective environmental enrichment tools in reservoirs, particularly in those with homogeneous characteristics and scarce refuge habitat, enhancing structural complexity and promoting recreational fishing opportunities. This study aimed to evaluate patterns in the use of prototype fish aggregation devices (FADs) in small size reservoirs. It was conducted at the Nascentes Reservoir (Crato), a small Mediterranean reservoir (ca. 10 ha) located in southern Portugal. These FADs were installed to enhance refuge habitat for fish species of interest to recreational fisheries, particularly largemouth bass (Micropterus salmoides Lacepède, 1802), thereby promoting the occurrence of trophy specimens. Two types of FADs were deployed and tested: (1) bank FADs (TREES), used in shallow waters near the margins; and (2) pelagic FADs (DAPs), suspended in the water column in deeper areas at the center of the reservoir. To monitor movement patterns and habitat use, an acoustic telemetry receiver array was deployed with a design to secure a three-dimensional fine-scale positioning with high accuracy. A total of 20 largemouth bass were tagged with acoustic transmitters equipped with pressure (i.e., depth) sensors. A before–after approach was used with 10 fish tracked before FAD deployment and 10 after. Results of fish behavior analysis provide strong evidence of fish using DAPs, but not TREES. In the presence of FADs, fish reduced their home ranges and movement amplitudes, becoming closely associated with these artificial habitats. Several environmental predictors explained fish behavior in the presence of artificial refuges, namely, diel period, moonlight intensity, and fish depth. The findings of this study are expected to contribute to the development of guidelines for refuge habitat enhancement in small- to medium-sized Mediterranean reservoirs, thereby increasing their recreational fishing attractiveness. Full article

Introduction: Fish consumption in Portugal (53.61 kg/year) and Spain (40.68 kg/year) remains the highest in the European Union, highlighting the nutritional and economic relevance of small pelagic species. However, fish composition is highly dynamic and influenced by biological and environmental factors, including reproductive cycle, seasonality, and feeding patterns. European anchovy (Engraulis encrasicolus, EE) and European sardine (Sardina pilchardus, SP) exhibit complementary spawning periods, summer and winter breeders, respectively, making them ideal models to study seasonal nutritional variability. A systematic evaluation of their proximate composition is essential not only for quality control but also to support sustainable fisheries management and nutritional recommendations. Objective: This study aimed to comparatively assess the seasonal variation in proximate composition of EE and SP fillets in early autumn and early spring, identifying species-specific nutritional advantages linked to their reproductive cycles. Methodology: Twelve composite samples (six per season) were analysed, each comprising multiple specimens of the same species (EE or SP). Standard proximate analyses were performed to determine moisture, ash, protein, and lipid content, and energy values were calculated. Statistical comparisons were conducted using SPSS (Version 21) to evaluate seasonal and interspecific differences. Results: Sardines showed higher ash, lipid, and energy values, whereas anchovies exhibited higher protein overall. Marked seasonal differences (p < 0.05) were observed: sardine (SP)—autumn: higher lipid (10.00 g/100 g) and energy (176.22 kcal/100 g); spring: higher protein (21.69 g/100 g) and ash (1.96 g/100 g); and anchovy (EE)—spring: higher protein (23.18 g/100 g), lipid (2.44 g/100 g), and energy (117.68 kcal/100 g). Notably, in early spring, anchovies surpassed sardines in protein, lipid, and energy content, highlighting a seasonal inversion of nutritional value between species. Conclusions: Results demonstrate a clear seasonal complementarity in the nutritional value of anchovies and sardines, directly linked to their reproductive cycles. Sardine reaches its peak nutritional quality in autumn, while anchovy becomes nutritionally superior in spring. The alternating pattern suggests that seasonally targeted consumption and fisheries management strategies could optimise both nutritional intake and resource sustainability. These findings provide a strong basis for developing evidence-based recommendations for consumers, industry, and policymakers. Future research should expand this approach by incorporating fatty acid profiles, micronutrients (vitamin D, selenium), and contaminants (e.g., mercury), enabling a more comprehensive evaluation of nutritional quality and food safety. Full article

Introduction: Microplastic (MP) contamination can endanger marine ecosystems and indirectly affect the well-being of humans through the ingestion of marine species. While most research investigates the digestive system, such as the gills and gastrointestinal tract of fish, it still fails to address a major oversight in understanding MP deposition in edible tissues, which is the primary route of human exposure. The differences in contamination levels among pelagic, demersal, and benthic fish in Malaysian waters remain poorly understood. This preliminary study uses Laser Direct Infrared Imaging (LDIR), a new, high-resolution, automated technique, to examine synthetic MP contamination in the edible portion of fish. Materials and Methods: The MPs were extracted from the edible tissue of three fish species representing pelagic (Fish A), benthic (Fish B), and demersal (Fish C) using KOH and sieved onto a gold mesh filter before analysis using LDIR. Results and Discussion: LDIR identified 162 MP particles, revealing clear differences by polymer type and habitat. Pelagic species mostly contained polyethylene (PE) and rubber (n = 8). Demersal species had mostly polyethylene terephthalate (PET) with small amounts of PE and rubber (n = 57). Benthic species showed the highest load, dominated by PET and polypropylene (PP) (n = 97). The morphological assessment of the MPs indicated that the polymers in pelagic fish were smaller, with an area of 2047.82 µm² and a circularity range of 0.14–0.74, indicating consistent shape. Conversely, MPs are irregular and larger in benthic fish, with areas up to 38,837.50 µm² and circularities ranging from 0.02 to 0.81. This pattern reflects specific accumulation related to habitat and potential environmental degradation processes. Conclusions: This preliminary study demonstrates the effectiveness of LDIR for detecting MPs in edible fish tissues. The findings provide a fundamental dataset on MP contamination in edible tissue and emphasize its distribution across ecological zones. Nevertheless, broader research is required to substantiate these data and assess the implications of MP contamination for the environmental stability of human and marine well-being. Full article

The present study examined fish biodiversity, livelihood dependence, cultural importance, and genetic connectivity in two ecologically linked habitats of the Sylhet region, Bangladesh: Hakaluki Haor and the Surma River. Surveys documented 60 fish species with distinct assemblage patterns between sites. Hakaluki Haor was dominated by floodplain spawners and small indigenous species that contribute to year-round subsistence harvests, whereas the Surma River supported a greater proportion of migratory and pelagic species, most notably Tenualosa ilisha. These ecological contrasts reflected differences in hydrology, habitat diversity, and fishing intensity. Household surveys confirmed the central role of fisheries in sustaining income and food security, while cultural practices surrounding hilsa consumption reinforced local stewardship norms. Mitochondrial cytochrome b sequence analysis of T. ilisha revealed low genetic differentiation between sites, indicating a single, well-connected stock maintained by seasonal flooding and the absence of major migration barriers. This convergence of ecological and genetic evidence supports treating the two sites as an integrated management unit. Effective conservation will require protecting hydrological connectivity, safeguarding dry season refugia, coordinating seasonal fishing restrictions across habitats, and incorporating cultural values into policy frameworks. The findings strengthen the scientific basis for national and regional conservation strategies and demonstrate the value of combining biological, socio-economic, and cultural dimensions in managing connected wetland–river systems. This approach can serve as a transferable model for other tropical floodplain–river complexes facing similar ecological and livelihood challenges. Full article

Understanding the reproductive physiology of marine fish is critical for sustainable fisheries management, particularly under environmental variability. This study evaluated seasonal changes in body parameters (condition factor, Kn, and gonadosomatic index, GSI, as proxies for body condition and reproductive status, respectively) and biochemical composition (P, proteins; G, glucose; L, lipids; fatty acids; and bioenergetic ratios L/P, LG, all as proxy of integrated biochemical condition) of female gonads in Strangomera bentincki, a key pelagic species in the Humboldt Current System (HCS) off south-central Chile. Moreover, environmental factors (sea surface temperature and chlorophyll-a) were also analyzed to explore their influence on the FA profile of gonads. Female body parameters showed significant seasonal variations, with high values of Kn and GSI in autumn and spring, respectively. The biochemical composition also revealed significant seasonal variation in protein and glucose content, with the highest protein levels in winter and elevated glucose in autumn. While total lipid and energy content remained relatively stable across seasons, the L/P and L/G ratios presented seasonal variations. Similarly, the fatty acid composition showed pronounced seasonal differences, particularly with increased polyunsaturated fatty acids (e.g., DHA) in winter. The SST was the environmental factor with the greatest influence on the seasonal variations in the gonadal FA profile. Altogether, these findings suggest a partial capital breeding strategy in S. bentincki, where reproductive investment depends on both accumulated reserves and environmental conditions during reproduction. This study underscores the importance of incorporating reproductive biochemical indicators into ecosystem-based fisheries management models to improve assessments of stock health and reproductive potential. Full article

Small pelagic fish are nutrient-dense foods, but whether domestic cooking alters their capacity to modulate probiotic adhesion is unclear. We prepared sardines and sprats using five household techniques (raw, cooked, steamed, baked, and fried) and generated in vitro digestates using the INFOGEST method. We tested two concentrations in two intestinal co-cultures—Caco-2/HT29 and mucin-producing Caco-2/HT29-MTX. Adhesion of Lacticaseibacillus rhamnosus, Lactobacillus gasseri, and Lactobacillus brevis were quantified. Digestates altered adhesion in a probiotic strain species in a process-dependent manner. Sprat digestates from fried or baked preparations produced the strongest stimulation, exceeding 150% in Caco-2/HT29; responses in HT29-MTX were directionally similar but attenuated. In contrast, cooked or steamed sardine digestates frequently inhibited adhesion, particularly at 0.5% (e.g., L. gasseri < 50%). Raw preparations yielded divergent outcomes across models. A two-way ANOVA confirmed significant effects of processing, concentration, and their interaction, with the interaction explaining up to 21% of the observed variance. Across conditions, L. rhamnosus adhered most consistently, whereas L. brevis and L. gasseri were more environmentally sensitive. These findings suggest that standard cooking practices alter the bioactivity of fish-derived digestates and, consequently, the adhesion of beneficial lactobacilli in intestinal cell models, selecting sprats and employing dry-heat methods may favor probiotic–host interactions under in vitro conditions. Full article

Small pelagic fish, including sardines, are essential to global fisheries and aquaculture feed production. However, these species are increasingly exposed to intense exploitation. In Chile, the common sardine (Strangomera bentincki), endemic to the Humboldt Current System, supports major industrial and artisanal fisheries. Landings are expected to reach 300,000 tons by 2025, mostly for fishmeal production. As a keystone species, S. bentincki is highly sensitive to environmental variability during early development, which can reduce recruitment and threaten long-term population sustainability. This interdisciplinary approach integrates ecological and biotechnological perspectives to assess the feasibility of controlled juvenile sardine production in land-based Ecological Aquaculture (EA) systems, including Recirculating Aquaculture Systems (RAS) and Integrated Multi-Trophic Aquaculture (IMTA), which are designed to reduce environmental impacts. These systems enable precise control of temperature, feeding regimes, and water quality, facilitating investigations into larval and juvenile survival, growth performance, and physiological responses under variable thermal and nutritional conditions. Emphasis is placed on fatty acid metabolism during ontogeny, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are essential for somatic growth, reproductive development, and thermal tolerance. Developing standardized protocols for juvenile S. bentincki culture addresses key gaps in husbandry and physiology (temperature threshold, nutrient density, larval growth rate, etc.) while introducing a novel ecological–aquaculture integration framework. This approach links early-life ecology with applied rearing techniques to support stock enhancement, strengthen artisanal fisheries, and promote sustainable aquaculture diversification under increasing environmental variability. Full article

The Japanese chub mackerel (Scomber japonicus) is a small pelagic economically important fish species in the northwest Pacific Ocean, and its abundance and distribution are influenced by water temperature changes. In recent years, frequent marine heatwaves (MHWs), defined as prolonged anomalously warm sea surface temperature events, in this region have significantly impacted marine ecosystems and fishery resources. The effects of MHWs on Japanese chub mackerel remain poorly understood. This study analyzed the relationship between Japanese chub mackerel abundance and MHW characteristics in the northwest Pacific Ocean from 2014 to 2021. It includes comparative analyses on the spatiotemporal patterns of catch per unit effort (CPUE) and MHWs, an exploration of CPUE distribution under varying MHW intensities and durations, and an assessment of the relationship between MHW characteristics and CPUE using a Generalized Additive Model (GAM) approach. Additionally, CPUE variations before, during, and after MHWs in 2016, 2018, and 2021 across different regions are measured. Results reveal significant interannual variability in MHWs, with increasing trends in the frequency, intensity, and duration of MHWs. As the frequency, intensity, and duration of MHWs increased, the abundance of Japanese chub mackerel decreased, particularly in years with higher intensity and longer lasting MHWs. The study concludes that MHWs negatively impact Japanese chub mackerel, highlighting the urgent need for climate-adaptive fishing and management strategies. Full article

This review examines the animal welfare implications associated with the purse seine fishing method as applied to the following small pelagic species: Atlantic herring (Clupea harengus), Peruvian anchoveta (Engraulis ringens), Atlantic chub mackerel (Scomber colias), and Atlantic mackerel (Scomber scombrus). The analysis is based on synthesized data from the purse seine Method Profile, recently introduced in the catch branch of the fair-fish database—an open-access platform dedicated to compiling, evaluating, and systematically categorizing technical and/or scientific literature on aquatic animal behaviour and welfare. The Method Profile is a novel tool that outlines the commercial relevance of the respective fishing method, its target species, and general operational setup. It provides a structured overview of welfare hazards encountered across the main phases of the fishing process, including prospection, setting, capture, hauling, emersion, gear release, sorting, storage, and stunning and slaughter. In addition, this profile also addresses bycatch and discarding issues as well as environmental hazards associated with the fishing method. Identified welfare concerns in purse seining for the four small pelagic species include high stress levels resulting from intense crowding—primarily leading to hypoxia, mechanical injuries, and mortality—as well as issues related to scooping or pumping fish on board, (live) storage, and the lack of effective stunning and slaughter protocols. Furthermore, the bycatch rate of (undersized) target and diverse non-target species, as well as ghost fishing from abandoned, lost, or discarded gear, pose significant risks requiring effective mitigation. In this review, we critically evaluate factors influencing the welfare outcomes of the four pelagic species caught by purse seine and discuss potential mitigation strategies, such as operational improvements, gear modifications, and management measures. Full article

Small pelagic fish, such as sardines and sprats, are an affordable and nutritionally rich source of omega-3 fatty acids and bioactive peptides. While their nutritional value is well established, the impact of standard household cooking methods on their immunomodulatory potential and effects on intestinal integrity remains poorly understood. Fish were prepared using five culinary techniques (raw, boiled, steamed, baked, and fried), digested via the INFOGEST protocol, and applied at 1% concentration in a Caco-2 co-culture model combined with lipopolysaccharide-stimulated RAW264.7 macrophages. NO and TNF-α production, and epithelial permeability were assessed. Steamed sardines induced the highest NO levels (122%) in activated macrophages, while raw sardines inhibited NO production (73%). Baked sardines and raw sprats triggered higher TNF-α production (>400 pg/mL). Boiled sardines and baked sprats caused the strongest disruption of epithelial permeability (>13%), whereas steamed sardines and raw sprats preserved barrier integrity (<11%). Notably, digested baked and fried fish preserved suppressive effects on NO and TNF-α even after translocation across the epithelial layer. Culinary processing significantly modulates the bioactivity of fish. In general comparison, steaming is gentler than dry heat cooking methods, as it better preserves anti-inflammatory effects and barrier-promoting properties. These findings highlight the relevance of cooking practices in modulating the functional benefits of fish consumption. Full article