Search Results (146)

Pseudotolithus elongatus is one of the most commercially important species supporting artisanal fisheries in Guinea-Bissau; however, its population biology and reproductive characteristics remain poorly understood, particularly in estuarine ecosystems. This study provides the first integrated biological characterisation of P. elongatus in the Cacine River Estuary, Guinea-Bissau, based on 1776 specimens collected through three independent sampling programmes. Length at first sexual maturity (L₅₀) was estimated using binomial generalised linear models (GLMs); length–weight relationships were assessed by ordinary least squares regression and analysis of covariance (ANCOVA); sexual size dimorphism was evaluated using a battery of parametric and non-parametric tests (ANOVA, Welch’s t-test, Kruskal–Wallis, Kolmogorov–Smirnov); and sex ratio was tested using chi-square goodness-of-fit tests with Yates’ continuity correction. Females attained sexual maturity at a significantly smaller size than males (L₅₀ = 224.9 mm vs. 306.8 mm), and both sexes exhibited positive allometric growth. Females attained larger body sizes and predominated in the largest length classes, confirming pronounced sexual size dimorphism. Reproductive activity occurred throughout the year, with a distinct spawning peak during the dry season (February–April), and the overall sex ratio remained close to parity despite significant variation among length classes and months. These findings provide a biological baseline to support evidence-informed fishery management of P. elongatus in Guinea-Bissau and highlight the need for long-term, standardised monitoring in the Cacine River Estuary. Full article

Currently, emerging pharmaceutical contaminants (EPCs) pose a significant risk to aquatic biodiversity on both a global and regional scale. Their accumulation in the environment presents several challenges to both human health and ecological integrity. Among EPCs, cyclophosphamide (COP), a widely used alkylating cytotoxic and immunosuppressive drug in human and veterinary oncology, has become one of the most frequently detected environmental contaminants. It has been reported to impair the immune system, induce oxidative stress, and exhibit genotoxic and cytotoxic effects in various fish species. However, limited research has evaluated its toxicity in the Siamese fighting fish (Betta splendens), an endemic significant aquatic species in Thailand. This study evaluated the acute toxicity of COP in Betta splendens by assessing systemic oxidative stress responses, alterations in gene expression, and localized histopathological changes within both hepatic and renal tissues. The 96 h of median lethal concentration (LC₅₀) value for COP in Betta splendens was determined to be 793.4 mg/L. High-concentration exposure (800 mg/L) induced severe systemic oxidative stress, evidenced by a significant reduction in superoxide dismutase (SOD) activity and a marked elevation in malondialdehyde (MDA) levels across both liver and kidney. At the transcriptomic level, acute COP exposure significantly upregulated pro-inflammatory (interleukin-1β, IL-1β and tumor necrosis factor, TNF-α), cellular stress (heat shock protein 70, HSP70), and apoptotic (caspase-3, Casp3) genes. Semi-quantitative histopathological evaluation revealed severe concentration-dependent structural damage. Hepatic lesions peaked at 800 mg/L characterized by diffuse vacuolation, vascular congestion, and extensive necrosis. Similarly, severe renal damage occurred at 800 mg/L, featuring marked vascular congestion, melanomacrophage aggregation, and widespread tubular necrosis. Overall, these findings demonstrate that acute waterborne COP exposure induces severe hepatotoxicity and nephrotoxicity in Betta splendens driven by oxidative stress, pro-inflammatory signaling, and apoptotic pathways. This study provides essential baseline toxicity thresholds and highlights the physiological risks COP spills pose to tropical freshwater labyrinth fish. Full article

Reproductive biology is fundamental for understanding fish population dynamics and for guiding fisheries management and aquaculture practices. Key reproductive and fishery-related variables such as catch size, age at maturity, spawning season, aggregation behavior, and the implementation of seasonal closures are critical to ensuring fish population sustainability. Snappers have been targeted for commercial aquaculture development due to their plasticity and ability to adapt to captive conditions. In Mexico, reproductive biology information on snappers remains fragmented and largely species-specific along both Pacific and Gulf coasts. This review reveals a lack of integrated perspective on snappers’ reproductive biology and identifies key knowledge gaps that may limit the development of effective conservation measures and aquaculture strategies. The absence of species-specific regulations for many snapper species along the Mexican Pacific coast reflects limited biological information and restricts the development of effective management policies. Increasing catch rates may indicate overexploitation, highlighting the need for targeted research to address existing information gaps and support effective conservation strategies for snapper populations. This review synthesizes available information on snapper reproductive biology and discusses how these traits can inform broodstock management, spawning control, and seed production in snappers from the Mexican coastal regions. Full article

Introduction: Skates (Rajidae) are cornerstone elasmobranchs, yet their intrinsic biological constraints, like slow growth, late maturation, and low fecundity, render them exceptionally susceptible to anthropogenic pressure. Despite their ecological and economic importance, tracking their population trajectories is historically hindered by “taxonomic blurring” and aggregated reporting in commercial fisheries. Objective: This study evaluates long-term conservation trends and exploitation dynamics of Rajidae species in the Northeast Atlantic and the Mediterranean Sea. Methodology: We analyzed 31 Rajidae species across the Northeast Atlantic and the Mediterranean Sea (FAO Areas 27 and 37) by integrating IUCN Red List assessments, species-specific life-history traits (maximum body size and depth distribution), and FAO fisheries landing data from 1992 to 2023. Descriptive analyses and Spearman correlations were used to assess temporal trends in conservation status and exploitation patterns. Results: Our synthesis reveals that some species show improvements in IUCN Red List category assessments, likely driven by recent management interventions such as species-specific reporting, catch quotas, and targeted retention bans. However, we also identify a critical mismatch between policy and biology: current Total Allowable Catches (TACs) and minimum landing sizes often do not explicitly incorporate species-specific life-history traits, inadvertently favoring smaller, less-marketable taxa while leaving larger, vulnerable species at risk. While FAO landings offer a valuable broad-scale overview of exploitation, the results highlight the limitations of aggregated fisheries statistics for species-level conservation assessments. Conclusions: These findings underline the need to adopt more precise and species-specific fisheries management approaches for Rajidae, including expanded regional monitoring programs, the use of data collected by on-board observers or electronic monitoring tools, and improved control of data reporting procedures, to prevent continued aggregation of species-level data. Full article

Introduction: The colossal European catfish (Silurus glanis) is the largest invasive freshwater fish on the Iberian Peninsula, reaching up to 2.8 metres and 130 kg in weight. Its large size makes it a highly valued target for recreational anglers, leading to repeated illegal introductions across several Iberian watersheds. Despite its appeal to anglers, this species is recognised as a high-impact invasive predator with substantial ecological consequences for European freshwater ecosystems. Recently, large catfish aggregations have been reported by anglers and environmentalists in several areas of Portugal and Spain. These impressive aggregations are frequently documented on videos and posted on social media networks (Facebook, WhatsApp groups, etc) or shared directly with our team members. Objective: Such records provide a valuable source of information for identifying the habitats and seasonal periods associated with aggregation behaviours and may therefore support more efficient management and population control actions. Methodology: We compiled information on European catfish aggregation events in Southern Iberia, namely date and location. The catfish aggregations were mapped, and their general habitat characteristics were described. Results: We recorded 10 catfish aggregation events, most of which occurred between May and June. These were generally located in transitional areas between lentic and lotic habitats, especially in narrower river sections. Possible explanations include hydromorphological constraints, seasonal environmental conditions, and species-specific behavioural responses, although these mechanisms require further investigation. Conclusions: Within the LIFE PREDATOR project, which focuses on the management of European catfish in the Tagus watershed, knowledge of aggregation locations is important to direct population control efforts aimed at reducing the abundance of this invasive fish. Moreover, the identification of common habitat characteristics may help predict other potential aggregation sites and improve the planning of future management actions. Full article

Morphological descriptions of 13 wild fighting fish species were revised by examining specimens collected as near as possible to the type specimen localities. The description has been revised for certainty and consistency. Principal Component Analysis (PCA) and Kruskal–Wallis with Dunn’s post hoc tests were analyzed and revealed previously described morphological characteristics were evaluated for distinguishing features. The PCA showed that the high loading factor of the principal component 1 (PC1) indicated that head length (0.221) was beneficial for the fish species identification. The Kruskal–Wallis test indicated the significant differences in morphometric characteristics among the fish species (p < 0.05). Then the significant differences in Dunn’s post hoc test (p < 0.001) in head length distinguished the mouth-brooders (i.e., Betta apollon, B. ferox, B. kuehnei, B. pallida, B. pi, B. prima, B. pugnax, and B. simplex) from bubble-nesters (i.e., B. imbellis, B. mahachaiensis, B. siamorientalis, B. smaragdina, and B. splendens) with a head length range of 29.27–36.42 vs. 24.14–28.31% of standard length, including the symmetrical caudal fin. Some characteristics distinguish the fish into subgroups and some species, such as a greater number of anal soft fin rays and lateral line scales of B. pi among the mouth-brooding species (28–29 vs. 22–26 fin rays and 33–35 vs. 26–32 scales) or of B. smaragdina among the bubble-nesting species (26–28 vs. 22–25 fin rays and 31–33 vs. 27–30 scales). Additionally, descriptive characteristics such as anal and caudal fin shape and melanophore pigmentation on the head, body, and fins, including the coloration of live specimens, are useful for distinguish among species and generating a dichotomous identification key. Full article

The armless snake eel, Dalophis imberbis, is a fossorial rare species. It is considered to be a non-target fishery resource with elusive behavior, and there is a paucity of knowledge regarding its distribution and biology. This study reports three new documented occurrence records of D. imberbis along the northern and southeastern coastal areas of Sicily (central Mediterranean Sea) during 2025. Specimens were collected at depths ranging from 43 m to an unusually shallow depth of 5.4 m, extending the known upper vertical limit of the species, which was previously considered a 20 m depth. Environmental parameters were collected through a multiparametric probe and integrated with products from the Copernicus Marine Service (CMS), providing new insights which highlight the presence of the species in relatively warm (17.6–20.8 °C) and moderately oxygen-undersaturated (6.9–8.5 mg/L) waters. A global distributional analysis was performed by aggregating the field data with literature records and datasets published in the Global Biodiversity Information Facility (GBIF), refining the distribution of the species in the Mediterranean and Atlantic Ocean. Thus, the three new records expand the known distribution of the species in the center of the Mediterranean Sea, providing an updated bathymetric range and the first preliminary insights into the environmental preferences of this data-deficient ophichthid. This work underscores the importance of combining traditional surveys with big-data repositories and remote sensing to monitor rare marine biodiversity. Full article

Chicken (Gallus gallus domesticus) domestication, likely associated with dry-rice farming in central Thailand, has led to substantial loss of ancestral immune-related genetic diversity in commercial chicken lineages. This study addresses allelic loss by providing the first comprehensive analysis of the highly polymorphic BG1 gene, an MHC-linked marker across the wild–domestic interface in Thailand and Vietnam, using high-depth Illumina amplicon sequencing. Genomic DNA from 47 Thai and Vietnamese chicken populations was extracted using a salting-out protocol following ethical sampling. Allelic variation was examined by targeting the BG1 intron 15–exon 16 region using triplicate PCR and Salus Pro NGS sequencing. Evolutionary dynamics and selection pressures were analyzed using AmpliSAS, MrBayes, and Datamonkey, while AlphaFold 3 was used to predict and validate 3D protein structures. We identified 98 novel alleles and 172 polymorphic sites within the BG1 intron 15–exon 16 region encoding an Ig-like domain. Extensive allele sharing between indigenous chickens and red junglefowl indicated strong balancing selection and trans-species polymorphism. Selection analyses showed that purifying selection conserved structural integrity at codons 9, 13, and 18, while variation at other sites enhanced immune recognition. AlphaFold 3 modeling confirmed conservation of the β-sandwich fold across variants, maintaining stability of the Immunoreceptor Tyrosine-based Inhibition Motif (ITIM). Thus, despite the regional gene flow, geographic isolation has shaped distinct signatures, as evidenced by the presence of 38 unique Thai and 9 unique Vietnamese alleles in addition to breed-specific private markers in the Betong (BG1*TH88), Decoy (BG1*TH91), and Tre (BG1*VN54) populations. A notable adaptive outlier under positive selection (ω = 1.357) was detected in the Dong Tao population, suggesting a recent selective sweep. These findings support the mission of the Siam Chicken Bioresource Project (SCBP) to utilize indigenous breeds as genetic reservoirs and provide a molecular basis for restoring resilience traits in domestic poultry to enhance global food security. Full article

Populations of several billfish species are declining due to overfishing and bycatch, and fundamental aspects of their biology and population dynamics remain poorly understood. We provide the first assessment of the population genetic structure of longbill spearfish (Tetrapturus pfluegeri) in the western Atlantic Ocean. We screened variation at 12 nuclear microsatellite loci (n = 144) and mitochondrial DNA control region sequences (mtCR, n = 177). Both marker types revealed three genetically differentiated clusters, with mean values for microsatellites showing differentiation of F_ST = 0.136 and D_EST = 0.201, and for mtCR F_ST = 0.645. Microsatellite markers demonstrated moderate-to-high genetic diversity, with a mean allelic richness of 6.73 alleles per locus, moderate heterozygosities (Ho = 0.446, He = 0.604), and a positive inbreeding coefficient (F_IS = 0.22) across the three sample collection sites. The overall estimated effective population size was 789.2 (95% CI: 246.7–∞). The mtCR exhibited 96 haplotypes, with high haplotype (0.989 ± 0.003) and nucleotide (0.025 ± 1.3%) diversities. We found higher mean relatedness within clusters than among them, supporting the interpretation of population subdivision and the Wahlund effect. Tajima’s D and Fu’s Fs were negative across all localities, with significant values observed along the Brazilian coast but not in the Caribbean Sea. These neutrality test results, together with low Harpending’s raggedness indices from DNA sequence mismatch distributions, are consistent with historical demographic expansion. Our findings establish a genetic baseline for fishery monitoring and management, contributing to the conservation of T. pfluegeri populations in the western Atlantic Ocean. Full article

Parasites are integral components of marine ecosystems, providing insights into host biology, trophic interactions, and environmental variability. This study presents the first systematic characterization of the metazoan parasite community of the Green Jack (Caranx caballus) in the northern Colombian Pacific, a region designated as an Exclusive Artisanal Fishing Zone (ZEPA) but with limited parasitological research. Specimens were collected from the Cupica Gulf across wet and dry seasons, and parasitological analyses were conducted to evaluate parasite load, community structure, spatial distribution, and seasonal variation. Of 46 fish examined, 20 were parasitized (overall prevalence: 43.5%), with low infection intensities (1–3 parasites per fish). Nine parasite species were identified, including monogeneans, digeneans, and copepods. Copepods (Caligus sp.) represented the most species-rich and dominant group, while Allopyragraphorus caballeroi exhibited aggregated distribution. Parasite communities showed low richness and diversity, seasonal stability, and strong trophic linkages to crustacean prey, particularly brachyuran megalopa. Host condition was unaffected by parasitism, suggesting resilience under current infection levels. These findings provide the first reference on parasite richness and diversity for C. caballus in Colombia, extending the known distribution of several species within the Eastern Tropical Pacific and underscoring the role of parasites as biological markers for fisheries monitoring and ecosystem change. Full article

Spiny lobster aquaculture in Southeast Asia represents one of the most economically valuable and socially important forms of small-scale coastal aquaculture globally. Unlike most aquaculture sectors, production in Vietnam, Indonesia, and the Philippines has developed almost entirely on the basis of wild-caught pueruli (postlarval lobsters) rather than hatchery-produced seed. This reliance on wild seed has generated persistent debate regarding biological sustainability, environmental risk, and compatibility with responsible aquaculture principles. Here, we synthesise more than two decades of regional production data, fisheries observations, larval biology research, population genetics, and oceanographic modelling to evaluate the sustainability of puerulus fishing in Southeast Asia. Evidence indicates that many major settlement areas function as recruitment sinks, characterised by extremely high natural mortality and weak coupling between local settlement and local adult spawning biomass. Under these conditions, harvesting pueruli prior to inevitable natural mortality is unlikely to reduce adult lobster stocks when spatially targeted and appropriately regulated. We further demonstrate that puerulus fisheries exhibit exceptionally low environmental impact while underpinning substantial livelihood benefits for coastal communities. We conclude that wild seed fisheries, when embedded within effective governance frameworks, represent a legitimate and sustainable foundation for crustacean aquaculture during the transition toward commercial hatchery technologies. Full article

The Manila clam Ruditapes philippinarum is a commercially important bivalve worldwide, with China being the leading producer. While the reproductive biology of this species has been extensively studied in its native or long-established ranges, knowledge of how populations cultured from non-native seed sources adapt their reproductive cycles to new environmental conditions remains limited. In this observational study, we investigated the annual reproductive cycle of a Manila clam population originating from subtropical waters (Zhejiang Province, Southern China) that was cultured in temperate aquaculture grounds in Zhuanghe Bay, Northern China. Monthly histological examination of 50 clams demonstrated that the gametogenic cycle synchronized between male and female clams. Gametogenesis started in March when seawater temperature exceeded 5.7 °C, and most gametes matured by May. A distinct bimodal spawning pattern was observed: a minor spawning event occurred from May to July, followed by a major spawning phase from September to November after a one-month gonadal recovery period in August. The condition index (CI), analyzed monthly in 30 clams, effectively reflected reproductive stages, increasing during gametogenesis and declining sharply during spawning, with its amplitude indicating spawning intensity. Seawater temperature was identified as the primary regulatory factor driving reproductive development from gametogenesis to spawning, while food availability (indicated by chlorophyll a concentration) played a crucial role in supporting gonadal recovery during summer. These results align with observations in other temperate populations, demonstrating that subtropical-origin clams can successfully acclimate their reproductive cycles to temperate environmental conditions. This study provides the first comprehensive description of the reproductive biology of transplanted Manila clams in Northern China, offering critical benchmarks for optimizing hatchery production schedules and informing sustainable fishery management practices in the region. Full article

The extent of consumer approval for lamb is intimately connected to meat quality standards. Within this context, the distinctive ‘mutton taint’ serves as a critical benchmark for assessment, a characteristic that is largely governed by the concentrations of three fundamental branched-chain fatty acids (KBCFA), specifically 4-methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA), and 4-methylnonanoic acid (MNA). While Allium mongolicum Regel (AMR)—an Allium species prevalent in arid Asian regions known for its abundant bioactive constituents—is known to improve meat quality and mitigate these off-flavors, the potential mediating role of the rumen fluid in this process remains unclear. This study investigated whether rumen fluid transplantation (RFT) from AMR-fed donors could mimic the impacts of directly adding AMR to the diet on KBCFA accumulation and meat attributes. Thirty male lambs (23 ± 2 kg BW) were allocated at random into three distinct treatments (n = 10): a control set (CON), a dietary supplementation group administered 15 g/d of AMR (AMG), along with a rumen fluid transplantation treatment (RTG) inoculated with rumen fluid from AMR-fed donors. The carcass traits, physicochemical properties, and makeup of amino acids, as well as the fatty acid constitution of the longissimus thoracis muscle, were subjected to analysis. Data revealed that the levels of KBCFAs associated with off-flavors were markedly lowered in both the AMG and RTG. Specifically, decreases ranging from 49% to 64% were observed in MOA, EOA, and MNA concentrations (p < 0.05). Relative to the control group, drip loss and cooking loss were reduced in the treatment groups (p < 0.05), whereas ash (p = 0.047) and crude protein (p = 0.001) were increased. Moreover, the interventions improved the composition of essential amino acids (EAA), flavor-enhancing amino acids, and polyunsaturated fatty acids (PUFAs). In conclusion, rumen fluid transplantation effectively replicates the beneficial effects of dietary AMR on meat quality, particularly in reducing taint-related KBCFA. Such outcomes imply that rumen microbial communities likely act as a crucial mediator in controlling meat flavor. Full article