Aquaculture, Fish and Fisheries最新文献

This study investigates the widespread degradation of river ecosystems in Bangladesh and its impact on fish biodiversity and identifies potential strategies for ecosystem restoration. Combining community perceptions from focus group discussions (FGDs) with fish market study for spatial analyses of fish species diversity across the Barak–Meghna, Brahmaputra–Jamuna and Ganges–Padma basins, the research identifies pollution, destructive fishing practices, habitat destruction and mismanagement of water bodies as major threats. Results from 36 FGDs indicated that pollution from poultry farms, industrial waste from factories and pesticide runoff from agriculture were major contributors to the degradation of the Barak–Meghna basin, collectively affecting fish biodiversity. Fish market study identified a total of 57 fish species across the basins, far fewer than the over 260 species known to inhabit the freshwaters of Bangladesh. The Shannon–Wiener Diversity Index revealed low indices in Dhaka (0.00) and Rajshahi (1.73), signifying ecological degradation and anthropogenic stress, respectively, while Chandpur (2.52) and Pabna districts (2.30) exhibited comparatively higher diversity, pointing to potential conservation hotspots. The study highlights the perceptions of declining fish biodiversity with the percentages of FGDs reporting a decline of 83.3%, 90.9% and 91.7% in Barak–Meghna, Brahmaputra–Jamuna and Ganges–Padma basins, respectively. The study recommends an integrated approach combining physical interventions like collaborative dredging of rivers with pollution control measures, strengthened fisheries governance, community-based co-management, equitable water body leasing policies and transboundary coordination to ensure sustainable river restoration and biodiversity conservation.

Tank colour is a crucial environmental factor that influences growth performance; however, its effect on Channa striata fry under laboratory environments is not widely recognized. This study investigated the influence of tank coloration on growth, survival, cannibalism, and pigmentation of C. striata larvae under nursery rearing conditions. A 35-day rearing trial was conducted using five treatments: control, white, black, blue, and red, each in triplicate. Larvae were fed trash fish paste and live feed at 5%–10% of body weight three times a day and adjusted weekly. Growth and survival differed significantly (p < 0.05) among treatments. The results showed that fish reared in blue and white tanks achieved the highest final lengths (7.57 ± 0.88 cm and 7.32 ± 0.52 cm) and weight gains (3.40 ± 0.19 g and 3.18 ± 0.21 g), along with favourable feed conversion ratios. Survival rates were the highest in the white and blue colour tanks, whereas the control group exhibited the lowest survival rate. Cannibalism significantly decreased in blue and white tanks, while it remained high in the black and control treatments. Pigmentation assessment showed that tank background affected skin colour, with blue tanks having the highest hue angle and red tanks having the highest chroma value. The findings suggest that the rearing of C. striata larvae in blue and white tanks can considerably enhance growth and survival, providing a feasible and cost-effective technique for improving the quality of seeds and the efficiency of production in snakehead aquaculture.

Despite the large perceived popularity of fishing as a recreational activity, its multiple tourism dimensions, such as constraints, have received somewhat limited research interests. Leisure constraints research sheds insights into consumer travel, helping tourism service providers and developers develop and target services more efficiently. Exploring why people seek or avoid destination activities, such as recreational fishing, helps craft strategies to address these constraints and modulate participation. This study examines the leisure constraints of recreational fishing within a tourism context by exploring both participants' and potential participants' perceived and experienced constraints in activity participation. Employing a case study approach, the study investigates the Russian tourists' constraints in recreational fishing activities in Finland, including an examination of water quality as a constraint in their fishing activities. Research panel data from 465 Russian tourists who had visited Finland suggests that leisure constraints vary across recreational fishing participants and potential participants. Russian tourists who had fished in Finland noted constraints related to language skills and fishing expenses. For those who had not fished, intrapersonal and structural constraints, namely, ‘knowledge about Finnish fishing environment’ and ‘service provider information’ were the strongest ones. Respondent's language skills were the highest rated constraint across both participants and potential participants. While female participants were generally more constrained than male participants, a closer look at gender among potential participants showed that males were more constrained across several constraints. The study shows the relevance of examining a group of potential participants to pinpoint their constraints and needs. Based on the results, easier accessibility regarding fishing related information would likely help international tourists ‘go fishing’ during their trip.

Aquaculture is the fastest-growing sector of animal food production, yet it faces increasing challenges in maintaining fish health and sustainability due to the widespread use of antibiotics and synthetic feed additives. Green tea (Camellia sinensis), a natural source of polyphenols and bioactive compounds, has gained attention as a functional feed additive capable of enhancing growth performance, immune function and disease resistance in aquaculture species. This review critically examines genomic and omics-based evidence supporting the efficacy of C. sinensis in fish and shrimp nutrition. Findings from quantitative PCR (qPCR) and transcriptomic studies reveal that green tea supplementation significantly modulates the expression of key immune and antioxidant genes, including IL-1β, TNF-α, SOD and CAT, thereby strengthening innate immune responses and oxidative stress resistance. In addition, green tea influences critical stress and pathogen-response pathways through the upregulation of HSP70, toll-like receptors (TLRs) and activation of the NF-κB signalling cascade. These molecular responses collectively contribute to enhanced physiological resilience and reduced reliance on antibiotics. Comparative data indicate consistent improvements in growth metrics, gene expression profiles and immune biomarkers across multiple aquaculture species, emphasizing dose specificity and conserved pathways across species. The integration of green tea into aquafeeds presents a sustainable, eco-friendly strategy aligned with modern functional feed innovations. Future research should aim to optimize dosage levels, evaluate species-specific responses and employ integrative multi-omics approaches to further elucidate long-term effects on aquatic health and environmental sustainability.

Coastal communities in Bangladesh face significant challenges due to long-term salinity intrusion, leading to economic vulnerability and environmental stress. The remarkable adaptability of mud crabs to saline environments has encouraged coastal farmers to transition from shrimp aquaculture to mud crab fattening as an adaptive strategy. However, the sustainability of this practice is challenged by the overexploitation of wild seed, elevated mortality rates, suboptimal stocking densities and lack of standardized hatchery-produced crablets. Therefore, the present study aimed to evaluate the growth performance and survival of juvenile mud crabs (Scylla olivacea) reared at three different stocking densities (2, 4 and 6 crab/m²) randomly allocated in triplicate earthen grow-out ponds over a 90-day culture period. Hatchery-reared juvenile mud crabs (1.78 ± 0.18 g) were stocked into 80 m² earthen ponds, where Nypa palm (Nypa fruticans) leaves were used as shelters covering 30% of the pond area. Survival rate, growth performance and key physicochemical parameters were monitored throughout the culture period. Principal component analysis (PCA) was also done to explain other factors that may influence the growth performance of crabs during culture. Crabs were fed once daily in southwestern areas with experimentally formulated feed with 45% protein. The findings revealed that stocking density significantly affected (p < 0.05) the survival rate. Crablets stocked at 2 and 4 crab/m² had a significantly (p < 0.05) higher final mean weight than crablets stocked at 6 crab/m². Crabs reared at a moderate stocking density (4 crab/m²) demonstrated higher yields than other treatments. Stocking with 6 crab/m² exhibited the higher number of deformed crabs. These results indicate that a stocking density of 4 crab/m² is recommended for the grow-out of S. olivacea crablets in earthen ponds. Optimal stocking density will provide scientific basis to enhance production efficiency, reduce mortality and promote sustainable mud crab aquaculture in Bangladesh.

Microalgal biomass has emerged as a valuable resource in recirculating aquaculture systems (RAS), due to its natural capacity to recover nutrients. In addition, microalgae are potential source of fish-feed in the aquaculture industry. However, its application in RAS needs careful consideration, as microalgae can interact with geosmin, a common off-flavor compound found in RAS, which may taint fish quality and makes it unsaleable for the market. In this study, we investigate the potential interaction between geosmin and different microalgal strains, Nannochloropsis oculata and a consortium of Tetraselmis suecica and Phaeodactylum tricornutum, including both living and dead biomasses. Experimental studies with dead biomass revealed that N. oculata and the microalgal consortium can uptake geosmin with an efficiency of 53 ± 0.48% and 25 ± 1.63% over 24 h, respectively. Similarly, with living biomass, uptake efficiencies were 54 ± 0.68% and 42 ± 4.14%, respectively. Based on the higher uptake efficiency, N. oculata was selected for further investigation. Different non-linear isotherm models (Langmuir, Freundlich, and Henry's Law), kinetic models (pseudo-first order model, pseudo second-order model, and Elovich model), and desorption study were used to understand potential sorption mechanisms and assess risks associated with geosmin accumulation in microalgal biomass. Geosmin adsorption by dead N. oculata was best described by Henry's isotherm law and the pseudo-second order kinetic model, while adsorption on living biomass aligned best with Langmuir isotherm model and the pseudo-second order kinetic model. Geosmin is released higher from living biomass (79 ± 3.18%) than dead biomass (47 ± 1.74%) when desorbed in water, suggesting harvested microalgae may contain geosmin. While microalgal water treatment combined with biomass utilization for fish feed fits very well within the circular economy, more research is needed to ensure the safe use of microalgal biomass.

Fisheries management increasingly demands robust forecasting tools to address growing environmental variability, anthropogenic pressures and complex ecological dynamics. This review systematically examines innovative modelling and forecasting approaches in fisheries, focusing on their descriptions, applications, strengths and limitations and comparative performance based on quantitative and qualitative evaluation criteria. Drawing on major scientific databases with studies published between 2000 and 2023, the review covers a broad spectrum of models, including Population Dynamics Models, Ecosystem Models, Statistical and Time Series Models, Machine Learning Models, Bioeconomic Models, Simulation Models, Spatial and Habitat Models and other emerging approaches. Historically, fisheries forecasting evolved from basic observational methods to advanced computational and statistical techniques. Conventional models such as surplus production and age-structured models remain valuable for certain stable systems with limited data. However, ecosystem-based models (e.g., Ecopath with Ecosim, Atlantis) and machine learning techniques (e.g., neural networks, random forests, deep learning) offer enhanced adaptability and predictive accuracy, particularly under dynamic and uncertain conditions. Despite these advances, challenges persist, including data scarcity, difficulties in model validation and integration of socio-economic and climate-related variables. Hybrid models that combine ecological, economic and social factors, especially those incorporating real-time data and artificial intelligence, show promise for improving fisheries forecasting. Progress in this field will require interdisciplinary collaboration, enhanced data systems and stronger policy integration to ensure sustainable fisheries management. This review provides a structured framework to guide researchers and decision-makers in selecting and developing more adaptive, accurate and actionable forecasting tools in the face of global environmental change.

Saprolegniosis, typically induced by oomycete Saprolegnia parasitica, is one of the most difficult pathogens in fish and other aquatic animals in freshwater systems. It is especially harmful for the endangered species landlocked salmon (Salmo salar m. sebago). Currently, there are only few alternatives to prevent and treat saprolegniosis occurrences, which can lead to major fish deaths and financial losses at fish farms. In this study, surface-modified cellulose materials were used at an experimental flow-through fish farm rearing landlocked salmon, which often suffers from saprolegniosis occurrences. The results showed that the material's cationic surfaces were able to capture the spores of S. parasitica (experimental part I and part II). The cellulose material was chemically modified with a high density of cationic quaternary ammonium groups, which performed better than a material with a weak cationic charge by amino groups obtained via physisorption of chitosan on the surface, resulting in fewer S. parasitica spores in the rearing tank water (experimental part I). The results are promising and offer a novel method for controlling saprolegniosis occurrences without harmful chemicals. However, certain environmental conditions (in experimental part II) inhibited the detection method (real-time quantitative polymerase chain reaction) used for the detection of S. parasitica. This highlights the need for further method development for the detection of S. parasitica. Overall, the results are promising in terms of reducing S. parasitica spores in rearing water and further controlling saprolegniosis occurrences. More process optimization is required to achieve the method's full potential in industrial scale processes.

The current study assessed the impact of organic and inorganic feeding management on water quality, growth performance and plankton communities in a pond-based polyculture system over 9 months, using three treatments: Ctrl (C), organic feeding (T1) and inorganic feeding (T2). Significant differences were observed in electrical conductivity (EC) and total dissolved solids (TDS), with inorganic feeding showing the highest EC (1719.95 ± 41.05 µS/cm, p = 0.0017) and TDS (884.80 ± 4.90 mg/L, p = 0.0122), while other water parameters such as DO, pH and temperature showed no significant variation (p > 0.05). In terms of growth, grass carp in organic feeding showed the highest weight gain (1264.0 ± 5.0 g) and specific growth rate (2.31 ± 0.01%/day), significantly higher than inorganic feeding (1089.4 ± 1.6 g, p < 0.0001). The overall gross yield was also highest in organic feeding (238,506.5 ± 29,668.4 g/ha, p < 0.0001). Phytoplankton and zooplankton diversity and abundance were significantly greater in organic feeding, with total densities of 31,224.0 ± 145.0 and 16,485.0 ± 524.0 cells/mL, respectively (p < 0.001). Proximate composition revealed significant improvements in organic feeding fish for protein (e.g., grass carp: 22.19 ± 0.79%, p < 0.0001), fat, ash and moisture content. Organoleptic evaluation also favored organic feeding, showing significantly better texture (8.16 ± 0.22), flavour (8.43 ± 0.26) and overall acceptability (8.01 ± 0.20) compared to organic and inorganic feeding management (p < 0.0001). These findings suggest that organic feeding management (organic feeding) improves water quality (excluding EC and TDS), enhances fish growth, promotes richer plankton communities and improves fish nutrition.