Aquaculture Research最新文献

MyD88 and IκBα are inflammation-related genes involved in various immune responses in vertebrate, but their function in Acanthopagrus schlegelii was not clear. In this article, the open reading frame (ORF) of A. schlegelii MyD88 (AsMyD88) is 867 bp, encoding 288 amino acids, and containing a death domain and a TIR domain. The ORF of A. schlegelii κBα (AsIκBα) is 951 bp, encoding 324 amino acids and containing multiple ANK domains. The results of qRT-PCR showed that AsMyD88 was most distributed in the liver, followed by the gill, while AsIκBα was highly distributed in the kidney and muscle. After infection with Vibrio parahaemolyticus, the transcription of AsMyD88 in the liver and kidney was significantly increased, and the transcription of AsIκBα in the liver and kidney was inhibited. After the successful overexpression in RAW264.7 cells, it was found that the overexpressed AsMyD88 was distributed in both the nucleus and cytoplasm, while the IκBα was mainly located in the cytoplasm. The expression of p65 was increased, while the expression of IκBα was decreased after AsMyD88 overexpression. Meanwhile, the transcription of inflammatory factors was significantly increased after overexpression of AsMyD88, while the transcription of inflammatory factors was inhibited after overexpression of AsIκBα. The result showed that NF-κB pathway was activated by AsMyD88. Meanwhile, the phosphorylation of JNK, ERK, and p38 was significantly changed after overexpression of AsMyD88 and AsIκBα, respectively. In conclusion, AsMyD88 and AsIκBα could regulate cellular inflammatory response to participate in the immune response of fish.

In this study, we developed an injectable DNA vaccine targeting the aopB gene of Aeromonas hydrophila, encapsulated within poly(lactic-co-glycolic acid) (PLGA) nanoparticles, for use in common carp. Juvenile common carp were divided into six groups with three replicates each. Groups A and B received intramuscular injections of the plasmid containing the target gene (pCDNA3.1-aopB) with or without encapsulation, respectively. Groups C and D received the plasmid lacking the target gene via the same route. Group E received PLGA, while Group F (control) received phosphate-buffered saline. Sampling occurred on days 0, 30, and 60, and hematological and immunological indices were compared among the groups. On day 60, all groups were challenged with Aeromonas hydrophila, and cumulative mortality rates were assessed. Our results indicated successful detection of the target gene in various tissues of vaccinated fish. Notably, vaccinated groups exhibited a significant decrease in cumulative mortality (p < 0.05). Immunological indices, such as serum antibody titer and nonspecific immune responses, significantly improved in vaccinated groups, particularly those receiving the DNA vaccine with PLGA encapsulation (p  < 0.05). Overall, the DNA vaccine, especially when nanoencapsulated with PLGA, demonstrated efficacy and immunogenicity against A. Hydrophila in common carp, suggesting its potential as a vaccination strategy against this infection. Further research could optimize its effectiveness and applicability.

Rationing aquaculture farming feed is challenging for producers due to high feed costs, representing 30%–60% of the total operating costs. Therefore, optimal timing of feeding could lead to improved economic returns from an aquatic system. An optimal dynamic feeding model has been determined considering the von Bertalanffy growth model. A bioeconomic model of tilapia production in Mexico for specific markets was used for numerical illustration. The von Bertalanffy growth model was parameterized with experimental data from tilapia (Oreochromis niloticus) fed four ration sizes (50%, 80%, 100%, and satiety), in order to determine different optimal rationing for different fish sizes (200, 300, and 400 g), market prices (Monterrey, Cancún, Mexico City, and On site), and optimal harvesting times (OHT), considering the time value of money. The results of the modeled optimal feeding trajectories show a continuous decrease from stocking to reach a minimum value and then slightly approaching the harvest size. This result contrasts with the recommendations of the feed suppliers and with those found when a potential growth model was used. The results in the case study showed that the Monterrey market presented the highest present value of the benefits in the OHT and the different market sizes. The implications of the Bertalanffy model for optimal rationing trajectories are presented in the discussion.

Barramundi (Lates calcarifer) is an important aquaculture species extensively farmed throughout its natural distribution of Australia and Southeast Asia, as well as being increasingly farmed in the Middle East, USA, and Europe. Barramundi has a firm, pink-white flesh; however, fillets from farmed barramundi often exhibit grey colouration. This grey colouration detracts from its market appeal, leading to challenges in consumer acceptance and competitiveness of the product against other white fillet fish. Selective breeding, environmental manipulation, and dietary adjustments are being investigated to reduce grey flesh colouration. Yet, the absence of a rapid, noninvasive approach to predict greyness in flesh means that large numbers of samples cannot be quickly evaluated, and issues cannot be mitigated preharvest and noninvasively to preserve the fish. To address this issue, rapid analysis of flesh greyness was developed using noninvasive near-infrared (NIR) spectroscopy through the fish skin. Thirty fish were purchased from a barramundi farm, filleted, and divided into 3 cm sections, yielding a total of 335 samples from both dorsal and ventral fillet regions. NIR spectral data were obtained from the skin side of all samples, and colouration data were collected from the flesh side of the same samples. Data were randomised into a training set (256 spectra) and a validation set (79 spectra). Predictive models were developed using flesh colour as the training input for skin NIR spectra. The refined partial least squares regression model explained 78% of the variation in the medial flesh colour (R²_pe of 0.776, an RMSEP of 2.820, and an RPD_pe of 2.122) demonstrating the ability to adequately predict the flesh quality through skin spectra. This highlights the potential of NIR spectroscopy as a dependable, noninvasive tool, enabling the rapid evaluation of large samples and offering the potential to address flesh colouration issues in barramundi preharvest.

Climate-smart agriculture (CSA) has been promoted in Kenya as a panacea for climate change impacts on agricultural productivity. Consequently, various climate-smart aquaculture technologies, innovations, and management practices (CSA-TIMPs) have been developed, validated, and adopted through the Kenya Climate-Smart Agriculture Project (KCSAP). Nevertheless, there has been no evaluation of the climate-smartness of the CSA-TIMPs for priority setting. In this study, we evaluated and ranked the CSA-TIMPs using a modified Climate-smart Agriculture Prioritization Framework (CSA-PF). The prioritization process included multistakeholder validation workshops involving researchers, fisheries officers, farmers, traders, and policy makers. The climate-smartness scores of the CSA-TIMPs were given based on the CSA pillars (i.e., adaptation, mitigation, and productivity) under various climate-smartness indicators, with a score ranging from −10 (for a negative impact) to +10 (for a positive impact). This resulted in the identification and documentation of forty (40) CSA-TIMPs. Climate-smartness scores varied from 3.8 to 6.1, with higher values indicating strong synergies between the CSA pillars, with productivity having the highest average score of 6.4. The top 5 list of CSA-TIMPs with the best synergies among the CSA pillars was then developed for prioritization. Adoption of these CSA-TIMPs would be instrumental in achieving the CSA triple wins, especially in improving aquaculture productivity. Therefore, sustained efforts in stakeholder engagement, capacity building, and policy support are essential to ensure the successful adoption of CSA-TIMPs in Kenya. A dynamic approach that includes continuous validation, comprehensive monitoring and evaluation, and an enabling environment for adoption will be key to achieving sustainable and scalable impacts.

Rainbow trout (Oncorhynchus mykiss) acclimated to 9°C were exposed to 1.8 ± 1.0°C water for 30 days. Survival rate decreased by 8%, and RNA expression of the heat shock protein heatshock protein 90 (hsp90) gene was upregulated, indicating thermal stress. The fish exhibited no growth but lost weight (daily growth rate −0.17% ± 0.03%). This was not due to depletion of energy reserves, as liver glycogen, liver triglycerides, and visceral fat levels remained unchanged. The growth hormone receptor 1 (ghr1) gene, encoding a growth hormone receptor, and the ATP synthase membrane subunit f (atp5j2) gene, encoding a component of mitochondrial ATP synthase, were downregulated, suggesting a reduced metabolic rate. Hematological investigations revealed the following results: Immune activity was suppressed, evidenced by decreased numbers of granulocytes, lymphocytes, thrombocytes, and total immunoglobulin levels. Serum aspartate aminotransferase and alanine aminotransferase activities increased by 90% and 230%, respectively, indicating disturbance in liver functions. Adaptations to the cold included changes in erythrocyte morphology and blood hemoglobin concentration. Erythrocyte cell volume increased by 15%, cytoplasm volume by 10%, nucleus volume by 5%, and cell surface area by 7%, with a concurrent rise in hemoglobin content. These changes likely represent adaptations to altered metabolic demands. Concentrations of blood erythrocytes, erythroblasts, serum Na⁺, K⁺, Cl⁻, and activities of lactate dehydrogenase, lysozyme, and the alternative complement pathway remained consistent between the two temperature regimes. In summary, the data demonstrate that exposing rainbow trout to temperatures of 1.8 ± 1.0°C leads to negative effects on fish performance, the development of thermal stress, suppression of immune parameters, and liver damage. Potential adaptations were observed in erythrocyte size and hemoglobin content.

The recent expansion of the aquaculture industry into the offshore marine environment is perceived to have a comparatively low environmental impact coupled with a high growth potential as a sustainable, large-scale source of healthy protein. This study assessed changes in sediment characteristics and infauna assemblages following the development of the first large-scale offshore longline mussel farm in the United Kingdom. By evaluating the effects of the farm on the sediment ecosystem and by studying infaunal sediment environmental parameters along a distance gradient away from the farm, the first before–after control–impact (BACI) study of an offshore shellfish farm is presented. Sediment grabs from the farm and control sites were analysed for sediment parameters (organic matter content (OM), particle size (PS), oxidation–reduction or redox potential (ORP) and trace elements) and infauna assemblages. There was no difference in sediment organic matter levels between the farm and control sites. Within the farm, the mean sediment grain size and ORP increased over time. Trace element concentrations were the lowest within farm sites compared to outside; concentrations increased with increasing distance from the farm. A total of 76 benthic macrofauna taxa were identified, with polychaetes being the dominant class. Over time, the number of taxa significantly increased within the farm while remaining relatively constant in control samples. Biodiversity metrics, including abundance and Shannon and Pielou’s index, were all greater within the farm compared to control areas. Overall, measures of assemblage health were higher within the farm than outside. This study demonstrates the long-term aquaculture–environment interactions that offshore shellfish farming can have on the seabed and its significance in terms of ecosystem services.

The use of antimicrobials is essential for the aquaculture sector; however, their misuse is cause for concern because it could adversely affect the environment and human health. Irresponsible use of antimicrobials can lead to antimicrobial resistance and result in the presence of unwanted residues in aquaculture products. The establishment of maximum residue limits (MRLs) for antimicrobials is of great importance for monitoring their correct use, but the lack of harmonized standards as well as the regulatory gaps for the aquatic products create a challenging situation, as it is reflected in import notifications related to food safety. This paper collects information about current MRLs for antimicrobials in aquatic commodities in the main importing and exporting countries of aquatic products and compares them with each other and with MRLs set by Codex Alimentarius. This analysis highlighted the need for Codex Alimentarius guidance regarding MRLs for nine antimicrobials in aquaculture products (chlortetracycline, doxycycline, enrofloxacin, erythromycin, florfenicol, sulfadimethoxine + ormetoprim, sulfamerazine, tetracycline, and trimethoprim). This paper shows that there is still work to do to implement exhaustive science-based international standards for residues permitted in aquatic commodities and promote harmonization.

The emergence of acute hepatopancreatic necrosis disease (AHPND) caused by pathogenic strains of Vibrio parahaemolyticus (VP_AHPND) had economically impacted shrimp farmers. There is great interest in using phytogenics as antibiotic alternatives in mitigating bacterial diseases. A 28-day feeding trial using quadruplicate groups of Penaeus vannamei was conducted to evaluate the efficacy of bromelain (BM), a pineapple extract, on growth, gut microbiota, and resistance to AHPND. Dietary 1% or 2% BM enhanced growth of shrimp, which was significantly (P  < 0.05) higher at 2% BM compared to control (0% BM). In the first AHPND challenge, shrimp survival (mean ± SE) fed 1% or 2% BM were 84.8% ± 3.8% and 78.3% ± 2.5%, respectively, and significantly higher compared to the positive control group (69.6% ± 1.8%). Surviving shrimp were then regrouped into triplicates and fed the control diet for 14 days. This wash-out period was used to determine if prior dietary BM had a longer-term effect on shrimp health. In the second AHPND challenge, shrimp survival previously fed 1% or 2% BM was 71.1% ± 9.7% and 73.3% ± 3.8%, respectively, and significantly higher compared to the control group (51.1% ± 2.2%). Hepatopancreas showed less damage and harbored significantly lower Vibrio counts in shrimp fed BM-added diets. Dietary BM modulated the stomach bacterial community and imparted the highest alpha diversity. At the phylum level, Proteobacteria, Actinobacteria, and Bacteroidetes were the main groups across treatments but with varying relative abundance. Luteolibacter, Paracoccus, Planctomyces, and Demequina were identified as the main contributors for the diversity differences observed among treatment groups. The relative abundance of Luteolibacter was significantly enriched and Vibrio bacteria significantly lowered in the stomach of the BM-added groups. It was concluded that dietary BM induced modulation of the stomach microbiota of shrimp, which potentially enhanced its resistance to AHPND-causing VP.