Aquaculture and Fisheries最新文献

A poor environment increases fish's susceptibility to myxosporean infection that can cause the death of larval fish, especially for koi fish (Cyprinus carpio). This study aimed to determine the effect of probiotics, local anti-parasitic drugs (kutuklin), and the chemical compound diflubenzuron treatments on the koi immune response. This study used PCR with specific primer 18S SSU rDNA and DNA sequencing to detect Myxobulus phylogenetic. The treatments were divided into 5 groups: Treatment (A) (healthy koi without treatment), (B) (infected koi without treatment), (C) (infected koi with 0.55 mL/30 L probiotics), (D) (infected koi with 1 μL/g of feed kutuklin), and (E) (infected koi with 0.02 mg/5 L dimilin). Myxospore has observed with Scanning Electron Microscopy (SEM) and 4′,6-diamidino-2-phenylindole (DAPI) fluorescence staining. The histological analysis using semi-quantitative scoring methods, and flow cytometry was conducted to analyse the immune response of Cluster of differentiation 4 (CD4⁺), Cluster of differentiation 8 (CD8⁺), Tumor Necrosis Factor-alpha (TNF-α), Interferon gamma (IFN-γ) cells in the gills. Results show that the histological analysis indicated edema, hyperplasia, lamella fusion, congestion, and hypertrophy lesions in infected koi. Treatment with probiotics shows the lowest damage (30.6%). The immune responses of CD4⁺ and CD8⁺ cells to dimilin treatment were 10.54% and 16.86%, respectively. The largest TNF-α and IFN-γ response were for the kutuklin treatment (29.26%) and probiotics treatment (8.23%).

The size selectivity and catch pattern of Trichiurus lepturus in 40 mm diamond and square mesh codends were investigated in this study. A 34 m high opening trawl was used, which is a common design used by fishermen operating along the northwest coast of India, and the cover codend method was employed to determine codend selectivity. Along with the changes in the length at 50% retention rate for Trichiurus lepturus with the usage of the square and diamond mesh codends, indicators to understand the exploitation pattern of this species in the fishery were assessed based on the total number of individuals and on total weight of the catch. The mean selection length increased and discard fraction is reduced when 40 mm square mesh codends are used in place of diamond meshes, however, it is observed that individuals at commercial length are also lost. The results demonstrate that mandatory use of legal mesh sizes alone will be insufficient to aid in the sustainable harvest of this species, given its estimated length at first sexual maturity of 61.2 cm. This is the first study to compare the size selection of this species in 40 mm diamond and square mesh codends along Northwest coast of India. Results of the study will help as a baseline for gear-based regulations in the region.

The giant freshwater prawn (Macrobrachium rosenbergii) is a commercially cultured species in China. A sex chromosome-specific marker is crucial for sex identification and distinguishing sex chromosomes. Here, based on the results of reduced-representation genome sequencing and genome survey of M. rosenbergii, we identified steady sex-linked markers. Further nucleotide alignment analysis revealed 83.42% nucleotide similarity between the amplified W- and Z-chromosome fragments. qPCR confirmed that Z chromosome-specific fragments were present in males approximately twice as often compared to females. Similarly, the W chromosome-specific fragments were present in super females approximately twice as often compared to females. Our findings elucidate the ZW/ZZ sex determination type and contribute to exploring sex-related or sex-determining genes present on the sex chromosomes of M. rosenbergii.

Gastrin (gas) is a peptide hormone that stimulates gastric acid secretion by gastric parietal cells and stimulates gastric motility. The cholecystokinin B receptor (cckbr) can act as a receptor for gastrin, conveying regulatory information on gastrin, but there are fewer studies on its function in fish. The Lateolabrax maculatus is one of the marine aquaculture species in China, it widely distribute in coastal areas. In the study, we cloned the genes of Lateolabrax maculatus gastrin (Lm-gas) and Lateolabrax maculatus cholecystokinin B receptor (Lm-cckbr). The results showed that the full-length gene of Lm-gas is 638bp and the carboxy-terminal conserved domain (DFGRR) is the core functional domain of gastrin protein. The Lm-cckbr gene has a total nucleotide sequence of 2066 bp, and the open reading frame encodes a total of 453 amino acids. The result of protein sequence alignment showed that the similarity between Lm-cckbr protein and other different species was 50.11%–89.67%. The PCR results showed that Lm-gas and Lm-cckbr were expressed in brain and stomach. Further localization by immunehistochemical staining showed that Lm-gas protein was located in the mucosal layer of the gastric wall, but the expression signal was weak in the brain. Hunger causeed a significant decrease in these two genes. The results provided basic research data for further study on the function of Lm-gas and its recepter Lm-cckbr in the in the central nervous system and digestive system of Lateolabrax maculatus.

The research aimed to create a shelf life prediction model for Trachinotus ovatus in different freezing temperatures by using back propagation (BP) neural network model. The pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), water retention (water holding capacity [WHC]; cooking loss), and sensory evaluation were measured under 266 K, 255 K, 243 K, 233 K, and 218 K temperatures. The results of TVB-N and water retention during 266 K, 255 K, 233 K, and 218 K conditions were selected to build a BP neural network model and verify the model at 243 K. Results indicated that low temperatures retarded the rise of pH, TVB-N, and TBA values, improving water retention capacity of Trachinotus ovatus. The BP neural network model had high regression coefficients (r²: 0.8642–0.9904), low mean square error (MES: 0.1658–1.7882), and relative error within 10% and could accurately predict the quality change of Trachinotus ovatus under the freezing temperatures of 266 K–218 K. Therefore, (BP) neural network model has great potential in predicting the shelf life of Trachinotus ovatus in frozen storage.

The present study was conducted to determine the effects of dietary phosphorus (P) levels on growth performance, body composition, liver histology and enzymatic activity, and expression of lipid metabolism-related genes in spotted seabass (Lateolabrax maculatus). Seven diets were prepared to contain available P levels of 0.48% (the control group), 0.69%, 0.89%, 1.10%, 1.28%, 1.51% and 1.77% and feed fish (4.26 ± 0.03 g) to satiety twice daily for 10 weeks. Significantly higher weight gain and specific growth rate were recorded at P levels of 0.69%–1.51% compared to the control group. Feed conversion ratio decreased with increasing P levels up to 0.89% and increased thereafter. The lowest liver lipid content, viscerosomatic index and lipid content of whole-body were obtained in the 0.89%-P group among dietary treatments. P and calcium (Ca) contents in whole body were increased, while liver triglyceride and cholesterol contents were decreased with increasing dietary P levels from 0.48% to 1.77%. The highest activity of hepatic lipase was recorded in the 1.10%-P group among dietary treatments. Compared to the control group, 1.10% P enhanced the proportion of HUFA and reduced the proportion of SFA and MUFA. The histological observations showed that P deficiency (0.48%) led to the vacuolization of hepatocytes and increased number of lipid droplets. Meanwhile, overall liver tissue structure was improved when P level increased to 1.28%. Compared to the control group, expression of lipid metabolism-related genes such as FAS, ACC-2 and SREBP-1 was decreased at 0.89%–1.10% P group while an opposite trend was observed in the expression of PPARa2 and CPT-1 genes. The current study showed that 0.89% dietary P levels could promote growth performance of spotted seabass and reduce lipid accumulation in the liver. A broken-line regression analysis based on weight gain showed that the optimum dietary P level (available P) for juvenile spotted seabass reared in freshwater was 0.72%.

Seaweed is a promising marine macroalgae of the millennium, providing various ecological, social, and economic benefits. At present, seaweed production reached 35.8 million t from farming, accounting for 97% of global seaweed output, with a world market of US$ 11.8 billion. Seaweeds are an excellent source of nutritious human food because of their low lipid content, high minerals, fibers, polyunsaturated fatty acids, polysaccharides, vitamins, and bioactive compounds. Many seaweed sub-products offer unique properties to develop various functional foods for the food processing industries. In the perspective of climate change mitigation, seaweed farms absorb carbon, serve as a CO₂ sink and reduce agricultural emissions by providing raw materials for biofuel production and livestock feed. Seaweed farming system also helps in climate change adaptation by absorbing wave energy, safeguarding shorelines, raising the pH of the surrounding water, and oxygenating the waters to minimize the impacts of ocean acidification and hypoxia on a localized scale. Moreover, it contributes substantially to the sustainable development of the economic condition of coastal women by providing livelihood opportunities and ensuring financial solvency. This review paper highlights the significance of seaweed farming in global food and nutritional security, mitigation and adaptation to global climate change, and women empowerment within a single frame. This review paper also outlined the major issues and challenges of seaweed farming for obtaining maximum benefits in these aspects. The main challenges of making seaweed as a staple diet to millions of people include producing suitable species of seaweeds, making seaweed products accessible, affordable, nutritionally balanced, and attractive to the consumers. Various food products must be developed from seaweeds that may be considered equivalent to the foods consumed by humans today. Lack of effective marine spatial planning to avoid user conflicts is vital for expanding the seaweed farming systems to provide aquatic foods and contribute globally for mitigation and adaptation of climate change impacts. Hence, women's empowerment through seaweed farming is primarily constrained by the lack of technical knowledge and financial resources to establish the coastal farming system. All the information discussed in this paper will help to understand the critical needs for large-scale seaweed farming for climate resilience mariculture, potentials for global food security, and future research on various aspects of seaweed farming and their diverse utilization.

Often, catch and release regulations are meant to maximize a fisheries potential to create trophy fish. I evaluated adult Brown Trout populations at five locations within Rapid Creek within Rapid City, SD over a two-year period. In each year, one of these locations was within a catch and release area, while two were outside. In 2012, density and biomass estimates were higher in a site located outside of the catch and release area. Additionally, size structure within the catch and release area was only significantly larger than one of the two sites outside of the regulation area. Mean relative weight values were inversely related to density estimates, with the lowest density sites having the highest mean relative weights. Similarly, a site outside of the catch and release area had the highest abundance and biomass estimates in 2013. The cumulative length distribution was significantly different between the site within the catch and release area and the two located outside. Relative weight was significantly higher in the catch and release area than the two sites outside. As population characteristics within the catch and release area were not consistently better than outside, it is more likely that factors such as habitat and density dependence are impacting the Brown Trout population more than the regulation itself.