Journal of The World Aquaculture Society最新文献

SYCP1 and SYCP3 are essential testis-specific genes for centromere pairing during meiosis, as well as for spermatogenesis and fertility in male germ cells. However, it is still unclear regarding the expression patterns in the fertile reciprocal hybrid offspring of Megalobrama amblycephala (blunt snout bream, BSB, 2n = 48) × Culter alburnus (topmouth culter, TC, 2n = 48). This research elucidated the genetic and expression characteristics of SYCP1 and SYCP3 through molecular cloning, sequence alignment, Western blotting, and immunohistochemistry to assess their roles in both hybrids and parents. The findings revealed that SYCP1 and SYCP3 exhibited high homology between M. amblycephala and C. alburnus, with varying degrees of chimerism in the BT and TB hybrids. The expression level of SYCP1 in these hybrids was intermediate between parents, while SYCP3 was more similar to M. amblycephala and significantly different from C. alburnus (p < 0.05). Western blotting confirmed the normal expression of both SYCP1 and SYCP3 proteins in the hybrid offspring. Immunohistochemistry verified the significant presence of these proteins in the testes of mature hybrids. These findings suggested that BT and TB hybrids retained the stability of the SYCP1 and SYCP3 genes inherited from their heterozygous parental origins, supporting independent protein expression despite slight variations in the CDS structure. Our results demonstrate that the normal expression of key meiotic genes plays an important role in overcoming reproductive barriers in distant hybridization, which is of great significance for genetic breeding in fish.

The aquaculture industry faces several global challenges, particularly concerning the environmental impacts of effluent discharge and the spread of viral and bacterial diseases. Diverse strategies have been implemented with different degrees of success. These include recirculating aquaculture systems (RAS, BioRAS), integrated multitrophic aquaculture (IMTA, Aquaponics and FlocPonics), and the use of microbial aggregates on submerged floating substrates (biofloc technology or BFT). Over the past two decades, BFT has emerged as a viable alternative for producing food from aquatic organisms, primarily due to its ability to recycle waste and significantly reduce water usage. Despite this, the technology is not yet used on a large scale around the world. Examples of commercial microbial-based systems are found in Vietnam using chemoautotrophic-based BFT and in Thailand using heterotrophic-based BFT (Emerenciano et al., 2022). The effectiveness of this technology has yet to be fully established in regions experiencing extreme environmental fluctuations, such as variations in temperature and salinity. This editorial provides insights into how BFT can be adapted and implemented under such conditions, including recommendations for assembling, managing, and optimizing microbial consortia that are suitable for coping with extreme environmental changes.

Aquaculture is an agro-industry whose contribution to human development has been evident throughout many decades, not only as a food source but also as a generator of foreign exchange, employment, and social welfare. It has even been considered a mitigator of overexploitation by fishing. However, despite its numerous benefits, diverse environmental impacts have been associated with the activity, primarily due to the discharge of effluents containing high concentrations of nitrogenous compounds, organic matter, antibiotics, and various chemical compounds. These effluents could degrade the environment, leading to unfavorable conditions for the surrounding ecosystems' flora, fauna, and microbiota (Martinez-Porchas & Martinez-Cordova, 2012).

BFT was developed in the 1970s but emerged strongly at the beginning of the 2000s as a solid strategy to overcome some of these problems. Based on the bioaugmentation of heterotrophic bacteria through bio preparation of the systems conditions, including a high carbon: nitrogen ratio, pond lining, reduced light intensity, high alkalinity, proper aeration, and solids removal protocols, the system produces edible microbial biomass for the cultured animals while recycling generated wastes (Khanjani et al., 2024). Despite this strategy gaining popularity and solving several aquaculture drawbacks, it was conceived to perform under optimal conditions in which regulating environmental variations is achievable. However, this is not the case for large farms, particularly those in arid, dry climates. In these regions, high temper

In this feeding trial, the replacement of fishmeal (FM) with peanut meal (PM) was examined to assess its effects on growth performance, body composition, digestibility, and immunity in cultured juvenile beluga (Huso huso; initial weight: 132 ± 8.5 g). Four experimental diets were tested (3 replicates; 12 fish each), including a control diet (0% replacement) and diets with 10%, 20%, and 30% PM replacement levels, fed to fish over a 56-day period. The results showed that fish fed a diet with 10% PM replacement achieved the highest final weight, weight gain, and specific growth rate, as well as the lowest feed conversion ratio (FCR). As PM replacement levels increased, muscle protein content increased, while lipid content decreased (p < 0.05). Analysis of muscle fatty acids indicated that with higher replacement levels, saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFAs) increased (p < 0.05), while highly unsaturated fatty acids (HUFAs) decreased (p < 0.05). Additionally, the 10% replacement treatment exhibited the highest levels of essential amino acids in muscle tissue (p < 0.05), along with the greatest digestibility of dry matter and crude protein (p < 0.05). Immune parameters, specifically lysozyme and ACH50, showed significant increases compared to the control as PM replacement levels rose (p < 0.05). Based on the results, it can be concluded that partial replacement of FM with PM at a level of around 10% can enhance growth performance, nutrient digestibility, and immune response in Juvenile beluga.

This study investigated the effects of dietary black soldier fly (BSF) larvae, Hermetia illucens, meal on growth performance, feed utilization, intestinal health, and immune response in Nile tilapia, Oreochromis niloticus, juveniles. The fish (initial weight: 7.28 ± 0.09 g) were reared in a recirculatory aquaculture system (RAS) and fed diets containing different levels of defatted BSF larvae meal: 0% (control diet), 20% (BSF20), and 40% (BSF40). At the end of the feeding trial, the final body weight, weight gain, specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were significantly (p < 0.05) improved with increasing BSF meal inclusion levels in the diet. Histological analysis of the intestine revealed that mucosal fold length (MFL), muscularis thickness (MT), and goblet cell density (GCD) were significantly elevated by the BSF meal compared with the control. In addition, intraepithelial lymphocytes (IELs) and the enterocyte microvilli length were significantly elevated in BSF40-fed fish compared with the control. Gene expression analysis showed that intestinal chitin digestion-related (endochitinase A) and amino acid transporter (Slc6a18) genes were not significantly affected by the BSF meal. However, the expression of peptide transporter Slc15a1a was upregulated in the fish fed BSF40 compared to the control. Moreover, posterior intestine and head kidney cytokine (IL-1β, TNF-α, and IL-10) gene expression levels were not significantly affected by the inclusion of the BSF meal. Therefore, these results suggest that the BSF meal up to a 40% inclusion level can be used as an alternative protein source in the diets of Nile tilapia juveniles to promote growth and intestinal health.

The kuruma shrimp (Marsupenaeus japonicus) is a highly fecund marine aquaculture species with substantial variance in reproductive success. These traits may lead to genetic diversity loss and inbreeding, particularly under mass selection programs. In this study, we assessed genetic diversity levels and effective population size across 18 M. japonicus families using 10 microsatellite markers. The results demonstrated that the cultured families of M. japonicus exhibited lower heterozygosity. Pairwise comparisons of genetic differentiation coefficients revealed moderate to high differentiation among the families. Phylogenetic, structural, and discriminant analyses of principal components identified two distinct genetic clusters within the sampled families. Low effective population size estimates and genetic bottleneck signatures were observed, likely due to incomplete or skewed parental contributions to offspring. Therefore, we recommend implementing mating schemes involving genetically distant brooders. These findings provide critical insights for population level genetic studies and breeding strategy optimization in M. japonicus.

The flatfish is a major farmed species consumed globally in large quantities. However, due to the densely populated farming environment, flatfish are susceptible to lesions and diseases, making early lesion detection crucial. Traditionally, lesions were detected through visual inspection, but observing large numbers of fish is challenging. Automated approaches based on deep learning technologies have been widely used to address this problem, but accurate detection remains difficult due to the diversity of the fish and the lack of a fish lesion and disease dataset. This study augments fish lesion images using generative adversarial networks and image harmonization methods. Next, lesion detectors are trained separately for three body parts (head, fins, and body) to address individual lesions properly. Additionally, a flatfish lesion and disease image dataset, called FlatIMG, was created and verified using the proposed methods on the dataset. A flash salmon lesion dataset was also tested to validate the generalizability of the proposed methods. The results achieved 12% higher performance than the baseline framework. This study is the first attempt to create a high-quality flatfish lesion image dataset with detailed annotations and proposes an effective lesion detection framework. Automatic lesion and disease monitoring can be achieved in farming environments using the proposed methods and dataset.

Gracilariaceae species are among the most economically important seaweeds, with a wide range of applications. Large-scale cultivation of Gracilariopsis lemaneiformis has already been established along the eastern coast of China. However, as global demand for Gracilariaceae species rises, it is crucial for China to expand large-scale cultivation of these species to other coastal regions. Although the South China Sea harbors rich macroalgal resources, including Gracilariaceae, large-scale cultivation of these species has yet to be implemented in the region. To identify heat-tolerant Gracilariaceae species suitable for large-scale cultivation in the South China Sea, we conducted surveys between June and August from 2021 to 2024. Several heat-tolerant species were identified. Taxonomic identity was confirmed through detailed morphological examination and molecular analysis of rbcL and cox1 gene sequences. We identified eight species of Gracilariaceae, including one Gracilariopsis (Gp.) species and seven Gracilaria (G.) species. Morphologically, the species were characterized as follows: Gp. heteroclada (long secondary branches with short or spiny tertiary branches), G. salicornia (club-shaped segments), G. vermiculophylla and G. tenuistipitata (slender-branched), G. edulis (broom-like appearance with red-tinged branch bases), G. firma (highly constricted branch bases), and two unclassified species, Gracilaria sp.1 and Gracilaria sp.2. This study contributes to the taxonomic knowledge of Gracilariaceae and provides valuable information for the development of heat-tolerant species suited for large-scale cultivation in the South China Sea.

Microalgae are essential food sources for fish and shellfish aquaculture and contain abundant lipids with diverse fatty acid profiles. Quantification of total lipids in microalgae could assist commercial microalgal culture operations, harvest, and management in hatchery farms. Currently, reported protocols for lipid quantification are mainly for biofuel microalgal species. This study aimed to develop effective methodologies for total lipid quantification in three aquaculture microalgae using lipid-specific probe BODIPY™ 505/515 and flow cytometry. The objectives were to determine the effects of (1) staining concentration and time; (2) microalgal concentration; and (3) microalgal age. For Tisochrysis lutea, Chaetoceros muelleri, and Tetraselmis suecica, the optimal staining concentrations and times were 2.0 μg/mL for 0.5–30 min, 2.5 μg/mL for 5–30 min, and 1.5 μg/mL for 5–30 min, and the suitable algal concentrations were 5 × 10^5–6, 5 × 10^4–6, and 1 × 10^4–6 cells/mL. The total lipid accumulation in all three microalgae was contrary to the cell growth— low at the exponential growth stage and high at the stationary stage (beyond day 9). Overall, the methodologies developed in this study could be used to quantify total lipids in microalgae rapidly and accurately and require a small sample biomass (about 1 mL directly from algal culture). To produce microalgae with high total lipid accumulation, the best time to harvest may be at the stationary stage but not at the exponential growth stage. This study provided a better understanding of the lipid accumulation dynamics in the three aquaculture microalgae.

A by-product of black soldier fly (Hermetia illucens) larvae (BSFL) farming is the chitin-rich “exuviae” (exoskeleton shell) that is left behind after the prepupae larvae metamorphose into adults. Moreover, exuviae is present in BSFL meal and frass. In this 8-week trial, tilapia (initial weight of 2.93 g) were fed diets with increasing inclusions of dietary BSFL exuviae (0%, 0.05%, 0.1%, or 0.5%) and the growth, biochemical composition, hepatic expression set of genes related to metabolism as well as liver/intestinal histomorphology were examined. Growth metrics tended (p = 0.066) to increase linearly with increasing exuviae level, although the feed conversion ratio was unaffected. Muscle P and Zn content were significantly linear and/or quadratic with respect to dietary exuviae level and were highest in fish fed the control diet and lower in fish fed diets with exuviae. Dietary BSFL exuviae at 0.1% and 0.5% significantly downregulated the hepatic expression of lipoprotein lipase, trypsinogen, and cytochrome P450 1A (cyp1a) genes relative to control. Liver histology and scoring revealed mild to severe changes ranging from localized inflammation to necrosis and hemorrhaging with increasing exuviae content, while intestinal histology appeared similar among treatments. Muscle protein and amino acids decreased either linearly or quadratically with increasing BSFL exuviae. Muscle lipid and fatty acid profiles were not significantly impacted by dietary treatments. Results suggest that dietary inclusion of BSFL exuviae up to 0.5% of diet did not limit tilapia performance, but further research is needed on treatments of BSFL meal or exuviae prior to diet inclusion to reduce liver pathologies and potentially enhance fish production.

Pre-slaughter processes impact trout production, but the optimization of pre-harvest crowding in an industry affected by global warming has scarcely been studied. In this study, we evaluated the effect of two crowding methods on the welfare of rainbow trout (Oncorhynchus mykiss) across two seasons (winter and summer). Each season 660 trout were distributed into separate tanks, and two crowding methods were applied: reducing water level (WL) and applying lateral compression (LC) within the tanks. Welfare indicators included plasma metabolites and tissue color, while fillet quality was evaluated based on indicators such as muscle color, muscle pH, and rigor mortis. These parameters were evaluated to determine the impact of each crowding method on both fish welfare and fillet quality. Tests were conducted in winter (8.80 ± 1.79°C) (WI) and summer (22.0 ± 0.06°C) (SU). Cortisol, creatine phosphokinase, and lactate levels in plasma were lower using WL, indicating a reduced stress response, supported by various skin color attributes (a*, b*, C*, and h*), liver (a*, C*, and h*), and fillet (h*). Similarly, muscle acidification (pH) was lower using LC, which could lead to potential texture deterioration. Temperature was a crucial factor globally across all parameters, with better results in WI. The combination of both treatments showed, on one hand, abnormal values of cortisol, glucose, and skin color attributes (a* and C*) and fillet (24 h post-mortem) (b* and C*) in summer LC, and on the other, better muscle pH and fillet color (b* and C*) at 0 h post-mortem using WL in WI. Overall, stress response was lower and fillet quality was better in WL fish. This trend was similar in winter compared to summer trout, regardless of the crowding method. Despite the poorer outcomes from LC, whether due to increased swimming difficulties or worse distribution of dissolved oxygen, its use in summer is discouraged due to cumulative effects, recommending its use only in winter when unavoidable.