Journal of The World Aquaculture Society最新文献

Acidifiers serve as effective feed additives that enhance fish growth and welfare. This study investigates the effects of a mixture of lactic acid, citric acid, and potassium sorbate (denoted as OA, in a 1:1:1 ratio) on common carp (Cyprinus carpio) for the first time. A total of 240 fish, each weighing approximately 18.5 grams, were randomly assigned to four treatment groups, each consisting of four replicates containing 15 fish. The fish were fed diets supplemented with varying levels of OA: 0 g/kg (Control), 2.5 g/kg (A-2.5), 5 g/kg (A-5), and 10 g/kg (A-10) for a duration of 56 days. Growth performance, calcium and phosphorus levels in vertebrae and muscle, intestinal antioxidant status, bacterial populations, gene expressions, as well as immunological parameters in skin mucus and blood plasma were analyzed at the end of the experiment. The results indicated a significant (p < 0.0001) increase in the abundance of Lactobacillus sp. in the OA-treated groups compared to the Control group. Conversely, the intestinal populations of Vibrio sp. (p < 0.0001) and Aeromonas sp. (p = 0.010) significantly decreased in the OA-treated groups, particularly in the A-10 treatment. Moreover, significant (p < 0.0001) up-regulations were observed in the expression of intestinal tumor necrosis factor-alpha (tnf-a), interleukin-1 beta (il-1b), heat shock protein 70 (hsp70), and mucin-2 (muc-2) across all OA-treated groups when compared to the Control group. All OA-treated groups, especially the A-5 treatment, exhibited significant (p < 0.0001) increases in the expression of intestinal lysozyme (lys), mucin-5 (muc-5), and beta-defensin (b-def) relative to the Control group. Furthermore, intestinal levels of reduced glutathione (GSH) significantly increased (p = 0.0003), while malondialdehyde (MDA) levels decreased (p = 0.002) in all OA-treated groups, particularly in the A-5 treatment. Notably, plasma lysozyme (p = 0.002), alternative complement (AC; p = 0.022), skin mucus protease (p = 0.011), lysozyme (p = 0.002), and alkaline phosphatase (ALP; p = 0.001) showed significant increases in the A-5 and/or A-10 treatments compared to the Control group. Dietary supplementation with OA significantly enhanced muscle and vertebral ash, phosphorus, and calcium levels, particularly in the A-5 treatment. Additionally, growth performance and feed efficiency significantly improved in the A-5 treatment when compared to the Control group. In conclusion, dietary supplementation with 5 g/kg of OA proved beneficial for common carp by enhancing intestinal health, humoral and mucosal immune responses, calcium and phosphorus retention, as well as overall growth performance.

Seedstring cultivation is a fundamental method for Pyropia yezoensis aquaculture, as it provides an artificial substrate for the attachment of P. yezoensis spores and growth of gametophytes. This method has been widely used in the P. yezoensis aquaculture all over the world because of its convenience for seaweed management and harvest. However, the composition and types of seedstrings vary in different countries. Little is known about the effect of different seedstrings in terms of spore attachment and early development of gametophytes in P. yezoensis. In this study, four types of commercially available seedstrings from Korea (KR), China (CN), and Japan (JP1 and 2) and three new seedstring types developed by W.L. Gore & Associates, Inc. (Gore A, B, and C) were compared in terms of seeding density, growth rate, and biomass yield. Our results show that the Gore C seedstring had the highest seeding density and yield among all seedstrings. The Gore B had the lowest seeding density and yield. The Gore A and B seedstrings had the highest growth rate at early stages in development. The CN and KR seedstring showed lower growth rates than the other seedstring types. A comprehensive evaluation shows that the Gore C seedstring type had the best performance among all seven seedstrings under laboratory conditions. Future studies are needed to test the performance of the seedstrings on Pyropia farms.

Climate change has driven global temperature increases, resulting in severe heat waves, altered precipitation patterns, and extreme weather events. In April 2024, a massive die-off of hybrid catfish larvae and fry occurred in Thai aquaculture farms, coinciding with elevated temperatures of air (37–41°C) and freshwater (30–32°C). This study aimed to investigate the correlation between elevated temperatures and abnormal embryonic development in hybrid catfish. Controlled mating of male North African catfish (Clarias gariepinus) and female bighead catfish (Clarias macrocephalus) was conducted in May and June 2024. We examined the effects of water temperature changes in hybrid catfish, focusing on fertilization, hatching, yolk sac absorption, and mouth morphology, while keeping the conditions of water quality, feeding, and disease management constant. The fertilization rate was 67.7% at 29°C, whereas it significantly decreased to 59.0% at 32°C. The hatching rate decreased from 43.4% at 29°C to 26.6% at 32°C. Survival rates plummeted, with no larvae surviving beyond 72 h post-hatching (hph) at 32°C. Yolk sac absorption was notably accelerated at 32°C, being completely absorbed by 48 hph. Mouth morphometry revealed that a gap in the mouth started to develop 12 hph, and the opening size of the mouth increased out to 72 h. These findings indicate that higher temperatures (32°C) lead to faster yolk absorption, causing embryos to deplete yolk reserves rapidly, potentially before full development and independent feeding. This results in a smaller body size and lower survival rates. Present study provides crucial insights for enhancing breeding practices and creating management protocols for hybrid catfish hatcheries during the period season of high temperature in the context of climate change.

This study reports on an outbreak of motile Aeromonas septicemia (MAS) that caused significant mortalities in iridescent shark catfish (Pangasius hypophthalmus) in biofloc systems in the Punjab province of Pakistan. Clinical symptoms observed on the affected fish included anal fin hemorrhaging, mouth area bleeding, skin ulcerations, interstitial nephritis, and focal fusion of secondary lamellae. According to necropsy findings and a molecular phylogenetic analysis based on gyrB gene sequences, the etiologic agent of the disease was identified as Aeromonas dhakensis Ali.Pk01. The new isolate displayed resistance to multiple antibiotics such as ampicillin, cefuroxime sodium, meropenem, and penicillin, but remained susceptible to several antibiotics including amikacin, ceftazidime, chloramphenicol, ciprofloxacin, levofloxacin, and oxytetracycline. To fulfill Koch's postulates, fish were challenged by intraperitoneal injection with A. dhakensis Ali.Pk01, revealing its high virulence. Also, this isolate was found to encode multiple virulence genes including act, ela, alt, lip, and hyl. This study offers crucial information for local catfish farmers, highlighting the potential spread of virulent multidrug-resistant pathogens and the need for better biosecurity and disease control measures without reliance on antibiotics.

This study examines the temporal and spatial variations in soil properties and microbial populations in Pacific white shrimp ponds throughout a production cycle in Phuket Province, southern Thailand, aiming to refine shrimp farming methodologies and enhance pond soil management. We collected soil samples from four ponds across two aquaculture sites at six different stages of the production cycle—Before Sediment Flushing (BSF), After Sediment Flushing (ASF), and during each month of the four-month cycle (M1 to M4). These samples were analyzed from both central and peripheral pond zones at three soil depths (0–5 cm, 5–10 cm, and 10–15 cm). The results indicated negligible variation in soil characteristics and microbial loads across all stages. Nevertheless, a significant finding was the fluctuation in levels of easily decomposable organic matter (EDOM), which is critical for maintaining soil and water quality and affects both shrimp growth and disease incidence. EDOM levels decreased to their lowest after ASF, then progressively increased, reaching a peak at M4 (p < 0.05). The study suggests that effective sediment flushing post-cultivation not only mitigates the accumulation of deleterious residues, but also reduces the necessity for prolonged pond desiccation, thereby offering a sustainable strategy to maintain the ecological balance of shrimp ponds over successive farming cycles.

US seafood retail markets are highly competitive and have evolved rapidly to supply an increased diversity of seafood products. Retail scanner data collected from grocery outlets using Universal Product Codes (UPC) reveals realistic market trends and provides deeper understanding of consumer trends. Using weekly store-based scanner data (NielsenIQ ScanTrack data) from September 2016 to August 2021, this study analyzed the product characteristics that influence seafood consumption in retail markets for general seafood as well as specific seafood categories such as finfish, crustacea, and mollusks. Explanatory variables included: price of seafood, whether the product was farm-raised, promotional share, product form (frozen or refrigerated seafood, entrée, or others), value-addition, labeling characteristics, seasons, regions, and the effect of the pandemic period. Price had a significantly inverse relationship with the quantity of general and specific seafood products sold. Being farm-raised had a positive impact on the quantity of seafood products sold in retail markets. Promotional practices also had positive effects on retail seafood sales, however with diminishing marginal returns. Among seasons, the spring season had significantly higher sales in the retail market for general seafood and finfish, but significantly lower sales for crustacean and mollusk products. Sales in the Southern region had a consistently positive effect on overall retail seafood sales. Results also indicated that retail market seafood sales were significantly higher during the COVID-19 pandemic period. Private labeling (store brands) exhibited a positive influence on seafood quantity, the same with products without any labeling information compared to products with company labels. The study highlights key market trends in US retail outlets and suggests specific marketing strategies that could be useful for seafood products.

Polychaetes are a promising intertidal resources due to their widespread distribution, considerable biomass, and high nutrition value. The nutritional profiles of two novel tropical polychaetes species (Marphysa sp. and Halla sp.) were determined. Additionally, comparing nutritional levels of polychaetes with other species and requirements of main aquatic animals, this study aimed to explore their potential as aquaculture feed ingredients. The results revealed that both polychaetes species are nutrient-rich with significant interspecific variation. Marphysa sp. showed higher protein, total essential amino acid (EAA) ratio (17.32 ± 0.46 mg/g), lipid, eicosapentaenoic acid (EPA; 10.99%), α-Linolenic acid (ALA; 1.25%), ash and energy content compared to Halla sp. (p < 0.05). Conversely, Halla sp. had a significantly higher docosahexaenoic acid (DHA; 5.68%) index compared to Marphysa sp. (DHA; 2.57%). Meanwhile, the levels of macroelements (K, Ca, Na) and trace elements (Mg, Mn, Cu) also exhibited differences in the two species. Compared with other polychaetes and aquatic feed, both Marphysa sp. and Halla sp. are promising high-quality feed ingredients, as they contain high levels of minerals, essential amino acids, and beneficial lipid profiles. This study will support the identification of alternative substitutes to meet the growing demand for aquafeed ingredients.

To improve the growth of genetically improved farmed tilapia (GIFT), the supplementation of Schizochytrium limacinum and Lactococcus lactis was sequentially optimized by a single-factor method and central composite design combined with response surface methodology (CCD-RSM) using a developed desirability function (Df) as the response value. The optimum supplementary prescriptions obtained by the single-factor method and CCD-RSM were alone 1.5% S. limacinum, alone 1 × 10⁷ CFU/g L. lactis, and 1.22% S. limacinum + 4.01 × 10⁷ CFU/g L. lactis respectively. The Df of the tilapia fed with the diets supplemented with these optimum prescriptions were 0.53, 0.54, and 0.61, respectively. The Df, weight gain rate (WGR), and feed conversion rate (FCR) of the tilapia fed with the optimum prescriptions obtained by CCD-RSM were significantly higher than those of the tilapia fed with the diets obtained by single-factor experiments and the basic diet for 28 days. Furthermore, the results of CCD-RSM can show that there were significant interactive effects between S. limacinum and L. lactis on trypsin, α-amylase, lipase, total cholesterol (TC)⁻¹ and low-density lipoprotein cholesterol (LDL-C)⁻¹, and Df, but those of single-factor method cannot.

The use of processing by-products may reduce pressure on fish stocks as well as diminish wastes and negative environmental impact. Different studies investigated fish by-products used as alternative nutritional source to conventional feedstuffs. Fish protein hydrolysates (FPH), as a protein source derived from discards of rainbow trout processing, were included in feeds and effects were evaluated on productive performances, liver status, and body composition in gilthead sea bream, Sparus aurata L., juveniles. Three groups of 170 juveniles each (initial weight 37.8 ± 0.5 g), in triplicate indoor tanks of 2 m³ volume each, were fed including FPH in L1 (7.5 g/kg) and L2 (15 g/kg) feeds in replacement of fishmeal. LC diet was used as control having fish meal and soybean meal as main protein sources. At the end of the trial (85 days), satisfactory productive performances were obtained in all the groups with similar performances. The final mean weight ranged from 76.6 to 78.0 g. The two FPH diets exhibited high palatability equal to LC. Liver histology did not differ although fat accumulation was detected in all fish. Body composition and fatty acids were similar. FPH as substitute of protein source is suitable in the feeding of gilthead sea bream juveniles.

Toll-like receptor (TLR) is one of the most important pattern recognition receptors in both invertebrate and vertebrate animals. In previous study, three different kinds of TLR cDNAs (PtToll1-3) have been cloned from Portunus trituberculatus. In this study, a novel PtToll4 cDNA sequence was identified in this crab. The PtToll4 ORF is predicted to encode 894 peptides with an initiating signal peptide, an extracellular LRRs domain, a transmembrane region, and an intracellular toll-interleukin-1 receptor domain. Based on the sequence and phylogenetic analysis, PtToll4 distinctly clustered with almost all crustacean tolls, which mostly clustered with some shrimp TLRs and Eriocheir sinensis Toll 2 (EsToll 2). The real-time quantitative polymerase chain reaction analysis showed that the transcript of PtToll4 was constitutively expressed in tissues. In hemocytes, the transcript of PtToll4 in large granulocytes is approximately threefold higher than in small granulocytes and hyalocytes. Moreover, the expression of PtToll4 could be moderately and shortly upregulated by Vibrio alginolyticus or lipopolysaccharide challenge in the primary cultured hemocytes. In HEK 293T cell model, over-expressed PtToll4 was not able to activate the mammal NF-κB, compared with a positive plasmid. In the Drosophila S2 cell model, over-expressed PtToll4 distributed mainly in cell membrane and could affect the activation of some Drosophila antimicrobial peptides promoters. The RNA interference experiment showed that the expressions of PtToll4 was significantly inhibited by its specific double-stranded RNA in the crab hemocytes and accompanied by the suppressed expressions of the anti-lipopolysaccharide factor 4 (ALF4), ALF7, hyastatin3, crustin1, and crustin3.