Journal of The World Aquaculture Society最新文献

This study investigates the effects of incorporating Spirulina, krill meal, and corn gluten meal as dietary additives on the growth performance and body coloration of shrimp (Litopenaeus vannamei). Experimental diets containing varying percentages of Spirulina (1% and 3%), krill meal (2% and 5%), and corn gluten meal (3% and 6%) were formulated by replacing fish meal at different inclusion levels and compared to a Control diet with higher levels of fish meal. Results indicated that shrimp fed with 3% Spirulina exhibited the highest final weight and best feed conversion ratio (FCR), significantly outperforming the Control and the corn gluten meal treatments. Color analysis revealed that shrimp fed 3% Spirulina had significantly lower L* values (darker color) and higher b* values (yellow hue) suggesting improved pigmentation. Despite containing xanthophylls, corn gluten meal did not produce significant changes to the yellowish tone of the shrimp when raw, with less efficiency than other pigments. After cooking, all treatments showed increased L*, a* and b* values, with shrimp fed with 3% Spirulina and 6% corn gluten meal showing the most intense red-orange coloration. These findings highlight the potential of krill meal, spirulina, and corn gluten as natural dietary pigments and growth stimulators in shrimp aquaculture, providing valuable information to improve shrimp quality to meet market demands.

Adult black soldier flies (imagines, Hermetia illucens) are a by-product of large-scale insect larvae production. The suitability of this novel sidestream as a protein source in diets for juvenile Whiteleg shrimp (Penaeus vannamei, initial weight 5–6 g) was investigated in controlled feeding experiments in recirculating aquaculture systems. Three experimental diets, in which 50% (I50), 75% (I75), and 100% (I100) of the fish meal contents were replaced by defatted imago meal (IM), were tested in an acceptability and a growth trial. The acceptability of all IM-containing diets was reduced, leading to significantly lower apparent feed intake of the I75 and I100 diets during the growth experiment (p = 0.001). Shrimp growth was reduced in all IM-containing diets (p = 0.0005). IM-containing diets caused lower dry matter contents in shrimp muscle (p = 0.0136) and lower lipid contents in midgut glands (p = 0.0169). Survival, digestive enzyme activities, and hemolymph parameters were not affected by the diet, implying no adverse effects of IM on general shrimp health. More efficient defatting of IM, adequate balancing of n-3 fatty acids, and addition of attractants are suggested to improve the nutritional quality and use of imago meal as shrimp feed.

Aflatoxin B1 (AFB1) contamination of aquaculture feed poses serious health risks to fish and consumers. In this study, the efficacy of a novel anti-mycotoxin agent specific for aquatic species (AM-AQ) containing bentonite, sepiolite, and orange peel meal (Citrus Sinensis) in alleviating AFB1 toxicity in Nile tilapia (Oreochromis niloticus) was evaluated. Fish were fed a basal diet as a control group and diets containing AFB1 (50 μg/kg), AM-AQ (3 g/kg), or a combination of both for 6 weeks. AFB1 exposure significantly reduced growth, altered hematological parameters, protein profile, and digestive enzyme activities (p < 0.05), and suppressed respiratory burst activity (p < 0.001). It also altered the expression of liver and kidney function enzymes, lysozyme, and pro-inflammatory cytokines and generated oxidative stress (p < 0.05, p < 0.01). AM-AQ supplementation effectively counteracted these adverse effects by restoring these parameters to control levels. Notably, AM-AQ reduced AFB1 residues in the musculature by 99.6% after 6 weeks (p < 0.001). Histopathological analysis revealed severe liver, spleen, and intestinal damage in the group exposed to AFB1, which was markedly ameliorated by AM-AQ treatment (p < 0.05). These results demonstrate that the AM-AQ is a promising feed additive for protecting Nile tilapia against AFB1 toxicity and for reducing AFB1 transfer to edible tissues. Further research is required to optimize its application in aquaculture.

This study examined the effects of different food deprivation periods (0, 7, 14, 28, 42, and 84 days) on physical indexes, appetite gene expression, physiological and biochemical levels and intestinal histology in Japanese eel (Anguilla japonica). A total of 240 elvers (3.87 ± 0.06 g) were randomly divided into a starvation group (SG) and a feeding group (FG). The results showed that SG exhibited significant declines in body weight, condition factor, and hepatosomatic index with prolonged starvation. During the starvation period, appetite-related genes exhibited dynamic regulation. Compared to FG, the mRNA expression of neuropeptide Y (npy) and ghrelin in SG increased significantly at days 7, 28, and 84, while corticotropin-releasing hormone (crh), pro-opiomelanocortin (pomca), cholecystokinin (cck), and peptide YY (pyy) decreased significantly at days 7, 14, and 84. Superoxide dismutase and catalase activities in SG peaked at days 7 and 14, respectively, significantly higher than FG, but declined below FG by day 84. Additionally, malondialdehyde levels increased by 85.46% and total antioxidant capacity decreased by 62.88% in SG at day 84 compared with FG. Intestinal histology revealed villus atrophy, goblet cell loss, and structural damage during prolonged food deprivation, while digestive enzymes (protease, amylase, and lipase) in SG were significantly lower than FG. Metabolically, SG exhibited significantly lower glucose and serum triglyceride levels than FG at the 84th day, whereas hepatic cholesterol content was markedly elevated. Furthermore, liver glycogen and muscle glycogen in SG gradually declined, reaching the lowest level at the 84th day. These findings highlighted a specific adaptation strategy, characterized by glycogenolysis and antioxidant activation during short-term starvation, while long-term food deprivation led to metabolic collapse, oxidative damage, and intestinal dysfunction. This study elucidated survival strategies under nutritional stress, offering insights for optimizing feeding regimes in A. japonica farming.

Members of Bacillus cereus have been documented as important bacterial pathogens in aquaculture. However, scarce information is available on B. cereus isolates as causal pathogens of big-belly seahorses Hippocampus abdominalis. In the present study, a B. cereus isolate (SH1), recovered from a disease outbreak on a seahorse farm, was identified as a bacterial pathogen of big-belly seahorses, and its pathogenic potential in terms of pathogenicity-related factors, antimicrobial resistance, and virulence were analyzed. The isolate possessed β-hemolytic and proteolytic activities, and harbored 31 pathogenicity-related genes, including 20 virulence genes inhA, alo, cytK, hblA, hblC, hblD, nheA, nheB, asbA, asbB, asbC, asbD, asbE, asbF, dhbA, dhbB, dhbC, dhbE, dhbF, and hal encoding exoenzymes, exotoxins, and nutritional/metabolic factors, as well as 11 resistance genes BcI, BcII, BcIII, EF-Tu, vanR, vanS, mphM, satA, rpoB, fosB, tet(45) conferring resistance to β-lactams, elfamycins, glycopeptides, macrolides, nucleosides, rifamycins, phosphonic acids, and tetracyclines. Furthermore, the isolate correspondingly displayed phenotypic resistance to chephalosporins and penicillins and showed in vivo virulence to big-belly seahorses with the seven-day median lethal dose (LD₅₀) value of 1.51 × 10⁶ CFU/mL. To our knowledge, this is the first study to describe B. cereus as a pathogen of big-belly seahorses. The findings of this study underscore the need for targeted management of B. cereus infection in seahorses.

Ensuring fish welfare during stunning and slaughter is essential, as these procedures represent critical points in the production cycle that can significantly impact animal welfare. Cardiac activity serves as a key physiological indicator to assess stress responses and welfare in fish. Prolonged cardiac activity may reflect delayed death, which is relevant for evaluating welfare during the slaughtering process. In the present study, the effects of different slaughtering combinations on cardiac activity and internal temperature were evaluated in European seabass (Dicentrarchus labrax). To continuously monitor heart rate, biologgers were surgically implanted in adult seabass. Fish were subjected to different pre-slaughter treatments (ice slurry immersion or electrical stunning) followed by various slaughter methods (ice slurry, ikejime, or anesthetic overdose). The selected stunning and slaughter combinations represent the most used techniques in commercial aquaculture (ice treatments) and new alternatives that are currently under evaluation (electric stunning) or used as control treatments (ikejime and anesthetic overdose). Results indicated that slaughter in ice slurry resulted in the longest duration of cardiac activity, whereas ikejime and anesthetic overdose led to the fastest cessation, particularly when preceded by stunning. Electrical stunning significantly reduced the time to cardiac activity cessation compared with ice slurry immersion alone. The welfare concerns related to ice slurry slaughter are based on the prolonged cardiac activity observed, which may indicate physiological stress and delayed time to death. Based on cardiac activity and from an ethical and welfare perspective, electrical stunning followed by ikejime appeared to be the most effective method, ensuring rapid cessation of cardiac activity. However, both electrical stunning and ikejime require further neural validation to confirm that they reliably induce immediate and sustained loss of consciousness. While this combined method shows promise, its economic feasibility and practicality in commercial settings must be improved. At present, electrical stunning followed by ice slurry slaughter represents a more viable alternative, although it also requires neural validation. Future research should refine electrical stunning parameters, incorporate neurophysiological and biochemical indicators, and explore innovations to enhance welfare standards in seabass aquaculture.

The present study compared the effectiveness of dopamine antagonists and commercial hormonal agents containing GnRH analogs combined with dopamine antagonists for inducing ovulation and spermiation in Caspian kutum (Rutilus frisii) spawners. For this purpose, females (n = 15 for each treatment) and males (n = 10 for each treatment) were treated with different agents as follows: (1) Ovulin (sGnRHa combined with domperidone), (2) Ovopel (mGnRHa combined with metoclopramide), (3) domperidone, (4) metoclopramide, and (5) 0.9% saline solution (control group). During the study, ovulation success, latency time, reproductive performance, egg quality, sperm quality parameters, seminal plasma characteristics, relationships between sperm quality parameters and seminal plasma characteristics, and the performance of the freshly hatched larvae were recorded. There were no differences in the latency time of ovulation, which ranged from 340 to 450 degree-hours (DH) in treated groups (p > 0.05). Ovulation and spermiation rates were similar (p > 0.05) after treatment with hormonal agents (Ovulin or Ovopel) and dopamine antagonists (domperidone or metoclopramide). The number of stripped oocytes (116.1–137.3 g female⁻¹), fertilization success (86.9%–92.3%), and larvae survival rates (73.4%–81.1%) were comparable across all treatments (p > 0.05). However, MET-treated fish had the highest hatching rate at 90.8%, which was significantly higher than DOM (81.0%) and Ovopel (75.4%) treatments (p < 0.05). Moreover, lower larval malformation rates (1.1%–1.2%) were observed in domperidone and metoclopramide-treated groups (p < 0.05). The results of sperm volume, spermatozoa concentration, motility, and total sperm produced in dopamine antagonist-treated fish were within favorable ranges with no notable differences compared to the samples from the hormonal-treated groups (p > 0.05). The osmolality of seminal plasma was highest following application of hormonal treatments (252.2–260.7 mOsmol L⁻¹), which did not significantly differ from those stimulated with the dopamine antagonists (238.7–241.3 mOsmol L⁻¹) (p > 0.05). Together, these results demonstrated that both dopamine antagonists, domperidone and metoclopramide, were effective in inducing spawning of Caspian kutum without the addition of GnRHa. Therefore, their application can be suggested as efficient induction agents for controlled reproduction and conservation programs of Caspian kutum in hatchery centers.

Since the turn of the century, oysters have been the most successful US aquaculture product in terms of production growth. Most oysters are sold either at restaurants or in retail stores. However, there is very limited knowledge with respect to the market dynamics at the retail level. This is important as there is significant variation in seasonal availability and high price volatility. Moreover, many producers put an additional emphasis on product attributes like origin, as this can create price premiums. This article investigates sales trends of oysters at the retail level in the United States, utilizing weekly retail-level scanner data from 2016 to 2021. The total sales value of oysters has been rising annually, peaking at $146.9 million in 2021. There is strong seasonality in oyster sales, with a peak in November and December, and live oysters are the most popular category. The sales exhibited strong regional variation across distinct geographical market locations and oyster origin (e.g., Pacific oyster, Chesapeake Bay, etc.), but overall, there was limited differentiation, as 46.9% of the sales were labeled as generic oysters without any additional information.

Olive flounder (Paralichthys olivaceus) is known for its growth performance in aquaculture. Fish are typically raised at high densities in recirculating aquaculture systems (RAS), which may impact animal health. Flounder (55.2 ± 16.3 g) were stocked at three densities: a low density (LD) of 3 kg/m², medium density (MD) of 6 kg/m², and high density (HD) of 9 kg/m² in 1.2 m² tanks. Each treatment contained three replicate tanks, all of which shared a common sump and filtration system. Stress indicators, including serum cortisol, glucose, growth hormone (GH), and insulin-like growth factor-1 (IGF-1) levels, were analyzed. At the end of the 93-day experiment, individual weight was significantly higher in LD, followed by MD and HD, and survival was over 95% in all treatments. There was significantly greater biomass in HD, followed by MD and LD. No significant differences were found in GH and IGF-1 levels. However, glucose concentration was significantly higher in HD fish on day 30 and LD on day 93; cortisol levels were significantly lower in MD on day 30 and HD on day 61. Results suggest that olive flounder can be grown at a density of 55 kg/m² with little impact on health. However, a tradeoff exists between density and individual performance. This species seems well suited for RAS, although further research under commercial conditions is necessary.

This study examined the effects of fishmeal substitution with mealworm meal (MWM) in the diets of rainbow trout fingerlings (Oncorhynchus mykiss) on growth performance, flesh quality, amino acid digestibility, and digestive system histology. Five diets, which were iso-nitrogenous (average of 46.50% crude protein), iso-lipidic (average of 19.76% crude lipid), and iso-energetic (average of 15.74 kJ/g), were formulated and fed to triplicate groups of rainbow trout fingerlings (17.02 ± 1.33 g) for 90 days. Dietary treatments included one control (100% fishmeal) and four experimental diets. The experimental diets included MWM30 (150 g/kg MWM, no addition of methionine or arginine), MWM50 (250 g/kg MWM, 1 g/kg methionine, 1 g/kg arginine), MWM70 (350 g/kg MWM, 2 g/kg methionine, 2 g/kg arginine), and MWM100 (500 g/kg MWM, 4 g/kg methionine, 3 g/kg arginine). The growth performance was optimal up to the MWM70 group, while there was a significant decrease in the MWM100 group for weight gain (70.33 ± 1.13 g) and increased feed conversion ratio (1.04 ± 0.04). There was no significant difference in the proximate composition of MWM on crude protein and lipid levels in whole-body and fillet samples. Apparent digestibility coefficients were at acceptable levels, although there was a decrease in crude protein, crude lipid, and amino acid digestibility in parallel with increasing MWM levels. Histological analyses showed little adverse effects, with a significant reduction in liver vacuolization in MWM70 and MWM100 groups, and the experimental treatment did not result in severe negative effects on the formation of interstitial tissue, tubules, or glomeruli in the kidney.