Journal of The World Aquaculture Society最新文献

The study aimed to evaluate the effect of tributyrin on the growth performance, survival, hypoxia tolerance, and nutrient digestibility of Pacific white shrimp fed 25% and 50% soybean meal (SBM) diets. Six experimental diets were formulated: (1) 25% SBM without tributyrin; (2) 25% SBM with 0.05% tributyrin; (3) 25% SBM with 0.1% tributyrin; (4) 50% SBM without tributyrin; (5) 50% SBM with 0.05% tributyrin; and (6) 50% SBM with 0.1% tributyrin. The shrimp were fed the experimental diets daily for 10 weeks. Tributyrin supplementation at 0.1% diet significantly improved the weight gain of shrimp that fed 25% SBM but not the other groups. Nevertheless, shrimp that fed tributyrin had significant improvement in survival rate at both SBM levels. Significant reductions in Vibrio spp. counts in the hepatopancreas and intestine were also evident in all tributyrin-fed groups. In addition, 0.1% tributyrin in both SBM levels significantly enhanced the shrimp tolerance to hypoxia. Lastly, the digestibilities were generally unaffected by the tributyrin except only for the lipid digestibility of the 0.1% tributyrin in 25% SBM group, which showed a significant increase. Overall, tributyrin was proven beneficial for the shrimp's health, especially for those fed diet with a moderate level of SBM (25%).

Macrobrachium macrobrachion is an African native brackish river prawn with a high commercial value. Currently, there is little information on the post-larval production of this species. Two experiments were conducted in the laboratory to develop production techniques for this species. The first experiment analyzed the duration of yolk resorption and the second described the larval stages. Yolk resorption was studied in 240 newly hatched larvae for 24 h based on the reduction in yolk area over time. For larval development stages, six breeding tanks containing 100 L with a density of 50 larvae/L were used. Larvae were fed a combination of Artemia nauplii, Brachionusplicatilis, and pelleted food (Larviva ProStart, Biomar Efico). The results have shown that the area of yolk reserves varied significantly in the hours after hatching. At 14 h after hatching, each larva resorbed approximately 85% of its yolk reserve, and at 18 h after hatching, each of them still had approximately 6.1%. Twelve larval stages were identified and described in three critical stages. M. macrobrachion larvae are lecithotrophic and need to start exogenous feeding at 14 h at the earliest and 18 h at the latest after hatching. These results are the first to highlight the potential for mass production of brackish river prawns.

Reducing the time to settlement and metamorphosis of abalone larvae is critical for ensuring that abalone larvae settle within the seeding site for ocean ranching or to increase production in hatcheries. This study investigated the effect of biological (planktonic Nitzschia sp.) and chemical (potassium chloride) cues in inducing settlement and metamorphosis of abalone larvae Haliotis midae on diatom-coated plastic sheets. Larvae were exposed to different concentrations of KCl (10–20 mM), with settlement being highest at 10 mM in the first 20 h. Settlement of larvae exposed to a combined KCl and Nitzschia treatment for 24 h was highest, followed by larvae exposed to KCl for 12 h, while larvae exposed to KCl for 24 h, and both controls (12 and 24 h) had the lowest settlement. However, in both experiments, larval settlement in all treatments declined after 24 h of exposure, while that of the controls (no added settlement cues) increased and surpassed the other treatments after 24 h. Finally, the settlement was very low on uncoated sheets, compared to diatom-coated sheets, regardless of exposure to different combinations of KCl and Nitzschia. The exposure period's results should be interpreted with caution when drawing biological conclusions for field studies. This is due to the dramatic decrease in mean settlement post-exposure to the cue. Therefore, we hypothesize that exposure of H. midae larvae to 10 mM KCl and Nitzschia sp. will not enhance settlement in the ocean, as the inducers are primarily only effective at a KCl concentration level equal to 10 mM for 12 h. However, long-term exposure to KCl and Nitzschia over 24 h could be used in hatcheries to improve the settlement of H. midae larvae.

The economic impact of skeletal anomalies in aquaculture farming is a significant issue for the industry, as deformed fish are frequently discarded because of their low survival rate and a variety of other disadvantages, including increased costs, consumer distrust of aquaculture products, and ethical concerns. The goal of this article is to propose a method for calculating the direct costs of severe skeletal anomalies in typical Mediterranean seabream and seabass aquaculture hatcheries using a deterministic static model programmed in MATLAB that simulates their annual operation. Our findings suggest that larger hatcheries experience higher direct costs associated with severe skeletal anomalies but have better financial stability and significantly higher expected profits. Mean results indicate that the annual economic losses of severe skeletal anomalies for seabream and seabass Mediterranean aquaculture are 22.88 million euros per year for a scenario of low severe skeletal anomalies, 65.34 million euros per year for a scenario of medium severe skeletal anomalies, and 115.98 million euros per year for a scenario of high severe skeletal anomalies. Furthermore, some options for increasing the financial stability of the hatcheries are to increase the sale price of fingerlings, reduce the feed conversion ratio, and reduce the feed unit cost.

This study evaluated how light spectrum, salinity, and glucose level affect Spirulina morphology, using response surface methodology (RSM). A full factorial experiment was conducted including three light conditions with different predominant spectral characteristics (“white”: 100% white; “red”: 80% red, 15% blue, and 5% green; and “yellow”: 80% yellow, 15% blue, and 5% green), four NaCl concentrations (0, 5, 15, 30 g/L), and four glucose levels (0, 1.5, 2, 2.5 g/L). Light spectrum conditions and salinity had significant effects on the filament length, spiral diameter, and screw pitch length. Glucose only had a significant effect in terms of the spiral diameter. The maximum filament length (1274 μm; under 30 g/L NaCl and 2.5 g/L glucose), spiral diameter (47 μm; under 1 g/L NaCl and 2 g/L glucose), and screw pitch length (112 μm; under 1 g/L NaCl and 2 g/L glucose) were attained under yellow light. In line with the simulation, more compacted filaments, that is, with a greater diameter (41 μm) and shorter screw pitches (78 μm), are observed under “red” light (4 g/L NaCl and 2.5 g/L glucose). Because longer but compact filaments are desirable for easier harvesting, we recommend a light spectrum that is predominantly red with a NaCl concentration of 5.8 g/L deprived of glucose, for the cost-effective harvesting of Spirulina biomass.

Dietary inclusion effects of various levels of jack mackerel meal (JMM) on growth, feed utilization, biochemical composition, and innate immune response of rockfish were determined. The control (Con) diet included 550 g/kg fish meal (FM). Ten, 30, 50, 100, 200, 400, 600, and 1000 g/kg of JMM were included in the Con diet, referred to as the JMM₁₀, JMM₃₀, JMM₅₀, JMM₁₀₀, JMM₂₀₀, JMM₄₀₀, JMM₆₀₀, and JMM₁₀₀₀ diets, respectively. Eight hundred and ten fish (initial mean weight of 2.3 g) were distributed into 27 flow-through tanks. The experimental diets were assigned to triplicate groups of fish. Fish were hand-fed for 8 weeks. Weight gain of fish fed the JMM₄₀₀ diet was statistically better than that of fish fed the Con, JMM₁₀, JMM₃₀, JMM₅₀, JMM₁₀₀, and JMM₂₀₀ diets. Feed consumption of fish fed the JMM₄₀₀ diet was statistically higher than that of fish fed the Con, JMM₁₀, JMM₃₀, and JMM₅₀ diets. Dietary inclusion of JMM did not influence feed utilization, biochemical composition, and innate immune responses of fish. In conclusion, inclusion of JMM up to 400 g/kg of FM in diet improved growth and feed consumption of rockfish, and dietary optimum inclusion levels of JMM were estimated to be 396.7 and 403.1 g/kg based on regression analysis of weight gain and feed consumption, respectively.

A critical step in the administration of oral vaccines in aquaculture is the effective protection of the vaccine antigens through the delivery route of water to stomach to the mucosal immune system in the gut. Bioactive substances can be incorporated into protective matrices to ensure safe ingestion and controlled release into the posterior digestive tract. Polyethylene glycol and alginate are promising and frequently applied substances in the oral administration of pharmaceutical substances; however, their direct influence on the intestinal tract or inflammatory response is not well investigated in aquaculture fish. In the current study, these two substances were evaluated separately and in combination. They were included in a commercial diet for juvenile rainbow trout (18.7 ± 0.1 g) and applied over 22 days in controlled feeding to determine possible gut alterations and inflammatory responses. Three different sections of the intestine, the anterior pyloric caeca, the mid-intestine, and the posterior intestine, were histologically examined, and expression of inflammatory genes was measured in each. The inclusion of polyethylene glycol in the diet led to a significant reduction of villus height in the pyloric caeca and thus a significant reduction in active surface area. In the mid-intestine, alginate inclusion resulted in a significant reduction of the mucus-secreting goblet cells and a significant increase in villus width. In the posterior intestine, polyethylene glycol inclusion caused a significant increase in number of large vacuoles present; the addition of alginate buffered this effect. The results of the histological evaluation indicated symptoms that are usually evident in intestinal inflammation and can reduce functions of the respective intestinal segments. No significant increases in pro-inflammatory gene expression tumor necrosis factor-α, interleukin (IL)-8, or IL-1β were present, indicating no severe inflammatory response. Based on the observed histological impairments, negative consequences such as reduced efficiency of an oral vaccine or productivity of aquaculture rearing due to hindered nutrient digestion can be considered unlikely.

Evaluation of viability of new marine species in aquaculture systems is important to reduce negative social and environmental externalities, offering sustainable options for supply to fish markets. The objective was to describe the performance indicators of late juvenile yellowtail snapper (243.2 ± 57.1 mean weight of total fish) in an experimental recirculating aquaculture system (RAS) system supplied by seawater to determine its pre-feasibility. Two densities were stocked, D₁: 10 fish/tank (2.6 kg/m³, mean weight 258.3 ± 57 g) and D₂: 20 fish/tank (4.7 kg/m³, mean weight 235.6 ± 55.9 g). Fish were fed to satiety with an extruded diet containing 46% crude protein and 12% crude lipid. After 238 days, survival rate was 93% for both densities, and mean weight and biomass were 534.5 ± 19.4 g and 5.7 kg/m³ for D₁, and 606.9 ± 34.5 g and 10 kg/m³ for D₂. Final feed conversion rate (3.13 for D₁ and 3.03 for D₂) did not differ significantly between densities. The exponents (b) of the length–weight relationship calculated for D₁ (3.15) versus D₂ (3.10) and condition factor (2.12 ± 0.07 for D₁, and 2.03 ± 0.04 for D₂) demonstrated a higher condition factor than those of their wild counterparts. This study is one of the few reports on this species’ performance in late juvenile stage in RAS.