Exploring the relationship between production intensity and land use: A meta-analytic approach with shrimp aquaculture

Assessment of Performance, Microbial Community, Bacterial Food Quality, and Gene Expression of Whiteleg Shrimp (Litopenaeus vannamei) Reared under Different Density Biofloc Systems

Biofloc shrimp culture, as a way of improving shrimp production, gains worldwide consideration. However, the effects of the biofloc system on shrimp culture at high densities could be a challenge. Here, this study is aimed at identifying a better stocking density of whiteleg shrimp (Litopenaeus vannamei) between two intensive biofloc systems of 100 and 300 org./m². Achieving that was done by comparing growth performance, water quality, feed utilization, microbial loads from water and shrimps, and gene expression of growth, stress, and immune-related genes. Shrimp postlarvae with a mean weight of 35.4 ± 3.7 mg were reared in six indoor cement tanks (36 m³ total capacity each) at two stocking densities (3 replicates each) for a rearing period of 135 days. Better final weight, weight gain, average daily weight gain, specific growth rate, biomass increase percentage, and survival rate were associated with lower density (100/m²), whereas high-density showed significantly higher total biomass. Better feed utilization was found in the lower density treatment. Lower density treatment enhanced water quality parameters, including higher dissolved oxygen and lower nitrogenous wastes. Heterotrophic bacterial count in water samples was recorded as 5.28 ± 0.15 and 5.11 ± 0.28 log CFU/ml from the high- and low-density systems, respectively, with no significant difference. Beneficial bacteria such as Bacillus spp. were identified in water samples from both systems, still, the Vibrio-like count was developed in the higher density system. Regarding shrimp food bacterial quality, the total bacterial count in the shrimp was recorded as 5.09 ± 0.1 log CFU/g in the 300 org./m² treatment compared to 4.75 ± 0.24 log CFU/g in the lower density. Escherichia coli was isolated from the shrimps in a lower density group while Aeromonas hydrophila and Citrobacter freundii were associated with shrimps from a higher density system. Immune-related genes including prophenoloxidase, superoxide dismutase (SOD), and lysozyme (LYZ) expressions were all significantly higher expressed in the shrimp from the lower density treatment. Toll receptor (LvToll), penaiedin4 (PEN4), and stress-related gene (HSP 70) showed a decreased gene expression in the shrimp raised in the lower density. Significant upregulation of growth-related gene (Ras-related protein-RAP) expression was associated with the lower stocking density system. In conclusion, the current study found that applying high stocking density (300 org./m²) contributes negatively to performance, water quality, microbial community, bacterial food quality, and gene expression of immune, stress, and growth-related genes when compared with the lower stocking density system (100 org./m²) under biofloc system.

Simultaneous Detection and Analysis of Free Amino Acids and Glutathione in Different Shrimp

An amino acid analyzer method for the simultaneous determination of 20 free amino acids (FAAs) and glutathione (GSH) in Penaeus vannamei (PV), Penaeus vannamei, Penaeus hidulis (PH) and Penaeus japonicus (PJ) were developed. The effects of different concentrations of trichloroacetic acid (TCA) and ethanol on the extraction of free amino acids were investigated, and 120 g·L⁻¹ TCA was found to be ideal. The target analytes were eluted in sodium citrate buffer B1 (pH = 3.3) containing 135 mL·L⁻¹ ethanol and 1 mol·L⁻¹ sodium hydroxide (7 mL) and at the optimizing conversion time of sodium citrate buffer B2 (pH = 3.2) and sodium citrate buffer B3 (pH = 4.0) of 5.6 min, and the effective separation was achieved within 29.5 min. The developed method showed good linearity (R² ≥ 0.9991) in the range of 1–250 µg·mL⁻¹ with good intra-day and inter-day precision (relative standard deviations ≤ 2.38%) and spike recovery (86.42–103.64%). GSH and cysteine were used to identify marine prawn and freshwater shrimp. Hydroxyproline and serine were used to distinguish PV and Macrobrachium nipponense (MN) from others, respectively. The highest content of the total FAAs was found in PV, and principal component analysis revealed that PV had the highest comprehensive score for FAAs and GSH. Arginine was found to have the greatest influence on shrimp flavor.

The contribution of fisheries and aquaculture to the global protein supply

The contribution of aquatic animal protein to the global, animal-source protein supply and the relative importance of aquaculture to capture fisheries in supplying this protein is relevant in assessments and decisions related to the future of aquatic food production and its security. Meat of terrestrial animals, milk, and eggs resulted in 76,966 Kt crude protein compared with 13,950 Kt or 15.3% from aquatic animals in 2018.While aquaculture produced a greater tonnage of aquatic animals, capture fisheries resulted in 7,135 Kt crude protein while aquaculture yielded 6,815 Kt. Capture fisheries production has not increased in the past two decades, and aquaculture production must increase to assure the growing demand for fisheries products by a larger and more affluent population. We estimated based on status quo consumption, that aquaculture production would need to increase from 82,087 Kt in 2018 to 129,000 Kt by 2050 to meet the demand of the greater population. About two-thirds of finfish and crustacean production by aquaculture is feed-based, and feeds for these species include fishmeal and fish oil as ingredients. Aquaculture feeds require a major portion of the global supply of fishmeal and fish oil. An estimated 71.0% of fishmeal and 73.9% of fish oil are made from the catch with the rest coming from aquatic animal processing waste. The catch of small, pelagic fish from the ocean is not predicted to increase in the future. Aquaculture should reduce its fishmeal and oil use to lessen its dependency on small wild fish important to the integrity of marine food webs and food security for the poor in many coastal areas. Fishmeal and fish oil shortages for use in aquaculture feed will result in a limit on production in the future if goals to lessen their use in feeds are not met.