Journal of The World Aquaculture Society最新文献

This study aimed to evaluate the interactions between two low salinities (S = 4 and 8 g L⁻¹) and two ionic balances (Na⁺/Mg⁺²/Ca⁺²/K⁺ ratio, IB1 = 27.6/3.6/1.05/1 and IB2 = 40.6/4.7/1.98/1) on zootechnical performance and histology of Litopenaeus vannamei postlarvae (0.0073 ± 0.0007 g) and juveniles (0.2163 ± 0.0080 g) reared in a biofloc system at stocking density of 1500 and 300 individuals m⁻³, respectively, over two culture phases: nursery (30 days) and grow-out (60 days). High nitrification processes were detected at lower salinity treatments, with the lowest ammonia and nitrite concentration in those. There were no significant differences on shrimp survival between treatments; however, the best final weights were observed in the S8IB2 (0.24 ± 0.01 g) and S4IB1 (2.80 ± 0.12 g) treatments for the nursery and grow-out stages, respectively. The most frequent histological lesions were the absence of lipid vacuoles in the hepatopancreas and abundant organic debris in the gill lamellae. The viability of rearing L. vannamei juveniles in biofloc at low salinity is still relatively weak because of their low growth and low efficiency to store fatty acids in the hepatopancreas; however, higher postlarvae productivity was found at 8 g L⁻¹ and Na⁺/Mg⁺²/Ca⁺²/K⁺ ratio of 40.6/4.7/1.98/1 in the nursery stage.

Florida pompano, Trachinotus carolinus, can be fed soy-based, low-animal protein diets. However, anti-nutritional factors and carbohydrates limit digestibility. Dietary carbohydrase enzymes have been used to improve carbohydrate digestibility in several species and may be beneficial for Florida pompano. The present study was designed to evaluate the effects of using a carbohydrase enzyme complex (Natugrain® TS L, BASF Corporation, Ludwigshafen, Germany) composed of endo-1,4-ß-xylanase and endo-1,4-ß-glucanase (Xyl + Glu) on growth performance, feed utilization, and digestibility in diets fed to juvenile Florida pompano. A growth trial was conducted with iso-nitrogenous (40%) and iso-lipidic (8%) test diets containing 0, 0.015, 0.030, and 0.045% of Xyl + Glu. The trial was conducted in a recirculating system with 12, 1000-L tanks. Twenty fish (mean weight: 23.34 g ± 1.49 g) were stocked into each tank in a randomized design. Growth results indicated that there were no significant differences (p > 0.05) in growth and feed conversion; however, thermal growth coefficient displayed significant differences (p = 0.0499) between the 0.015 and 0.030% inclusion. All enzymatic treatments displayed significant differences (p = 0.029) in apparent digestibility of crude protein compared with the basal diet. Results indicate that Xyl + Glu enzyme complex can impact protein digestibility but did not significantly affect growth performance.

Male postsmolt maturation (“jacking”) is undesired in Atlantic salmon aquaculture due to economic and welfare impacts. Unfortunately, incidence of jacking has increased linked to intensive rearing conditions. This study subjected 1000 salmon (52.1 ± 5.2 g) to one of two temperatures (15, 12.5°C) and one of two photoperiods (constant light-LL, a 5-week LD12:12 winter signal regime-WS) to assess their effects on spermatogenesis regulation. Indicators included testis histology images, mRNA transcription of gonadotropin receptors for follicle-stimulating hormone (fshr) and luteinizing hormone (lhr), and of factors regulating spermatogenesis like anti-Müllerian hormone (amh), gonadal-soma-derived factors 1 and 2 (gsdf1 and gsdf2), and insulin-like growth factor-3 (igf3). High temperature (15°C) induced early testis development processes irrespective of photoperiod, evidenced by presence of type B spermatogonia before clear increases in testis size or any transcriptional changes. The winter signal at 15°C caused a synchronized onset of spermatogenesis not present under constant light. This was evidenced by a pronounced downregulation of the spermatogenesis-inhibiting factor amh and a clear upregulation in the stimulating factor igf3. Consequently, combining high temperatures with winter signal regimes pose risk; high temperature can stimulate early cellular/endocrine processes of spermatogenesis, which can later be synchronized in the population by an increase in daylength.

The Florida pompano, Trachinotus carolinus, is an ideal species for commercial aquaculture because of its rapid growth, tolerance to a range of environmental parameters, and high demand in the seafood market. This study detailed embryonic and early larval development of this species. Florida pompano followed similar developmental sequences to those observed in other marine teleosts, and embryos hatched between 22 and 28 h post-fertilization. Significant brain lobe differentiation occurred prior to hatching. Pectoral fins were functional within 1-day post-hatch (dph). Substantial eye development occurred within 3 dph, indicating visual acuity prior to the onset of exogenous live feeding. Intestinal segments were differentiated by 3 dph, and rotifers were seen in the digestive tract by 4 dph. Digestive functions were limited through the first 7 dph because of the absence of functional gastric glands and gastric mucous cells in the rudimentary stomach, lipid vacuoles in the anterior intestines, and the persistence of acidophilic supranuclear vesicles in the posterior intestines. Within 7 dph, the pharyngeal arches differentiated, and hematopoietic tissue and mesonephric tubules were visible in the larval kidney. Their rapid larval development and organogenesis are additional factors that make Florida pompano an ideal species for aquaculture production and should encourage continued efforts toward commercialization.