Aquaculture Research最新文献

This study assessed the performance of domesticated tiger shrimp Penaeus monodon postlarvae and mud crab Scylla paramamosain co-cultured in 90 extensive rice-shrimp ponds in the Mekong River Delta of Vietnam from 2022 to Sep 2023. Limited supplementary feeding was applied for only 20% of the studied ponds. Results show that ponds stocked with domesticated postlarvae produced significantly larger shrimps at harvest and had better postlarvae usage efficiency (P < 0.05) compared with those stocked with older postlarvae produced by wild-caught broodstock. Furthermore, a combination of stocking domesticated postlarvae and using organic fertilizer for pond preparation and during the crop was found to significantly improve productivity by 28% and final harvest size by 67% (P < 0.05). Larger shrimps fetched 54% higher farm-gate prices, thus significantly increasing gross revenue for farmers. Co-culture of mud crab in rice-shrimp ponds at low densities (0.2–0.7 pcs/m²) was popular and profitable. Productivity was 116–187 kg/ha/crop with a profit margin up to 92.8%. Income from mud crab was very similar to that from shrimp. The results of this study suggest that domesticated postlarvae of P. monodon should be used for stocking extensive systems, preferably in combination of using organic fertilizer to enhance natural foods. Further improvement of income and profit can be achieved if more attention is paid on crablet quality and quality improvement.

Spotlighting the current state of largemouth bass (Micropterus salmoides) aquaculture, this study exhibited the effects of steroidal saponins (SS) on the liver health of largemouth bass under high-temperature stress. The study consisted of two experiments: the first trial was designed to evaluate the growth performance of fish fed the experimental diets containing SS 0% and 0.1% (SS₀ and SS_0.1) for 30 days. And then, the second trial was used to evaluate the health of the livers of these fish under high-temperature (34°C) stress which lasts for 1 week, and the groups were named as SS₀, HSS₀, SS_0.1, and HSS_0.1, respectively. In the first feeding trial, except for the higher feeding rate observed in the SS_0.1 group (P < 0.05), no significant difference was observed between the groups SS₀ and SS_0.1 in survival rate, weight gain rate, specific growth rate, and feed conversion rate, respectively. After 1 week of high-temperature stress, the specific growth rate and weight gain rate of fish were significantly lowered in the HSS₀ and HSS_0.1 groups (P < 0.05). In terms of feeding rate, the SS_0.1 and HSS_0.1 groups were significantly higher than the other two groups (P < 0.05). Under high-temperature stress, gene expressions of caspase-3, caspase-8, caspase-9, tnf-α, il-8, and hsp70 were significantly downregulated in the liver of largemouth bass in the HSS_0.1 group (P < 0.05). The activities of antioxidant enzymes, including catalase, total superoxide dismutase, and glutathione peroxidase in the liver, were significantly increased, while the serum enzyme activities of aspartate aminotransferase and alanine aminotransferase were significantly decreased in the HSS_0.1 group (P < 0.05). Compared to the HSS₀ group, hepatic vacuolization areas of fish in the HSS_0.1 group were improved (P < 0.05). Therefore, the results of the study supported that the 0.1% SS used in largemouth bass diet for 30 days could strengthen the liver and body health and help fish resist heat stress.

Research on the development of innovative cryobanking techniques can aid coral restoration and conservation. This study applied a customized freezing device and “cryojig” along with vitrification and laser warming techniques to create the first cryorepository for pelagic-phase larvae of the corals Seriatopora caliendrum, Pocillopora verrucosa, Stylophora pistillata, and Pocillopora acuta. Three vitrification solutions (VSs) were prepared, with each composed of two of four cryoprotective agents. These included VS1: 2 M ethylene glycol (EG) and 1 M propylene glycol; VS2: 2 M EG and 1 M glycerol; VS3: 2 M dimethyl sulfoxide and 1 M EG. Larvae were then mixed with the VSs, 40% (w/v) Ficoll, and 10% (v/v) gold nanoparticles (GNPs) at a final concentration of 1.2 × 10¹⁸ particles/m³ and using our customized device for vitrification and laser warming. Over a thousand coral larvae (576 S. caliendrum, 376 P. verrucosa, 238 S. pistillata, and 524 P. acuta) were successfully stored in the cryorepository and the proportions of coral larvae that were noted to be actively swimming or settled after vitrification and laser warming. This is the first project to establish a coral larvae cryorepository, and the methods applied could represent a critical tool for reef restoration and maintenance of marine biodiversity.

Globally, parasitic infections hinder aquaculture productivity and sustainability. Improper water quality parameters reduce fish immunity, make them susceptible to parasites, and enhance parasitic proliferation in culture systems. Subsequently, this study aimed to determine the prevalence and intensity of ecto- and endo-parasite infesting Oreochromis niloticus in varying water quality in aquaculture systems in Kericho, Bomet, and Nakuru counties. A total of 220 Oreochromis niloticus samples were captured from 11 liner ponds, eight earthen ponds, two concrete ponds, and one plastic tank from 22 farms in the three counties. External and internal organs were examined for parasite infestation. Skin scrapings and squash preparation of fish eyes were also examined to reveal the organisms through microscopic examination. A Pearson’s correlation analysis between physicochemical parameters and parasitic prevalence was used to determine the strength and direction of correlation coefficients with significance at 95%. Overall parasitic prevalence infestation was 39.6% (87/220). Ten parasite genera were recovered, with Dactylogyrus species dominating overall at 15.9% (35/220), followed by Trichodina spp. (7.7%; 17/220). Epistylis species had the highest mean intensity of 12.8 ± 35.7 (total number of Epistylis parasites (141)/total of infested fish (11)). Earthen ponds had a significantly higher (36.2%, 29/80) prevalence of Dactylogyrus sp. than liner ponds (3.6%, 4/110) (p < 0.001). Dissolved oxygen levels were 16.9 ± 0.7 mgL⁻¹ in Bomet, 14.9 ± 0.3 mgL⁻¹ in Kericho, and 12.5 ± 0.5 mgL⁻¹ in Nakuru which were above desirable range for fish culture. The electrical conductivity in Bomet was 76 ± 5 µS/cm and Kericho 52 ± 4 µS/cm below the desirable range. Temperature, pH, phosphate, nitrates, and nitrites were within the desirable limit for fish farming. Electrical conductivity and pH had positive correlation of 1 and 0.97, respectively, with the prevalence of Acanthocephalus, Euclinostomum, and Trichodina species. Temperature and nitrate positively correlated between 0.80–0.89 and 0.90–0.99, respectively, with the prevalence of Dactylogyrus, Riboscyphidia, Epistylis, Camallanus, and Paracamallanus species. The study demonstrates that water quality significantly influences parasitic prevalence in aquaculture systems. Therefore, it is crucial for farmers to monitor water quality parameters to mitigate parasitic infestations.

Climate change is leading to worldwide ocean temperature rise and increased occurrence of low oxygen events. Dissolved oxygen and water temperature play a crucial role in the growth and health of fish becoming determining factors of welfare. In order to counteract the effects of low oxygen events, farms worldwide have begun to experiment with oxygen supplementation systems. In this study, high-resolution, high-frequency acoustic tags were used to monitor the movement of Atlantic salmon (Salmo salar) at a commercial farm where an oxygen supplementation system was installed. A 2-month study period was selected, which allowed the characterization of fish movement during and after the oxygen supplementation project. The positioning of 15 fish was recorded using high temporal resolution (3 s). Fish movement was characterized by calculating four fish variables: velocity (ms⁻¹), distance from the center of the cage (m), turning angle (°), and relative measurements of depth (m). During the oxygenation trial, all tagged individuals recorded slower swimming velocities than after the trial. Seventy-seven percent of the tagged population swam nearer to the cage edge during the trial than after, and 85% displayed straighter swimming patterns during the trial than after. Lastly, during the trial, 85% of the tagged population swam shallower than after the trial. Although causality cannot be related to the oxygen supplementation experiment due to the potential effect of confounding variables naturally occurring in the environment, this study highlights that increased farm technology can provide more insight into the effects of oxygenation systems on fish behavior.

Fin clipping is a common method of fish marking to distinguish between particular cohorts, yet a comparison of specific marks/clips has yet to be thoroughly conducted. Nine ponds were stocked with pikeperch (Sander lucioperca, L., 20 specimens each) in spring 2023, and different fins or parts of fins were clipped in each pond. The regeneration and readability of different 1-year-old pikeperch fins after fin-clipping were investigated by repeated recaptures at monthly intervals during the growing season (April–October). Although prey fish were absent in all ponds and the pikeperch grew slowly, fin regeneration was relatively rapid. Readability naturally decreased as the season progressed. Better readability was observed when the soft fin rays were cut off. In cases where only the hard fin rays were cut off, readability decreased rapidly over the course of the season. In general, the best readability was found for the pelvic fin when the entire fin or its posterior part was cut off as well as for the anterior and posterior part of the second dorsal fin. Conversely, the worst readability was found for the anterior part of the pelvic fin and both the anterior and posterior parts of the first dorsal fin. The readability of the anal fin section can be described as average. The degree of regeneration (ratio between regenerated and original fin parts) was usually above 50% at the end of the growing season and due to the limited food supply in all ponds, the survival rate between stocking and harvesting was never above 40% (10%–40%).

The molecular features from the coding sequence and part of the 5′-UTR of the scaffolding protein receptor for activated C kinase (CxRACK1) gene from the jellyfish Cassiopea xamachana were assessed by a combination of regular and inverse PCR amplifications. The final CxRACK1 mRNA sequence contained 1,041 bp with an open reading frame of 954 bp that translated into 317 amino acids. The translated primary sequence contained the canonical seven WD40 domains, one ribosome, and three conserved protein kinase C (PKC)-binding sites as well as the Tyr amino acid targets for Src phosphorylation. The protein showed a conserved CxRACK1 tertiary structure since the seven WD40 domains clearly assembled into the characteristic β-propeller shape displaying surface exposed amino acids critical for regulation by phosphorylation. Within the 5′-UTR, cis-acting regulatory elements were analyzed with available software from the closest organismal phylogeny which corresponded to that of chordates, plants, and fungi. Of note were one element related to retinol binding, three that corresponded to light regulation, two to target binding sites for zinc finger domain proteins, and two more were transcriptional activators. Further phylogenetic analysis placed CxRACK1 within the Scyphozoa group as expected. RT-qPCR analysis of distinct physiological stages through the C. xamachana metamorphic cycle showed slightly but consistent lower CxRACK1 mRNA levels in scyphistomae, strobilae, and ephyrae than those in buds and larvae. This suggested an increased expression and possible involvement of this molecule in signal transduction processes related to the transition to these initial metamorphic stages.

With the increasing demand for global food resources, improving aquaculture production has been the focus for years. Tilapia has become one of the most commonly farmed and economically important fish species globally. Research efforts have recognized the significant roles that microbial communities play in improving the health and aquaculture performance of tilapia. However, interactions between tilapia and its associated microbial communities remain poorly understood. In this review, the current understanding of tilapia microbiomes is summarized. With fish being in intimate relationship with its environment, studies characterizing the microbial communities present in the rearing environment and how they affect tilapia microbiomes and health are also examined. Having an in-depth understanding of the different microbiomes and their roles and interactions in the tilapia culture system is a crucial step toward managing and modulating these microbial communities to improve tilapia health. This review also sheds light on the different factors that influence tilapia microbiomes such as developmental stages, organ tissues, and types of culture systems. The effects of on-farm practices such as diet; feeding regimes; use of probiotics, prebiotics, and synbiotics; vaccination; application of antibiotics; disinfection; and pond fertilization on tilapia microbiome are also discussed. Through this review, future research needs are identified that can provide a deeper understanding of the relationships among tilapia microbiomes, health, and productivity. These knowledge in turn can be harnessed into practical applications and potential microbiome-based management protocols to improve future best management practices for tilapia aquaculture.

This study investigates the impact of total dissolved gas supersaturation (TDGS) on the swimming capabilities of migratory fish (S. prenanti), a common issue during high dam discharges in flood seasons. We assessed fish exposed to 130% TDGS for 2 hr, focusing on their swimming performance in a controlled environment. In our experiments, control group fish, utilizing prolonged swimming, showed reduced maximum distances as flow velocities increased from 3 to 10 BL/s (body length per second), covering distances between 1,285 and 119 BL. In contrast, TDGS-exposed fish achieved only 15%–95% of these distances. Under burst swimming conditions, control group fish also demonstrated a decrease in maximum distances with increasing flow velocity, achieving 280–124 BL, while TDGS-exposed fish reached just 48%–64% of these distances. Notably, the critical flow velocity (U_fcrit) for transitioning from prolonged to burst activity level was lower for the TDGS group (7.2 BL/s) compared with the control (9.8 BL/s). In open flume trials, TDGS-exposed fish displayed a stronger upstream swimming inclination beyond U_fcrit, indicated by quicker times, higher speeds, and shorter trajectories. This study provides novel insights into the adaptive swimming strategies and flow velocity responses of fish under TDGS stress.

The Malaysian Straits, a region of significant ecological and economic importance, face growing challenges due to climate change and human activities. This study aimed to assess fish diversity in the Pulai River, situated within the Malaysian Straits, and examine the impact of urbanization and climate change on these fish populations. Rapid industrialization, urbanization, and agricultural runoff have contributed to habitat degradation and water pollution, exacerbating stressors on marine ecosystems. The objective of this study was to evaluate the current status of fish diversity and understand how environmental changes affect fish diversity. Field surveys were conducted to identify fish species in the Pulai River, with specimens collected and categorized into families. The study identified representatives from families such as Latidae, Serranidae, Lutjanidae, Polynemidae, Sciaenidae, Scombridae, and Carangidae, with Carangidae emerging as the dominant family, accounting for 163 individuals out of a total of 380 fish observed. Diversity indices for the marine fish community were calculated, yielding a diversity index (H′) of 2.02143, a species richness index (R′) of 2.474168, and an evenness index (E′) of 0.877896. The analysis revealed a positive allometric growth pattern (b = 1.73), indicating that as fish length increases, their weight decreases disproportionately. These findings highlight the complex responses of fish populations to environmental stressors such as water quality deterioration and habitat alteration. This study provides valuable insights into the fish ecology of the Malaysian Straits, particularly regarding the impacts of urbanization and climate change on fish diversity. The research supports informed conservation efforts aimed at preserving biodiversity in this ecologically significant region. Recommendations for future studies include ongoing monitoring of fish populations, assessment of specific pollutants and habitat changes, and the implementation of targeted conservation strategies to mitigate the impacts of urbanization and climate change on marine ecosystems in the Malaysian Straits.