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Birds visiting garden feeders doesn’t stop them from pollinating wild plants, say South African scientists.

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Abstract

In aquaculture, accurately counting fish fries is a prerequisite for fish population management and marketing. However, due to the fry overlapping and occlusion issues, the manual counting method is time-consuming, and the counting result might be inaccurate. Therefore, we utilized the computer vision technique to develop a lightweight fish fry counting model to address this issue. First, we constructed a diverse dataset containing images of largemouth bass in varying numbers, captured under different lighting conditions and water depths. Then, we optimized the YOLOv5s model by channel pruning to reduce the model size, while maintaining the detection accuracy. Through extensive experiments, we examined the effect of different pruning rates on the model performance and compared the pruned YOLOv5s model with state-of-the-art detection models through the evaluation criteria like precision, recall, mean average precision (mAP), model size, GFLOPs, and detection speed. In addition, we investigated the impact of environmental factors, such as lighting conditions and water depths, on the detection performance of the pruned YOLOv5s model. The experimental results demonstrated that the YOLOv5s model with a pruning rate of 15% achieved over 90% accuracy and 13 FPS in the dense and complex scenes, which met the practical requirement for the fry counting task. In addition, we also identified that the pruned YOLOv5s model would achieve the optimal performance under the white illumination and shallow water depth setting. In conclusion, this study provided an efficient solution for fish fry counting, and the proposed model was expected to be applied in the real-world application.

Abstract

Nitrite constitutes a significant pollutant that impedes the growth of P. vannamei. Conventional treatments are primarily geared toward decreasing nitrite concentrations from an environmental standpoint. Nevertheless, investigating methodologies to enhance the ability of Pacific white shrimp to withstand nitrite-induced stresses on an individual basis remains an unexplored topic. The present study examines the impact of autophagy on Pacific white shrimp’s response to high nitrite environments through rapamycin injection. The research findings indicate that activating autophagy can effectively enhance the survival rate of Pacific white shrimp under high nitrite conditions. Additionally, total hemocyte count (THC) results in the hemolymph demonstrate that autophagy can alleviate the reduction in blood cell count caused by nitrite stress. The transcriptome results show that upregulation of 718 genes and downregulation of 1071 genes after nitrite stress. The majority of these differentially expressed genes (DEGs) were related to physiological processes, including oxidative stress, energy metabolism, and lysosomes. In addition, there were 911 upregulated genes and 713 downregulated genes upon activation of autophagy. These DEGs are associated with immune responses, specifically involving glutathione metabolism, drug metabolism-cytochrome P450, and metabolism of xenobiotics by cytochrome P450, lysosomes, autophagy, phagosomes, melanization, and MAPK signaling pathways. These pathways can reduce oxidative stress and promote the metabolism of harmful substances in the body, in shrimp, thereby improving their survival rates. These findings provide new insights for research aimed at enhancing nitrite tolerance in Pacific white shrimp.

Abstract

This study explored the effects of β-1,3/1,6-glucan derived from Saccharomyces cerevisiae cell walls on the growth, survival, and physiological responses of post-larvae (PL) of M. rosenbergii. Over a 3-week period, larvae were fed a formulated egg custard diet containing varying amounts of β-glucan. The findings revealed that incorporating β-glucan into the diet had a substantial positive impact. The inclusion of β-glucans significantly enhanced survival (59.14% for the PL fed 0.2% β-glucan versus 46.58% for the control; p < 0.05), promoted growth (13.58 mg wet weight for the PL fed 0.2% β-glucan versus 9.53 mg for the PL fed the control diet; p < 0.05), and accelerated the time to metamorphosis (26.67 days for the PL fed 0.2% β-glucan versus 28.0 days for the PL fed the control diet). As the amount of β-glucan in the diet increased, larval growth performance consistently improved. The group receiving 0.2% β-glucan exhibited the highest performance in terms of wet and dry weight, total length, and mean production of PL. Furthermore, the study assessed the influence of β-glucan supplementation on larval tolerance to hypersaline stress. Although the differences were not statistically significant, the addition of β-glucan resulted in incremental improvements in the ability of larvae to withstand hypersaline conditions. In conclusion, the dietary supplement containing 0.2% β-glucan exhibited the highest performance among the inclusion levels tested. Further investigation is recommended to determine the nutritional and physiological effects of β-glucan supplementation under salinity stress conditions.

Abstract

To popularize Kuruma shrimp, Penaeus (Marsupenaeus) japonicus Form II, as a part of the diversification of shrimp farming across India, seed production and growth performance studies were conducted. In experiment I, the reproductive performance of Kuruma shrimp was studied in captive system. In experiment II, a 75-day growth performance study was carried out in 2 × 2 factorial design with and without sandy bottom (S) as the first factor and outdoor units having natural light (O) and indoor units with restricted light (I) as the second factor resulting in four treatments: O+S, O-S, I+S and I-S. The seed production trial recorded an average survival of nauplius to post larvae (PL) 36 ± 12%. In experiment II, the PL (0.02 ± 0.01 g) was stocked at 300 PL m⁻³ to study the effect of sandy bottom and light intensity on growth performance. Results indicated that the highest final body weight (0.63 ± 0.05 g) and survival (80 ± 2.0 %) were registered in outdoor units without (O-S) and with sandy bottom (O+S), respectively. Although no difference (p > 0.05) in body weights were recorded among the treatments, the Kuruma shrimps reared under indoor units with restricted light intensity had lower (p < 0.05) survival (43–45%). The light intensity varied from 459 to 6583 lux in the outdoor system whereas indoor units had only 8–35 lux. A significant interaction effect (p < 0.01) between the sandy bottom and light intensity on food conversion ratio (FCR), coefficient of variation at final weight, CV_abw (%), nitrite-N, TSS and chl–a level were noticed. The Kuruma shrimp reared under outdoor units (O+S and O+S) had well-developed chromatophores; meanwhile, the transparent colouration was recorded in the shrimps reared under restricted light intensity. The present study concludes the potential to rear P. japonicus Form II in tank or lined rearing system without the sandy bottom and scope to develop location-specific culture and seed production techniques.

Abstract

As the global demand for seafood surges, the expanding aquaculture industry faces a pressing need for viable aquafeed ingredients. The raw material for fish oil is limited and expensive due to unpredictable fishery resources in the fishing zones and the overexploitation of wild fisheries, underscoring the urgency of finding alternatives. This review explores diverse plant oil sources, including soybean, rapeseed, linseed, and algal oils, emphasizing their crucial role in nutritionally balanced aquafeeds. These oils support aquatic animals’ growth, health, and development, influencing membrane structure, energy storage, and hormone production. Genetically modified oilseeds (GM), such as camelina and canola, offer a controlled nutrient content, enabling customized nutrient profiles. This comprehensive review provides an overview of different plant oil sources, elucidates their nutrient profiles, and assesses their potential applications in aquaculture. The discussion encompasses their impact on growth, feed efficiency, lipid profile, health, immunological status, disease resistance, and overall performance of both freshwater and marine fish. Furthermore, the review compiles relevant data on the current status of genetically modified plant oils and explores their potential integration into aquaculture practices. In summary, substituting plant oils for fish oil in aquafeed presents a promising solution to aquaculture industry challenges to meet nutritional requirements for fish.