Reviews in Aquaculture最新文献

Dynamic optimization (DO) has been applied to aquaculture industry to determine optimal management strategies of aquaculture production systems. Optimal control of feeding, optimal stocking successions, and harvesting time among other factors has been studied. This work shows a review of the application of optimal control theory (OCT) and dynamic programming in economics and management of aquaculture. The Pontriagyn's maximum principle and the Bellman's optimality are the most commonly used mechanisms to solve control problems that optimize the producer's benefit or cost. Recently, model-based predictive control has also been applied. Such tools have been used in aspects involving the design, planning, and monitoring of variables relevant to the optimal management of the culture system. It was found that in aquaculture there is low scientific productivity in the application of DO in bioeconomic models. In this review, an example of OCT applied to the control of feeding of farmed tilapia using a bioeconomic model is shown. DO represents a useful tool for optimal decision-making and this review discusses the implications of the use of DO in aquaculture and recommendations for its use in the future.

Mass mortality events (MMEs) are defined as the death of large numbers of fish over a short period of time. These events can result in catastrophic losses to the Atlantic salmon aquaculture industry and the local economy. However, they are challenging to understand because of their relative infrequency and the high number of potential factors involved. As a result, the causes and consequences of MMEs in Atlantic salmon aquaculture are not well understood. In this study, we developed a structural network of causal risk factors for MMEs for aquaculture and the communities that depend on Atlantic salmon aquaculture. Using the Interpretive Structural Modeling (ISM) technique, we analysed the causes of Atlantic salmon mass mortalities due to environmental (abiotic), biological (biotic) and nutritional risk factors. The consequences of MMEs were also assessed for the occupational health and safety of aquaculture workers and their implications for the livelihoods of local communities. This structural network deepens our understanding of MMEs and points to management actions and interventions that can help mitigate mass mortalities. MMEs are typically not the result of a single risk factor but are caused by the systematic interaction of risk factors related to the environment, fish diseases, feeding/nutrition and cage-site management. Results also indicate that considerations of health and safety risk, through pre- and post-event risk assessments, may help to minimize workplace injuries and eliminate potential risks of human fatalities. Company and government-assisted socio-economic measures could help mitigate post-mass mortality impacts. Appropriate and timely management actions may help reduce MMEs at Atlantic salmon cage sites and minimize the physical and social vulnerabilities of workers and local communities.

Managing waste nutrients from intensive freshwater and marine pond aquaculture is a global challenge. Nutrient-enriched water released from farms can have detrimental effects on aquatic ecosystem health. There are a range of treatment options for discharge water from fish and crustacean ponds, and this review examines the benefits and limitations of these options. Much of the nutrient waste is derived from the addition of formulated feed. In recent years, reduction in waste from feeds and feeding has been largely incremental. In terms of treatment, there are low-cost approaches, such as settlement ponds, but they are inefficient at reducing nutrients. Biological systems, using aquatic plants, microalgae and filter feeders to reduce nutrient release from farms have variable levels of effectiveness. Establishing wetlands requires considerable additional land area, and success to date has been highly variable. Overall, this review found no simple cost-effective solution for managing nutrient enriched water from ponds. This is due, in many cases, to challenges with treating the large volumes of discharge water with relatively low nutrient concentrations. This means that more technologically advanced and reliable treatment options, for example, bioreactors, are prohibitively expensive. However, some systems, such as use of recirculation systems typically increase nutrient concentrations, and hence the efficiency and effectiveness of more expensive treatment methods. Biofloc systems can also provide a mechanism for in-situ nutrient treatment as well as a supplementary food source for animals. Overall, there is scope to improve treatment of waste nutrients, but significant modifications to many production systems are needed to achieve this.

High-intensity aquaculture may cause the aquatic animals to experience elevated stress levels, which in turn will increase their susceptibility to illness and result in substantial losses. Farmers frequently use chemical and antibiotic treatments for fish diseases, which have led to drug-resistant and hazardous residues in farmed fish and the environment. Consequently, finding substitutes for chemicals and antibiotics is crucial for disease management in aquaculture. Terminalia catappa L. or commonly called Indian almond is well known for its medicinal properties and widely distributed in tropical and subtropical regions. T. catappa contains chemical compounds such as tannin and flavonoid that play an important role in antibacterial, anti-allergy, anti-inflammation, and anti-cancer. Numerous studies have been conducted on leaves, bark, fruits, and seed of T. catappa for their applications, including medicinal, bioremediation (dye absorption), and aquaculture use. Much research can be found on the utilization of T. catappa leaves to improve fish well-being, mostly in the ornamental fish industry. Extract of T. catappa has been found to improve fish survival, growth rate, inhibit bacterial infection, improve water quality, enhance fish colouration, and boost the immune response. Although T. catappa leaves have undergone substantial research, it has not been systematically described in connection to fish species used in aquaculture. This review will systematically discuss the biotoxicity of T. catappa evaluation of growth-promoting properties, eggs and larviculture performance, and enhancement of fish resistance to various bacteria, fungi, and parasites. In addition, the article also highlights the future perspectives of using T. catappa to improve fish culture.

The aquaculture sector is currently experiencing a global disease crisis. Emerging bacterial diseases—often opportunistic or syndromic—have collapsed production in nations across the world. Losses in the shrimp industry associated with opportunistic Vibrio spp. exceed 40% of global capacity. This paper reviews potential drivers of syndromic diseases involving opportunistic bacterial pathogens affecting global aquaculture. We provide key examples from major industries where such conditions have prompted greater antibiotic use and have resulted in significant mortality. We challenge the conventional definitions of opportunistic pathogens and propose a fluid categorisation that acknowledges the continuum of host adaptation and the complexity of microbial ecology. We discuss the implications of environmental and dietary stressors such as climate change, coastal eutrophication and pollution, and the transition to plant-based feeds, which have been linked to impaired epithelial barrier function, gut health disorders and increased disease susceptibility. We critique the ‘one-pathogen one-disease’ paradigm, suggesting that Rothman's causal pie model is more useful for understanding opportunistic infections as it emphasises the multicausal nature of disease. We provide examples of bacterial and viral interactions in aquatic disease and occurrence of bacterial diseases resulting from host damage from eukaryotic parasites or increasing frequency and severity of interventions to control such parasites. We recognise the need for corroborative evidence to validate the rise of opportunistic bacterial pathogens as a global trend, and we advocate for the application of nuanced disease causation models to reduce the incidence of opportunistic infections and improve the sustainability of the aquaculture industry.

Recent evidence has demonstrated the unique properties of the innate immune system, known as innate immune memory, immune priming, or trained immunity. These properties have been described as the ability of the innate immune system to learn from previous microbial experiences, which improves survival after subsequent infection. In this review, we present the state of knowledge on trained immunity in invertebrates and provide a comprehensive overview of these capabilities in cultured marine molluscs, which are currently threatened by recurrent diseases. Studies have shown that exposure to environmental microbiota, pathogens, or derived elements, can provide a stronger response and protection against future infections. These studies highlight common and distinct features of protection, mechanisms, specificity, and duration that vary with immune markers, and methods of stimulation. While the cellular and molecular basis of these responses is only partially understood, effects on phagocytosis, haemocyte populations, apoptosis, oxidative stress, and immune gene expression have been suggested. Finally, we propose a framework for future research to go beyond the current evidence and address potential limitations in the implementation of trained immunity-based strategies to control disease. Immune training may provide a unique opportunity to promote the sustainable development of marine mollusc aquaculture.

The effective implementation of machine vision has played a crucial role in advancing intelligent aquaculture across various domains. Stereo vision, as a branch of machine vision, has become a mainstream technology in aquaculture. Its distinctive capability to conduct comprehensive underwater monitoring from multiple angles, unaffected by object occlusion has propelled it to the forefront of aquaculture applications. This article offers a comprehensive review of the diverse applications of stereo vision in aquaculture spanning from its inception to present. The exploration encompasses its role in crucial areas such as biomass estimation and behavioural analysis, which include fish counting, weight estimation, swimming behaviour, feeding behaviour and abnormal behaviour. Furthermore, the paper delves into the advantages of stereo vision over traditional 2D machine vision approaches, while also acknowledging limitations, and identifying future challenges that must be addressed to fully leverage its potential in aquaculture. The review emphasizes the prospect of advancement in deep learning stereo-matching algorithms specifically designed for underwater environments to catalyse a breakthrough in stereo vision technology. In summary, this review aims to provide researchers and practitioners with a better understanding of the current development of stereo vision in aquaculture, optimizing stereo vision technology and better serving the aquaculture field.

The review encapsulates the comprehensive exploration of RNA interference technology's application in shrimp aquaculture, covering molecular intricacies, production methods, and practical applications. The emphasis is on exploring the stability and delivery of gene-specific double-stranded RNA, particularly through nanoencapsulation. This is because the susceptibility of dsRNA to degradation and limited cellular penetration, emphasising the need for effective delivery mechanisms. The review presents an in-depth exploration of nanoparticles for the encapsulation and delivery of dsRNA, including virus-like particles (VLPs), and non-viral based nanoparticles such as liposomes, chitosan, and beta-glucan. VLPs, derived from non-infectious shrimp virus structures, exhibit biocompatibility and natural functionality, making them suitable carriers for dsRNA. The application of chitosan and its derivatives are explored for their efficacy in reducing viral infections in shrimp. Beta-glucan particles are examined for their immunostimulant properties in shrimp aquaculture. The text emphasises the use of yeast-based glucan particles for encapsulating dsRNA, showcasing their potential in preventing viral diseases in shrimp. The review introduces cautionary considerations for nanoparticle formulation, highlighting factors such as pH, organic solvents, metal ions, and environmental ribonuclease that can impact dsRNA stability during synthesis. In conclusion, the text discusses the potential economic worthiness and environmental risk assessment of dsRNA technology in shrimp aquaculture. While acknowledging successful applications in other environments, it underscores the need for regulatory approval and risk assessment for dsRNA-based products in the aquaculture industry. The evaluation of dsRNA in real-world shrimp farms is deemed necessary for commercial utilisation, taking into account income, expenses, safety, and environmental considerations.

Nitrogenous waste is a global concern in aquatic ecosystems. In the shrimp farming system, feeding is the main input of nitrogen, which leads to the accumulation of nitrogenous waste, such as ammonia, nitrite, and nitrate. Nitrogen cycling is crucial for nitrogenous waste removal and for the stability of the aquaculture system. Under the action of different functional microorganisms, a variety of nitrogen cycling pathways can be used for the transformation and removal of nitrogenous waste. Understanding the complexity of the nitrogen cycle is necessary for improving the aquaculture environment. This review examines the many components and mechanisms involved in the nitrogen cycle in shrimp farming system, including nitrification, denitrification, anammox, heterotrophic assimilation, and autotrophic assimilation. Because of the difference in aquaculture characteristics, nitrogen cycling pathways in different shrimp culture modes are diverse. The current application of the nitrogen cycle in shrimp farming system, including the outdoor pond mode and indoor industrialized mode, was presented in combination with the requirements for dissolved oxygen (DO), organic matter, carbon–nitrogen ratio, light, and other environmental factors. Overall, nitrification, heterotrophic assimilation, autotrophic assimilation, and heterotrophic denitrification are the main nitrogen cycle processes in the shrimp culture system. According to the characteristics of aquaculture modes and microorganisms, utilizing different nitrogen cycle processes can enhance the efficiency of the nitrogen cycle, facilitate the elimination of nitrogenous waste, optimize the aquaculture water environment, and improve overall aquaculture benefits.

Salmonids, specifically Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), are commonly farmed and their gut microbiota plays important roles for optimal growth, health, and physiology. However, differences in experimental design, technical factors and bioinformatics make it challenging to compare the results from different studies and draw general conclusions about their influence on the fish gut microbiota. For a more comprehensive understanding of the gut microbiota, we collected all the publicly accessible 16S rRNA gene sequencing data with clearly stated sample metadata from freshwater Atlantic salmon and rainbow trout intestinal contents and mucosa sequenced on the Illumina MiSeq platform. A total of 783 samples from 19 published studies were included in this meta-analysis to test the impact of the technical, environmental, and host-accociated factors. This meta-analysis revealed that all the tested factors significantly influenced the alpha and beta diversities of the gut microbiota of salmon and trout. Technical factors, especially target region and DNA extraction kit, affected the beta diversity to a larger extent, while host-associated and environmental factors, especially diet and initial fish weight, had a higher impact on the alpha diversity. Salmon had a higher alpha diversity and higher abundance of Enterococcus and Staphylococcus than trout, which had higher abundance of Weissella and Mycoplasma. The results of this meta-analysis fill in a critical knowledge gap that demonstrate technical methodologies must be standardized and factors associated with host and environment need to be accounted for in the future design of salmonid gut microbiota experiments.