We reviewed 148 assessments of animal source food (ASF) production for livestock, aquaculture, and capture fisheries that measured four metrics of environmental impact (energy use, greenhouse‐gas emissions, release of nutrients, and acidifying compounds) and standardized these per unit of protein production. We also examined additional literature on freshwater demand, pesticide use, and antibiotic use. There are up to 100‐fold differences in impacts between specific products and, in some cases, for the same product, depending on the production method being used. The lowest impact production methods were small pelagic fisheries and mollusk aquaculture, whereas the highest impact production methods were beef production and catfish aquaculture. Many production methods have not been evaluated, limiting our analysis to the range of studies that have been published. Regulatory restrictions on ASF production methods, as well as consumer guidance, should consider the relative environmental impact of these systems, since, currently, there appears to be little relationship between regulatory restrictions and impact in most developed countries.
Antibiotics are increasingly used and released into the environment due to the rapid development of aquaculture, resulting in spread of antibiotic resistance. This study investigated the distribution and diversity of antibiotic resistance genes (ARGs) in the aquaculture waterbody of different aquaculture systems in Guangdong, as well as their associations with opportunistic pathogens. A comparative analysis of 92 samples revealed that selected ARGs were more prevalent in freshwater aquaculture systems (FAS) than in marine aquaculture systems (MAS), with higher accumulation levels of tetracycline (Tet) and sulfonamide (Sul) resistance genes observed in FAS. Notably, certain ARGs such as tetG_F and mphA were more abundant in MAS compared to FAS, suggesting differing antibiotic selection pressures across the two systems. Analysis of bacterial communities revealed distinct compositions: FAS was dominated by Acidobacteria and Chloroflexi, while Actinobacteria and Bacteroidetes were more prevalent in MAS. Network analysis showed positive correlations between opportunistic pathogens and selected ARGs, suggesting that these pathogens may serve as reservoirs for resistance genes and pose potential public health risks. Bacterial community assembly in MAS was primarily driven by stochastic processes, whereas both deterministic and stochastic processes influenced community structure in FAS. Moreover, TN, NH4+ , NO2-, and PO43- strongly influence bacterial communities and ARGs, with greater effects in MAS. Overall, this study reveals the complex interactions among microbial diversity, ARGs, and environmental factors, providing a theoretical foundation for mitigating the spread of antibiotic resistance in aquaculture and improving ecosystem health.
Amir Parviz Salati, Saeed Keyvanshokooh, Mahdi Naderi
et al.
Biofloc technology has emerged as a sustainable aquaculture strategy that improves water quality and enhances nutrient recycling, offering the possibility of reducing commercial feed inputs without compromising fish performance. Stocking density and feeding rate are two key factors shaping both microbial dynamics in biofloc systems and the physiological responses of cultured fish. This study evaluated the combined effects of these factors on Cyprinus carpio. Juvenile fish (21.55 ± 1.79 g) were reared for 60 days under five treatments: a clear-water control (10 kg m⁻³; fed 3 % of body weight per day) and four biofloc groups representing two stocking densities—low density (10 kg m⁻³) and high density (20 kg m⁻³)—each fed either 3 % or 2.1 % of body weight per day (LD-3 %, LD-2.1 %, HD-3 %, HD-2.1 %). The 2.1 % feeding rate represented a 30 % reduction in commercial feed input. Water quality remained within acceptable ranges across biofloc treatments. Fish fed 2.1 % of body weight per day exhibited improved feed conversion and protein efficiency ratios without reductions in growth or survival. The LD-2.1 % group showed the most favorable physiological responses, including higher digestive enzyme activities (protease, lipase), elevated glutathione peroxidase activity, enhanced immune status (lysozyme and alternative complement activity), and lower hepatic malondialdehyde concentrations. Prior to acute crowding stress, fish fed 2.1 % displayed lower baseline cortisol and glucose levels and recovered more rapidly after stress exposure. Overall, reducing the feeding rate by 30 % under biofloc conditions improved feed efficiency and physiological robustness, and this feeding reduction remained feasible even at higher stocking density.
Angelica R. Valdez, Mitchell P. Marabella, Jon‐Paul Bingham
ABSTRACT Settlement and metamorphosis are critical life stages for marine mollusks that transition larvae to their adult forms. Often acting as bottlenecks in aquaculture production, as it is the most difficult step in a hatchery due to the changes in anatomical structures, for example, loss of velum and gain of adult shell structures. With various methods for induction explored through the years, this review explores the use of synthetic compounds, endogenous neurotransmitters, native‐inducing compounds and genomics in larval settlement and metamorphosis. Synthetic compounds typically lead to higher mortality and reduced effectiveness than native compounds. However, they produce varied effects across many marine mollusks, serving as valuable tools for studying behaviour and morphology during this transition. In contrast, native‐inducing compounds from environmental factors have species‐specific effects, demonstrating high efficacy and low mortality. Although native larval inducers are often unknown, difficult to identify and highly specific to individual species, understanding trends in other organisms may provide insights into methodologies, especially with the increasingly significant role of genomics. Genomics has the potential to aid in identifying valuable life history information to streamline and increase the effectiveness of grow‐out techniques in production settings. This understanding has the potential to significantly influence aquaculture by exemplifying multidisciplinary strategies, refining future initiatives and encouraging similar research efforts.
Petra Camilla Lindholm‐Lehto, Katri S. Kontturi, Kristoffer Meinander
et al.
ABSTRACT Saprolegniosis, typically induced by oomycete Saprolegnia parasitica , is one of the most difficult pathogens in fish and other aquatic animals in freshwater systems. It is especially harmful for the endangered species landlocked salmon ( Salmo salar m. sebago ). Currently, there are only few alternatives to prevent and treat saprolegniosis occurrences, which can lead to major fish deaths and financial losses at fish farms. In this study, surface‐modified cellulose materials were used at an experimental flow‐through fish farm rearing landlocked salmon, which often suffers from saprolegniosis occurrences. The results showed that the material's cationic surfaces were able to capture the spores of S. parasitica (experimental part I and part II). The cellulose material was chemically modified with a high density of cationic quaternary ammonium groups, which performed better than a material with a weak cationic charge by amino groups obtained via physisorption of chitosan on the surface, resulting in fewer S. parasitica spores in the rearing tank water (experimental part I). The results are promising and offer a novel method for controlling saprolegniosis occurrences without harmful chemicals. However, certain environmental conditions (in experimental part II) inhibited the detection method (real‐time quantitative polymerase chain reaction) used for the detection of S. parasitica . This highlights the need for further method development for the detection of S. parasitica . Overall, the results are promising in terms of reducing S. parasitica spores in rearing water and further controlling saprolegniosis occurrences. More process optimization is required to achieve the method's full potential in industrial scale processes.
The wetting behavior of drops on natural and industrial surfaces is determined by the advancing and receding contact angles. They are commonly measured by the sessile drop technique, also called goniometry, which doses liquid through a solid needle. Consequently, this method requires substantial drop volumes, long contact times, tends to be user-dependent, and is difficult to automate. Here, we propose the stood-up drop (SUD) technique as an alternative to measure receding contact angles. The method consists of depositing a liquid drop on a surface by a short liquid jet, at which it spreads radially forming a pancake-shaped film. Then the liquid retracts, forming a spherical cap drop shape (stood-up drop). At this quasi-equilibrium state, the contact angle ($θ_\text{SUD}$) closely resembles the receding contact angle measured by goniometry. Our method is suitable for a wide variety of surfaces from hydrophilic to hydrophobic, overcoming typical complications of goniometry such as needle-induced distortion of the drop shape, and it reduces user dependence. We delineate when the receding contact angle can be obtained by the stood-up method using Volume-of-Fluid (VoF) simulations that systematically vary viscosity, contact angle, and deposited drop volume. Finally, we provide simple scaling criteria to predict when the stood-up drop technique works.
Estimating the directions of arrival (DOAs) of incoming plane waves is an essential topic in array signal processing. Widely adopted uniform linear arrays can only provide estimates of source azimuth. Thus, uniform circular arrays (UCAs) are attractive in that they can provide $360^{\circ}$ azimuthal coverage and additional elevation angle information. Considering that with a massive UCA, its polar angles of array sensors can approximately represent azimuth angles over $360^{\circ}$ using angle quantization, a simple two-dimensional DOA estimation method for a single source is proposed. In this method, the quantized azimuth angle estimate is obtained by only calculating and comparing a number of covariances, based on which the elevation angle estimate is then obtained by an explicit formula. Thus, the proposed method is computationally simple and suitable for real-time signal processing. Numerical results verify that the proposed method can obtain azimuth as well as elevation angle estimates and the estimates can be used as starting points of multidimensional searches for methods with higher accuracy. Additionally, the proposed method can still work in the presence of nonuniform noise.
Jeny Ernawati Tambunan, Eddy Suprayitno, Heder Djamaludin
et al.
Kulit ikan gabus (Channa striata) memiliki kandungan kolagen sekitar 13,60% yang dapat dimanfaatkan sebagai bahan baku produk nutraceutical. Hidrolisat kolagen kulit ikan gabus (Channa striata) diketahui memiliki aktivitas antihipertensi dengan aktivitas penghambatan Angiotensin Converting Enzyme (ACE) sebesar 78%. Penelitian dilaksanakan pada Bulan Maret hingga Mei 2024 di Laboratorium Advance Fakultas Perikanan dan Ilmu Kelautan Universitas Brawijaya, Laboratorium Perekayasaan Hasil Perikanan Fakultas Perikanan dan Ilmu Kelautan Universitas Brawijaya, dan Laboratorium Uji Hewan Farmakologi Universitas Brawijaya. Metode penelitian ini menggunakan Rancangan Acak Kelompok (RAK) dengan jumlah sampel hewan model sebanyak 24 ekor dengan 6 level kelompok perlakuan yakni Kelompok Normal (N); Kelompok Kontrol Positif (K+); Kelompok Kontrol Negatif (K-); Kelompok Perlakuan Dosis Hidrolisat Kolagen Kulit Ikan (P1, P2, P3). Penelitian ini terdiri atas 2 tahap yakni tahap 1 dan tahap 2. Tahap 1 berupa pembuatan dan karakterisasi hidrolisat kolagen kulit ikan gabus (Channa striata) sedangkan tahap 2 berupa analisis aktivitas antihipertensi hidrolisat kolagen kulit ikan gabus (Channa striata) melalui hewan model secara in vivo. Pemberian hidrolisat kolagen kulit ikan gabus (Channa striata) dapat mencegah terjadinya peningkatan luas glomerulus ginjal hewan model serta mencegah terjadinya disfungsi endotel dan injury pada sel endotel dan podosit yang dapat mencegah terjadinya sklerotik glomerulus.
Snakehead fish skin (Channa striata) contains about 13.60% collagen, which can be utilized as a raw material for nutraceutical products. Collagen hydrolysate from snakehead fish skin (Channa striata) has been shown to have antihypertensive activity, with an Angiotensin Converting Enzyme (ACE) inhibition activity of 78%. The research was conducted from March to May 2024 at the Advance Laboratory of the Faculty of Fisheries and Marine Science, Brawijaya University, the Fishery Product Engineering Laboratory of the Faculty of Fisheries and Marine Science, Brawijaya University, and the Pharmacological Animal Testing Laboratory of Brawijaya University. The research method used a Completely Randomized Design (CRD) with 24 animal model samples divided into 6 treatment groups: Normal Group (N), Positive Control Group (K+), Negative Control Group (K-), and Treatment Groups with Collagen Hydrolysate from Fish Skin (P1, P2, P3). This study consists of two stages: Stage 1 involves the preparation and characterization of collagen hydrolysate from snakehead fish skin (Channa striata), while Stage 2 involves analyzing the antihypertensive activity of the collagen hydrolysate from snakehead fish skin (Channa striata) in vivo using an animal model. The administration of collagen hydrolysate from snakehead fish skin (Channa striata) can prevent an increase in the glomerular area of the animal model’s kidneys, as well as prevent endothelial dysfunction and injury in endothelial and podocyte cells, which could help prevent glomerulosclerosis.
Selenium nanoparticles (SeNPs) are considered safe selenium supplements. At appropriate concentrations, SeNPs can promote growth, boost immunity, and modulate intestinal microbiota in aquatic animals. However, their effects on the metabolome of aquatic species have not yet been identified. This study evaluated the in vitro effects of our previous synthesized SeNPs, coated with abalone visceral polysaccharide-protein complexes (PSP-SeNPs), on the proliferation of probiotics and common aquatic pathogens, and the in vivo effects on the gut microbiome and metabolome of tilapia. PSP-SeNPs selectively promoted the growth of probiotics Lactobacillus rhamnosus and Lactococcus lactis, while inhibiting the growth of pathogens such as Staphylococcus aureus and Aeromonas hydrophila. In the fish breeding experiment, 360 healthy juvenile tilapias (initial weight 1.5 ± 0.5 g/fish) were divided into four groups (3 replicates/group, 30 fish/replicate): group C was fed with basal diet, groups Y, M and H, were fed with the basal diet supplemented with 0.3 mg/kg of Na2SeO3, 0.3 mg/kg of PSP-SeNPs, and 4.5 mg/kg of PSP-SeNPs, respectively. All fish were tested after 7 weeks of breeding in a recirculating aquaculture system. Results showed that group M significantly increased intestinal microbial diversity and potential probiotics (e.g., Cetobacterium, Fimbriiglobus, and Gemmata), while significantly decreased potential pathogens (Plesiomonas, Citrobacter freundii, and Aeromonas hydrophila). Groups H and Y significantly reduced Citrobacter freundii, but both groups decreased gut microbial diversity to varying degrees. Additionally, the pathogenic bacterial genus Plesiomonas significantly increased in group Y. In group M, the growth-promoting intestinal metabolite alpha-tocotrienol was significantly upregulated, whereas some essential amino acids were significantly downregulated in groups Y and H. In summary, 0.3 mg/kg SeNPs supplementation can regulate the intestinal microbiota, while 4.5 mg/kg SeNPs and 0.3 mg/kg Na2SeO3 can cause amino acid metabolism disorders. SeNPs showed higher safety than Na2SeO3.
Based on the data from the Kodaikanal and Mount Wilson observatories, we investigate the relationships of the tilt angle of sunspot group (SG), including the mean tilt angle and the tilt-angle scatter, during the declining phase with the parameters of the next solar cycle (SC). The main findings are summarized in the following three points. (1) During the declining phase, the correlation between the mean tilt angle and the tilt-angle scatter is statistically insignificant. (2) Six quantities measured during the declining phase show significant anti-correlations with the strength and amplitude of the next SC, and positive correlations with the duration of the ascending phase of the next SC: the standard deviation of tilt angles, the root-mean-square tilt angle, the mean absolute value of tilt angles, the area-weighted absolute value of tilt angles, the latitude-weighted absolute value of tilt angles, and the area- and latitude-weighted absolute value of tilt angles. (3) The correlations of the mean tilt angle, the area-weighted tilt angle, the latitude-weighted tilt angle, and the area- and latitude- weighted tilt angle during the declining phase with the strength, amplitude, and duration of the ascending phase of the next SC are statistically insignificant. These findings demonstrate that the modulation of parameters of the next SC by the tilt-angle scatter during the declining phase plays a vital role in regulating SC variability.
Mohamed M. Refaey, Ahmed I. Mehrim, Mahmoud F. Salem
et al.
This experiment was designed to examine the impacts of different dietary protein levels (DPLs) and their interaction on the growth and some physiological indices of juvenile striped catfish, Pangasianodon hypophthalmus, reared at different stocking densities (SDs) for 15 weeks. A total of 1440 striped catfish (initial weight = 10.0 ± 2.2 g) were randomly allocated into six equal treated groups (three replicates per treated group). Fish were fed two DPLs of 25 % and 30 % and reared under different SDs of 20, 40, and 60 fish/m3. The obtained results indicated that with increasing DPL, growth parameters, and digestive enzyme activities, the liver function enzyme activities, serum protein constituents' levels, and concentrations of thyroid hormones significantly increased, while levels of serum glucose, total cholesterol, and triglycerides remarkably decreased. On the other hand, increasing SD negatively affects growth, digestive and liver enzyme activities, some hematological parameters, and fish-body chemical analysis. The interaction between DPLs and different SDs significantly improved the most estimated parameters with increasing DPLs despite intensifying SDs. In general, afforded striped catfish diets containing 30 % DPL and stocked at 20 fish/m3 presented the best performance, consumed feed efficiency, and health status. Thus, the interaction between DPLs and SDs demonstrated the favorable benefits of increasing DPLs by diminishing some of the adverse impacts generated by high SDs, which may subsequently lead to high production and increased revenues for fish farmers.
Luke O. J. Harrison, G. Engelhard, R. H. Thurstan
et al.
Developed countries are increasingly dependent on international trade to meet seafood requirements, which has important social, environmental, and economic implications. After becoming an independent coastal state following Brexit, the UK faces increased trade barriers and changes in seafood availability and cost. We compiled a long-term (120-year) dataset of UK seafood production (landings and aquaculture), imports, and exports, and assessed the influence of policy change and consumer preference on domestic production and consumption. In the early twentieth century, distant-water fisheries met an increasing demand for large, flaky fish such as cod and haddock that are more abundant in northerly waters. Accordingly, from 1900 to 1975, the UK fleet supplied almost 90% of these fish. However, policy changes in the mid-1970s such as the widespread establishment of Exclusive Economic Zones and the UK joining the European Union resulted in large declines in distant-water fisheries and a growing mismatch between seafood production versus consumption in the UK. While in 1975, UK landings and aquaculture accounted for 89% of seafood consumed by the British public, by 2019 this was only 40%. The combination of policy changes and staunch consumer preferences for non-local species has resulted in today’s situation, where the vast majority of seafood consumed in the UK is imported, and most seafood produced domestically is exported. There are also health considerations. The UK public currently consumes 31% less seafood than is recommended by government guidelines, and even if local species were more popular, total domestic production would still be 73% below recommended levels. In the face of climate change, global overfishing and potentially restrictive trade barriers, promoting locally sourced seafood and non-seafood alternatives would be prudent to help meet national food security demands, and health and environmental targets.
The aim of this study was to investigate the effects of dietary Spirulina platensis supplementation on the growth and immunity of Mystus cavasius. Fish were fed on the experimental diets, where the fish meal was replaced with S. platensis meal at 0%, 2.5%, 5.0%, 7.5%, and 10% levels, respectively. Triplicate groups of fish were fed with each diet twice a day near satiation and reared for 10 weeks. After the trial, serum lysozyme levels, whole-body composition, feed utilization, growth performance, and blood characteristics were examined. The pathogenic Aeromonas hydrophila was administered intra-peritoneally to 10 fish from each group and monitored for daily mortality rate. Metagenomics analysis was used to investigate the gut microbiota. When more than 7.5% of fish meal in the diet was replaced with S. platensis meal, the body weight, and specific growth rate were higher than in the control diet. The protein efficiency and feed conversion ratio were also positively affected by dietary S. platensis meal supplementation. The replacement of 7.5–10% fishmeal with S. platensis increased the whole-body protein and ash contents more than the control. The red blood cells, white blood cells, hemoglobin, hematocrit, and mean corpuscular hemoglobin levels of M. cavasius rose when fish were fed 7.5–10% S. platensis compared with the control. The serum lysozyme test result showed an increase in the lysozyme value as dietary S. platensis supplementation was gradually increased. The abundance of bacterial composition was found to be higher with gradually increasing S. platensis supplementation, especially up to 5–10% supplementation level. The total mortality of fish was decreased with higher inclusion of S. platensis when challenged by A. hydrophila. These findings suggest that dietary S. platensis has positive effects on the growth and immune system of M. cavasius, and maintaining dietary replacement of 7.5–10% fish meal with S. platensis can be suggested for feed formulation of M. cavasius.
Abstract Since it is not usually possible to observe all of the fish in a school, it is difficult to monitor farmed fish in a crowded cage with the aim of scrutinising their condition. One possible solution to this problem is the use of simulations. The aim of this study is to simulate fish movement in a cage to be able to propose an optimal monitoring method based on limited observations made by instruments. In this study, we observed a Yellowtail ( Seriola quinqueradiata ) school in a fish cage at a fish farm and attempted to simulate their movement. The Yellowtail, while milling in a cage, forms a stable truncated cone‐shaped school. We successfully reproduced this shape of school by including the effects of negative phototropism and the hypothetical forces that fish experience from the cage wall, in addition to the forces of attraction, repulsion and orientation that have been postulated in previous studies. We also included the effect of intraspecific interaction. We hypothesise that longer fish exert a greater repulsive force on smaller fish. The results of our simulation suggest that the position of any fish in a school is thus a function of its length.