The Center for Aquaculture Technologies

We investigated the dietary effects of the single application of Saccharomyces cerevisiae, Lactobacillus bulgaricus, and their combination on growth, proximate composition of whole fish body, antioxidant defense, and histoarchitecture of hapa-reared Mugil capito. Healthy fish (Fish weighed = 10.30 ± 0.10 g at first) were randomly allocated into 4 equal groups, each with three replicates. These groups were designed as follows: (1) a group fed a basal diet without probiotics (control), (2) a group fed a diet containing S. cerevisiae (4 g/kg diet), (3) a group fed a diet containing L. bulgaricus (2 g/kg diet), and (4) the last group fed a diet containing a combination of both, all for a duration of 60 days. Probiotic-treated groups showed significantly better growth and nutrition utilization than the control group. Significant differences were observed in the crude fat and crude protein contents among the groups, with the combination group exhibiting the highest levels. However, there were no significant variations in ash content across all groups. The highest hepatic antioxidant capacity (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) enzyme activities) was observed in the combination group. Thiobarbituric acid reactive substance (TBARS) concentrations were decreased significantly in all probiotic groups, suggesting improved oxidative stress resilience in these groups. The histomorphological analysis of the hepatopancreatic tissues revealed well-arranged parenchyma, increased glycogen storage, and melanomacrophage centers in probiotic-treated groups, particularly the combined probiotics group. Furthermore, the probiotic supplementation improved the histoarchitecture of the intestinal villi compared to the control group. To put it briefly, combined dietary administration of these probiotics improved growth, body composition, antioxidant defenses, and hepatic and intestinal health in hapa-reared M. capito, highlighting their promising role in promoting welfare and productivity.

This study investigated the dietary effects of coated l-ascorbic acid (LA) on growth, feed utilization, survival, serum biochemical indices, immunity, antioxidant capacity, and intestinal and hepatopancreatic histology of the pre-adult red swamp crayfish. Four isoproteinous and isolipidic diets were formulated to contain several LA levels as 0, 1300, 1600, and 1900 mg/kg and designated as control (LA0), LA13, LA16, and LA19, respectively. However, the analyzed LA concentrations in diets were 0.00, 199.57, 360.45, and 487.50 mg/kg in LA0, LA13, LA16, and LA19, respectively. Triplicate treatments of crayfish (21.60 ± 0.14 g) were fed the test diets and reared in fiberglass tanks with a density of 20 individuals per each for eight weeks. Results revealed that all LA treatments had significantly enhanced growth performance compared to the control. Of interest, the LA16 treatment recorded the highest final tank biomass, biomass gain, total feed intake, condition factor, and muscle yield among the other treatments. The tank feed conversion ratio was significantly decreased in LA treatments compared to the control. Moreover, dietary LA16 and LA19 had significantly higher survival rates (93.3%) compared to (85.0%) in the LA0 group. All dietary doses of LA significantly increased serum parameters (total protein, albumin, globulin, lysozyme activity) and respiratory burst activity compared to the LA0 treatment. Dietary LA16 significantly boosted the hepatopancreatic antioxidant capacity, manifested by decreased malondialdehyde concentrations, increased catalase, superoxide dismutase, and glutathione peroxidase enzyme activities, and reduced glutathione content compared to the LA-free diet. A normal histoarchitecture of the hepatopancreatic tubules was found in all LA treatments except with some minor degenerative changes in the tubular lumen, and hepatopancreatic cells associated with enlarged nuclei were found in the LA19. However, normal intestinal histoarchitecture was found in all treatments with no recorded intestinal lesions. Of interest, the polynomial regression performed on the analyzed LA concentrations suggested that 380 mg/kg would be suitable to provide maximal biomass gain for pre-adult crayfish. In conclusion, results revealed that coated LA could enhance the growth, immunity, and antioxidant capacity of pre-adult red swamp crayfish, suggesting its potential as a functional and necessary micronutrient for crayfish diets.

Salmonella isolated from dairy farms has a significant effect on animal health and productivity. Different serogroups of Salmonella affect both human and bovine cattle causing illness in both reservoirs. Dairy cows and calves can be silent Salmonella shedders, increasing the possibility of dispensing Salmonella within the farm. The aim of this study was to determine the genomic characteristics of Salmonella isolates from dairy farms and to detect the presence of virulence and antimicrobial resistance genes. A total of 377 samples were collected in a cross-sectional study from calves, peri-parturient cow feces, and maternity beds in 55 dairy farms from the states of Aguascalientes, Luis Potosi, Tlaxcala, and Zacatecas. Twenty Salmonella isolates were selected as representative strains for whole genome sequencing. The serological classification of the strains was able to assign groups to only 12 isolates, but with only 5 of those being consistent with the genomic serotyping. The most prevalent serovar was Salmonella Montevideo followed by Salmonella Meleagridis. All isolates presented the chromosomal aac(6)-Iaa gene that confers resistance to aminoglycosides. The antibiotic resistance genes qnrB19, qnrA1, sul2, aph(6)-Id, aph(3)-ld, dfrA1, tetA, tetC, flor2, sul1_15, mph(A), aadA2, blaCARB, and qacE were identified. Ten pathogenicity islands were identified, and the most prevalent plasmid was Col(pHAD28). The main source of Salmonella enterica is the maternity areas, where periparturient shedders are contaminants and perpetuate the pathogen within the dairy in manure, sand, and concrete surfaces. This study demonstrated the necessity of implementing One Health control actions to diminish the prevalence of antimicrobial resistant and virulent pathogens including Salmonella.

We evaluated the growth performance of pacu and tambaqui and their reciprocal hybrids (tambacu and paqui) under different feeding programs. We raised 30 individuals from each species and their respective crosses, distributing them into three replicate cages with 10 individuals each. Throughout the 5-month experimental period, the fish were weighed six times while exposed to diverse feeding regimens involving three commercial diets with varying combinations of crude protein (CP) levels: 24%, 28%, and 32%. Growth curves were adjusted using nonlinear models. The evaluation period was insufficient for adjusting the logistic model for the tambaqui and paqui treatments with the highest initial protein intake. Pure pacu had a higher (p < 0.05) growth rate (k = 0.0185) than in the tambacu hybrid (k = 0.0134) and proved to have an early performance since animals from this group reached their weight at inflection faster. Despite growing more slowly, tambacu reached a higher (p < 0.05) final weight (A = 1137.12) than in the pacu (A = 889.12). Among the feeding programs, animals that received less CP showed greater growth potential; however, longer evaluation is important to verify if the initial CP intake has no significant positive effect on fish growth.

The increasing use of plastics and the growing concern about their impact on the environment and living beings makes it necessary to study how microplastics (MP) affect aquaculture systems. In order to gain an in-depth understanding of these systems, this study covers the water intake, the purification treatment at the inlet, the water in the culture tanks, as well as the feed used in the feeding and the organism itself. For this purpose, five samples were taken, both in the water line, feed and sea bass during the weeks of the experiment. It is shown that the available purification systems reduce the amount of MP entering from the receiving environment. However, new MP are observed in the sea bass tank, which may be due mainly to those added through the feed and found in the feed, as well as in the piping and other materials used in current aquaculture systems (PTFE, PA, among others). If focusing on the feed that can reach the consumer, in the case of this study, carried out with sea bass, some types of MP (PE, PTFE, PS and PA) were found in 4 head samples and 4 skin/muscle samples. Although inlet water purification systems manage to reduce a high percentage of MPs in the system, it is observed that there are other access routes that should be considered and reduced in aquaculture facilities to prevent them from reaching the human consumer.

Larval cod require live prey as food, and prey concentration (PC) and feeding frequency (FF) often affect their growth and survival. Apart from this, water exchange rates/water flow (WER/WF) and water current (WC) also affect the prey resident time in the tank and larval/early juvenile behaviour, respectively. High water current is also known to induce stress in finfish larvae, and this stress response is believed to be dependent on larval developmental stage. Thus, we conducted a study to evaluate three larval rearing protocols varying in prey concentration, feeding frequency, and water current/exchange rate. Three protocols were used: low prey concentration (PC), low feeding frequency (FF), and low water flow (protocol 1); medium PC, medium FF, and medium WF (protocol 2); and high PC, high FF, and high WF (protocol 3) (see Table 1). Larvae were sampled periodically for growth and cortisol measurements. Cortisol extraction and radioimmunoassay (RIA) were conducted using methods previously validated for cod larvae. Larvae reared using protocols 2 and 3 were significantly bigger and heavier than larvae reared using protocol 1. Rearing protocol had a significant effect on the cortisol level in larval cod. Larvae showed a developmental stage-dependent stress response. Protocol 2 had significantly higher survival than protocols 1 and 3. Our results indicate that an intermediate PC, FF, and WF (protocol 2) is suitable during cod larval rearing.

Citation: Machimbirike, V.I.; Vasquez, I.; Cao, T.; Chukwu-Osazuwa, J.; Onireti, O.; Segovia, C.; Khunrae, P.; Rattanarojpong, T.; Booman, M.; Jones, S.; et al. Comparative Genomic Analysis of Virulent Vibrio (Listonella) anguillarum Serotypes Revealed Genetic Diversity and Genomic Signatures in the O-Antigen Abstract: Vibrio anguillarum is the most frequent pathogen affecting fish worldwide. The only known virulent strains of V. anguillarum are serotypes O1, O2, and O3. Genetic differences between the serotypes that could shed insight on the evolution and serotype differences of this marine pathogen are unknown. Here, we fully sequenced and characterized a strain of V. anguillarum O1 (J382) isolated from winter steelhead trout (Oncorhynchus mykiss irideus) in British Columbia, Canada. Koch's postulates using the O1 strain were replicated in naïve lumpfish (Cyclopterus lumpus) and compared to O2. Phenotypic and genotypic comparisons were conducted for serotypes O1, O2, and O3, using biochemical tests and bioinformatic tools, respectively. The genome of V. anguillarum O1 (J382) contains two chromosomes (3.13 Mb and 1.03 Mb) and two typical pJM1-like plasmids (65,573 and 76,959 bp). Furthermore, V. anguillarum O1 (J382) displayed resistance to colistin sulphate, which differs from serotype O2 and could be attributed to the presence of the ugd gene. Comparative genomic analysis, among the serotypes, showed that intra-species evolution is driven by insertion sequences, bacteriophages, and a different repertoire of putative ncRNAs. Genetic heterogeneity in the O-antigen biosynthesis gene cluster is characterized by the absence or the presence of unique genes, which could result in differences in the immune evasion mechanisms employed by the respective serotypes. This study contributes to understanding the genetic differences among V. anguillarum serovars and their evolution.

Nowadays, the importance of using macrophytes in accumulation of heavy metals has gained great concerns. So, this study aimed at extracting the land use/cover types of three indices and surface temperatures in the habitats inside 100 m buffers from recent satellite images around three highly economic macrophytes namely; Phragmites australis, Typha domingensis and Potamogeton pectinatus species. In addition to land surface temperature (LST), three important indices expressing the land cover of habitats namely; normalized different vegetation index (NDVI), normalized different water index (NDWI), and normalized different moisture index (NDMI) were extracted to find out there influence on the efficiency of macrophytes in the accumulation of these metal ions; Fe, Cu, Zn, Cd and Pb. The Polynomial regression models were calculated to predict the accumulation factors of plants within the remotely sensed indices and LST. Results showed different accumulation values for individual or more metals in the below-ground and above-ground parts of macrophytes within different habitats. This study considers as an innovative approach using remote sensing technique and satellite images for the selecting of species that can accumulate more metals within different habitats. The obtained results will be useful for the optimal management of these macrophytes in Lake Burullus, a Ramsar site.

Abstract Background Chrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON) health status were investigated in Asejire Reservoir (AR) and Lagos Lagoon (LL), South-west Nigeria. Fish samples collected were separated into sexes. Growth pattern {length (cm); weight (g), Isometric index, condition factor (K)} were measured. Heavy metals (lead (Pb), iron (Fe), zinc (Zn), copper (Cu), and chromium (Cr) in ppm concentrations were determined in Lagos Lagoon and Asejire reservoir. Results Fish samples ranged at one male to one or two females. No significant difference in length and weight of O. niloticus between locations. Significant difference in weight occurred in C. nigrodigitatus between locations; highest condition factor was recorded in Asejire Reservoir O. niloticus, (ARON); lowest condition factor was observed in Asejire Reservoir C. nigrodigitatus (ARCN) as this indicated a negative allometric value, normal in Bagridae species. Male species possessed higher condition (K)—factor than female species within locations, between locations, between species, and within species, female C. nigrodigitatus having higher condition factor than male ARCN. Highest isometric value occurred in ARON and lowest in Lagos Lagoon C. nigrodigitatus (LLCN). Male ARON had highest isometric value, and O. niloticus species had higher isometric value (b ≤ 3) and positive allometric (b > 3); and C. nigrodigitatus has negative allometric (b

Background Infectious Salmon Anaemia virus (ISAV) is an orthomyxovirus responsible for large losses in Atlantic salmon ( Salmo salar ) aquaculture. Current available treatments and vaccines are not fully effective, and therefore selective breeding to produce ISAV-resistant strains of Atlantic salmon is a high priority for the industry. Genomic selection and potentially genome editing can be applied to enhance the disease resistance of aquaculture stocks, and both approaches can benefit from increased knowledge on the genomic mechanisms of resistance to ISAV. To improve our understanding of the mechanisms underlying resistance to ISAV in Atlantic salmon we performed a transcriptomic study in ISAV-infected salmon with contrasting levels of resistance to this virus. Results Three different tissues (gills, head kidney and spleen) were collected on 12 resistant and 12 susceptible fish at three timepoints (pre-challenge, 7 and 14 days post challenge) and RNA sequenced. The transcriptomes of infected and non-infected fish and of resistant and susceptible fish were compared at each timepoint. The results show that the responses to ISAV are organ-specific; an important response to the infection was observed in the head kidney, with up-regulation of immune processes such as interferon and NLR pathways, while in gills and spleen the response was more moderate. In addition to immune related genes, our results suggest that other processes such as ubiquitination and ribosomal processing are important during early infection with ISAV. Moreover, the comparison between resistant and susceptible fish has also highlighted some interesting genes related to ubiquitination, intracellular transport and the inflammasome. Conclusions Atlantic salmon infection by ISAV revealed an organ-specific response, implying differential function during the infection. An immune response was observed in the head kidney in these early timepoints, while gills and spleen showed modest responses in comparison. Comparison between resistance and susceptible samples have highlighted genes of interest for further studies, for instance those related to ubiquitination or the inflammasome.

In developing a holistic and innovative approach to determining the carrying capacity in marine finfish aquaculture, we carried out a modified Delphi exercise in which we asked industry experts to identify the factors influencing the production levels of the activity under different scenarios. We disseminated and discussed three rounds of questionnaires in sectoral roundtables and workshops with experts, culminating in the development of a simple formula that adapts production levels to the physical, ecological, social and economic conditions of the activity on the Spanish Mediterranean coast. We used this formula to approach the carrying capacity of the system. Based on the developed model and its theoretical application, we estimated the carrying capacity for floating cages on the Spanish Mediterranean coast at 119,404 t—about 1.2 times the current production level of 96,440 t. We therefore concluded that, subject to the execution of an in-situ validation of the model, the production level of floating nurseries on the Spanish Mediterranean coast could be increased by up to 33.5%.

This study examines the impacts of the Covid-19 pandemic and adaptive strategies to build resilience among stakeholders and actors in the aquaculture value chain in Kenya. Prior to the pandemic, Kenya's aquaculture sector had progressed from a minor player to a key component of the country's fish food system. Fish and fishery products have become the most heavily traded food commodity in the Kenyan markets. The results indicate the pandemic had significant impacts on the access to aquaculture inputs, fish trade, and socio-economic livelihoods of the aquaculture value chain stakeholders and actors during the two whole years. Thus, initial and longer-term adaptive measures, in particular by private sector players and government agencies, can contribute to building resilience to multiple shocks and stressors among stakeholders and actors in the aquaculture sector. Some measures include a government incentive package to overcome the damage to the fisheries and aquaculture sector, improve farming operations and win the market trust and adopt new methods such as intelligent sensors, camera systems and automated or remotely controlled monitoring/feeding strategies to reduce labour intensity. Such measures and policies can cushion the sector against future shocks occasioned by such pandemics.

Water scarcity is on the rise due to an abrupt increase in population and the competitive use of water resources. This necessitates the reuse of wastewater such as grey water and aquaculture wastewater for irrigation, particularly in developing countries, where treatment and reuse of wastewaters have not been prioritized. This study was conducted to evaluate aquaculture wastewater treated in constructed wetland using Azolla pinnata, and studies that comprehensively evaluated the efficacy of A. pinnata for the treatment of aquaculture wastewater is scanty. Aquaculture water from a Research Fishpond was treated with A. pinnata on a 5 day retention time, untreated and treated water from the constructed wetland (CW) were sampled for determination of physical, chemical and microbiological properties. The result from the study showed that the constructed wetland was capable of removing microbial counts within the 50 and 77% range, while the percentage removal of heavy metal ranged within 2.98 and 82.4% In addition, in most cases the physico-chemical properties of the treated aquaculture wastewater were within the permissible limit recommended by Food and Agriculture Organization (FAO) and World Health Organization (WHO), hence, its suitability for irrigation purpose. However, the chemical properties were significantly highest (p < 0.05) in the untreated aquaculture water compared to groundwater and treated aquaculture water. Therefore, this study has innovatively shown the efficacy and effectiveness of A. pinnata in treating aquaculture wastewater for irrigation purposes.

Abstract The performance, efficiency of consumed feed, body chemical composition, survival rate, antioxidant and immunity parameters of Nile tilapia (Oreochromis niloticus) reared in probiotic-treated water were studied. Two hundred apparently healthy Nile tilapia (20 ± 0.3 g) juveniles were reared for 70 days in five different treatments, with five replications as the control group (clean water) and four test groups with two probiotics strains (Bacillus toyonensis and Geobacillus stearothermophilus) at two different levels (1 or 2 × 105 CFU ml−1) applied in rearing water. Fish reared in water supplemented with G. stearothermophilus at low level demonstrated significantly enhanced (p

This study was conducted to elucidate the effects of rearing conditions on the composition of different phospholipid (PLs) classes and triacylglycerols (TAG) of the thick-lipped grey mullet (Chelon labrosus), a muscle originating from seawater and geothermal water. The major fatty acids in the examined lipid classes of the two fish groups were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1n-9), linoleic acid (C18:2n-6), arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n-3), and docosahexaenoic acid (C22:6n-3). The analyses demonstrated that the fatty acid profiles of the PL classes in the seawater fish group were characterized by the predominance of n-3 polyunsaturated fatty acids (PUFA). By contrast, in geothermal fish, the distribution of PUFA series proportions differed between the phospholipid fractions. It was found PUFA n-3 was particularly abundant in PS and PI, while the n-6 series dominated the PC and PE PUFA group. Nonetheless, it was found that neutral lipid fatty acids were characterized by saturated fatty acids (SFA) followed by monounsaturated fatty acids (MUFA) in the seawater fish and by PUFA in the geothermal fish. The results presented here give useful information on the role of lipid classes in the physiological adaptation of C. labrosus which can serve for the optiminzation of these aquaculture systems.

The effect of dietary Kefir supplementation on the biometric, biochemical, and histological parameters of Nile tilapia (Oreochromis niloticus) exposed to aflatoxin B1 (AFB1, 200 µg/kg diet) contamination was studied. The yeasts were dominant in Kefir followed by lactic and acetic acid bacteria. The Kefir showed relatively interesting antioxidant potential in the DPPH• (IC50 = 0.9 ± 0.02 mg/ml) and ABTS•+ (IC50 = 2.2 ± 0.03 mg/ml) scavenging activities, Fe3+‐reducing power (EC0.5 = 1.2 ± 0.01 mg/ml), and β‐carotene bleaching assay (IC50 = 3.3 ± 0.02 mg/ml). Three hundred and sixty Nile tilapia weighing 23 ± 5 g were divided into four groups (30 fish/group with 3 replicates), and fed with diets containing Kefir (D2), AFB1 (D3), and Kefir+AFB1 (D4) for 4 weeks, whereas D1 was kept as control group where fish were fed with basal diet. The Kefir supplementation in D4 group significantly increased (p < .05) the percent weight gain as compared to D3 group. Moreover, Kefir improved the antioxidant enzymes in the liver, such as catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities, that significantly increased (p < .05) by 2‐, 3‐, and 1.5‐folds, respectively, as compared to D3 group. The Kefir treatment significantly decreased (p < .05) the liver malonaldehyde content by ~50% as compared to D3 group. Histopathological analysis revealed the hepatoprotective effects of Kefir by showing normal liver histological architecture in D4 group, as compared to degenerative changes observed in D3 group. These results suggest that Kefir could be considered as a potential probiotic in Nile tilapia feed to mitigate the AFB1 harmful effects. Kefir showed interesting in vitro antioxidant and DNA‐protective activities. Aflatoxin B1 (AFB1) enhanced the oxidative stress in the liver. Kefir improved the antioxidant defense systems in Nile tilapia subjected to AFB1. Kefir prevented AFB1‐induced hepatotoxicity in Nile tilapia.

Knowledge of the genetic diversity and composition of stocks enable decisions on improving the genotypes of the populations, and their family structure, as well as the potential use of genetic selection. The present study sought to assess the genetic diversity of stocks of Penaeus vannamei used by the shrimp industry in Cuba by means of single nucleotide polymorphisms (SNP) and growth-related traits. We evaluated a total of 310 individuals from six stocks using a panel of 192 SNPs. We analyzed the diversity and genetic structure of six commercial stocks. We also compared the stocks using growth-related traits (harvest weight (g), specific growth rate (g), survival (%), yield (kg/ha/harvest), feed conversion efficiency, and culture duration (days). The pair-wise Fst value estimation indicates a moderate level of genetic differentiation among the stocks. The factorial correspondence analysis plots indicated that the six stocks show genetic distinctness. A comparison of some growth-related traits from different stocks showing genetic diversity was performed and, in this study, showed that stock 24 has the highest survival 80.9 ± 1.3% and yield at 1505 ± 50 kg/ha/harvest. From our data, survival negatively correlates with growth (r = −0.55) and feed conversion efficiency (−0.45). The genetic diversity measures indicate that the six stock populations contain moderate to moderately-high levels of genetic diversity. After ten years without new shrimp broodstock introductions into Cuba, there appeared to be little or no inbreeding depression of the growth-related traits.

The use of technologies in assisted reproduction, such as the use of centrifugation, has been reported as a tool that allows separating the best portion of sperm from cryopreserved milt. The main of this work was to compare two separation techniques, differential and density gradient, on thawed Rhamdia quelen milt, based on sperm functionality and fertilization capacity. Three treatments were compared: control, differential centrifugation or pelletization (T1), and density gradient centrifugation (T2). Motility percentage was better for differential (42.58 ± 6.50%) than for the control treatment (32.44 ± 6.03%). Membrane integrity and kinetic parameters was not different between treatments. The presence of normal sperm was higher in T2 treatment (13.55 ± 5.82%) when compared to the control (10.72 ± 3.53%) and T1 (3.97 ± 1.95%). There was a lower rate of morphological tail damage in the T1 (26.91 ± 7.13%) treatment compared to the T2 (37.48 ± 10.81%) and control (45.88 ± 4.84%). For the head morphologies, the lowest percentages were for the control (35.72 ± 5.89%) and T2 (4.89 ± 14.94%) treatments compared to the T1 treatment (62.59 ± 9.67%). In the MTT (3- (4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) test (AU/100 million sptz), the centrifuged treatments resulted in values of 1.58 ± 0.79 (T1) and 2.02 ± 1.88 (T2), better than the treatment control (0.20 ± 0.08). Likewise, the fertilization and hatching rates, respectly, were better for the T1 (76.68 ± 15.22% and 54.62 ± 17.39%) and T2 (69.85 ± 17.85% and 50.87 ± 20.59%) treatments, than the control treatment (40.03 ± 11.67% and 24.14 ± 13.97%). The comparison of differential centrifugation with density gradient centrifugation was carried out for the first time with cryopreserved milt of R. quelen. In summary, both centrifugation techniques proved to be efficient in obtaining a better portion of functional sperm from thawed milt. This is based on the high rates of embryonic survival and hatching obtained after both differential and density gradient separation.