Cage Aquaculture Research Articles

Modelling Open Ocean Aquaculture Structures Using CFD and a Simulation-Based Screen Force Model

The numerical framework of the open source CFD solver REEF3D is utilised to study the fluid–structure interaction of an open ocean aquaculture system and waves. The presence of the net is considered in the momentum equations of the fluid using a forcing term based on Lagrangian–Eulerian coupling and the hydrodynamic loads on the net. They are defined semi-empirically using a screen force model. Here, the hydrodynamic force coefficients are calculated from the net geometry and fluid velocity. The necessary force coefficients are predicted from a new simulation-based screen force model. Here, CFD simulations are performed to obtain the hydrodynamic loads on net panels for varying net geometries, angles of attack and velocities. Then, a Kriging metamodel is applied to fit a polynomial to the data. The proposed net model is validated against measurements for waves and current through rigid net panels and applied to simulate the dynamics of an open ocean aquaculture cage in waves. In current, the model predicts the drag forces and velocity reduction within a 10% error band, whereas it tends to under-predict the lift forces by up to 20%. In waves, the model tends to over-predict the crests with increasing wave height, but the deviations are also within a 10% error band.

Impact assessment of biofouling resistant nano copper oxide–polyaniline coating on aquaculture cage nets

Biofouling is a major issue in aquaculture cages and nano materials based antifouling strategies became more prominent in recent years. Polyethylene aquaculture cage net surface which is modified with polyaniline and nano-copper oxide (CuO), reported to have biofouling resistance. Leaching of nano CuO from the net to the aquatic environment and its bioaccumulation in fish is the major concern against the technology adoption. The present study aimed to understand the accumulation of copper in fishes grown in a nano CuO treated aquaculture cage net. Studied the leaching pattern of nano CuO, biofouling inhibition and changes in strength of the cage net due to the nano CuO treatments. Fishes grown in the treated cages exhibited normal growth characteristics with no signs of abnormalities and also copper in their organs were within the prescribed standard limit. The CuO treated cage net exhibited excellent biofouling resistance and the percentage of occlusion of mesh by foulers were 56.77% more efficient than untreated cage net. Rate of nano CuO leached to the aquatic system was less than 8 μg/g·d. The fouling organism assemblage on untreated and treated net was 18 and 11 species, respectively. Major calcareous shelled foulers were absent on treated nets. The study highlighted the potential application of nano CuO treatment to control biofouling in aquaculture cages.

Loading Capacity of Water Pollution from Cage Aquaculture in South Kalimantan Rivers

Decreasing of water quality and exceeding the loading capacity of water pollution are the main causes of the high mortality of cage aquaculture along the river in South Kalimantan province. The research objective was to analyze the river water quality profile, and to evaluate the loading capacity of water pollution around the cage aquaculture. The observations were made at 3 points (upstream, middle and downstream) along Harus river where is the center for the development of cage aquaculture in Banua Lawas District, Tabalong Regency. On each of these points, measurement of physico-chemical parameters of water and flow rates were carried out. Measurement and data collection were performed twice with intervals between measurements for 30 days. Water quality parameters analyzed were water temperature, pH, TSS, NH<sub>3</sub>-N, NO<sub>3</sub>-N, PO<sub>4</sub>-P, BOD, COD, and DO. Based the eight water quality parameters measured, there were three parameters that tend to exceeding the loading capacity of water pollution on all the river segments, namely PO<sub>4</sub>-P, (at middle = 16 kg day<sup>-1</sup>, and downstream = 459 kg day<sup>-1</sup>), BOD (at upstream = 301 kg day<sup>-1</sup>, middle = 547 kg day<sup>-1</sup>, and downstream = 2,086 kg day<sup>-1</sup>) and COD (at upstream = 521 kg day<sup>-1</sup>, middle = 380 kg day<sup>-1</sup> and downstream = 1,249 kg day<sup>-1</sup>). Exceeding the load capacity of BOD and COD were prone to cause depletion of DO in the river in which can potentially cause massive fish mortality.

Monitoring Marine Aquaculture and Implications for Marine Spatial Planning—An Example from Shandong Province, China

Offshore marine aquaculture can not only provide a large amount of high-quality food for humans, but also effectively relieve the pressure on land space. However, it is difficult for traditional statistical data to reflect changes in spatial dynamics in marine aquaculture. It is also difficult to effectively manage marine space development given the current status of spatial planning regarding land–sea integration. This study used multiphase satellite remote sensing images of Shandong Province together with an automatic extraction algorithm for aquaculture to obtain spatial distribution data of marine aquaculture (surface of seawater visible by remote sensing, types of rafts, and cage aquaculture). GIS spatial overlay analysis technology was used to superimpose marine functional zoning (2010–2020) data for comparative analysis to evaluate implementation effectiveness and existing problems in marine functional zoning. Results showed that the critical time regarding substantial change in marine aquaculture area was around 2010, concurrent with the implementation of the current round of marine functional areas. The aquaculture area in the agricultural and fishery planning area increased from 228.33 km2 in 2010 to 344.6 km2 in 2018, and the overall proportion of aquaculture increased from 65.53% to 70.48%. This indicated that marine function planning can exert a guiding influence. The port area and protection area were found to be other major areas for the expansion of marine aquaculture. We also used field investigations in uncovering the phenomenon of the combined marine functions of marine aquaculture and tourism. On this basis, the role of spatial information technology in marine spatial planning was analyzed, which revealed the importance of coordinated integration of land–sea space for effective control of marine development.

The Influence of a Suspended Cage Aquaculture Farm on the Hydrodynamic Environment in a Semienclosed Bay, SE China

Hydrodynamic responses of the aquaculture farm structures have been increasingly studied because of their importance in informing the aquaculture carrying capacity and ecological sustainability. The hydrodynamical effect of the suspended cage farm on flow structures and vertical mixing in the Sansha Bay, SE China, is examined using observational data of two comparative stations inside and outside the cage farm. The results show that current velocities are relatively uniform in the vertical except a bottom boundary layer outside the cage farm. Within the cage farm, the surface boundary layer produced by the cage-induced friction is obvious with current velocities decreasing upward, combining the classic bottom boundary layer to form a “double-drag layers” structure in the water column. The cage-induced drag decreases with water depth in the surface boundary layer with a maximum thickness of 3/4 the water column, and the current velocities can be reduced by 54%. The cage-induced friction can also significantly hinder the horizontal water exchange in the farm. Periodic stratification phenomena exist at both stations under the influence of lateral circulation. However, the subsurface (5–10 m below the sea surface) water column below the cage facilities is well-mixed as indicated by the vertical density profile, where the velocity shear (10–3 m–2) is about 10 times higher than that of the subsurface layer outside the cage farm. Therefore, we speculate that the well-mixing of the subsurface water column results from the local turbulence induced by the velocity shear, which in turn is produced by the friction of cage structures.

Floating cage aquaculture production in Indonesia: Assessment of opportunities and challenges in Lake Maninjau

<abstract> <p>Aquaculture in floating cages in Lake Maninjau has recorded significant growth, even as the largest contributor to total annual aquacultural production in West Sumatra Province. In this study, we assessed the output of floating net cages in Lake Maninjau, Indonesia. We analyzed the characteristics of fish farming, fish fry, feed supply, and production, and the challenges and opportunities for increasing aquacultural production in the future. We used purposive sampling in this study with an interview questionnaire to obtain information from 80 fish-cultivating households in Lake Maninjau. We then used descriptive statistical methods of data analysis. The results showed that in 2018, there were 17596 floating net cages. The majority (n = 33, 41.25%) of fish farmers have 20 to 40 floating net cages per household, and 67.5% (n = 54) are used for tilapia cultivation. We recorded that 77.5% (n = 62) of fingerlings were sourced from private hatcheries. Six companies supply commercial feed pellets in an amount of 2000 tons per month for aquaculture activities. Japfa Comfeed Indonesia Ltd. provides 35% of the feed. The fish species cultivated were Nile tilapia, common carp, giant gourami, Clarias catfish, and pangasius catfish, with gross yields (kg/m<sup>3</sup>/cycle) of 12, 11.5, 10.4, 7.88, and 8.89, respectively. Fish farmers face challenging conditions: poor water quality, mass mortality of tilapia, high fish feed prices and low fish sale prices, and noncash payments. We recommend ensuring the development of floating net cages in Lake Maninjau for a more sustainable future. Therefore, it is necessary to operate as many as 6000 nets to meet guidelines for carrying capacity and cultivation based on the Regional Regulation of Agam Regency Number 5 of 2014 concerning the management of Maninjau Lake, which is accessible proportionally by eight villages. Giant gourami is prioritized for cultivation because it is resistant to poor water quality and high market prices.</p> </abstract>

Performance Assessment of a Combined Circular Aquaculture Cage Floater and Point Absorber Wave Energy Converters

Performance Assessment of a Combined Circular Aquaculture Cage Floater and Point Absorber Wave Energy Converters

Factors Affecting Fishers’ Attitude and Willingness to use Cage Aquaculture as an Alternative Livelihood for Reducing Fishing Pressure in Haor Areas, Bangladesh

Inland capture fisheries are providing cost of livings of about 1.2 million BDT in Bangladesh. However, overexploitation causes the declination of the abundance of native fish species which adversely affects the livelihoods of haor dwellers. The present study was conducted in two haor villages (Sutarpara and Changnoagaon) of Kishoreganj, Bangladesh to explore the factors (economic and non-economic) affecting fishers’ attitude and willingness about cage aquaculture considered as livelihood alternative for reducing fishing pressure. The methodologies applied to do this study were semi-structured face-to-face interview, key informants and questionnaire survey using Likert scale (LS), focus group discussions (FGD). The result revealed that willingness to switch from traditional way of fishing to cage aquaculture activities was significantly (p<0.05) higher in those fishers’ groups that had more inclination in fishing activities. Simultaneously, non-economic factors like powerful traders and fishers, traditional belief, taking risk, launching period of cage aquaculture venture and investment duration played vital role in decisions on whether to fish or not. The economic factors were fewer in number than non-economic factors. This comparative research is significantly important for future social aquaculture researchers as well as the country policy makers for giving emphasis to gather data based on the prevailing economic and non-economic factors to innovate alternative livelihood activity concurrently.

Alternative Livelihood Potential of Fishermen Households in The Liukang Tangaya Aquatic Conservation Area, Pangkajene Islands Regency

The potential and development of alternative livelihoods for fishermen households in marine conservation areas must be relevant to or refer to the context of contextual technical considerations (locality), and not a deduction or bottom-up policies derivation so that they can grow and develop (facilitating) local fishermen's households in production activities that are complementary to increasing the spirit of the locality, community harmonious with natural resoureces and welfare through the opening of new economic spaces that can be accessed and controlled by the local community themselves. This type of research is qualitative with a case study approach. Data was collected through direct observation and in-depth interviews with some informants. There are 30 fisherman’s household which is used as primary data source informants. Qualitative analysis based on technical variables, namely community interest, availability of local raw materials/natural resources, availability of labor and market opportunities through content analysis from compilation of interview results through snowball technique with reference to triangulation principle. While quantitative data analysis is carried out with business feasibility indicators for new alternative types of livelihoods that can be applied to fishermen households, namely B/C Ratio indicators, Return Of Investment (ROI), and Payback Period (PP). Research result show that based on the analysis of technical variables, the potential alternative livelihoods carried out by fishermen households are seaweed aquaculture, floating net cage aquaculture, processed fishery products, coconut and household scale chicken and duck farming. The B/C ratio value of these businesses is > 1 with very profitable criteria to do.

Vibration mitigation of an integrated structure consisting of a monopile offshore wind turbine and aquaculture cage under earthquake, wind, and wave loads

To realize multi-purpose exploration of marine resources, a novel design consisting of a monopile offshore wind turbine and steel aquaculture cage in an integrated structure is proposed in this paper; the structure is denoted as MOWTAC. Based on the theories of the screen model, a hydrodynamic analysis module is developed in the OWT simulation tool FASTv8. Then, in combination with a seismic analysis module, the fully coupled analysis model of the MOWTAC is established in the updated FAST v8. Based on the coupled model, the dynamic characteristics and coupling mechanisms of the MOWTAC under earthquake, wind, and wave loads are investigated. A tuned mass damper (TMD) is applied to the MOWTAC under earthquakes, and the influence of the TMD parameters on the mitigation effects is studied. Furthermore, a multiple tuned mass damper (MTMD) with various tuning frequencies is applied, and comparisons with the TMD are carried out. Based on the reduction of seismic responses using the TMD and MTMD, vibration control methods and related design parameters are recommended for the MOWTAC under earthquake, wind, and wave loads.

Isolation and characterization of Bacillus spp. from aquaculture cage water and its inhibitory effect against selected Vibrio spp.

The aim of this study was to evaluate the probiotic potential of Bacillus strains with antibacterial activity against Vibrio spp. in vitro. 13 Bacillus strains were selected using Bacillus-selective agar. Among the strains elected in the preliminary screening for antagonistic effect, only the strain PJ_11 with better antibacterial ability was selected and used in further experiments. Based on the morphological and biochemical features with phylogenetic analysis of the 16S rRNA sequencing, selected strain was identified as B. pumilus. PJ_11 showed probiotic properties such as able to survive in wide range of temperatures and salinity, tolerance to 0.3% oxgal and pH 2.0, and high cell-adhesion activity. In this study, there was no special feature regarding the inhibitory effect of the isolate against Gram-positive or Gram-negative indicator bacteria. However, the inhibition effect of the culture was found to be greater than that of the supernatant. PJ_11 exhibited strong antibacterial activity against Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio anguillarum that were isolated from fish (Dicentrarchus labrax) with disease symptoms. The inhibition diameter of strain PJ_11 ranged from 17.63 to 26.68mm. In co-culture assay with the strain PJ_11 culture, the growth of V. vulnificus, V. parahaemolyticus and V. anguillarum was inhibited after 120h with an initial level of 1.0 × 108CFU/mL. PJ_11 had antibiotic susceptibility to commonly used antibiotics in aquaculture but only resistant to chloramphenicol. Isolate was non-hemolytic. These findings suggested that the strain PJ_11 is good probiotic candidate and may have potential applications to prevent/control vibriosis in aquaculture.

Spatio-temporal variability of a chlorophyll-a based biomass index and influence of coastal sources of enrichment in the Algerian Basin

This study investigates the spatial distribution and temporal variability of chlorophyll-a (Chl-a) biomass in the Algerian Basin (AB) along its meridional and cross-shore dimensions, focusing on coastal enrichments. After correcting most atmospheric disturbances in the daily MODIS Level-2 data series between 2003 and 2018, a fortnightly climatology of 1-km resolution Chl-a has been generated to account for specific coastal features previously poorly evidenced from 4-km Level-3 data. The AB is characterised by two extreme seasons of high and low biomass, separated by sharp transitions, that characterise the offshore domain. The coastal area (<10 km) reveals an intense and distinct dynamic associated with highly productive local hotspots rather than seasonal variability. A biomass index is proposed as the horizontally integrated Chl-a concentration from the coastline to the most offshore extension of the 0.5 mg m-3 Chl-a isopleth. This index separately quantifies the cumulative biomass of both offshore and coastal domains with large alongshore variability. Low values (<5 g m-2) were observed in the offshore area during summer and high values during the spring blooms (up to 40 g m-2), while maximum values (>50 g m-2) were locally observed in the coastal domain. The narrow coastal area alone represents 44% of the total biomass, with coastal hotspots where the enrichment is up to 5 times higher than offshore. Multivariate modelling of the potential factors favouring coastal enrichments shows that the phytoplanktonic biomass in coastal waters is mainly associated with enrichments from wadis and seasonally from city sewage as well as by the presence of a bay. A separate source of enrichment is undoubtedly associated with the presence of aquaculture cages.

Potensi Harmful Algae Bloom (HAB) di Keramba Jaring Apung Perairan Desa Sumberkima Kecamatan Gerokgak, Kabupaten Buleleng

Sumberkima Village is one of the villages in Gerokgak sub-district that has the most floating net cage cultivation in Buleleng regency. The development of fish farming activities with floating net cage techniques had an impact on the waters. The leftover feed that is not consumed, and the metabolic wastes produced by aquaculture increased the fertility of the waters so that it is feared that phytoplankton are potentially causing the Harmful Algae Bloom (HAB) phenomenon in the floating net cage aquaculture area of Sumberkima village which can have an impact on water quality, aquatic biota and cultivator’s income. This study aimed to identify the genus phytoplankton that has the potential to cause Harmful Algae Bloom (HAB) and the abundance of phytoplankton that has the potential to cause the Harmful Algae Bloom (HAB) phenomenon. This research was conducted in February 2019 at the floating net cage in Sumberkima village, Gerokgak sub-district, Buleleng regency. The study was spread over 10 points of floating net cages determined by purposive random sampling to represent floating net cages in Sumberkima village. Data were analyzed descriptively with phytoplankton abundance calculation using APHA (2005) method. From the research that has been done, it was found that the type of phytoplankton suspected to have HAB potential was found in 2 class groups namely Dinophyceae with a percentage of 15% consisting of: Prorocentrum, Dinophysis, Alexandrium and Peridinium then Bacillariophyceae with a percentage of 85% as many as 7 genera include: Thalassiosira, Pseudonitzschia, Biddulphia, Nitzschia, Skeletonema, Chaetoceros and Ceratium.

Research on intelligent damage detection of far-sea cage based on machine vision and deep learning

Far-sea cage is an essential way for aquaculture. In the process of far-sea cage aquaculture, the damage of net structure can cause severe economic property losses to farmers, so it is necessary to check the cage's integrity. At present, the typical way to inspect cages is to hire professional divers for manual inspection. This type of inspection is time-consuming and has security concerns. This paper proposes a method for detecting the damage of a far-sea cage based on machine vision and deep learning, which can detect the structure of a far-sea cage in real time and accurately detect the damaged area of the cage. Firstly, the cage image data were collected by autonomous cruising ROV. According to the characteristics of the captured images, an improved multi-scale fusion algorithm was proposed to better the performance of denoising and smoothing effect of the original method. Secondly, we use the MobileNet-SSD and key-frame extraction detection method to detect the damage of underwater cage video. The MobileNet-SSD model has been optimized in model size and detection speed compared with the SSD model. In the experiment, the simulated damaged images of the far-sea cage were used for testing. The experimental results have shown that the scheme can improve the efficiency of far-sea cage inspection and accurately detect the damaged areas in the cage in real-time.

Analysis of the Competitiveness of Floating Net Cage Aquaculture in Indonesia

The purpose of this study is to analyze the competitiveness profile of floating net cage aquaculture in Indonesia. The research was conducted in February – June 2021 at the Directorate General of Aquaculture, Ministry of Marine Affairs and Fisheries of the Republic of Indonesia. The data collection method used in this study is the literature survey method. Primary data in the form of questionnaires with expert judgment respondents as many as 13 people consisting of 11 Lecturers of the Faculty of Fisheries and Marine Sciences, Padjadjaran University, and 2 employees of the Directorate General of Aquaculture, Ministry of Marine Affairs and Fisheries of the Republic of Indonesia regarding the proportion of competitiveness of floating net cage aquaculture fisheries. Secondary data in the form of statistical data on floating net cage aquaculture in 2017 was obtained from the Directorate General of Aquaculture, Ministry of Marine Affairs and Fisheries of the Republic of Indonesia. Data analysis was carried out by using quantitative descriptive analysis. The results showed that Central Java Province which was supported by facilities and infrastructure variables, West Java Province which was supported by human resources and production variables, and North Sulawesi Province which was supported by science and technology variables were in the top three with very high competitiveness category, while the Riau Islands Province and the Bangka Belitung Islands Province are in the bottom two ranks with the low competitiveness category.

Organochlorine Pesticides and Polychlorinated Biphenyls in Sediment Impacted by Cage Aquaculture in the Volta Basin of Ghana.

Seventeen organochlorine pesticides (OCPs) and seven indicator polychlorinated biphenyls (PCBs) residues in 80 sediment samples from four cage aquaculture farms on the Volta Basin were determined to find out the extent of their contamination as well as their risk to biota in the aquatic ecosystem. The extracted residues of the OCPs and PCBs were analysed on a gas chromatograph equipped with an electron capture detector and mass spectrometer, respectively. Eleven (11) OCPs: methoxychlor, δ-HCH, o,p'-DDD, α-endosulphan, β-HCH, o,p-DDE, p,p-DDE, p,p'-DDT, β-endosulphan, endrin, and heptachlor and seven (7) PCBs: PCB 18, PCB 28, PCB 52, PCB 101, PCB 138, PCB 153, and PCB 180 were detected in the sediments from the farms. The OCPs level ranged < LOD - 33.0µg/kg. δ-HCH (8.154 ± 0.414µg/kg), α-endosulphan (6.000 ± 1.414µg/kg), o,p'-DDD (2.010 ± 1.46µg/kg), endrin (13.867 ± 8.716µg/kg), and α-endosulphan (0.503 ± 0.398µg/kg) were predominant with frequencies of detection 100%, 45%, 68%, 92%, and 25% in fish farms A, B, C, D and controls, respectively. PCBs concentrations ranged 0.042-5.320ng/g wet weight. PCB 153 recorded the highest concentration of 3.328 ± 1.700ng/g in farm D. PCB 18 and PCB 180 dominated the profiles in the sediment from all the farms. The ecotoxicological risk of the OCPs and PCBs in the surface sediment using the SQGs indicated that ∑HCH in the sediment from all the farms except that the controls may pose a health risk to the benthic organisms. Therefore, a comprehensive remedial intervention is required to arrest the situation.

Optimization of stocking density for mono-sex Nile tilapia (Oreochromis niloticus) production in riverine cage culture in Bangladesh

Determining a suitable stocking density of fish for an ambient condition is very important for economic benefit in cage aquaculture, which is not yet tested for many species in Sylhet district of Bangladesh. Therefore, current research was conducted in order to explore the effect of various stocking densities on growth and production performances of mono-sex Nile tilapia cage aquaculture in an open running water body, the Gurukchi River. Considering maximizing economic benefit, it is the first instance of such research in the Sylhet district of Bangladesh. In the three treatments (T1, T2, and T3), fingerlings were stocked at 40, 60 and 80 fish/m3, respectively with initial weights of 39.51 ± 0.91, 39.61 ± 0.71 and 38.54 ± 0.57g, respectively. Fish were fed with commercial floating pellet feed at 8-4% of their body weight. The results showed that growth performance of Nile tilapia significantly decreased with increasing stocking density. The mean total yields were 13.25 ± 0.48, 18.43 ± 0.88 and 22.76 ± 0.63 kg/m3 in T1, T2 and T3, respectively, which showed significant variations (p < 0.05) among treatments. The benefit-cost ratio analysis revealed that T1 (1.512 ± 0.022) and T2 (1.499 ± 0.063) were significantly (p < 0.05) higher than T3 (1.191 ± 0.071), with no significant differences observed between T1 and T2. Notably, a significantly higher (p < 0.05) net profit was observed in T2 than in T1 and T3. Overall, 60 fish/m3 stocking density was the best stocking density for commercial cage aquaculture of tilapia in a riverine environment of the north-eastern Bangladesh.

Motion Simulation for Triangular-Shaped Autonomous Underwater Vehicle (TAUV) with Controllable Rudder

The dynamic model and motion simulation for a Triangular-Shaped Autonomous Underwater Vehicle (TAUV) with independently controlled rudders are described in this paper. The TAUV is designed for biofouling cleaning in aquaculture cage fishnet. It is buoyant underwater and moves by controlling two thrusters. Hence, in this research work, the authors designed a TAUV that is propelled by two thrusters and maneuvered by using an independently controllable rudder. This paper discussed the development of a mathematical model for the TAUV and its dynamic characteristics. The mathematical model was simulated by using Matlab and Simulink to analyze the TAUV’s motion based on open-loop control of different rudder angles. The position, linear and angular velocities, angle of attack, and underwater vehicle speed are all demonstrated in the findings.

Determination of effective standards for the introduction of fodder additive Aquatan in the diet of rainbow trut with a biological assessment of the influence on fisheries

In connection with the global tendency to prohibit the use of antibiotics in animal husbandry, the prospect of using in ichthyopathological practice preparations from plant materials, which are mostly non-toxic, rarely cause side effects, have an antibacterial effect against a wide range of pathogens of bacterial diseases, opens up. One of these preparations is the feed additive Aquatan (Farmatan Aqua) based on ellagitannins from sweet chestnut wood manufactured by Tanin Sevnica (Slovenia). The aim of this work was to study the effect of different dosages of Aquatan on the survival rate, the rate of mass accumulation and the growth rate of rainbow trout reared in the industrial conditions of the cage farm on the waste warm waters of the nuclear power plant and to assess the production and economic efficiency of the application. The tests were carried out for 34 days in February-March 2021 on the basis of an aquaculture cage farm of LLC “Fish Federation”, located in the water area of the waste canal of warm waste water of the Leningrad nuclear power plant (LNPP) in the area of the LNPP-2 industrial zone in the city of Sosnovy Bor, Leningrad Region. The object of the study is rainbow trout yearlings brought from different fish farms. A total of 247,131 specimens were planted, with an average weight of 156.5–235.7 g and a total weight of 43 950.67 kg. The main hydrochemical indicators of water at the enterprise for the trial period met the water quality requirements for growing salmon fish OST 15.372-87. The feeding was carried out with the production compound feed for salmonids of the firm Alltech® Coppens Supreme-22. In experimental cages, fish were fed with compound feed with the addition of the preparation Aquatan at various concentrations (1, 2, and 3 g/kg of feed); in the control, feed without additive was used. As a result of the experiment, a positive effect of the Aquatan additive in dosages of 2–3 g / 1 kg of feed on growth, mass accumulation, survival and feed costs was established, while when adding 1 g / 1 kg of feed, such an effect was not recorded.

Genome-wide association analysis on host resistance against the rotten body disease in a naturally infected population of large yellow croaker Larimichthys crocea

Large yellow croaker (Larimichthys crocea) is one of the most important marine fish in China, representing the highest yield of fish species in marine net cage aquaculture. In recent years, the rotten body disease caused by scuticociliate was the main perniciousness for the fish fry, and led considerable economic losses. To date, no treatments had proven to be effective to the disease, so it was urgent to carry out the researches on disease-resistance breeding of this fish. Based on genome resequence for a natural population, a genome-wide association study (GWAS) to identify those loci associated with the rotten body disease resistance was performed in this work. A total of 3000 fish from 6 sub-populations were collected, and 270 phenotypic extremes were selected for genotyping. Two analysis models were employed to verify the accuracy and reliability of GWAS results. 2,019,067 SNPs were remained, and 14 SNPs were finally identified to be correlated with disease resistance, explaining phenotypic variance ranging from 5.4% to 9.2%. Within these regions, 5 candidate genes, NF-κB1, UBXN1, PTX3, DAB2IP and CYR61, which were involved in NF-κB signaling pathway, suggested the importance of NF-κB signaling pathway in the disease resistance. These results showed the complex polygenic architecture in large yellow croaker resistance against parasite scuticociliate. It also provided valuable foundation for future marker-assisted selection breeding of large yellow croaker against scuticociliate.