Fish Cages Research Articles

Environmental impacts of fish cage cultures in the southern Caspian Sea.

In the last two decades, cage culture industries have developed in Iranian seas, supplying a portion of the needed protein and contributing to food security. In this paper, environmental impacts of cage culture are investigated, focusing on the physical, hydrodynamical, chemical, geological, and biological oceanographic aspects at the Abbas Abad fish farm in the southern Caspian Sea. Multidisciplinary field measurements were conducted from fall 2018 to late summer 2019 in different oceanographic aspects. Results showed that the cages have not significantly affected the hydrodynamics and physical parameters of the aroundwater, and have actually caused a slight decrease in current speed within a few 10m of the cage. The maximum levels of inorganic phosphates, total phosphorus, total organic phosphorus, nitrite, nitrate, ammonium, total nitrogen, silicate, BOD5 and COD were 22ppb, 34.91ppb, 26.92ppb, 6ppb, 103.69ppb, 69.5ppb, 1423.99ppb, 679.06ppb, 1.9 mg/l, 80 mg/l respectively. The water quality is considered safe and not concerning based on levels of phosphate, nitrite, nitrate, ammonium, BOD5, and COD. Also, planltonic (phyto and zooplankton) and benthic communities and benthic around the cages were the same with sourounding waters. This paper presented comprehensive information about the effects of cage culture farms on the surrounding waters of the Caspian Sea.

Acoustic tags versus camera—a case study on feeding behaviour of European seabass in sea cages

IntoductionWith the expansion of the aquaculture industry, the need arises for scalable, reliable, and robust methods to assess fish behaviour in sea cages to guide operational management, which includes feeding optimisation and welfare assessments. Fish cage monitoring utilising either acoustic transmitters or underwater cameras is well-studied. However, the relationship between those two different measurement types seems to have not been explored, nor have they been evaluated together in one experimental site.MethodsIn our 1-month study, we compared the activity of 14 sentinel fish and the artificial intelligence (AI)-inferred speed of individuals from the European seabass (Dicentrarchus labrax) sea cage population in three feeding trials. Comparisons include a maximum activity comparison using persistent peaks, fish behavioural pattern establishment and retention, and periodical behavioural patterns.ResultsOur results demonstrate that under certain circumstances, both technologies are interchangeable from the perspective of persistent peaks and periodicity, but complementary when it comes to behaviour analysis such as food anticipatory behaviour (FAB).DiscussionWe anticipate that our findings will stimulate advances where multiple sensor types are in use to achieve a more holistic understanding of fish behaviour in the aquaculture sector using underwater technologies.

Status of phytoplankton biomass and physico-chemical parameters of water during fish cage culture fallowing: a case study of Southeast Arm of Lake Malawi

Status of phytoplankton biomass and physico-chemical parameters of water during fish cage culture fallowing: a case study of Southeast Arm of Lake Malawi

Особенности морфофункционального и физиологического состояния осетровых рыб с нефрокальцинозом в условиях садковой аквакультуры

When growing sturgeon fish in cages, which are especially valuable nowadays, great attention should be paid to their health. Along with other pathological manifestations of various natures, a disease such as kidney nephrocalcinosis can pose a potential danger to these aquaculture objects. This pathology was recorded in juvenile sterlet (age – 0+ years), in immature individuals of Russian sturgeon (age – 2 years), in which clinical and pathological examinations were carried out, including pieces of kidneys were selected for histological analysis, blood samples for carrying out hematological and biochemical studies. The appearance of nephrocalcinates in the kidneys of sturgeon fish was confirmed using histological methods: corresponding pathological transformations were found on micropreparations of the kidneys of Russian sturgeon and sterlet. Morphophysiological changes in the condition of the kidneys of the studied sturgeon fish can be assessed as moderate and minor, not life-threatening. Thus, 60% of the examined individuals of Russian sturgeon did not have any detected pathohistological changes in the organ; among sterlet there were 80% of such individuals. When analyzing hematological and biochemical blood parameters, deviations of some indicators were found. Thus, the sterlet had a low level of hemoglobin, all fish had an insufficient number of red blood cells in the blood; in Russian sturgeon, a high level of pathologically altered erythrocytes was determined, the amount of serum protein was increased, deviations were found in the ratio of its fractions, high levels of uric acid, low levels of triglycerides, β-lipoproteins, ALT and AST activity in the blood. Indirectly, these changes in the physiological state of sturgeon fish with nephrocalcinosis indicate that this disease most likely arose as a result of the influence of a complex of factors on the fish, among which the main ones may be disturbances in the hydrochemical regime and the balance of feeding.

A Study on the Extraction of Satellite Image Information for Two Types of Coastal Fishery Facility Fish Cages and Rafts Influenced by Clouds and Vessels

Research on the extraction of satellite information for the areas of coastal fish cages and rafts is important to quickly grasp the pattern and structure of the coastal fishery aquaculture industry. This study proposes a multi-feature and rule-based object-oriented image classification (MROIC) model, integrating spatial-spectral enhancement techniques with object-based image analysis classification methods. The MROIC model enhances spectral information by constructing ratio bands alongside principal component analysis, subsequently employing rule sets, edge detection algorithms, and comprehensive algorithmic merging techniques. It is applicable to satellite image classification tasks in complex environments, including influence of clouds and vessels. The information of fish cage and raft facilities is extracted via the MROIC model on the southwest coast of Xiapu County, Fujian Province, as an example. The results showed that the MROIC model attained an average total classification accuracy of 90.43% and a Kappa coefficient of 0.80. Extracting the area of fisheries facilities under the influence of clouds and vessels can provide better extraction accuracy and lower omission error. The MROIC model proposed in this study demonstrates high extraction accuracy and strong applicability, offering technical support for government planning in fishery facility areas and aiding in the risk assessment and management efficiency of fishery facility insurance.

One-Way CFD/FEM Analysis of a Fish Cage in Current Conditions

This study explores the hydrodynamic behaviour of a fish cage in a steady current by employing a fluid–structure interaction model with one-way coupling between a fluid solver and a structural model. The fluid field around the fish cage is predicted using a computational fluid dynamics solver, while the stress and deformation of the netting are calculated using finite element structural algorithm with solid elements reflecting their real geometry. The fluid velocity and hydrodynamic pressure are calculated and mapped to the structural analysis model. The fluid–structure interaction model is validated by comparing drag force results with published experimental data at different current conditions. Instead of modelling the netting of the fish cage as porous media or using lumped mass methods, the complete structural model is built in detail. The analysis of the fluid field around the nets shows that the change in the current condition has a limited impact on the flow behaviour, but the increase in the current velocity significantly enhances the magnitude of the drag force. This study reveals a reduction in flow within and downstream of the net, consistent with prior experimental findings and established research. Mechanical analysis shows that knotted nets have better performance than knotless ones, and although fluid pressure causes some structural deformation, it remains within safe limits, preventing material failure.

Clean valorization of distillery industry co-product for fish cage aquaculture: a waste-to-wealth approach

The present study investigated the use of brewery waste as a sustainable and cost-effective feed ingredient for Pangasianodon hypophthalmus farming in floating cages in tropical reservoirs. Three isonitrogenous and isocaloric diets were formulated: brewery waste-based floating (T2), brewery waste-based sinking (T3), and soybean meal-based floating (control). Fish fingerlings were fed each diet for 60 days and their growth performance, feed utilization, nutrient retention, and carcass composition were evaluated. Fish fed brewery waste-based floating feed (T2) had the highest weight gain, specific growth rate, and protein efficiency ratio, and the lowest feed conversion ratio. Their growth performance was statistically significant (p < 0.05) compared to fish fed brewery waste-based sinking feed (T3), but not statistically different (p > 0.05) from fish fed soybean meal-based floating feed (control).The cost of brewery waste-based floating feed was 31.45% lower than the cost of soybean meal-based floating feed. Overall, the results of this study suggest that brewery waste is a promising feed ingredient for Pangasianodon hypophthalmus farming in floating cages in tropical reservoirs. It can be used to replace expensive soybean meal without compromising fish growth performance. The use of brewery waste also reduces feed costs and makes cage farming of Pangasianodon hypophthalmus more economically sustainable.

Hydrobiological and Geochemical Responses to Trout Cage Aquaculture in Lake Ecosystem

This study investigates the seasonal dynamics and interrelationships between geochemical and hydrobiological parameters in lake ecosystems impacted by fish cage farming in Lake Ladoga, Russia. Environmental conditions at three trout farms were assessed, focusing on water and sediment quality as well as benthic and zooplankton communities. For each farm, two categories of sampling sites were designated: cage sites and reference sites located 100–600 m away from the cages. Fieldwork was carried out across four seasons in 2023: February, June, August, and November. The findings indicate that intensive fish feeding results in significant organic waste accumulation beneath trout cages, altering the composition and abundance of planktonic and benthic organisms. The organic matter content in sediments beneath the cages during periods of intensive feeding was found to increase 2–5 times compared to the reference sites. In winter, accumulated organic matter in the sediments underwent mineralization, bringing hydrobiological indicators closer to the reference values. The geochemical and hydrobiological parameters analyzed in this study serve as valuable indicators for developing ecological monitoring approaches in freshwater cage aquaculture.

Forecasting Upwelling Phenomena in Lake Laut Tawar: A Semi-Supervised Learning Approach

The current climate change is causing the upwelling phenomenon to occur frequently in lakes and reservoirs. As a result of this phenomenon, thousands of fish die, causing floating net cage fish farmers to suffer losses. From existing studies, temperature sensors are used to determine the current condition of a body of water experiencing upwelling or not. Therefore, this study applies clustering to historical climate data from 2017-2023 using a semi-supervised learning approach that produces two labels: "potential for upwelling" and "no potential for upwelling." In the clustering process, the data is divided into two clusters using K-Means Clustering, and Support Vector Machine (SVM) is chosen to classify them. The performance of the proposed algorithm is expressed with accuracy, precision, recall, and F1-score values of 0.99, 0.995, 0.970, and 0.985, respectively. The analysis results show that this model has excellent performance in identifying upwelling potential. By using this method, information about upwelling potential can be obtained more quickly and accurately, allowing fish farmers to take appropriate preventive measures. This study also shows that the combination of K-Means Clustering and Support Vector Machine (SVM) can be effectively used to analyze historical climate data and generate useful predictions.

Influence of cage fish farms in the dietary aspects at the individual level of a non-native fish species

Influence of cage fish farms in the dietary aspects at the individual level of a non-native fish species

Fabrication of Hierarchically Porous “Fish Cage”‐like Carbonaceous Nanomaterials via Soft Template‐assisted Strategy for Cr Removal: Accelerated Stepped Adsorption and Enhanced Coordination Effect

AbstractThe negative impact of heavy metal pollution, specifically chromium (VI), on human health is well‐documented. To solve this issue, hollow anisotropic hierarchically porous “Fish Cage”‐like carbonaceous nanomaterial (N,S‐HFC‐180) with multi‐active groups is synthesized. Hierarchically porous structure provides stepped adsorption effect. The addition of K2C2O4 leads to an increase in the specific surface area of N,S‐HFC‐180 to 1914.21 m2 g−1 (an increase of ~552 times compared to HFC‐180). Thiourea introduces multi‐active groups that act as “Barbs” in “Fish Cage”, further reducing Cr(VI) to Cr(III) and sequestrating Cr(III) by coordination effect. Subsequent batch studies suggest that N,S‐HFC‐180 exhibits a high removal capacity of 164.29 mg g−1 for Cr(VI) at pH=2. The kinetics and isotherm analyses display an outstanding maximum adsorption capacity of 393.88 mg g−1 at 298 K. In addition, even after seven cycles, the removal rate of Cr(VI) using N,S‐HFC‐180 remains&gt;85.00 %, and it effectively reduces the concentration of electroplating wastewater from 55.82 to 0.14 mg L−1. Pore filling, chemical reduction and chelation, hydrogen bond and electrostatic attraction are the primary adsorption drivers. The results suggest that, the recoverable N,S‐HFC‐180 highlights its viability for practical applications in wastewater treatment processes.

Experimental study on hydrodynamic performance of the semi-submersible vessel-shaped fish cage

Deep-sea net cages play a vital role in expanding offshore farming in modern marine fisheries. In this paper, a model-scale 1:40 tank experiment was conducted for a vessel-shaped truss-structured single-point mooring deep-sea aquaculture net cage. The study focused on the hydrodynamic characteristics, including the effect of current, wave, and net on the mooring force, heave, and pitch motion behaviors. Experimental results indicate that the mooring force increases with the current velocity, draught of the cage, and wave height, but decreases with the wave period increase. Both heave and pitch movements amplitudes increase with wave height. While heave motion amplitude initially declines and then ascends with wave periods, pitch motion shows the opposite pattern. Besides the net has an obvious damping effect on the pitch motion. These results can provide data support for the design and offshore installation of vessel-shaped truss-structured net cages in the future.

Lymphocystis viral disease impacts the diversity and functional profiles of the skin microbiome in gilthead seabream.

Lymphocystis viral disease (LVD) is a highly transmissible disease known to affect multiple fishes worldwide. Although this disease is usually benign, mortalities can occur in cases where infection is severe or secondary infection with bacterial pathogens and parasites occur. However, little is known about the bacterial dynamics of fish with LVD or what bacterial pathogens may be responsible for secondary infections. Here we assessed the effects of LVD on the skin microbiome of gilthead seabream by comparing 30 symptomatic, asymptomatic and recovered (three weeks after infection) fish using 16S rRNA high-throughput sequencing. Our results show that LVD is associated with significant changes in microbiome structure and function. Importantly, fish pathogens like Tenacibaculum maritimum and some Vibrio species increased their abundance. Moreover, microbial metabolic activities of the commensal microbiota that may confer some protection to fish were suppressed in diseased fish. After reducing fish cage density to treat symptoms and three weeks of recovery, the abundance of pathogens was significantly reduced and microbiome functionality was recovered, although community structure remained significantly different. These results show that LVD can severely disrupt the bacterial communities of the skin of the gilthead seabream, leading to an increase in bacterial pathogens responsible for relevant diseases in gilthead seabream farms.

Viability and Profitability of Cage Fish Farming on Lake Victoria: A Case of Bugiri-Kiwuulwe Cage Fish Farms in Wakiso District, Uganda

Fisheries and aquaculture have crucial contributions to world’s wellbeing and prosperity. Among aquaculture practices, cage fish farming ranks highest in fish production. This study was set out to assess viability and profitability of cage fish farming on Lake Victoria, a case of Bugiri-Kiwuulwe cage fish farms in Katabi Town Council, Wakiso District, Uganda. The study sought to assess water quality physico-chemical parameters within and around fish cages, investigates costs of materials used in fish cage fabrications and production, and to find profitability of cage fish farm units. A case study design with quantitative and qualitative approaches were employed to obtain data for the stated objectives. A total of 66 respondents from a target population of 79 study participants were used to generate data, which were entered into SPSS version 23 for analysis. Both male and females, including a few youths participated in the study. Their education levels ranged from primary to university. Majority were single, while others were married and a few were widows and widowers. Most of the water parameters tested were in the recommended ranges by WHO and supported aquatic life, hence promoted cage fish farming apart from total hardness, calcium and magnesium hardness, calcium, chemical oxygen demand and potassium which were slightly below the recommended ranges. Majority of the farmers had participated in the business for less than 5 years and the activity brought profits to the farmers an equivalent of UGX 8,943,200 ($ 2,354) to the farmers per season, an indicator that the business venture is very profitable and viable. Hence, it can easily be adopted by members of the community for improvement of their livelihoods. It is recommended that more research be undertaken such that there is formulation of the fish feeds at the local level aimed at the reduction of the higher costs incurred on the imported fish feeds. The government is also encouraged to subsidize on the taxes imposed on implements used in cage fish farming for encouraging more and more farmers to join in the business venture.

Pollution Characteristics, Risk Assessment and Source Identification of Heavy Metals in Surface Sediments from the Cage Fish Farm of Poyang Lake, China

ABSTRACT With the development of cage culture, increasing heavy metals concentrations are being taken into sediments. The accumulation of heavy metals in sediments may cause long term environmental issues and pose threat to human health. Fourteen surface sediment samples were collected to assess the contamination status and potential ecological risk of heavy metals, and identify their potential sources from the cage fish farm of Poyang Lake. The concentrations of Cu, Pb, Zn, Cd, Cr, As and Ni in the sediments were measured by ICP-MS. The geo-accumulation index, enrichment factor and potential ecological risk index were implied to evaluate their pollution levels and ecological risk. The principal component analysis was used to identify their potential sources. The results showed that all of the examined heavy metals content exceeded their background values. These heavy metals (except Cd, Cr and As) presented moderately polluted level. Cu showed significant enrichment, Zn, Pb and Ni exhibited moderate enrichment, As and Cd presented minimal enrichment. Cu and Cd posed a moderate ecological risk, and the other heavy metals posed a low ecological risk. The comprehensive potential ecological risk was associated with considerable ecological risk. Cage culture, smelting, mining and agriculture activities were their primary pollution sources.

Numerical Modelling of Fish Cage Structural Responses in Regular and Irregular Waves Using Modified XPBD

Abstract The structural response of gravity-type fish cages in waves and current is numerically investigated. A Morison model is adopted to compute the hydrodynamic forces acting on the net ropes of the aquaculture nets and a screen model is used to compute the hydrodynamic forces on the net twines of the fish cages. The irregular waves are created based on the JONSWAP wave spectrum. The structure of the aquaculture nets is modeled using a modified extended position-based dynamics (XPBD) algorithm. The proposed method is effectively validated against the published experiment data to ensure its accuracy and reliability. The static response of the fish cage at various current speeds and the dynamic responses of the fish cage in regular and irregular waves are analyzed. Results show that the volume of the investigated fish cage is reduced by 30% in a current of 0.5m/s. The tension at the bottom net can reach about five times of maximum tension of the case without current. In the regular or irregular waves, the drag force of the fish cage is higher than that in a uniform flow with the same current speed and the fish cage volume decreases. The increase in drag force rises from the coupling between the waves and current. Therefore, the hydrodynamic model including the regular and irregular modeling, Morison model and screen model is successfully implemented into the framework of the present modified XPBD algorithm to provide the structural response of fish cages in waves and current.

Features of environments for cage fish farming in the Astrakhan Region on example of the Khurdun River

Features of environments for cage fish farming in the Astrakhan Region on example of the Khurdun River

Technology of the fish abundance accounting in fish farming cages using hydroacoustic and software tools

The purpose of the work: improvement of methods of fish number accounting in growing cages and reservoirs of fish farms using hydroacoustic tools and information technologies.Methods used: solving the problem of non-contact (non-invasive) measurement of the number of fish in cages using the hydroacoustic echo integration method. Investigation of the reflective properties of fish using a calibrated scientific echo sounder with a split beam. Carrying out measurements with different numbers of fish in cage. Identification and analysis of factors affecting the accuracy of the echo integration estimation of the number of fishes in cage.Novelty: the elements of novelty are the use of a scientific echo sounder with vertically oriented antenna and split beam to estimate the number of fishes in cages, the algorithm for calculating the number of fishes in cages by the echo integration method, the results of the study of reflective properties of Amur carp and identified optimal measurement conditions that allow hydroacoustic estimates of number with maximum accuracy.Results: the dependences of target strength on the linear size of Amur carp are obtained. An algorithmic scheme for calculating the number of fishes in cages by the hydroacoustic echo integration method has been developed. Experiments were carried out with different numbers of fish in the cage. It is established that the main factors affecting the accuracy of the population estimate are the number of individuals in the cage and the daily distribution of fish. Measurements at night and at concentrations above the threshold (50 pcs./m2) can significantly bring the estimated and true numbers of fish in the cage closer and reduce the variability of density estimates.Practical significance: solving the problem of remote measurement of the fish number in growing cages will allow farmers to optimize feed needs, which, in turn, will ensure rapid growth of fish without overfilling it and not polluting the reservoir.

Comparison of water quality, planktonic community, and volatile organic compounds in the seawater from five cage culture areas of large yellow croaker

The rapid development of marine fish cage farming has led to ecological damage, adversely affecting fish quality. Significant regional quality differences in large yellow croaker under similar farming conditions suggest that the water environment plays a crucial role in fish quality. Using full-length18s/16 s rRNA sequencing with bacterial absolute quantity and headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC–MS), we investigated the planktonic community and volatile organic compounds (VOCs) in seawater from cages housing large yellow croaker at five major mariculture sites in China, including ND (26.627°E, 119.638°N), NJ (27.479°E, 121.052°N), DT (27.981°E, 121.196°N), NC (28.470°E, 121.907°N), and DJ (30.198°E, 122.698°N). Notably, three dominant ciliates, Mesodinium rubrum, Strombidium sp., and Pseudotontonia simplicidens, were identified in NJ as bioindicators for water quality. Additionally, NJ cages had the highest bacterial biomass with 54 % Synechococcus CC9902, and the lowest abundance of bacteria with pathogenic activities. These may explain NJ's optimal water quality parameters and the highest eukaryotic biodiversity. In contrast, DT and DC contained only the core ciliate M. rubrum, with no dominant ciliate in ND. Styela gibbsii, a filter feeder, predominated in ND cages, adhering to the net. The occurrence of red tide-causing species and pathogenic bacteria or fungi was notable in DJ, DC, DT, and ND, including Akashiwo sanguinea, an unclassified Dinophyceae, Gyrodinium fusiforme, Pirum gemmate, Candida parapsilosis, Hortaea werneckii, and Pseudomonas juntendi. Bacterial functional analysis showed that ND cages harbored unique strains linked to ureolysis and various pathogenic activities. Co-association networks suggested that 2,4-Di-tert-butylphenol and pentadecane might play roles in communication within plankton communities. A rise in pleasant VOCs such as acetyl valeryl, pentadecane, butyl butyrate, tetradecane, and 5-butyldihydro-2(3H)-furanone was observed in DJ, DC, DT, and NJ, compared to ND. The results provide valuable insights for improving aquaculture practices and mitigating environmental impacts. The results provide valuable bioindicators for monitoring water quality using microbial communities and VOC profiles.

A Review of the Hydroelastic Theoretical Models of Floating Porous Nets and Floaters for Offshore Aquaculture

The present review focuses on the theoretical model developments made in floating flexible net fish cages and the floating bodies application to offshore aquaculture. A brief discussion of the essential mathematical equations related to various theoretical models of flexible net cages in the frequency domain is presented. The single and array of floating or submerged flexible net cages connected with or without mooring lines are discussed. Further, as the combined effect of the hydroelastic behaviour of floaters and the flexible behaviour of fish cages are necessary to assess their efficiency and survivability from structural damages, the issues and the knowledge gap between the recent and future models are also discussed. In conclusion, the practical suggestions concerning advancements in future research and directions within floating flexible net cages and the hydroelastic response of elastic floaters are highlighted.