Traditional aquatic product traceability system has problems of tampering data, opaque links, and centralized management. To address the above problems, this paper designs master-slave multi-chain storage model to manage supply chain traceability information based on the analysis of the aquatic product supply chain and key information, so as to ensure the security of private data of enterprises and reduce the storage pressure of single-chain structure. At the same time, this paper designs an on-chain management and control smart contract to intelligently monitor all links of aquatic products from breeding to sales, and manage and control from the source. On this basis, this paper designs the traceability information management system of aquatic product blockchain based on master-slave multi-chain, implements the system based on Hyperledger Fabric, and proves the applicability of the system in combination with the actual application cases. Finally, this paper makes a comparative test with the blockchain single chain architecture. The results show that the storage model proposed in this paper carries out concurrent and hierarchical storage of traceability information, takes into account the two aspects of unnecessary sharing of private data and large single chain load, ensures the authenticity of traceability data, and achieves transparency in the traceability process.

Aquaculture is the farming activity of economical aquatic plants and animals by factitious control in natural or artificial waters. Its utilizing range covers extensive water space which included ocean, intertidal zone, pond, lake, reservoir, and river. As the core part of the fishery, aquaculture plays an increasingly important role in ensuring the supply of high-quality protein, building the water ecological civilization, accelerating the fishery transformation and upgrading as well as promoting industrial economic development. With the status of comprehensive speed up the construction for fishery modernization, aquaculture has gradually from the past reliant resource factors input turned into dependent technology innovation and improving the efficiency of production, furthermore, from pursuing quantity increased into higher quality, better benefit and more sustainable development way. In recent years, over upgrading the pattern with prep facility and equipment progress in aquaculture, the industry faces a flourishing developmental opportunity and serial challenges. This paper synthetically discusses the significance of developing aquaculture, analyzes its current developmental status, and summarizes the major problems which restrict the development of aquaculture. Imperative research-intensive tasks are proposed that involve preserving the genetic resources and researching the breeding technology, improving the target traits and breeding the significant varieties, optimizing the production mode and upgrading the traditional pattern, developing the cultured facilities and creating the large equipment, exploiting the high-efficiency feed and accurately preventing the diseases as well as analyzing the quality safety and constructing the traceability system. Relevant development suggestions are also proposed, such as doing well the integrated layout for scientific and technological innovation, doing real the construction of research platform and base, optimizing the safeguard for policy and law system, doing fine building the regional typical case, which aims to provide the lesson and reference for realizing accelerating from aquaculture country to a strong one.

In the scene of monitoring fishing boat targets at the high point of the fishing port, a fishing vessel target detection model based on improved yolov5 is proposed to solve the problems of frequent loss and detection error of fishing vessel detection. Firstly, the anchor frame is re-clustered by the Kmeans++ algorithm, and the anchor frame size suitable for the fishing vessel data set is selected; Then, the weighted bidirectional feature pyramid network (BiFPN) is used to replace the original Feature Pyramid Networks (FPN) + Pixel Aggregation Network (PAN) structure for fast multi-scale feature fusion; Finally, the detection scale of large targets is removed, the detection scale of smaller targets is added, and three new detection scales are used to improve the detection accuracy of the model for small target fishing vessels. The results show that compared with the original yolov5 algorithm, the accuracy, recall and average accuracy of the improved algorithm are improved by 29.5%, 0.5% and 4.5% respectively, and the number of detection frames per second reaches 90.6, which greatly improves the effect of fishing boat target detection.The research shows that the improved yolov5 algorithm meets the accuracy and real-time requirements of fishing vessel target detection during the fishing moratorium.

Shipping and weighing are important in the process of aquatic products trading. The short distance transport weighing system of live fish was designed to analyze and explain the overall structure design and working principle. The system consists of electric lifting device, pneumatic loading and unloading device, automatic weighing and measuring device and control device. The control part is based on the programmable logic controller (PLC)to drive the electric hoist and the cylinder to lift, load and unload the live fish separately, and convey the fish to the transport vehicle on shore along the inclined chute by self-weight for transshipment to the destination. The software part, based on LabVIEW visualization platform, is designed with a transport system display interface that has the functions of system communication and data storage operation. The application effect of the system shows that the single conveying capacity of 300 kg for the short distance transport weighting system of live fish and the transport amount of 2 t/h have improved the transport efficiency of live fish, reduced a lot of manpower and the mechanical damage rate of live fish, and improved the mechanization level of fishery production.

With the increasing concern of governments and the public about global warming, greenhouse gas emissions have become one of the emerging research hotspots in recent years. However, as an important source of greenhouse gases, freshwater aquaculture ponds have not received enough attention. In this paper, the existing researches on greenhouse gas emission from freshwater ponds at home and abroad are reviewed systematically, the estimation methods and relevant results of carbon dioxide (CO2) and nitrous oxide (N2O) emissions are emphatically introduced, the factors affecting greenhouse gas emission are mainly discussed, and the limitations and improvement direction of current research are discussed. The estimation methods include the carbon footprint concept for assessing CO2, the ORNL method, the IPCC emission factor method and the N2O emission factor method. The results show that the pond emission is huge and cannot be ignored. The influencing factors are mainly analyzed from four aspects, including water temperature, drainage activity, breeding species and breeding mode, which indicates the complexity of greenhouse gas emission mechanism. Finally, according to the current research status and trend of greenhouse gas emissions, the research on greenhouse gas emissions from freshwater aquaculture ponds is prospected from the specific analysis of emission structure and the standardization of estimation methods, so as to promote the development of relevant theories and practices.

Aquaponics is a technology which uses aquaculture effluent to provide nutrients for plants. It produces two crops (fish and plants) from one nitrogen source (fish feed), with such characteristics as efficient use of water and nitrogen sources, no use of fertilizers and antibiotics, and environmental friendliness, which make it a sustainable way of agricultural development. This paper divides the historical process of aquaponics into four stages: the origin stage (before 1970), the beginning stage (1970-1990), the global expansion stage (1990-2010) and the rapid growth stage (2010-present), analyzes three typical systems of aquaponics, proposes the three main developing trends of aquaponics: system construction towards uncoupled, system layout towards urbanized and three-dimensional and hardware facility towards ecological and intelligent, and puts forward four suggestions for development: strengthening the research on the transformation mechanism of nitrogen and phosphorus, building a theoretical model of the system, strengthening the application of artificial intelligence technology, and strengthening the research on commercial-scale systems.

Drying is one of the important methods of storage, processing and production of algaes. Different drying methods have great influences on dehydration efficiency, energy consumption and quality of algaes. This paper analyzes the characteristics, research and applications between using the traditional drying technique and new drying technique for algaes. Researches showed solar-energy drying technique can fully realize the green and environmental protection, an solve the problem of solar energy discontinuity when working together air-source heat pumps; superheated steam-drying products are of high efficiency, low energy consumption, having good rehydration of algaes after drying; vacuum freeze-drying products are of high quality and can maintain the nutrition and functional components of algaes; the far-infrared heating technique is used to dry kelps, compared with the hot air drying, can shorten the drying time and reduce the energy consumption; for drying gracilaria with microwave vacuum drying technique, drying time decreased by 70% than that of air drying. Finally, in this paper, the problems existed in the algae drying techniques and equipment are summarized, the development trends of domestic algae drying techniques and equipment are discussed, and measures and suggestions are put forward.

Hook depth has significant influence on pelagic longline catch performance. This study conducted two-way fluid-structure coupling simulation by using the numerical simulation software ANSYS Workbench 19.2 for tuna pelagic longline which was modeled by Tauti Criterion. In addition, 42 hook depth data measured from tuna pelagic longline operations at 6 survey stations in the high seas near Polynesia Islands (4°S~15°S, 140°W~160°W) in 2016 were compared with the numerical simulation hook depth based on ANSYS Workbench. SPSS t-test was used to analyze the difference between measured hook depth and numerical simulation hook depth. The results show that, the simulated deepest hook depth of pelagic longline is 280~310m, and the hook depth is negatively correlated with velocity. When velocity is low (X=-0.11~0.05 m/s; Y=-0.05~0.03 m/s; Z=0.03~0.11 m/s）, the simulated deepest hook depth is about 310 m. When velocity is high (X=0.28~0.75 m/s; Y=-0.10~0.52 m/s; Z=0.04~0.13 m/s）, the simulated deepest hook depth is about 280 m. There is no significant difference between the simulated and measured hook depth (P=0.241 > 0.05), nor significant difference between the simulated and measured hook depth at each station (P1=0.790, P2=0.337, P3=0.476, P4=0.369, P5=0.175, P6=0.136). The results suggest that the developed longline fishing gear model based on Tauti Criterion and ANSYS Workbench numerical simulation software can be used in the study of longline hook depth.

The net will be contaminated by marine animals and plants and other biofouling in the process of deep-water cage culture, which will affect the water exchange in the cages and is not conducive to the growth and survival of cultured fish. In addition, the contamination of biofouling can cause the weight of the net to increase, thus making it easy to damage the culture equipment. The present paper, based on the analysis of domestic and foreign cage cleaning device and research status quo, compared the technical characteristics of mobile underwater cage cleaning device, tide power type cage cleaning device and underwater cleaning robot, and put forward the future development direction of cage cleaning technology and device with the development of big data and other emerging technologies.

 It is regarded as an environment friendly way to obtain aquatic products by realizing the re-use of aquaculture water and closed production in recirculating aquaculture systems. The biological conversion of nitrite nitrogen to nitrate nitrogen is called Nitrification, which is the most common way to control ammonia-nitrogen in the present recirculating aquaculture systems.  Fixed-film biological filter, as a common way to realize nitrification and a key unit in a recirculating aquaculture system, can provide attachment surfaces for nitrobacteria to form bio-films. It can be divided into several types according to the different ways of contact between the bio-film carrier and the water flow or the different positions where the bio-film carrier flows through the fixed-film biological filter in the water body. The paper reviewed several types of frequently-used fixed-film bio-filters in recirculating aquaculture systems including trickling bio-filter, submerged bio-filter, fluid bed bio-filter, moving bed bio-film reactor,etc. in which the advantages and disadvantages of them were analyzed and compared, and specific cases were taken to illustrate the designs of bio-filters, thus providing reference for the construction of circulating aquaculture systems.

In aquaculture, feed cost occupies a large proportion of the total cost of aquaculture. Effective feeding strategies are an important way to reduce the cost of aquaculture production. During the feeding process of feeding equipment, both the growth and nutritional needs of the fish must be met, and excessive feeding should be avoided to reduce environmental pollution. At present, the intelligence level of domestic aquaculture feeding equipment is relatively low. The feeding strategy is mainly based on artificial experience and quantitative feeding. The deviation of each feeding cumulatively affects the economic benefits of the entire catch. Therefore, scientific feeding strategies can effectively reduce the cost of farming and improve the welfare of farming. This paper mainly introduces the fish growth and feeding model based on artificial experience and bioenergy flow, the technical methods of sensing fish feeding behavior based on machine vision and machine acoustics, and the development status of intelligent feeding control system, and proposes the specific implementation of feeding strategies to provide a reference for the upgrading of aquaculture feeding equipment from automatic to intelligent.

In the process of fishery transformation and development, the development of deepsea mariculture is the strategic direction to break through the challenges of ecological environment and natural resources constraint and realize the sustainable development of China’s mariculture industry in the new era. This paper defines the concept of deepsea mariculture in China with consideration of the development level of mariculture industry and marine geological conditions based on the definition of deepsea mariculture proposed by FAO. It is proposed that selecting aquaculture species, constructing aquaculture systems and planning aquaculture sea areas are important factors for the steady and orderly development of deepsea mariculture. Emphasis should be given to economic potential, adaptive temperature and aquaculture techniques in the selection of aquaculture species. The suitability, safety performance and economic feasibility of different aquaculture systems for deepsea mariculture are analyzed and compared in the construction of aquaculture systems. Aquaculture discharge, environmental carrying capacity and marine geological conditions should be mainly considered in the planning of aquaculture sea areas.

Net clogging by attached organisms is one of the serious problems in deep sea aquaculture cage. How to realize the safe and efficient cleaning of cage is an urgent problem. In this paper, the structure of cage underwater cleaning robot was studied，and cavitating jet technology was used to clean the attachment on the surface of cage. The cavitation flow field inside the nozzle was simulated numerically by FLUENT software according to the underwater cleaning condition of the cage. The distribution of velocity field and vapor volume fraction near the nozzle was obtained by means of mixture model, cavitation model and Realizable Ƙ - ε turbulence model. The influence of nozzle inlet pressure and cleaning depth on cavitation effect of cavitating jet was also studied. The results show that the cavitation mainly occurs on the wall of the nozzle expansion section. Increasing the nozzle inlet pressure can improve the jet speed and high-speed flow range, and effectively improve the cavitation intensity, so as to enhance the cleaning strike force. However, with the increase of water depth, cavitation will be weakened. The results can provide a theoretical reference for the application of cavitating jet in aquaculture cage.

There are many kinds of fish in China, and their shape is an important basis for their classification. In order to solve the difficulty in artificial fish identification, an intelligent fish identification system based on deep learning has been proposed to realize the intelligent identification of 1400 species of fish in China. The system first uses convolutional neural network’s EfficientNet model to train a dataset of 500,000 pictures of 1,400 species of fish. The accuracy of the model is 95%, and the recognition time of a single picture is only 0.2 seconds, the model’s size is 74.5 MB. Then the front-end of the system uses Wechat applet, the back-end uses Spring + Spring MVC + Mybatis SSM architecture, invoking the training of the model file for identification, the realization of fish identification, page rendering, statistical analysis and recommendation of adjacent species. The system’s design and implementation  provide a feasible idea for the application of intelligent fish identification technology to mobile terminal, which   marine researchers and developers can use as reference.

n order to provide a scientific basis for the fishing permit of cage nets in artificial reef areas, the catch performance of cage nets with different mesh sizes (20, 30, 40, 50, 60 mm) was investigated by using the cover net method in Laizhou Bay of Bohai Sea in April 2018. The index of relative importance (IRI), catch, dominant body length of main catches, number and weight escape rate, catch of economic species and body length distribution of Oratosquilla oratoria were analyzed. The results showed that 37 species of catches were caught in the experiment, among which 8 species were dominant species. The weight, quantity and species escape rate of the catches increased with the increase of mesh size. The species escape rate in 40-60mm mesh was about 80%, the number escape rate was over 90%, and the weight escape rate was more than 50%, which indicated that the 40-60mm mesh had obvious releasing effect. There was a positive correlation between the proportion of the catch of economic varieties and the mesh size. According to the analysis of the main catch species Oratosquilla oratoria, the proportion of Oratosquilla oratoria not reaching the length of capture with 50 mm net was the smallest, 10.3%. Through comprehensive analysis, the catch performance of cage net with mesh size of 50 mm is better, which meets the requirements of production and ecology. Therefore, it is recommended to use cage net with mesh size of 50 mm in marine pasture area.

In recent years, China’s aquaculture industry has developed rapidly, and aquatic animal feeding strategies have gradually received attention. A series of related research contents of aquatic animal feeding strategies at home and abroad are enumerated and analyzed for systematic arrangement and summary. Feeding strategies are important production management factor in modern intensive aquaculture production process. Its technical connotation can be summarized as feeding frequency, feeding amount and feeding mode, etc. Different aquatic animal species and different breeding stages require different feeding strategies. The effects of feeding strategies on the growth performance, digestion and metabolism, stress immunity, behavioral response and survival rate of farmed animals are described to provide a reference for the selection of aquatic animal feeding strategies and the research on related technical theories.

 To solve the problems of lack of domestic fish pump products, long development cycle, and so on, taking the existing siphon fish pump as the research object, the CFD numerical calculation method was used to simulate the three-dimensional flow field in the fish pump under three different influent speeds (1 m/s, 1.5 m/s, 2 m/s), and the internal flow characteristics including velocity distribution, eddy viscosity, and pressure distribution were obtained. At the same time, the validity of the numerical calculation was verified by the experimental results. The results show that the pressure and flow velocity show an increasing trend with the increase of the inlet velocity, and the maximum pressure is mainly concentrated at the upper end of the outlet side of the fish suction pump, which will have a certain impact on the fish. In addition, the incoming flow collides with the wall of the fish suction pump to form reflux, and the reflux landing point is also prone to secondary damage to the fish. When the inlet velocity is 1m/s, the velocity of the bottom wall of the suction pump is 0.13m/s, and the experimental value is 0.15m/s. The difference between the experimental results and the numerical simulation results is about 13.3 %, which verifies the effectiveness of the calculation results. The research results provide an important basis and reference for the subsequent research and design of the fish suction pump.

Artificial reefs is one of the major means to realize sea ranching construction, marine ecology control and marine habitat restoration. The fish accumulating effect of artificial reefs depends on many factors such as reef materials, structure form, hydrodynamic features and reefs layout. This paper summarizes the advances in artificial reef engineering technology at home and abroad from the following aspects: the advantage and disadvantage of current artificial reef materials and the application potentials of new composite materials, major reef configurations and current designing methods, researches in reef hydrodynamic behaviors using hydrodynamic model test and numerical calculation methods, as well as methods of artificially induced flow field and reef layout. Then according to the present situation of artificial reefs in China, it points out the development trend and key research directions of artificial reefs design and application, in the wish to provide reference for artificial reefs construction and upgrading in China.

As an important equipment in marine fisheries, Multi-beam fishery sonar makes use of sound waves to detect underwater creatures, with the beamforming algorithms being the core technology in its development process. Based on the traditional shifted sideband beamforming (SSB) algorithm, this paper proposes an improved algorithm which converts parallel processing to serial processing, and increases the signal processing speed without causing performance loss. Firstly, this improved algorithm was compared with SSB. Then the improved algorithm was implemented on the field gate array (FPGA) platform, and performance evaluation and resource consumption were analyzed for the two algorithms. Finally a directive test was conducted over the FPGA realization of the improved algorithms in an anechoic sonar pond, and the simulated beam pattern was compared with the measured beam pattern through MATLAB. The results showed no difference of the two algorithms in their performance, while the resource consumption of the improved algorithm was nearly 70% lower than SSB. Meanwhile, the measured results of the improved algorithm were roughly consistent with the theoretical simulations, and the deviation was in a reasonable range.

Multi-beam fishery sonar is an important tool for efficient, accurate and selective fishing in marine fisheries. In this paper, in order to systematically analyze the detection performance of multi-beam fishery sonar and the influence of main constraints on the operating range, for the multi-beam fishery sonar based on cylindrical array, the detection performance of the fishery sonar in noise and reverberation environments is analyzed with the method of underwater acoustic system simulation, the detection performance of fish school with different noise intensity under different sea conditions is compared, the abilities of narrowband system and broadband system to reduce reverberation are analyzed, and the detection performance of the fishery sonar in the mixed environment of noise and reverberation is simulated and analyzed. Finally, from the aspects of system design, transmitting mode, receiving mode and so on, the methods to improve the detection performance of the fishery sonar are put forward, which provides an improvement direction for the development of long-distance, high-resolution multi-beam fishery sonar.

Netting is an important fishing material, which directly affects the efficiency and safety of fishery production. In this study, the performance, modification research and application status of three high performance netting materials for fishing: ultra-high molecular weight polyethylene netting, copper alloy netting and polyester netting, were summarized. The advantages and disadvantages of their comprehensive properties such as impact resistance, wear resistance and antifouling performance, as well as the modification research on creep properties of ultra-high molecular weight polyethylene netting and crystallization properties of polyester netting, were analyzed. The development of the three kinds of netting in fishery field was introduced to provide theoretical reference for further research and development and application of new materials for fishing. In addition, this paper also discussed the future research direction and key difficulties in application technology of high-performance netting materials for fishing, and suggested strengthening the basic research and industrial application technology research of netting materials.

In this paper, high-throughput sequencing was used to analyze the diversity of water flora in the biofloc system during nitrogen transformation. A control group and a test group were set in the test. The control group had clean and disinfected seawater, and the test group was a biofloc group. The test period was 30 days. The results show that in the test group, the mass concentration of ammonia nitrogen reached its maximum (2.99 mg/L) on day 5 and then decreased to 0 mg/L; in the control group, the mass concentration reached its maximum (7.51 mg/L) on day 9 and then decreased to 0 mg/L. In the test group, the mass concentration of nitrite nitrogen reached its maximum (12.54 mg/L) on day 17 and then decreased to 0 mg/L; in the control group, it showed a rising trend during the test period and reached 13.42 mg/L on day 30. The mass concentration of nitrate nitrogen in the test group was higher than that in the control group, reaching 19.56 and 6.31 mg/L respectively on day 30. The biofloc system was obviously able to remove ammonia nitrogen and nitrite nitrogen, and the nitrogen transformation rate of the test group was higher than that of the control group. High-throughput sequencing showed that the flora abundance and diversity index of the microorganisms in the biofloc system increased significantly with the increase of the breeding cycle, and the differences were significant in different periods. During the test period, a total of 23 phylum and 549 genera were identified. At the phylum level, the relative abundance of Proteobacteria decreased with time (from 67.72% to 44.45%), while that of Bacteroidetes and Chloroflexi increased with time (respectively from 5.99% and 6.68% to 16.06% and 19.02%). The main bacteria related to nitrogen transformation included Ardenscatena and Nitrospiraceae, whose relative abundance increased with time (respectively from 0.34% and 0.07% to 12.69% and 0.2%), while that of Nitrosopumilus decreased with time. The function and microbial diversity of the biofloc system showed significant changes during the breeding cycle. This study has reference value for improving the utilization efficiency of the biofloc system breeding mode.

Aiming at the problems of small sample size and low detection accuracy of diseased takifugu rubripes, a detection method of diseased takifugu rubripes based on ResNet50 and migration learning was proposed. First, ResNet50 was used to pre-train the model on the ImageNet dataset; then based on the pre-training results, the takifugu rubripes detection ResNet50 network was constructed, and the model weights, which were pre-trained and contained in 16 residual blocks, were transferred to the ResNet50 network for model weight initialization to reduce the training cost; in order to further improve the accuracy of detection, a deconvolution layer was added after the last convolution layer of the constructed ResNet50 network model to learn the details of the target; finally, the data set was constructed from the images of healthy and diseased takifugu rubripes, and the data was augmented using methods such as flipping, rotation, random cropping, chromaticity changes, and adding noise to increase the diversity of data samples and improve the robustness of the detection method. Experiments were conducted on the constructed dataset, the accuracy of the detection method for disinfected puffer fish based on ResNet50 and transfer learning can reach 99%. Compared with ResNet18, ResNet34, ResNet101 and ResNet152, the detection accuracy of the proposed method was improved by 10.7%, 6.6%, 6.2% and 5.6% respectively. Compared with the ResNet50 residual network without deconvolution, the detection accuracy of the proposed method was improved by 0.4%. The results showed that the method based on ResNet50 and transfer learning could effectively solve the problems of fewer samples and low accuracy of diseased puffer fish, and provide a reference for the study of diseased puffer fish detection

Multi-beam fishery sonar is an important tool for marine fish resources detection and spatial distribution analysis applying . hydroacoustic methods. This paper expounded the principle and working process of multi-beam fishery sonars. By analyzing underwater acoustics theories integrating with the application of multi-beam fishery sonars in marine fishing, this paper offered a range prediction model, and analyzed the main factors affecting the detection performance. Aiming at the omnidirectional detection of high sea purse seine and trawl fishing, this paper focused on the simulation and analysis of selection methods for the optimal operating frequency, and detection performance for cylindrical array multi-beam fishery sonars, revealing the constraint relationship among the maximum operating range, minimum size of transducer array and the best working frequency. The detection performance under the influence of noise and reverberation was evaluated respectively, the optimal operating frequency point to achieve the maximum detection distance under the given size of the transducer array and the optimal operating frequency point to achieve the minimum size of the transducer array under the setting of the maximum detection distance were both given. An optimal frequency selection method for multi-beam fishery sonars under certain deployment or application conditions was proposed, and the detection performance of fishery sonar was evaluated. It was proved that the diameter of the transducer applicable to the ocean fishing was 0.375 m, the maximum detection distance for the 0dB shoal was 2 600 m, and the optimal operating frequency best be 25kHz. The results will provide theoretical guidance for follow-up equipment development, testing and experimentation.

With the decline of marine fishing output, the deterioration of the coastal ecosystem and the continually growing demand for healthy and environmentally friendly seafood, the marine aquaculture has been continually prompted to entry into deep blue waters. The international community is becoming more and more fierce in the competition for ocean fishery resources. It is an important way to expand the cultivation area and improve the production output of sea products by carrying out deep sea aquaculture on a large scale of the fish species that can bring good economic benefits with high quality water resources in the deep waters. With a review and comparison of the successful cases and a focus on the transportation depression and excessive transport fleet in the present day, a technical research to transform a 300,000 DWT ore carrier to an aquaculture vessel was carried out by means of the previous successful experiences in this paper: remolding the hull structure, planning  aquaculture program and designing the matched fish allocation system, deep seawater temperature measurement and drainage system, feeding system, sewage disposal and water renewal system, catching system, etc. in deep waters, summarizing the problems to be solved, thus to promote the applicability, replicability and propagability of deep sea aquaculture and provide reference for the construction of deep blue fishery strategy.

The development of modern tropical marine ranching is an important means to conserve fishery resources and protect the marine ecological environment in the South China Sea, which has far-reaching significance for the conservation and scientific utilization of fishery resources in the South China Sea. Artificial reefs are one of the important tools to create marine ranching habitats. However, due to the deep water in the South China Sea, conventional reefs are difficult to play a role, whereas floating reefs can make use of the water space in the middle and upper layers, and are the best facilities to create deep water fishing grounds. This study reviews the types, functions, and application scenarios of floating fish reefs, summarizes relevant research and current status both domestically and internationally, and looks forward to the future of floating fish reefs in the South China Sea, including their role in information-based monitoring of ocean ranching, recreational fishing, conservation of upper-middle level fishery resources, and the construction of offshore ocean ranching.

Ultraviolet light-emitting diode (UV-LED, 200-400nm) semiconductor solid-state light source is energy saving, environmentally friendly, easy to operate and small in volume. With the continuous improvement of UV-LED performance, it is expected to replace the traditional ultraviolet mercury light source in the future. This paper first introduces the development of ultraviolet (UVC-LED, 200-280 nm,) technology, the existing problems and the route for technical improvement, and compares the research results of UVC in aquaculture industry at home and abroad. Then, based on the species of microbial diseases in aquaculture, the calculating method of the dose needed to inactivate harmful microbes and the design suggestion for actual application of UVC-LED in aquacultural microenvironment are given. Finally, the trend of UVC-LED to achieve large-scale application of sterilization is prospected, so as to help the sustainable development of aquaculture.

In the new century, China's fishery has developed more rapidly, and made a series of remarkable achievements, which greatly made up for the shortage of high-quality protein sources and provided an important guarantee for China's food security. However, fishery is an industry relatively highly depending on energy and resources. With its rapid development, it also pays the price for environment and energy consumption. The extensive production mode brings red tide and water bloom to the surrounding environment. The production cost of fishing vessel fuel oil has exceeded 2/3 of the total fishing cost, becoming a major obstacle to the sustainable development of fishery. The report of the 18th National Congress of the Communist Party of China proposed to vigorously promote ecological civilization and pointed out the development direction for fishery. This paper mainly introduces the development at home and abroad in energy conservation and emission reduction in aquaculture, fishing and fishing vessels and aquatic products processing. Compared with fishery developed countries, China started late with a weak foundation in the research and application of energy conservation and emission reduction technologies in those tree areas of fishery, but the development is fast and effects good, thus is highly motivated with development potentials promising. The paper also puts forward suggestions for future development: firstly to take active measures to promote production mode transferring toward energy saving and emission reducing, secondly to strengthen fundamental key technical research and promote the upgrading of traditional production, strengthen the demonstration and extension of new products and technologies, and build up leading new production modes of high-efficiency. This study is expected to provide references for fishery’s transformation and upgrading towards energy saving, emission reducing, green and sustainable development...

The pure oxygen oxygenation system with an oxygen cone as the gas-water mixing device has high oxygen dissolution efficiency, but it needs to generate a certain amount of pure oxygen and energy consumption. This paper uses relevant principles such as material balance to scientifically design the flow of pure oxygen gas into the oxygen cone and the flow of aquaculture water, analyze its operating costs, and discuss key design issues. The results show that: when the oxygen cone with a certain cone structure size is used, when the flow rate of pure oxygen gas is 14.6 L/min and the flow rate of aquaculture water is 1327.3 L/min (the water circulation volume of the aquaculture system is 79.6 m3/h), the oxygen can be 81.88%～89.07% utilized. The higher dissolved oxygen efficiency of the cone provides 1026.8-1116.9g/h of dissolved oxygen in the aquaculture system, which fully meets the dissolved oxygen demand of the recirculating aquaculture of Litopenaeus vannamei with a culture water body of 300 m3 and a culture density of 6kg/m3. The oxygen consumption of the oxygen cone is 1252.7 g/h and the power consumption is 2.9 kWh. This design provides support for improving the technical performance of the pure oxygen aeration system and promoting the wide application of pure oxygen aeration in high-density recirculating aquaculture.

 In order to study the influence of sloshing phenomenon of ballast tank on bulkhead structural strength of aquaculture vessels, the Smoothed Particle Hydrodynamics (SPH) method was used to simulate the slight sloshing and violent sloshing of ballast tank under rolling excitation. The influence of particle truncation error on or near the solid wall boundary of SPH method was solved by introducing dynamic boundary particle method. The simulation results of the two processing methods of dynamic boundary particles were validated by comparing with related literatures. The results show that the method used in this paper is reliable and effective, and is suitable for simulating the rolling and breaking of free surface during ballast tank sloshing. For slight tank sloshing, the boundary particle fixed method has higher calculation accuracy than the boundary particle motion method; both the boundary particle motion method and the fixed boundary particle method can effectively simulate the violent tank sloshing phenomenon. The results of this study can provide a reference for the numerical simulation of sloshing in the culture tanks of aquaculture vessels.

Antarctic krill has large resources, high nutritional value, and a variety of active substances. It is a type of offshore fishery resource with great development value. Shrimp meal is one of the most important processed products of Antarctic krill. During the processing, due to the influence of heating and other factors, it will cause the loss of nutrients and the destruction of active substances, especially in the heat treatment links such as cooking and drying. Tends to destroy or degrade heat-sensitive components such as unsaturated fatty acids and astaxanthin. The characteristics of the main nutritional active substances of Antarctic krill such as protein, lipid, and astaxanthin and their changes in the process of shrimp meal processing were introduced, the influence of processing procedures and process parameters on the quality of shrimp meal was analyzed, the main evaluation indicators and basis of shrimp meal quality were summarized, The main problems in the processing of shrimp meal, such as unclear process, poor equipment performance and unstable product quality, were discussed, and the future research directions such as the flow path of nutrient active substances, structural change mechanism, process optimization, equipment innovation, technology, and equipment integration, etc. It is expected to provide a theoretical basis and technical reference for the optimization of the process and technology of shrimp meal processing.

Marine fishery acoustic equipment plays an important role in the accurate detection and efficient fishing of marine fishery, and the improvement of its key technologies is of great importance to the improvement of equipment performance. This paper analyzed the research status of key technologies of marine acoustic equipment at home and abroad, the research progress of key technologies of single-beam, dual-beam, split-beam and multi-beam is discussed, and the significant progress of key technologies of multi-beam, multi-frequency and wide-band in marine acoustic equipment in recent ten years is emphasized. The research shows that the key technology of acoustic equipment in domestic fishery has advanced, but there is still a big gap with the advanced technology in foreign countries. Finally, the future development of the key technology of acoustic equipment in domestic fishery is prospected.

Deep sea aquaculture is an important way to expand new space for aquaculture development, and reduce the pressure on offshore ecological environment. It is of great significance to  improve the quality and efficiency of aquaculture, to modernize fisheries, to ensure world food security and to sustainable development of aquaculture. However, the equipment and technology of deep sea aquaculture are the key to support and realize the development and growth of deep sea aquaculture. This paper briefly introduces the research and application status of deep sea aquaculture vessels and deep sea aquaculture cages, and points out that there is still a big gap between China's deep-sea aquaculture and foreign fishery developed countries in the automation and intelligence of mechanical equipment. This paper discusses the current main problems and future research and development directions of deep sea aquaculture vessels and deep sea aquaculture cages, and makes corresponding discussions and thoughts on the future development of deep sea aquaculture, especially  planning objectives, function expansion, scientific and technological support of deep sea aquaculture. This study is expected to provide reference for the research and development of deep sea aquaculture equipment and technology and future marine construction in China.

Freshwater pond aquaculture water pollution has become an important factor restricting the healthy and sustainable development of the industry. Using engineering facilities to reduce the discharge of aquaculture feces, leftover feed  and tail water is the development trend for pond industry. At present, freshwater pond aquaculture emission reduction projects mainly include: constructed wetland based pond recirculation  culture-system, "three ponds and two dams" water purification system, "container + ecological pond" aquaculture system, green and efficient captive system, plant floating bed and pond integrated aquaculture system, tank-pond circulating aquaculture system and multi-trophic level integrated aquaculture system. In this paper, these 7 popular engineering facilities were reviewed and analyzed from the perspectives of aquaculture system engineering construction and operation. With these facilities, some of the nutrients were reused to certain extent by collecting sewage, discharging sewage, precipitation, microbial degradation and plant absorption. However, limited by technical defects and industrial foundation, the current popularization and utilization rate of the facilities for pond aquaculture and emission reduction is not high. This paper suggests that, in future, we should strengthen the basic research on nitrogen and phosphorus circulation in pond, actively develop efficient treatment facilities for aquaculture nitrogen and phosphorus pollutants, and improve the industrial chain of pond aquaculture emission reduction projects. This study will provide references for the sustainable and healthy freshwater pond aquaculture development in China.
 

Cylindrical array multi-beam fishery sonar, as important acoustic equipment for accurate fishing in marine fisheries, can realize omni-directional scanning of the detection waters. Its beamforming ability is one of the main technical indicators reflecting the detection performance of fishery sonar. In this research starting from the analysis of beamforming ability of cylindrical array multi-beam fishery sonar, the vertical and horizontal beamforming was simulated and the effects of amplitude shift, phase shift and frequency shift on the vertical and horizontal beamforming performance of the cylindrical array were analyzed by using the simulation method of underwater acoustic algorithm. The results show that the amplitude and phase shift has little influence on the main lobe in the vertical and horizontal directions of the cylindrical array, and the main lobe becomes wider; the influence on the side lobe is great, and the side lobe is significantly enlarged; when the offset is -5~15 dB, the gain of the first lobe is within 3dB, and when the offset is too large, the gain of the first lobe can be more than 6dB; the frequency shift has a little influence on beam directivity, the working frequency has a great influence on the width of the beam main lobe, and the width deviation of the main lobe is about 3°. This research can provide a reference for the independent development of high-precision and long-distance cylindrical array multi-beam fishery sonar in the future.

The anesthetic effects of clove oil, MS-222 and propofol on aquaculture of Larimichthys crocea were studied to provide a reference in the selection of anesthetics for live transportation. At the water temperature of 20 (±0.5) ℃, the appropriate mass concentrations of three anesthetics were firstly explored, and the appropriate mass concentrations were preliminarily obtained as follows: clove oil: 10 mg/L, MS-222: 40 mg/L, and propofol: 0.2 mg/L. Subsequently, the suitable water temperature for anesthesia of Larimichthys crocea was optimized, and the results showed that when clove oil was at 20 ℃, MS-222 at 15 ℃, and propofol at 25 ℃, the anesthetic effect was the best. According to the optimized mass concentration and water temperature, the simulated transportation of Larimichthys crocea anesthetized with three anesthetics was carried out. It was found that with the extension of simulated transportation time, the recovery rate of Larimichthys crocea anesthetized with the three anesthetics gradually decreased. After 24 h, the recovery rate of Larimichthys crocea anesthetized with clove oil and MS-222 could reach 90 %, but the recovery rate of Larimichthys crocea anesthetized with propofol was 70 %, indicating the anesthetic effects of clove oil and MS-222 were better. The economic cost analysis of clove oil and MS-222 shows that the cost of clove oil is relatively low, so it is more suitable to be used as an anesthetic for live transportation of Larimichthys crocea.    []

In order to explore the energy conservation performance of ocean fishing boat propulsion systems, in this paper, a tuna longline vessel that has realized energy-saving and emission-reducing was taken as an example to analyze the reasons behind, through probing into the structure of its diesel-electric hybrid system, engine load characteristics and the actual using conditions of the vessel. The results showed that the diesel-electric hybrid system of the vessel in use can easily switch between the conventional power and the electricity propulsion systems in accordance with the actual working conditions; by selecting the reasonable working conditions of the main engine, the output efficiency of the diesel engine could thus be improved and the diesel fuel consumption rate decreased, and considering the various working conditions, the system could save energy by more than 15%. The research showed that, at present, using hybrid power technology in tuna longline vessels is feasible and can play a role in energy conservation. With the core technology remaining the same and by adopting some innovative techniques such as multi-machine paddle split system to allow the system greater intelligent deployment role, the hybrid can be further extended to trawlers, purse seiners and other fishing vessels.

Affected by the limitation of offshore aquaculture space and environmental pollution problems, the marine aquaculture industry has gradually developed into the deep sea. However, the climate in the deep sea is more severe and complex. In order to ensure the structural safety of aquaculture equipment, it is necessary to conduct research on its hydrodynamic characteristics. As an important aquaculture equipment, the fishing net is taken as the research object. The porous medium theory was used to model the structure of the net,  the open source CFD software OpenFOAM was used to conduct numerical simulation research, and the interaction of the net with regular waves and focused waves was explored. The results show that in the case of regular waves as input, with the increase of solidity ratio of the fishing net and the characteristic velocity, the resistance of the net increases gradually, and with the increase of the characteristic length, the transmission coefficient of the wave behind the net location increases gradually; in the case of focused waves as input, the frequency domain distribution did not change significantly, and with the increase of mesh size, the mesh resistance gradually increased. Finally, based on the results of numerical results, the Reynolds number and KC number are used as output parameters to establish a prediction model for the mesh resistance of porous media under extreme waves.

In order to automatically detect the quantitative proportion of pigment deposition in the beaks of cephalopods, the deep learning network model of Mask-RCNN was used to realize the recognition and segmentation of beaks and its pigment deposition, and a new method of quantitatively automatic measurement for pigment deposition proportion in beaks was proposed. First of all, the beaks and their pigmentation were labeled, and the results were converted into a training set and imported into the residual network (Resnet50) to extract the characteristics of the beaks and their pigmentation. Based on the feature pyramid network (FPN), the features of each layer were merged, and then the region proposal network (RPN) was used to learn the features and generate candidate frames. Finally, the candidate frame was subjected to Non-Maximum Suppression (NMS) to obtain the candidate area of beaks and pigmentation, realizing the intelligent detection of the proportion of pigment deposition in beaks. The experiments showed that the segmentation accuracy of the upper beaks of the cephalopods was 93.60% and the pigmentation accuracy 92.47%; the segmentation accuracy of the lower beaks was 91.78% and the pigmentation accuracy 88.78%. The results show that the deep learning network model of Mask-RCNN could get the proportion of pigment deposition in the beaks and its pigment deposition, providing theoretical references for future studies in cephalopod feeding ecology.

Targeting the problem of ocean buoys data being attacked and stolen by hackers, and based on analyzing the operating mechanism of Beidou ocean buoy system, an attribute-based encryption ocean buoy data security management system was designed and proposed in this paper. In order to achieve fine-grained access control of ocean buoy data, this system contained three subsystems including data encryption and decryption, data management and key management, meanwhile, the process of data storage and data request were designed to manage the transfer of buoy data between data requester and data owner. Furthermore, the system was implemented based on the open source JPBC cryptographic library and popular front-end and back-end technologies, and compared with multiple encryption schemes. The results showed that the encryption scheme used in this paper had significant advantages in encryption efficiency and fine-grained buoy data sharing. Compared with the traditional buoy data management system, this system combined symmetric encryption and attribute-based encryption technologies to realize the security protection of buoy data and the fine-grained sharing of data. The research results provided references for buoy data security management, and promoting fishery informatization and modernization development.