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Bacterial diseases of fish pose a serious threat to the development of fish breeding industry, and the abuse of antibiotics and the emergence of drug resistance of pathogenic bacteria have a serious impact on the yield of fish breeding, the quality of aquatic products and the breeding environment. In order to promote the development of healthy fish breeding industry, it is urgent to innovate the green prevention and control technology of fish diseases. As a natural and non-residual bacterial killer, phage has the characteristics of strong specificity and high lysis efficiency. Using phage to treat bacterial diseases of fish will be an important technical approach. This paper reviews the important resource mining of phages, the mechanism of action in the prevention and control of bacterial diseases in fish and its application prospects, and puts forward measures to speed up the research of phage treatment technology in the field of healthy aquaculture of fish, which is of great significance for healthy aquaculture of fish. [ABSTRACT FROM AUTHOR]

Deep-sea aquaculture has developed rapidly in the world in recent years. Aquaculture equipment is required for largescale, mechanization, automation, and intelligence. Among them, the vacuum fish pump has been used widely in the process of fish catching and conveying. However there is a large range of strong vortexes in the tank during operation, leading to the mutual friction and collision injury between fish. In this study, the structure of the tank and the operation mode were improved to reduce the fish injury for the high working efficiency using a improved fish pump. The inlet pipe passed through the bottom of the tank and then entered the inside of the tank. A trumpet-shaped diversion structure was placed upside down at the top of the inlet pipe. An industrial centrifugal pump was selected as the driving device to replace the water ring vacuum pump. The water inlet of the centrifugal pump was connected to the water outlet of the tank. The fish-water mixture entered the tank, where the fish was separated from the water, due to the suction effect of the centrifugal pump. The incoming fish stayed in the tank, but the incoming water was discharged from the tank by the centrifugal pump. The baseline ratio of fish to water was 1:1 in the pool and the tank. When the ratio of fish to water in the pool was 1:2, 1:3, 1:4, and 1:5, respectively, it was calculated that the conveying time of the improved fish pump was reduced by 20.4%, 30.6%, 36.8%, and 40.8%, respectively, compared with the vacuum fish pump for conveying fish with the same quality. The numerical simulation was carried out to compare the water absorption of the vacuum and the improved fish pump using computational fluid dynamics. The results showed that there was a small vortex range in the tank of the improved fish pump, indicating the weak vortex intensity. An improved fish pump prototype was also designed and then manufactured to verify the numerical simulation in the performance experiments. Compared with the performance of the vacuum fish pump prototype, there was a relatively small vortex in the tank of the improved fish pump, and the conveying capacity did not changed with the change of fish lifting height. The improved fish pump was more friendly to fish conveying. The probability of fish injury was greatly reduced as well. The findings can provide a strong reference for the design of a large fish pump. [ABSTRACT FROM AUTHOR]

Feeding systems can dominate the primary efficiency and cost in aquaculture. The high management efficiency of feeding can also alleviate ecological environmental pollution. However, artificial identification has been widely used for fish feeding in the pond so far, leading to the time-consuming and laborious. Empirical feeding management cannot fully meet the large-scale pond aquaculture, in terms of production efficiency, environmental pressure, and aquaculture risk. In this study, a set of precision feeding systems was developed using fish feeding welfare. Four modules included water quality monitoring, decision control, drive execution, and remote monitoring. A systematic investigation was also implemented to clarify the effects of environmental factors on the physiology and energetics of fish. The affecting factors were then determined by the feeding demand of fish. The dissolved oxygen, temperature, and body growth were taken as the input parameters, whereas, the target demand was as the output parameters of the feeding system. The fuzzy PID control was combined with the particle swarm optimization (PSO) to realize the precision feeding operation. A comparative test of pond culture was carried out with the intensive grass carp as the research object, in order to verify the practicability and effectiveness of the system. A comprehensive evaluation was made from the aspects of regulation, growth performance, and economic and environmental benefits. The results showed that a stable and reliable control performance was achieved in the constructed precision feeding system, where the control error was less than 7%. The nash-sutcliffe (NS) index increased to 0.913 in the decision-making performance of the feeding system. whereas, the root mean squared error (RMSE) was reduced by 16.10, compared with the traditional. The feed conversion rate was significantly reduced by 11.73 % (P<0.05). Importantly, the aquaculture income increased by about 14 600 yuan/hm², whereas, the pollution was reduced by 241.40 kg per ton of fish produced. When the feed coefficient was 1.0, per ton of aquatic products brought about 500 kg of organic waste, 26 kg of nitrogen, and 13 kg of phosphorus. When the feed coefficient was 2.5, per ton of aquatic products produced 1 625 kg of organic waste, 117 kg of nitrogen, and 38 kg of phosphorus. By contrast, the grass carp produced per ton was equivalent to about 1 250 kg of organic waste, 86.70 kg of nitrogen, and 29.70 kg of phosphorus under the traditional feeding model. The total production of national grass carp in 2021 was 5.76×106 t. If all grass carp farming was adopted as the precise feeding system, it was equivalent to reducing the pollution emissions of 1.17×106 t organic waste, 9.43×104 t nitrogen, and 2.59×104 t phosphorus. The developed system can be expected to alleviate the environmental and ecological pollution caused by aquaculture. Strong comprehensive application performance can provide the theoretical reference and technical support for the research and development of other aquaculture modes and farmed fish. The feeding system should be further improved from three aspects in the future: monitoring quality and efficiency, decision-making model, and implementation cost. The sensor detection accuracy can be improved to optimize the processing efficiency of models. Systematic research of multiple feeding can be integrated using the logic line of “when to eat (feeding rhythm)-how much to eat (feeding demand characteristics)-how to eat”, in order to achieve an efficient and unified mode of breeding objects, feed, and machine. [ABSTRACT FROM AUTHOR]

In order to accelerate the healthy and sustainable development of deep-sea aquaculture in China and promote the spatial expansion of mariculture and the transformation and upgrading of marine fishery industry, the article expounds the current status of deep-sea aquaculture facilities, and equipment as well as technology in China and lists the latest technical progress and typical facilities of the main types of deep-sea aquaculture including gravity cages, truss-type cages and aquaculture vessels etc. Then in response to the technical requirements for the construction of deep-sea aquaculture system, the article clarifies the progress and development trend of science and technology innovation at home and abroad in the areas of breed cultivation, fry production, aquaculture facilities, and production management equipment, etc. The article further dissects the main problems existing at present, such as lack of good breeds, insufficient integration of disciplines, technical immaturity of facilities and equipment, as well as lack of standardization in design and construction based on the analysis on how to realize the sustainable and healthy development of deep-sea aquaculture in China. Last but not least, the key technical breakthroughs in species, facilities and equipment, and industrial chain are proposed to achieve safety, quantity and quality breeding, as well as deeper and farther deep-sea aquaculture in China, with the aim to provide reference for accelerating the sustainable development of deep-sea aquaculture in China. [ABSTRACT FROM AUTHOR]

It is necessary carrying out fishery cooperation between China and Papua New Guinea. This is mainly due to the broad market for Papua New Guinea's fish that attracts fishery cooperation, the implementation of the national strategies of both sides requiring in-depth fishery cooperation, the safe sea passages requiring the strengthening of fishery cooperation, and changes in international forces increase fishery cooperation opportunity. Meanwhile, carrying out fishery cooperation between China and Papua New Guinea is highly feasible, which has theoretical basis and legal basis, and has cognitive consensus and practical results. In this regard, China and Papua New Guinea should recognize the relevant challenges, and speed up the pace of cooperation by expanding the sources funding for fishery cooperation, improving the mechanism and law for fishery cooperation, consolidating the support forces for fishery cooperation, providing the governance plans for fisheries governance, and cultivating successful models for fishery cooperation [ABSTRACT FROM AUTHOR]

Much more advanced sensors have been used to greatly promote intelligent production with the development of smart fishery. Harsh requirements can be found for the accuracy and biosafety of sensors in practical applications. Wearable electronic devices can be expected to serve as one of the core components with great application prospects. Among them, various sensors can pose an important impact on the design and function of future wearable electronic devices. However, most traditional sensors cannot fully meet the application requirements, due mainly to their rigid characteristics. For example, the invasive detection behavior of rigid sensors can cause fish damage, fish growth and activity, easily leading to data loss. Particularly, the conventional rigid sensors cannot be suitable for the modern fishery, such as large volume and weight, as well as biological incompatibility. Fortunately, flexible wearable sensors have attracted extensive attention and research interest in the fisheries field in recent years, due to the lightweight, portability, high integration, and excellent electrical performance. The scope of sensor applications has also been broadened in fisheries, due to their excellent stretchability and biocompatibility. In this review, a systematic summary was proposed of the materials, processes, energy supply, and communication systems required for the preparation of flexible sensors. Flexible materials were divided into the substrate, function and packaging, materials, according to their functions. These materials were needed to meet the particularity of the fishery application environment, in terms of biocompatibility, air permeability and light transmittance. A comparison was made between the preparation materials and properties of existing flexible sensors. The core process of sensor preparation was introduced, together with better energy supply and communication systems. The emerging nano-friction power generation technology was proposed for fishery flexible electronic equipment. And then, the application of flexible wearable sensing technology was reviewed on fish motion monitoring, water environment monitoring and aquatic product quality detection. The quality detection of aquatic products was divided into biogenic amine, antibacterial drug, and pH detection. Flexible electronic technology was dominated in production cost, measurement accuracy, biocompatibility and application range. At the same time, some recommendations were also given in the future. Fish motion monitoring was necessary to capture the sensing information under sensor application scenarios and biomarker monitoring. The much more flexible sensors can be expected to detect the ammonia nitrogen and dissolved oxygen in the water environment, in order to use environmentally friendly materials during preparation. The challenges and development trends of flexible wearable devices in fishery applications were as follows: 1) To improve the stability and reliability of wearable device sensing under complex conditions, in order to ensure the sensing function of fishery special application environment. 2) To design a micro-sensor system for the multi-parameter integrated detection for better sensing function and application range. 3) To develop reliable self-powered modules for wearable devices, such as nanofriction power generation with excellent biocompatibility and flexibility. 4) To promote the application scenarios of flexible sensors in fisheries, such as fish health management, fish disease prediction and research, and testing medical drugs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper summarizes the achievements of China, s big data industry during the 13th Five・ Year Plan period and the cases of big data technology supporting marine fisheries, ocean transportation and early warning of marine emergencies, as well as the opportunities and challenges faced by the bromine extraction industry, which is an important part of marine chemical industry, in the new stage of economic development・ Based on the profound understanding of the bromine extraction industry and the full knowledge of big data technology to help upgrade and transform the seawater bromine extraction industry, from the perspective of the industry development, the specific entry points based on smart ocean and big data technology to promote the production management level and economic efficiency improvement are proposed ・ That is, to help improve production efficiency and promote energy-saving development of the industry ;to improve equipment operation and maintenance and enhance production safety; to coordinate upstream and downstream demands and optimize supply chain structure. To provide support for the good development of the bromine industry. [ABSTRACT FROM AUTHOR]

This study aims to reduce the damage to fish skin during the whole-skin peeling process. The integrity of the whole fish skin can also be achieved after peeling. A single-factor orthogonal test was carried out to optimize the cutting disc parameters in the self-built whole-skin peeling device of snakehead. Test results showed that the parameters of the cutting disc posed a significant effect on the whole-skin peeling process of snakehead. In addition, the cutting steps greatly contributed to the subsequent separation steps during skin and flesh peeling. Hence, the cutting disc parameters indirectly dominated the development of the fish industry. Taking snakehead with the typical morphological characteristics as the testing object, a systematic investigation was made to determine the relationships between the cutting performance and the cutting disc parameters in the cutting tests. Sensory evaluation and cutting index were used as the evaluation criteria, indicating the cutting quality and the injury degree of fish skin. Specifically, the higher the sensory score was, the higher the deep processing value of the fish skin was obtained. The cutting index represented the loss of fish skin after cutting, where the higher the cutting index was, the less waste of fish skin was. The testing factors were set as the cutting disc tooth structure (skewed, straight, and toothless cutting disc), and cutting disc rotation direction (consequent cutting and converse cutting). An optimal combination was achieved in the range of cutting disc diameter, thickness, and rotational speed were 60-140 mm, 1-2 mm, and 1 500-3 500 r/min, according to the equipment parameters and the morphological characteristics of the snakehead. Some factors with a significant influence in the single-factor test were selected for the orthogonal test. The single-factor test showed that the toothless cutting disc performed the best cutting performance, and the converse cutting was better than the consequent cutting. When the cutting discs with a diameter range of 60-100 mm were used, the cut of the fish skin was smooth and the cutting index presented a relatively high value after cutting. The optimal range of cutting disc thickness was 1.2-1.8 mm, leading to the high cutting index value and sensory evaluation score. Furthermore, the low rotation speed was used to prevent the fish skin from being cut through completely under the same conditions. As such, the cutting effect was gradually improved, as the rotation speed increased. The orthogonal test showed that the diameter and thickness of the cutting disc were the primary factors for the sensory evaluation, whereas, the diameter and rotation speed of the cutting disc were the primary factors for the cutting index. The best parameters were achieved in the cutting process of the whole skin peeling for the snakehead: the cutting disc diameter, thickness, and rotation speed were 80 mm, 1.2 mm, and 3 000 r/min, respectively. The parameter optimization tests demonstrated that the cutting disc with the optimal parameter combination performed the best in the validation test on the whole-skin peeling device of snakehead, indicating the excellent cutting effect. Specifically, there were smooth incisions without outstanding damage, while the sensory score of the incision reached 9.30 points and the cutting index reached 9.15. The cutting disc with the optimal parameter combination fully met the process requirements of whole-skin peeling of snakehead. The finding can provide theoretical support for the development of the whole fish skin peeling device. [ABSTRACT FROM AUTHOR]

Fishway is one of the common measures to maintain the continuity of rivers and protect fish resources in the world. Among them, the hydraulic characteristics of the early fishway cannot match the swimming ability and habits of the domestic fish, particularly in the early stage of construction. Fortunately, the internal structure can be optimized to improve the efficiency of fishways operation in recent years. However, the complicated physical experiment depends greatly on seasonal, temperature, light, and external factors. Additionally, the test cost is ever increasing in a large amount of fish and feeding. Therefore, it is a high demand to predict the fish migration routes in the field of fish conservation using mathematical models. Taking Schizothorax prenanti as the research object, this study aims to simulate fish migration in the vertical slot fishway. The original data set was divided using upstream data monitored in the previous test, according to the swimming characteristics of Schizothorax prenanti. Random Forest (RF), XGBoost, K-Nearest Neighbors (KNN), and Gradient Boosting Decision Tree (GBDT) were used to establish the multiple Behavior classification model (BCM), and Swimming speed regression model (SSRM). According to the evaluation indexes of the classification and regression model, the optimal model was selected to establish the mapping relationship between the fish behaviors and hydraulic indexes using the Eulerian-Lagrangian-agent method (ELAM) framework, and then the fish migration model was constructed. The improved model also considered the influence of velocity (magnitude, vector, and velocity gradient) and inertia factors on the movement of fish. Specifically, the perception area of the fish body was represented by a two-dimensional circular plane with the inductive distance as the radius, particularly with the center of the fish body as the origin. Finally, the simulated and the observed track were compared to verify the reliability of the fish migration model. The results showed that the RF model performed the best to predict the swimming behavior classification and swimming speed regression. The classification accuracy of swimming behavior was 0.804, the recall rate was 0.794, and the F1 score was 0.798. The R2 values were all greater than 0.75 for the swimming speed regression using the three data sets. The predicted trajectories of the migration model were better agreed with the actual. Most virtual fish successively passed through the mainstream and the right backflow area, indicating better consistency with the actual fish passing experiment. A comparison was made to obtain the characteristic track of the numerical simulation and the actual fish test. Consequently, the fish migration model can be expected to fully reflect the basic behavior characteristics of the target fish, and then to better predict the migration route of Schizothorax prenanti. The finding can also provide a strong reference to evaluate the fishway flow field for the protection measures in the fish industry. [ABSTRACT FROM AUTHOR]

The distribution of biological resource is of great significance in fisheries and marine ranching. The underwater robots can be expected to combine with the underwater object detection, due to the cost saving and the less risk of fishing operations, compared with the commonly-used manual detection. However, many difficulties and challenges are still remained under the complex and special underwater conditions susceptible to environmental interference, particularly for the underwater objects with the multiple scales, types, and small size. Most of the existing detection for the objects on the ground cannot fully meet the requirement of underwater marine objects, leading to the false and missing detection. Therefore, it is necessary to redesign the network structure suitable for the underwater objects. In this study, a two-stage network detection was proposed to integrate the multi-scale features and multiple attention networks for the underwater objects. Firstly, the multi-scale feature fusion was enhanced to expand the high-level receptive field for the more feature information of objects in the high-level feature maps using hybrid dilated convolution. As such, the network was better adapted to the multi-scale changes without losing the small objects. Then, the up sampling was performed on the effective jump fusion for the high-level channel information without the loss, in order to fully extract the object features. Secondly, a multi-attention network was constructed for the more spatial location and channel features, in view of the complex underwater background, blurred images, small size, and insignificant differences of underwater objects. The global feature dependencies in the space and channel dimensions were more fully utilized to further excavate the hidden feature of difficult samples, with emphasis on the location and feature information of the objects. Finally, the sample equalization was adopted to adaptively balance the proportion of positive and negative samples in training. The fast convergence and optimal training were achieved in the quality of samples for the less calculation of invalid samples. The data sources were selected as the open source UPRC2019, WildFish, and self-built UT datasets from the International Underwater Robot Competition. A series of ablation tests were then conducted on the three datasets to compare with the advanced detection. The results show that the mean Average Precision (mAP) of the improved model on the three datasets reached 85.3%, 96.9%, and 97.8%, respectively. On the basis of the benchmark network, the recall rate increased by 12.2, 8, and 6.6 percentage points, respectively, while the recall rate reached 90.6%, 98.7%, and 98.9%, respectively. Furthermore, the mAPs of the improved model were9.58, 12.2, and 4.1 percentage points higher than those of the mainstream deep learning-based detection, such as Libra RCNN (CVPR2019), Double head RCNN (ECCV2020), and STransFuse (2021), respectively. In addition, the detection time of a single underwater image was0.57s, fully meeting the real-time detection requirements of underwater objects. The findings can provide the technical support to monitor the biological objects for the high precision fishing operation of underwater robots in marine fishery. More importantly, the improved network can be modified to reduce the number of parameters without losing accuracy, particularly for the high detection speed and accuracy under the large-scale amount of data in practice. [ABSTRACT FROM AUTHOR]

An accurate forecast can be greatly contributed to the yellowfin tuna fishing ground in the western and Central Pacific. However, a large amount of fishery data, and high feature dimension have posed a great over-fitting on the various classification in recent years. The random forest parallel integration can be expected to achieve the excellent performance of the extreme gradient boosting decision tree algorithm. In this study, a hybrid integration model was proposed to combine the Xgboost with Random Forest (XGBRF) with the random forest and extreme gradient lifting decision tree. The fishery production data was also collected from the operation data of 43 distant-water longline fishing vessels of China Aquatic Group in the western and Central Pacific (0°-30°S; 110°E-170°W) from 2008 to 2019, including catch information, such as amount, job date, as well as the job latitude and longitude. A comparison was performed on the fishery data, including the concentration of chlorophyll a, eddy kinetic energy, sea surface height anomalies, temperature and salinity of the 0-500 m mixed water layer. A total of 36 variable combinations were used as the original data set, including the Southern Oscillation Index (SOI), the Arctic Oscillation Index (AOI), the Pacific Decadal Oscillation Index (PDOI), and North Pacific Gyre Oscillation Index (NPGOI). The original data set was divided into the training set and test set after the screening and normalization of the variance expansion factor, accounting for 80% and 20%, respectively. The training set was used to train eight models, including classification and regression, logistic regression, k-nearest neighbor, adaptive boosting, gradient boosting decision tree, xgboost, random forest, and XGBRF. The five-fold cross-validation was used for each model to determine the optimal parameters. Finally, the model was verified to superimpose the actual fishing ground of the test set. The experimental results showed that: 1) There was a significant correlation between the catch per unit fishing effort and various variable factors. There was also a great decrease in the degree of collinearity between the variables that were filtered by variance inflation factor. 2) The XGBRF hybrid ensemble model also significantly improved the performance of XGBoost and RF models. Specifically, the highest accuracy rate and Area Under Curve (AUC) were 75.39%, and 79.48%, respectively. The Receiver Operator Characteristic (ROC) curve of the XGBRF model was closer to the upper left, indicating the best performance of the forecasting model than before. 3) The sea surface temperature was the most important factor to dominate the distribution of yellowfin tuna fishing ground, accounting for 7.573%. The temperature of the 300 m water layer was equally important for the yellowfin tuna, which was 7.369%. In addition, the greater impact was also found in the salinity of the 50-meter water layer, the SOI, the concentration of chlorophyll a, and the surface salinity. There was a relatively low influence of other large-scale climatic factors, except for the SOI. 4) There was only a small deviation between the fishing ground predicted by the XGBRF model and the actual fishing ground, indicating the high accuracy and reliability of the prediction. Overall, the XGBRF ensemble model performed the best on the fishing ground forecast of yellowfin tuna in the western and Central Pacific. The finding can also provide a strong reference for the fishing ground forecast. [ABSTRACT FROM AUTHOR]

Underwater images have been highly required in many application scenarios, such as marine resources exploration, reservoir safety evaluation, and underwater aquaculture monitoring. But the captured images under water are usually degraded, due to the refraction, absorption, and scattering of light by the suspended particles in water. Some limitations of images can be low contrast, blurred details, and color distortion. Therefore, it is urgent for underwater image restoration. Much effort has been made on a variety of underwater image restoration using processing technology so far. However, land image restoration cannot be simply transformed the underwater images using background light estimation. The best restoration cannot be achieved in the current case, such as unnatural restoration, uneven brightness, and reddening color tone of the main body. In this study, an underwater image restoration was proposed using the adaptive fusion of double background lights and accurate estimation of the transmission map. First, two kinds of background lights of the underwater images were obtained using the maximum intensity prior background light estimation method based on underwater light attenuation and Quadtree background light estimation method based on background light flatness. Then, an adaptive fusion algorithm of double background lights was created to realize the accurate estimation of background lights in different scenes. Second, an accurate estimation of the transmission map was established to combine the new underwater dark channel prior, Reversed Saturation Map, and three-channel spectral attenuation coefficient. Furthermore, the restored underwater image was constructed using the obtained fused background light and accurate transmission map. The brightness of the image was adjusted to obtain the final underwater restored image. Finally, the experiment was carried out to verify the model using the aquaculture dataset of Guangdong Tilapia Breeding Farm and Underwater Image Enhancement Benchmark Dataset. The result showed that the improved estimation was better adapted to different underwater environments, thereby improving the contrast and color of the restored underwater image. A better restoration was achieved than the rest, such as dark channel prior, the maximum intensity prior, restoration using blur and light absorption, restoration using blue-green channel defogging, restoration using background light statistics model, and optimization of transmission map. Furthermore, the restoration was evaluated to deal with the current underwater image distortion, dim brightness, and reddish tone. The best value was also achieved among the seven objective evaluation indexes. The Peak Signal to Noise Ratio, Structural Similarity, Mean-Square Error, and Visual Information Fidelity increased by 0.52%, 2.1%, 3.4%, and 0.86%, respectively, in the evaluation indexes of reference image quality using the best underwater image restoration, compared with the second best. Correspondingly, the Natural Image Quality Evaluator, and Natural Image Quality Measure index were improved by 2.4% and 7.4%, respectively, in the evaluation index without reference image quality. Two datasets demonstrate that the proposed restoration can be expected to treat the unnatural restoration, uneven brightness, and reddish color in the traditional underwater image restoration. The finding can also provide a technical reference for underwater image restoration. [ABSTRACT FROM AUTHOR]

Patinopecten yessoensis have been one of the most valuable shellfish in the North Yellow Sea. Trawling has also been one of the most widely used harvestings. However, the bycatch of benthic fish and the impact of the trawling process on the bottom ecology have posed a great threat to the sustainable development of the scallop farming industry. Eco-friendly fishing has been a high demand in recent years. It is very necessary to optimize the structure of the net gear (the disturbing device and the trawling structure) and the speed of the trawling net in the combination with the bottom of the seabed. In this study, an environment-friendly fishing optimization and transformation scheme was proposed to evaluate the performance of the disturbing device and the trawl structure for the three scallop fishing nets, such as the dredge, cutting, and hydrodynamic types. The underwater video surveillance technology was also used to clarify the causes of the problems (leakage capture, broken, and choking mud) in the underwater operation of scallop fishing nets. The gravity mesh head, torsion spring type elastic teeth/multi-strand wire rope type elastic teeth, and flexible tail trawl were transformed into the adjustable hydraulic plate mesh head structure, follow-up the disturbing device, and flexible connection of rigid tail trawl net structure. As such, there was a significant decrease in the missed catch rate, broken shell rate, sediment content, and bottom-dwelling fish bycatch. The Ansys-Fluent software was utilized to simulate the three hydraulic plates (plate, positive angle of attack arc, and negative angle of attack arc type) at four towing speeds of 1, 1.5, 2, and 2.5 m/s. The hydrodynamic characteristics demonstrated that the drag resistance of three hydraulic pressure plates increased with the increase of the outflow angle and the drag speed. There was less resistance of the positive angle of attack arc type and the negative angle of attack arc type hydraulic pressure plate, compared with the flat type. The negative lift generated by the hydraulic plate increased with the increase of the drag speed. Once the outflow angle was 22.5°, the negative lift generated by the negative angle of the attack arc hydraulic plate was smaller than those of the flat plate type and the positive angle of the attack arc. When the angles were 30° and 45°, the negative lift generated by the negative angle of attack arc type hydraulic plate was greater than those of the flat plate type and the positive angle of attack arc type. The maximum negative lift was achieved for the best solution to the shape of the negative angle of the attack arc hydraulic plate. Furthermore, the mesh head and the disturbing device were in the best working condition, when the towing speed was between 1.5 and 2 m/s. When the towing speed was 1.5 m/s and the towing water depth was 30-50 m, the optimal combination of parameters was achieved as follows: the towing critical rope length was about 34.87-58.12 m, the stable rope length was about 156.80-261.34 m, the critical angle was about 59.35°, and the critical drag force was 3 848.16 N, the stability angle was 11.03°, and the stable drag force was 1 998.85 N. When the towing speed was 2 m/s and the towing water depth was 30-50 m, the optimal combination of parameters was: the critical towing rope length was about 35.20-58.67 m, the stable rope length was about 156.80-261.34 m, the critical angle was about 58.45°, the critical drag force was 5 222.04 N, the stability angle was 11.03°, and the stable drag force was 2 783.93 N. When the optimal towed speed was 1.8 m/s and the towed water depth was 30-50 m, the optimal combination of parameters was: the length of the towed boundary rope was about 35.02-58.36 m, the stable rope length was about 156.80-261.34 m, the critical angle was about 58.95°, the critical drag force was 4 148.41 N, the stability angle was 11.03°, and the stable drag force was 2 275.83 N. The scallops were expected to smoothly enter the net bag when the height of the net opening was 350 mm. As such, there was a reduced introduction of benthic fish into the net bag by the water flow, which fully met the requirements for the limiting bycatch capacity of benthic fish. A comparison experiment of sea fishing demonstrated that there was no significant difference between the modified fishing nets and the fishing nets for production (P>0.5), but a significant decrease was found in the amount of shellfish and benthic fish (P<0.5), when the towing speed was 1.5, 1.8 and 2.0 m/s. The deviation rates of the average catch of single netting were 6.30%, 0.59%, and 5.55%, respectively, the deviation rates of the average shellfish yield of single netting were 90.63%, 84.78%, and 85.29%, respectively, and the deviation rates of the average concurrent catch of single netting benthic fish were 78.57%, 81.25%, and 84.85%, respectively. There was the lowest deviation rate of the average catch per net and the average shellfish per net, as well as the significantly reduced average concurrent catch of benthic fish when the towing speed was 1.8 m/s. Consequently, the optimal combination of structure and process parameters was achieved for the environmentally friendly fishing dredge and trawling. The finding can also provide promising theoretical support for the sustainable production of scallop fishing. [ABSTRACT FROM AUTHOR]

Although the four substantive areas of the negotiation of the BBNJ agreement do not directly refer to the conservation and development of fishery resources in the high seas of the Arctic Ocean, the specific contents are closely related to the sustainable development of fisheries. The BBNJ agreement should complement the international legal order for the conservation and development of fishery resources in the high seas of the Arctic Ocean, and jointly promote the integration of global marine interests and the reconstruction of order. The different concepts among international subjects, the conflict of interest in the high seas fisheries of the Arctic Ocean and the maintenance and supervision of fishery resources are the main constraints for China' s deep participation in the negotiation of the BBNJ agreement and the high seas fisheries of the Arctic Ocean. Guided by the concept of "Community of Shared Future for the Sea" and taking the negotiation of the BBNJ Agreement as an opportunity, China should promote the legalization of soft law governance in the field of high seas fisheries in the Arctic Ocean, and realize China' s participation in the conservation and sustainable development of high seas fisheries resources in the Arctic Ocean through multi —field synergy. [ABSTRACT FROM AUTHOR]

Among the fishery disputes in East Asia after World War II, Japan — ROK fishery disputes have the longest fighting time. The dispute originated from the "MacArthur Line" delimited by the United States in the waters near Japan, and the direct fuse was ROK' s Syngman Rhee Declaration. The United States is both the initiator of the dispute and the promoter of the solution to the problem, and is the most important external factor affecting the process and outcome of this historical event. With the intervention of the United States, Japan and ROK successfully resolved the contradiction, cleared up a major obstacle in the development of postwar relations between the two countries, and constructed a stable framework for Japan — ROK fishery relations. However, the U. S. intervention also left historical issues such as maritime delimitation and island ownership disputes in East Asia. Maritime sovereignty and territorial disputes have become the knot between Japan and ROK, which is also the root of the shadow of the United States that has always covered the relationship between Japan and ROK and the East Asian searea. [ABSTRACT FROM AUTHOR]

Medium-sized single trawlers are still lacking to catch the pelagic fishes in the Eastern Central Atlantic Ocean in recent years. In this study, an optimal design and test were performed on the mid-water trawl for the medium stern trawler, according to the structural and hydrodynamic parameters of the current large mid-water and large-mesh offshore trawl. Three kinds of perimeters were set for the specification of net mouths in the model and offshore production, including 552, 456, and 360 m. Specifically, the mesh size of net mouth was 12 m, the length of body net/circumference net-mouth was 0.217 m, and the length of wing/circumference net-mouth was 0.076 m. The results show that the average resistance of type 552 (Circumference net-mouth was 552 m ) was 151.82 kN, and the height of net opening was 28.74 m; the average resistance of type 456 (Circumference net-mouth was 456m) was 135.6 kN and the height of net opening was 24.96 m; the average resistance of type 360 (Circumference net-mouth was 360m) was 70.76 kN and the height of net opening was 20.20 m, when the trawl speed was 2.31 m/s, while, three kinds of expansion ratio were 0.35, 0.40, and 0.45 (wingtip space between /ground rope length L/S), respectively. A model test was also carried out in the Eastern Central Atlantic Ocean. It was found that the average yield per hour of type 552 was 0.13 t and the volume of filtered water per second was about 2442 m³ when the trawl speed was 2.06 m/s. Nevertheless, only 5% of the pelagic fish was captured after the detection of pelagic fish flocks, indicating the very low net output. When the trawl speed was 2.26 m/s, the average yield per hour of type 456 was 0.77t and the volume of filtered water per second was about 1927 m³. When the trawl speed was 2.52 m/s, the average yield per hour of type 360 was 1.13t and the volume of filtered water per second was about 1321 m³. The maximum towing speed of type 360 reached 2.67 m/s, and the maximum output of single net trawl operation in 4 hours reached 20t. Since type 360 presented the smallest net mouth and the water filtration volume per unit time, the output per unit time was much higher than that of the rest. Particularly, the mid-water trawls were adopted in the medium trawlers, in order to catch the small pelagic fish with better swimming ability, where the higher towing speed was required. Furthermore, a better yield was achieved, as the increase of the trawl speed in the range of 2.31-2.52 m/s. Once the mid-water trawl run a higher towing speed, the main engine of the fishing boat was consumed more power to overcome the fluid resistance. Therefore, the power consumption of the test net part (excluding otter board and warp) was recommended as 11%-16% of the rated power of the main engine, when the decreasing power was allocated to the net. In addition, the ultra-high molecular weight polyethylene (UHMWPE) fiber can be widely used to reduce the diameter and area of the test net, further reducing the resistance for the better performance of the test net. The finding can provide an important reference for the structural design and optimization of the mid-water trawl in the medium stern trawler on ocean fishing. [ABSTRACT FROM AUTHOR]

Entity relation extraction is a fundamental task to detect a list of triplets, including two entities and the semantic relations between them. An overlapping relationship has caused the low performance of standard entity relation extraction in fishery in recent years. In this study, a novel entity relation extraction was proposed in fishery using the dual attention mechanism. First, a sentence classification and labeling strategy were selected to solve the difficulty in labeling overlapping relations in fishery standard texts. Second, an extraction model of standard entity relationship was established using a combination of dual attention, and Bidirectional Encoder Representations from Transformers-Bi-directional Long Short-Term Memory-Conditional Random Field (BERT-BiLSTM-CRF). Five components were included from the bottom to top: BERT layer, BiLSTM layer, word attention mechanism, sentence attention, and CRF output layer. In the pre-trained BERT model, the dual-layer two-way conversion and decoding were used to automatically learn sentence features for the vector representation. In the BiLSTM model, the context feature of the target entity was learned from the BERT output. The word and sentence level attention was utilized to optimize the weight of target words and sentences in the paragraph, including the noise removal, and the accuracy of relationship extraction. The CRF decoder was used to represent the output of the attention layer in the form of sequence tags. Finally, a comparative experiment was designed to verify the effectiveness of the model. The results show that better overall performance was achieved in the entity relationship extraction using the dual attention on the fishery standard interaction (DLOU-FSI) dataset, where the accuracy, recall, and F1 value were 92.67%, 92.31%, and 92.49%, respectively. The overlapping relations were effectively solved in the extraction of fishery standard relations. In addition, the recognition accuracy rates in the seven relation categories were all higher than others. The accuracy rate, recall rate, and F1 value were greatly improved by more than 90% in the quotation relationship, regulation, release, proposal, drafting, and centralization. Nevertheless, the recall rate of the improved model was dropped slightly in the comparison test. The reason was that there was a sparse distribution of sentence samples in the related category of comparative relations. In the DLOU-FSI corpus, each standard text of fishery contained only 0-3 comparison relation triples, less than 1% of the total number of all relational triples. As such, the comprehensive relationship features were necessary to learn for the higher recognition in the relationship extraction task. In addition, the quality of corpus was determined on the extraction of fishery standard text relations. The higher quality and the more accurate recognition of the model were achieved, as the deep learning model was trained to learn more data. There was also a critical value, after which the model cannot be greatly improved. In the case of a model adaptation, the test data can be effectively expanded to increase the number and diversity of samples for a better overall effect of relationship extraction. This finding can lay a significant foundation for the construction of fishery standard knowledge graphs. [ABSTRACT FROM AUTHOR]

Fishery information service is a vital component to realize data analysis, feature extraction, and fishing forecasting, particularly for a high comprehensive production capacity and modernized management in fishery. The commonly-used keyword matching without standard contents cannot meet the high demand for accurate service in the current information system of fishery. The standard quantitative indicators in fishery have become one of the most important tasks in the information service. Therefore, it is very necessary to accurately identify the effective standard quantitative indicators for the automatic extraction of fishery. Combining the attention mechanism and the BERT+BiLSTM+CRF (Bidirectional Encoder Representations from Transformers + Bi-directional Long Short-Term Memory + Conditional Random Field) model, this study aims to propose a highly accurate recognition method of standard quantitative indicators in fishery, further to replace the commonly-used entity recognition. The quantitative indicators were firstly divided into four types of entities: the indicator name, indicator value, unit, and qualified words for identification. This operation effectively dealt with the difficult identification of fishery standard quantitative indicator entities. It was found that the location information behaved a significant impact on the recognition of indicator names and other entities. Vector data was also utilized to improve the recognition of indicator names. Secondly, the BiLSTM model was used to learn the semantic features of long sequences in the fishery standard text quantitative indicators. The attention mechanism was then integrated to treat the long-sequence semantic dilution. Finally, all sequence tags were obtained through the CRF layer. The test results showed that the accuracy rate was 94.51%, the recall rate was 96.37%, and the F1 value was 95.43% for the fusion attention mechanism and the BERT+BiLSTM+CRF model. Compared with the fusion attention + BiLSTM + CRF (named entity recognition model), the accuracy, recall rate, and F1 value increased by 2.78, 6.73, and 4.65 percentage points, respectively. The word vectors, position vectors, and sentence features were combined for better recognition in the model. The self-attention mechanism of the BERT model was pre-trained, where a bidirectional encoder was used for the transformer layer in the BERT model, indicating a better performance on the text context memory. Compared with the BERT+BiLSTM+CRF model, the accuracy, recall, and F1 value increased by 1.62, 0.25, and 0.97 percentage points, respectively, indicating that the attention mechanism contributed to the greater weight of the target entity in the long- and short-term memory network. The features were then weighted to make the model more accurately identify quantitative indicators. The proposed model can be expected to more accurately identify the fishery standard quantitative indicators, especially the indicator names, indicator values, units, qualifiers. This investigation can provide promising data support to accurate information using standard content services. The effective fishery standard quantitative index can also offer new ideas for the identification of quantitative indicator named entities in agricultural, medical, and biological fields [ABSTRACT FROM AUTHOR]

The aim is to obtain the bacterial community of rice roots related to salt resistance, in order to provide support for the development of comprehensive planting and breeding technology in saline-alkali waters. [Method] The high-throughput sequencing method was used to study the changes of hydroponic rice root microbial community structure under different salt concentration stress. 【Result】Under different salt concentration stress, the abundance and diversity of rice root bacterial community showed a trend of first high and then low with the salt concentration, the highest under 3‰ concentration stress, and the lowest under 5‰ concentration stress. [Conclusion] The bacterial species of Rhodobacteraceae, Phyllobacteriaceae, Gemmobacter and Aquisphaera are significantly positively correlated with salt concentration (P<0.05). Therefore, the bacterial species belonging to these families and genera have potential value in the development of "fish-plant" integrated cultivation in saline-alkali water fishery in the future. [ABSTRACT FROM AUTHOR]

To improve the accuracy and practicability of fishery forecast in the Northwest Pacific, a method of constructing a forecast model of squid was proposed based on the principle of deep learning. In this study, the data included the fishery catch data from the North Pacific squid fishing boat production information and the Sea Surface Temperature (SST) from the moderate-resolution imaging spectroradiometer, from July to November 2000-2015. According to the combination of different channels, four kinds of datasets were formed for the model training, including the single-channel dataset only containing SST; 2-channels dataset of SST and month; 3-channels dataset of SST, longitude, and latitude; 4-channels dataset of SST, month, longitude, and latitude. To match the data of the first channel in dimensionality, the three-input data of longitude, latitude, and month needed to be expanded from a 0-dimensional scalar quantity to a 2-dimensional tensor with pixels of 65×65 and regarded as the second, third, and fourth channel. Because of the insufficiency of effective fishery catch data, these datasets were enhanced by random rotation of the SST image with a small-angle between -10° and +10° and a random 0.1° offset of the image center in four directions, including north, south, east and west. The AlexNet was chosen as the structure of the Convolutional Neural Network (CNN) model, and it consisted of five convolutional layers, three max-pooling layers, and three fully-connected layers with a final 2-way softmax. Different from traditional fishery forecast methods, this method used the Graphics Processing Unit (GPU) to accelerate training, and its extraction of environmental features was automatically completed by computer. SST, latitude, longitude, and month were all factors that needed to be considered when constructing a fishing ground forecast model. The impact of these factors on the accuracy of the fishing ground forecast was compared and analyzed. The results showed that 1) According to the migration laws of squid, the datasets from July to November were divided into three sub-datasets, including July to August, September, and October to November. This way of month combination increased the testing accuracy by at least 6.1 percent points. The testing accuracies of three sub-datasets of July to August, September, October to November were much higher than that of the whole dataset (74.4%) from July to November. 2) The training result of the 4-channels dataset was the best, and the testing accuracy was significantly higher than that of others. The single-channel dataset only containing SST achieved the testing accuracy of at least 73.5%, which indicated that SST was the most important factor among the four factors of SST, longitude, latitude, and month. 3) The actual fishery catch data of 2015 was used to validate the accuracy of the forecast model, and precision and recall were chosen as the evaluation indexes of this model. The average precision, recall, and F1-score were 66.6%, 82.3%, and 73.1%, respectively. The predicted high-yield fishing areas basically matched the actual high-CPUE (Catch Per Unit Effort) areas, and the monthly movement trends of both were also basically consistent. 4) The training results were satisfactory, and the testing accuracy converged to about 80.5% after 80 000 iterations of training. The accuracy of three testing datasets with 4-channels dataset of July to August, September, and October to November was 80.5%, 81.5%, and 81.4%, respectively. It could be concluded that SST and its temporal and spatial information played an important role in the forecast of the Northwest Pacific squid fishery. And the training results demonstrated that it was feasible to construct a squid fishery forecast model by using a dataset of single environmental factor SST and CNN. It also could be concluded that the migratory laws of squid were significant and could not be ignored in the process of the fishery forecast model construction [ABSTRACT FROM AUTHOR]

Fish feeding is a key process in fishery industry. With the advancement of fishery modernization, traditional manual feeding has been replaced by mechanized feeders. But most of existing feeders are designed for pellet feed, which are not quite suit for carnivorous aquatic species such as weevers, groupers, squids etc. Those species mainly feed frozen little fishes and shrimps called fresh feed. Taking Sepia pharaonis for example, the intensive droppoints of fresh feed caused by traditional feeders will make squids to fight for food and result in injury and death. Such phenominon highly raises the cost and reduces the production efficiency. In this study, the design idea of feeder with discrete casting for fresh feed was put forward. Firstly, in order to ensure that the feeder had a good effect on discrete droppoints of fresh feed, the multi-stage casting mode was specially designed. In this mode, the casting speed, direction and elevation angle of feeder can be adjusted in real time, which maked the droppoints of fresh feed relatively uniform and not gather in small area. In addition, to ensure feeding automation, the feeder was equiped with Siemens PLC and MCGS touching screen as the control core and human machine interface for user to adjust and monitor above running parameters. The static analysis of the electric pusher was done to ensure the necessary maximum load. And the complex-vector method was used to calculate the relation curve between running time of electric pusher and elevation angle to realize the accurate control of casting elevation angle. The relationship between elevation angle and pusher running time was close to the straight line. Furthermore, MATLAB was used to simulate the droppoints of the multi-stage casting mode and determine running parameters in the mode and the test was held in squid breeding site to confirm the basic performance and effect of the casting mode. The multi-stage casting mode test results showed that the feeder could realize the discrete casting with longitudinal casting distance range from 1.8 to 8.0 m, crosswise casting distance range from 0 to 3.9 m, the casting area 26 m2 . And this mode can cover 81.2 % of 8 m×4 m indoor breeding pool. Since the test was held in dry pool and fresh feed slide in the ground, the casting area was greater than that shown in the simulation of 17.95 m² . The performance test results showed that the average feed breakage rate was 3.3% when the rotating speed of the feeding machine was less than 900 r/min, while the rotating speed was higher than 900 r/min the breakage rate increased rapidly. Therefore, the maximum effective throwing distance was 10.5 m in speed of 900 r/min. The results showed the feeder and multi-stage casting mode were effective to realize the discrete casting with relatively uniform droppoint distribution, which reduced the behavior of fighting for food to death. The study can provide references for feeders design and discrete feeding. [ABSTRACT FROM AUTHOR]

Marine fishery economy is a crucial component of maritime economy. Marine fishery engineering is a potential and sustainable field in the future economy of marine fishery. Both China and Australia are countries with large maritime resources and marine fishery resources. How to more efficiently utilize these rich maritime resources and further develop the marine fishery economy are common issues faced by both countries. The current status and characteristics of Australian marine fishery engineering, adopts methods including research, big data statistics, and specific case analysis to distinguish the advantages and disadvantages of Australian marine fishery engineering were analyzed in this article. The basis, advantages, difficulties and challenges of Sino-Australian marine fishery economic cooperation, and investigate the prospects for deep cooperation between China and Australia in the field of marine fisheries to achieve mutual beneficial cooperation were analyzed. It is concluded that the launch of Sino-Australian marine fisheries economic cooperation and opening of the Blue Economic Corridor is an important part of China’s ‘Belt and Road’ initiative. It serves the fundamental interests of the two countries, as well as complements both respective economies. And it also, to an extent, resolves Australia’s misunderstanding of China’s ‘Belt and Road’ initiative. [ABSTRACT FROM AUTHOR]

According to the requirements of port management system, all fishing vessels must stop fishing and return to their registry ports during the summer fishing moratorium. Fishing vessels are not allowed to dock at the non-registry port. In order to investigate the fishing vessels docking at other provinces or cities’ ports which are not their registry ports during the summer fishing moratorium, a method to extract the off-site docking information of offshore fishing vessels based on Beidou navigation satellite system position data was proposed in this paper. First of all, we need to find out the time periods during which the fishing boat stoped sailing, and then selected the longest time period and obtained the longitude and latitude of the location where the boat stoped during the longest time period. The reverse address query web service provided by Gaud map was used to obtain the provinces, cities and districts based on the longitude and latitude. Then compared the docking address with that of registry ports to determine whether the vessel was off-site docked. Taking Zhejiang Province of China as an example, the fishing vessels positions data of vessel monitoring systems based on Beidu Navigation Satellite System was used to extract the off-site docking information and conduct statistical analysis. The results showed that 2.75% of fishing vessels docked across provinces, 5.86% of fishing vessels docked across cities in the province and 15.6% of fishing vessels docked accross district in the city。This method can quickly extract and count off-site docking information of fishing vessels, and provided technical support for fishing vessel's management information during the fishing moratorium. [ABSTRACT FROM AUTHOR]

Modern fishery farming is developing in the direction of refinement, and the application of the Internet of Things in fisheries is becoming more and more widely used. For the deployed terminal nodes, in addition to the need to obtain environmental awareness information, it is also necessary to obtain the location information of the node, so that the collected data have application value. Moreover, the higher the positioning accuracy of the node, the better the evaluation of the environmental state and the task execution, especially for the node with a buoy as the carrier. At present, the positioning accuracy of Global Positioning System (GPS) technology widely used is about 10 m, the use of RTK differential technology obtain high positioning accuracy, but the equipment price is too high, so it is not very suitable for fishery application. In this study, a low-cost GPS relative positioning method based on the Long Range (LoRa) network was proposed. First, the relative positioning strategy data model was established through error analysis, and then the relative positioning method based on the LoRa network and improved the Time Division Multiple Access (TDMA) transmission strategies were designed to achieve high-precision positioning and energy-efficient data transmission. The premise of the relative positioning of this study was that time synchronization could be achieved, GPS receiver provided accurate timing service, so before nodes started to locate, all nodes in the network were synchronized through GPS module, and every fixed cycle of synchronization operations, to ensure that all nodes had the same time benchmark. Gateways and terminals caused similar system errors due to atmospheric delay, convection, and ionosphere effects, and improved relative position accuracy through relative positioning calculation. The transmission of data based on the LoRa network was fully taken into account that LoRa was suitable for long-distance transmission, which was sufficient for applications in large fisheries environments. Secondly, the low power consumption of LoRa also reduced the cost of fishery production. When the terminal carried out information collection, LoRa went into a dormant state after the completion of work, which effectively reduced the power consumption. In this study, the latitude and longitude information of the gateway and terminal was set up to consist of an observation sequence consisting of satellite signal strength greater than 30 dB in the observed satellite, and each positioning required that the gateway and the terminal had more than 6 same satellites. Considering a large number of nodes in the Internet of Things system, to prevent information collision affected the positioning accuracy, the introduced TDMA technology assigned each terminal its time slot. Each terminal starts its work according to its task and then uploaded data. The transmission strategy of this study was different from the previous strategy, which stipulated that each cycle should firstly collect or locate the data according to the task broadcast in the previous cycle, then broadcasted the task of the next cycle, and finally the terminal response. This shortened the cycle and increased the reliability of information transmission. Finally, the hardware node was designed and the deployment test was carried out in the offshore fishery. The test calculation took the gateway as the origin, the positive east direction was the x-axis, the north direction is the Y-axis to establish a coordinate system, Vincenty method using the ellipsoid model to ensure the accuracy of the calculation. The experimental data showed the validity and reliability of the proposed method in this study. With a low-cost GPS commercial module, the average positioning accuracy of the terminal nodes 1 000 and 499 m from the gateway increased from 10 m to 4.8 and 2.4 m, respectively, and the data delivery rate increased from 80% to more than 95% [ABSTRACT FROM AUTHOR]

Atlantic salmon is one of aquaculture species with the largest production by value around the world according to the data from the Food and Agriculture Organization (FAO). The production of Atlantic salmon began from 1960s in Norway. After about 60 years, current Norway has become a leading country in salmon farming worldwide, and held various regulation including farming license, the maximum allowed biomass (MAB), traffic lights. The paper aims to systematically review the important advancements in the production of Atlantic salmon in Norway, and make recommendations for future development of Chinese aquaculture industry. According to the statistics number published by FAO, Norway produced 123.4 million tons of slaughtered Atlantic salmon in 2017, accounting for about 54.9% of production volume in world total, and 61.635 billion NOK by value. 10 global companies, including Salmar, Cermaq, and Marine Harvest, have produced 63.9% of the Norwegian production of Atlantic salmon. According to the prediction from Norsk Industry Alliance, the Norwegian Atlantic salmon production will achieve over 200 billion NOK in 2030, and 300 billion NOK in 2050, by solving the problems of sea lice, escaped fish and recycle of fish feces. In 2017, there were 986 sea farming sites, and 7499 employees working on salmon farming in Norway. A typical procedure of land-ocean relay farming mode can be found in Norwegian salmon raising. During the first year, fish eggs are fertilized, and then the fishes can grow to 100 grams in land-based freshwater supported by a recirculating aquaculture systems (RAS) facility. Subsequently, the fishes are transferred to sea farming sites, where they will be raised to about 4~5 kg per fish in the sea cage. In each sea site, there are normally 6~10 sea cages with the diameter of 50~200 m and the depth of 20~50 m, indicating the high-density culture of 25 kg/m³ when harvesting. Finally, one floating platform that people can live on can be set near the sea cages, to monitor the sea water quality and fish behavior in real time. Commercial working ship can also provide essential services to farmers, such as fish harvesting, fish transfer, and net cleaning. In order to protect the ecological environment of sea fields, the regulation that approved by Norwegian government requires: 1) the distance between sea sites must be larger than 1 km, 2) the distance between sea site and land-based raising facility must be larger than 3 km, and 3) the farming period cannot be longer than two years. With the deterioration of global warming and inshore water quality, it is demanding for more and more operation and management in salmon production. Norwegian salmon farming is now changing from open net cages to closed containment system, from inshore to offshore. In China, sea fish production began at 1980s for 40 years, and the technology and whole industry chain have been fast developed. The total production of sea fish has achieved 1400 kt with the total value of 65~70 billion Yuan in 2018. Compared with Norwegian production of Atlantic salmon, there are some big challenges for China’s to achieve high efficiency of enterprise organization, much more variety of fish species and promising faming mode. In this broad overview of Norwegian Atlantic salmon industry, some recommendations can be made for the future aquaculture industry in China. Four suggestions are: 1) To improve access requirements of fish farming, and strengthen process supervision and environmental assessment; 2) to set different development strategy for different species; 3) to introduce advanced system of fish fry production; 4) to accelerate the research on offshore farming facility and land-sea faming mode. [ABSTRACT FROM AUTHOR]

In order to provide relevant information for natural resource management, impact assessment and marine spatial planning, high-resolution estimation of longline fishing gear is needed. Because the use of satellite vessel monitoring system (VMS) data is limited by data access and receiving offshore ship location information. In this paper, based on the data of automatic identification system (AIS) and logbook data of Chinese longline fishing from October to November 2017, a model of fishing detection based on support vector machine (SVM) learning method is established to classify the fishing and non fishing activities in the central and Western Pacific Ocean, to carry out longline fishing and draw fishing effort map in the Western and Central Pacific Ocean. Before constructing a fishing detection model, each AIS point was classified and pre-labeled as potential fishing and non-fishing events by an expert based on information on information on fisheries characteristics as obtained from literature, analysis of the tracks and logbook data. The performance of the fishing detection model was evaluated by the overall accuracy, precision, sensibility and specificity. Fishing intensities were computed from the known fishing positions and the estimated fishing positions were compared with correlation coefficient. The spatial correlation coefficient of fishing intensities and catch data was computed to quantify the extent to which the distribution of longline vessels describes tuna distribution. The results showed that the overall accuracy and the Kappa coefficient of the model training dataset were 95.24% and 0.9, respectively. The precision, sensibility and specificity were 94.74%, 93.44%, 96.56%, respectively. The overall accuracy and the Kappa coefficient of the model testing dataset were 93.85% and 0.87 respectively. The precision, sensibility and specificity were 93.49%, 90.67%, 95.91%, respectively. Then the constructed model was used to identify all the AIS data for 12 longline fishing vessels in the Western and Central Pacific in October and November 2017, with an overall accuracy rate of 83.3% and the Kappa coefficient was 0.67. The precision, sensibility and specificity were 82.33%, 88.32%, and 77.27%, respectively. The longline fishing distinct in October and November 2017 mainly located in 168°E-173°E, 12°S-18°S, and there were three obvious high fishing intensity areas on the map. The spatial distribution of fishing effort was significantly different between October and November. The distribution of fishing intensity in November was closer to the island than in October and the value of fishing intensity in October was lower than November. The fishing intensity information based on the SVM model and logbook data records was highly correlated (r>0.98). The spatial distribution characteristics of the fishing effort of the fishing vessel identified by the SVM model were similar to the known fishing positions. But the fishing intensities were calculated from known fishing positions was higher than that of estimated fishing positions. The spatial correlation coefficients of cumulative fishing effort and catch per unit of effort (CPUE), catch tail, catch weight and number of hooks were 0.68, 0.93, 0.93 and 0.94, respectively. The fishing capacity of fishing vessels based on AIS information mining can also be used as an alternative method for fishery resource analysis. [ABSTRACT FROM AUTHOR]

In recent years, due to various environmental problems and resource conflicts in coastal areas, nearshore mariculture in China has been increasingly confronted with the severe challenge of space compression. However, in more exposed sea areas with the depth exceeds 20 m, the water quality is much better and the water utilization rate is much lower, less than 1%. With the development of aquaculture technology and equipment engineering, it is an inevitable trend for fish farms to transfer to offshore areas. To reduce the risk of fish farming in open sea areas with strong waves and current, offshore fish farm that having the distinct advantages with moderlization of culture and management were encouraged to develop in the past two years in China. Generally, offshore farm was considered as an integrated farming system composed of cultured fish, floating structure, automatic equipments, various facilities, which was expected to play a positive role in leading and promoting the offshore aquaculture industry. In this study, we conducted a series of physical model tests for a semi-submersible offshore fish farm called “Dehai No.1” in waves, in which the model scale was set as 1:30 and the scale of 1:1 was set for the net mesh size. The “Dehai No.1” offshore fish farm with truss structure was co-designed by South China Sea Fisheries Research Institute and Tianjin De-Sai Environmental Protection Technology Co.,Ltd in the year of 2018. The main experimental parameters of the offshore farm were as follows: length 3.04 m, width 0.92 m, height 0.34 m, designed draft of 0.22 m, no-load weight of 15.33 kg. Considering the actual production requirements, three kinds of single point mooring systems (L=2.67, L=5.34 or L=5.34 plus GW=200 g) and three kinds of ballast status (no-load, half-load or full-load) as well as different regular waves conditions (H=16.7-23.3 cm, T=1.64-2.01 s) were set as the test conditions for the fish farm. Through physical model experiments, the dynamic behaviour of the fish farm under different conditions were studied, and the results of mooring force and motion response were given and compared. Owing to the characteristics of the single point mooring system, the fish farm in practice inevitably drift within the scope of sea area in the center of mooring point on seabed with the variation of low-to-high water surface, studying the sway and surge as well as yaw for the fish farm could not testify its good stability. Therefore, we chose the heave, pitch and roll for analyzing the motion characteristics of the fish farm. The experimental results showed that the single-point mooring system with anchor chain length of 5.34 m and a weight of 200 g could better reduce the mooring force of the fish farm in waves. Among all of the wave conditions, the peak value of each movement component of the fish farm was relatively small. When the fish farm was subjected to the sea loads with wave height of 23.3 cm (7 m in full-scale) and wave period of 2.01 s (11 s in full-scale), the peak value for the heave, pitch and roll was 4.21 cm, 6.55° and 1.19°, respectively, which indicated that the fish farm had good performance for the stability of floating state. Comparing the maximum motion and mooring force of the fish farm under various floating conditions, including no-load and half-load as well as full-load, we found that, in the full-load floating state, the peak value for the mooring force, pitch and roll was biggest, but the peak value of the heave was biggest under the no-load floating state for the fish farm. With increasing wave height, both of the mooring force and motion of the fish farm became larger. The results provide a basis for further understanding the dynamic characteristics of fish farm, and help to provide theoretical and data reference for the structure design and installation of fish farm. [ABSTRACT FROM AUTHOR]

In recent years, due to various environmental problems and resource conflicts in coastal areas, nearshore mariculture in China has been increasingly confronted with the severe challenge of space compression. However, in more exposed sea areas with the depth exceeds 20 m, the water quality is much better and the water utilization rate is much lower, less than 1%. With the development of aquaculture technology and equipment engineering, it is an inevitable trend for fish farms to transfer to offshore areas. To reduce the risk of fish farming in open sea areas with strong waves and current, offshore fish farm that having the distinct advantages with moderlization of culture and management were encouraged to develop in the past two years in China. Generally, offshore farm was considered as an integrated farming system composed of cultured fish, floating structure, automatic equipments, various facilities, which was expected to play a positive role in leading and promoting the offshore aquaculture industry. In this study, we conducted a series of physical model tests for a semi-submersible offshore fish farm called “Dehai No.1” in waves, in which the model scale was set as 1:30 and the scale of 1:1 was set for the net mesh size . The “Dehai No.1” offshore fish farm with truss structure was co-designed by South China Sea Fisheries Research Institute and Tianjin De-Sai Environmental Protection Technology Co.,Ltd in the year of 2018. The main experimental parameters of the offshore farm were as follows: length 3.04 m, width 0.92 m, height 0.34 m, designed draft of 0.22 m, no-load weight of 15.33 kg. Considering the actual production requirements, three kinds of single point mooring systems (L=2.67, L=5.34 or L=5.34 plus GW=200 g) and three kinds of ballast status (no-load, half-load or full-load) as well as different regular waves conditions (H=16.7-23.3 cm, T=1.64-2.01 s) were set as the test conditions for the fish farm. Through physical model experiments, the dynamic behaviour of the fish farm under different conditions were studied, and the results of mooring force and motion response were given and compared. Owing to the characteristics of the single point mooring system, the fish farm in practice inevitably drift within the scope of sea area in the center of mooring point on seabed with the variation of low-to-high water surface, studying the sway and surge as well as yaw for the fish farm could not testify its good stability. Therefore, we chose the heave, pitch and roll for analyzing the motion characteristics of the fish farm. The experimental results showed that the single-point mooring system with anchor chain length of 5.34 m and a weight of 200g could better reduce the mooring force of the fish farm in waves. Among all of the wave conditions, the peak value of each movement component of the fish farm was relatively small. When the fish farm was subjected to the sea loads with wave height of 23.3 cm (7 m in full-scale) and wave period of 2.01 s (11 s in full-scale), the peak value for the heave, pitch and roll was 4.21 cm, 6.55° and 1.19°, respectively, which indicated that the fish farm had good performance for the stability of floating state. Comparing the maximum motion and mooring force of the fish farm under various floating conditions, including no-load and half-load as well as full-load, we found that, in the full-load floating state, the peak value for the mooring force, pitch and roll was biggest, but the peak value of the heave was biggest under the no-load floating state for the fish farm. With increasing wave height, both of the mooring force and motion of the fish farm became larger. The results provide a basis for further understanding the dynamic characteristics of fish farm, and help to provide theoretical and data reference for the structure design and installation of fish farm. [ABSTRACT FROM AUTHOR]

Antarctic krill is not only rich in biological resources, but also has high utilization value. As a new protein resource, Antarctic krill will get more and more attention as the offshore fishery resources dwindle. But Antarctic krill is very small and grows in the distant Antarctic seas. Krill is rich in active enzymes and tends to deteriorate. As a result, it needs to be processed quickly on board. Therefore, the fishing and processing of Antarctic krill require higher cost and have more difficulty. In the 1960s, the development of krill industry was started from abroad, and China has begun the research on krill processing technology in recent years. Some preliminary research results have been obtained in process and equipment. Krill is often used to produce shrimp meat or to extract shrimp oil. Peeling is another effective method for the utilization of Antarctic krill. Previous research has shown that roller extrusion is one of the effective methods for the peeling of Antarctic krill. There are many factors that influence the effect of peeling in actual production, such as rotation speed, extrusion distance, and roller clearance. It is also affected by the wind and waves of the sea. The wind and waves sway the ship and affect the safety of navigation. These include the impact on personnel and the impact on equipment. The influence of sway on the equipment is reflected in the change of stability and processing effect. A composite laminates peeling equipment is developed to explore the effect of waves on the peeling results of krill. The performance of the equipment under different swing conditions in the sea was analyzed. Ships would have varying degrees of lateral sway and vertical sway during the voyage. The yield rate and residual rate of shrimp shells were measured and recorded. The roller was divided into 4 areas according to the length. The completion rate of peeling in different regions was analyzed. The experimental results show that the swing of the ship affects the yield rate and the residual rate of the shell. But the difference is not significant. Krill shell residue ratio rises to 1.07% when the longitudinal swing reaches 7°. And it rises to 1.64% when the lateral oscillation reaches 5°. The swing of the ship also has a certain effect on the completion rate of the peeling. The completion rate of peeling in the same area shows a decreasing trend, with the increase of swing amplitude. It is found that increasing the length of the roller can effectively alleviate the problem of the decrease of the peeling completion rate caused by the swing. The completion rate is greater than 95% when the roller length is about 1200 mm. The retention time has a great effect on the peeling effect. The completion rate of peeling of the krill that is stored for 2 h decreases significantly after being caught. And peeling completion rate reduces to 94% in the regional Ⅳ. The residual rate of shrimp shells increases correspondingly. The results can provide reference for the application and industrialization of Antarctic krill peeler. [ABSTRACT FROM AUTHOR]

Autonomous navigation is one of the key technologies for an intelligent agricultural equipment, which has been widely used in modern agricultural production. Sea cucumber production and consumption are very large in China. At present, the sea cucumber harvest mainly relies on trawl or artificial fishing, which will cause a potential hazard to the health of divers and the marine ecology. Therefore, in order to overcome the shortcomings of traditional sea cucumber fishing methods, it is necessary to develop a sea cucumber fishing device with autonomous navigation and positioning functions. Strapdown inertial navigation system (SINS) is suitable for the navigation of the autonomous sea cucumber fishing device because of its autonomy, passivity and complete navigation parameters. For the SINS, initial alignment must be completed before starting a navigation mission. The purpose of the initial alignment is to determine the initial position of the carrier coordinate system relative to the navigation coordinate system, that is, to determine the initial value of the attitude matrix. Initial alignment is one of the key technologies of SINS, which is divided into coarse alignment and fine alignment, and the coarse alignment accuracy will directly determine the performance of the initial alignment. Therefore, it is of practical value to study a coarse alignment scheme with simple algorithm and high alignment precision. The traditional analytical coarse alignment algorithm directly utilizes the earth gravity vector and the earth rotation angular velocity vector to estimate the initial attitude matrix. In view of the problem that the horizontal alignment accuracy of SINS is affected by the measurement errors of gyroscope and accelerometer in the traditional analytical coarse alignment algorithm, a novel coarse alignment algorithm based on double-vector attitude determination is proposed. In general, the measurement error of the accelerometer is much smaller than that of the gyroscope, so the earth gravity vector in the proposed algorithm is chosen as the main reference vector. Then, 3 unit orthogonal vectors are constructed based on the earth gravity vector and the earth rotation angular velocity vector, and the resulting attitude matrix is a unit orthogonal matrix. The theoretical analysis shows that horizontal misalignment angles of SINS are only related to the accelerometer level measurement errors in the case of using the proposed algorithm, however, using the conventional algorithm, the horizontal misalignment angles are related to the accelerometer measurement errors and the gyroscope drift error. Therefore, the coarse alignment accuracy of SINS using the aforementioned algorithm is significantly improved. Based on the same measured data from an inertial measurement unit, the simulation experiment was carried out for 30 times using the conventional coarse alignment algorithm and the proposed algorithm, respectively. Simulation curves demonstrated that the variation of the horizontal attitude angles using the algorithm proposed was smoother. To further verify the effectiveness of the algorithm, the attitude angles calculated from the measured values of the inertial measurement unit were compared with the measured value of a high-precision three-dimensional electronic compass, and the experimental results showed that the horizontal error angles of the aforementioned coarse alignment algorithm did not exceed 1° and the azimuth error angle did not exceed 3°. The results can meet the accuracy requirement of coarse alignment and will provide an effective initial condition for the subsequent fine alignment using filtering methods. [ABSTRACT FROM AUTHOR]

Pond aquaculture plays a very important role in China's aquaculture industry and is the main source of aquatic product supply. To improve the effect of pond aquaculture, a partitioned recirculating aquaculture pond system (PRAPS) was designed and built based on the characteristics of pond aquaculture in freshwater, which consisted of feeding fish culture zone (20% of water surface) and filter-feeding fish culture zone (80% of water surface). The structure of facilities and equipment of PRAPS was optimized by setting up the overflow weir, propeller flow device, paddlewheel device, and pollutant absorption and collecting device. Tests on the mechanical properties revealed that both propeller flow device and paddlewheel device could achieve the design demand; the energy efficiency of the propeller flow device was about 340 m3/(kW·h), the flow rate was around 204 m3/h, and the no-load running noise was 60 dB; the energy efficiency of the paddlewheel device was about 360 m3/(kW·h), the flow rate was around 180 m3/h, and the no-load running noise was 67 dB; the total flow rate of the overflow weir was about 331 m3/h. The exchange capacity was totally about 7 900 m3/day, accounting for about 50% of the pond water capacity. Additionally, the system could reduce the total energy consumption and farming pollution and effectively improve the pond aquaculture ecological effect, which met the production requirement of energy saving and environmental protection. It was conducive to improve the water quality of the pond though the impeller disturbed the water. The pollutant could be gathered into the middle of bottom by the collecting device, and removed out of system by the pollutant absorption device, in which way the transparency of water was improved, and the content of TN (total nitrogen) and TP (total phosphorus) in the system was decreased. The propeller flow device and paddlewheel impeller stirring water could realize water convection in large scale, so the water was exposed to sunshine and air, which could increase the dissolved oxygen in the water. Tests showed that the dissolved oxygen of the middle and lower layer in the test pond was 59.5% higher than the control pond; the content of TN in the test pond was 21.4% lower than the control pond; the content of TP was 53.1% lower than the control pond; the chlorophyll a concentration in the test pond was lower than the control pond. Because the breeding density in the test pond was higher than the control pond, the content of ammonia nitrogen and nitrite nitrogen in the system was increased. Overall the water quality in the test pond was better than the control pond. For the PRAPS, the one-time investment was big at the beginning and it needed professional and technical personnel to maintain, while the PRAPS had a high economic efficiency. The yield of bream in the test pond was 10 280 kg, and the food coefficient was 1.7; the yield of bream in the control pond was 8 488 kg, and the food coefficient was 2.1. The result showed that the yield of bream increased by 21.1% using the PRAPS, the feed coefficient decreased by more than 23.5%, and the annual output value increased by 6%. The result provides the reference for the model establishment of healthy breeding pond system, which is helpful to make PRAPS become a more mature and reliable novel pond aquaculture system. [ABSTRACT FROM AUTHOR]

The Antarctic krill resource is very abundant in the area surrounding the Antarctic and the total production in China has reached nearly 60 000 t. At present, the existing problems are the lack of exclusive localization fishing gears for Antarctic krill fisheries and the low matching degree between the trawl net and the fishing vessels. Through collecting the production situation of fishery company at home and abroad, 6 kinds of different existing Antarctic krill trawl nets were selected as the experimental prototype. The model test was carried out in the flume of trawl fishing gear in East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences. The coefficient of energy consumption, net resistance and height of net opening of different trawl nets were measured under 3 test conditions. The model test results showed that the height of net opening of trawl net No.1-3 was higher than other types of trawl nets, but its mesh size was too large to stop the escape of Antarctic krill. The net resistance of trawl net No.4-6 was higher than others. Based on the analysis of the hydrodynamic performance of 6 kinds of existing Antarctic krill trawl nets imported from fishery developed countries, an improvement program of TN01 type four-panel Antarctic krill trawl net with small mesh was developed independently. In April 2015, a 9-day sea trial was carried out in the Antarctic krill fishing ground. The test fishing vessel was “Kaili” from Shanghai Kaichuang Ocean Fisheries Co., Ltd. The sea trial results showed that: 1) When the warp length was less than 230 m, the depth of cod-end was lower than body net, which meant the buoyancy force of cod-end was too large. When the warp length was longer than 230 m, the depth of cod-end and the working depth had a positive relationship. The best buoyancy-weight ratio was suggested to be 1:1.1; 2) No significant correlation was found between the length of the vertical net opening and the length of warp. When the trawl speed was 1.542 m/s, the height of the vertical net opening was 26-29 m and the vertical expansion ratio was 0.11-0.12. As releasing the warp length from 90 to 370 m, the height of the horizontal net opening increased from 14 to 20 m. The expansion ratio was 0.22-0.32. The expansion at vertical and horizontal direction had good effect, which has reached the requirement of design. 3) The comparative analysis of the catch showed no significant difference between the day and night. The average yield per net in the daytime was 33 t and the average yield per net at night was 28 t. The average yield per net in sea trial was 30 t, which increased by nearly 50% compared with other fishing vessels around the same fishing area (according to the statistical records, the average yield per net was about 20 t). The new type of Antarctic krill trawl net has the characteristics of high efficiency and is suitable for the fishing vessels, which can provide a theoretical basis for further independent research and development of the Antarctic krill trawl net. [ABSTRACT FROM AUTHOR]

Trawl winch is the most important equipment of trawler fishing. In order to ensure safe dragging operations of fishing vessel equipment under the complex sea conditions as well as to realize the quick response and precise control of trawl winch, and keep net shape good, in this study, the trawl tension automatic control system was designed based on electro-hydraulic control technology. The system mainly consisted of proportional directional valve, balance valve, overflow valve, pilot valve, oil pressure sensor, and electric control system. Through measured input and output pressure of motor, we calculated warp tension as the feedback signal and used PLC (programmable logic controller) to control the pressure of pilot relief valve, which was used to adjust the left and right warp tension and position, to maintain the dynamic balance of system as well as to keep the net shape good. The man-machine interface and operation mode of automatic tension control was developed based on LabVIEW, of which its main function consisted of parameter set, information management, system monitor and data inquire. The system facilitated operator monitoring the running state of the various equipment, and management equipment operation. In order to verify the characteristic and practicability of tension control of the system, application test was carried on the East China Sea area in 2015. The experiment continued about 4.5 hours, including three stages: shooting net, dragging net, and heaving net, which tested speed control and tension control performance of the system under the corresponding operating conditions, and measured relevant data such as shoot depth, shoot length, shoot speed, heave speed, warp tension and winch working pressure. The test result showed that dragging stage was the longest, and in this process, the left warp and right warp were kept balance, warp tension was mainly affected by hydrodynamic, warp weight, and water resistance of fishing gear. Warp shoot length range was 350-490 m, warp tension range was 118 -148 kN, corresponding to the system pressure of 2.3-2.7 MPa, and the average trawling speed of fishing vessel was 5.6 kN. Although warp tension various with the shoot length and shoot depth change, the winch was in constant tension state at the most. Data showed that the system could adjust the warp tension well to ensure trawl warp tension maintained in a certain range through adjusting the speed of receiving or releasing net, which suppressed effectively the interference of the warp tension variation on the nets. In addition, experiment also recorded the chart of net shape by netsonde, calculated the net expansion parameter. It could be known that net mouth perimeter was equal before and after using the tension automatic control system by comparison data. The net mouth height and net mouth roundness increased and the net mouth area was expanded by 9.5% after using tension control system, which effectively adjusted the net mouth expansion and improving the fishing efficiency. During the different stage of experiment, the set pressure of overflow valve should be different correspondingly. At the beginning of shooting, the pressure value was small, which can maintain good net mouth shape and position. Due to net speed increased relative to water flow, warp tension was increased and the maximum value reached 208 kN. The set pressure of overflow valve should be large so that it could be used to effectively protect warp and net safety, provided a guarantee for the safe production of fishing vessel. The experiment process was basically consistent with the actual fishing conditions. We concluded that in the tension automatic control mode, the trawl winch can automatically adjust speed of heave and shoot according to the fishing vessel speed and water flow. Though the system could generate heat and result in power loss during uses, the warp tension control system still cab meet the requirements of warp speed and tension control in the different trawl condition. [ABSTRACT FROM AUTHOR]

Aquaculture park is an important form to promote scale breeding, which has an important significance for the transformation of aquaculture production style and the structural reform of supply side. In this paper, we use the stochastic frontier approach to analyze the production efficiency of aquaculture park with large scale in Zhejiang Province and its influencing factors. The stochastic frontier analysis method is widely used in the studies on agricultural production, yet the research using this method to calculate the technology efficiency of aquaculture park and analyze its influencing factors is relatively few. The technical efficiency of tilapia culture in Guangxi and the technical efficiency of freshwater aquaculture in China have been studied by some scholars. However, most of these studies are limited to a single aquatic species or based on macro data, lacking the analysis of the operating efficiency of the micro main varieties. This paper chooses Zhejiang Province as the research area because of its developed aquaculture industry, typical park construction, standard breeding and industrial organization system. Based on previous studies, we investigate the technical efficiency of aquatic breeding park and its influencing factors, which aimed to provide reference for the healthy development of the aquaculture industry in China. The data of empirical analysis come from the Agriculture Department and the Financial Department of Zhejiang Province, which cover 116 modern fishery parks. Cross-sectional data of both before and after the construction of modern fishery park are collected. Statistical indicators mainly include the scale and efficiency (breeding area, total production, total output value, labor productivity per capita), capital investments (provincial capital investment, capital investment of owners), facilities and equipment investments (reservoir, cold storage preservation, supporting house for production, oxygen increasing machine, feeding machine), technology application and brand building (standardized production area, sewage purification treatment, disease prevention and treatment, aquatic products brand), and business entities (main operating company, cooperatives and farmers). Case data are discarded if key information is missing. At last, a total of 108 valid cases are obtained. In order to eliminate the impact of price changes, the output value of fishery park, the capital investments and other variables are divided by production price index. The results show that: (1) Scale production exerts a positive effect on the aquaculture production efficiency which has increased from 0.673 to 0.712 since the completion of the park; (2) The standardization level effectively improves the breeding technology efficiency of the park, with a regression coefficient of -0.0003; (3) Disease control equipment improves the technical inefficiency (the regression coefficient is 0.0033), which means that excessive investment in infrastructure will lead to idle equipment and hinder the improvement of technical efficiency; (4) Brand building positively influences the breeding technology efficiency of the park, with a regression coefficient of -0.0033; (5) Leading enterprises have the greatest positive effect on the level of technical efficiency, followed by the organization of fishery cooperation and the large professional farmers, with the regression coefficients of technical inefficiency being -0.0017, 0.0015 and -0.0008 respectively. But the regression coefficient of ordinary farmers is 0.0012, which implies no significant effect on the efficiency of aquaculture technology. Some policy implications can be drawn from the results of the empirical study. Increasing production of aquaculture park inputs, investing infrastructure following principle of moderate scale, paying attention to brand building and innovating the mode of fishery organization and so on may enhance the technical efficiency of aquaculture park. [ABSTRACT FROM AUTHOR]

Jing people is the only national marine fisheries of China. Under the long-term situation surrounded by mangrove plant, they have accumulated a wealth of knowledge and experience on how to use mangrove plants. However, these knowledges and experiences are still being kept under wraps. The aim of this work was to investigate the mangrove medicinal plants from classical mangrove knowledge of Jing ethnic group in Beibu Gulf, South China. We conducted a series of surveys regarding medicinal species composition and their application, and experience for sustainability via ethnobotanical and taxonmical methods. The results showed that a total 15 plant species were recorded belonging to 10 families, these species could provide 49 medicinal services, among which 20 medicinal services had been previously documented, and 29 medical purposes still had not been reported from previous research. The investigation on the level of awareness and dependence on mangrove medicinal ethnobotany showed that the situation of Jing people's dependence on Jing medical practitioner and mangrove medicinal plants were disappearing. In addition, the ecological knowledge with respects to how to harvest mangrove medicinal plants was also analyzed. These findings from this work can broaden our knowledge regarding mangrove medicinal plants from minorities in remote districts, and present a new perspective for the management and sustainable in utilization of mangrove plant resources. [ABSTRACT FROM AUTHOR]

The Antarctic krill is a marine organism with a large number. It has great value of development and utilization. As a new protein resource, Antarctic krill will get more and more attention since the offshore fishery resources are dwindling. Although the Antarctic krill has a high value of nutrition, it is hard to process because of its high fluorine content and strong enzyme activity. The krill has to be processed within 2 h on the ship after fishing in order to maintain its quality. Shelling is one of the effective methods to improve the quality of krill product. In previous studies peeling method was researched in order to get integral meat of Antarctic krill. Parameters such as body length and body weight of Antarctic krill that was just caught up were also measured. And we know that the peeling process conditions got from the response surface for Antarctic krill had a certain value in use and the method could be used on the ship. So the shelling prototype was developed and tested on the ship. In order to verify the krill shelling equipment and improve the production process, the research focused on the impacts of feeding rate, storage time and pre-cooling on shelling yield and residual rate, which would provide the bases for the practical production. The production process was considered carefully. Feeding speed was controlled by manpower in order to put the krill into a trough evenly. Then the krill would be pumped to the shelling machine after evenly mixing with water. The shrimp was put on the gauze for 2 min to filter the water after shelling, and then residual shells in shrimp were removed by manpower. The last processes were weighing, packaging and frozen. Test equipment unit was designed as 8 groups of rollers with reciprocating rotation. Yield was one of the most important indices for the evaluation of equipment ability, and residual rate was the other. The product quality of shrimp meat needed to be judged by sensory evaluation. The sensory evaluation team was made up of 5 seafarers who had a lot of experience of krill production on board. The comprehensive point was based on the integrity of shrimp, shell residue, plumpness and cleanliness. The results showed that the yield was about 24% and the residual rate was about 5%, and the shelling equipment was reliable. The yield of shelling from fresh Antarctic krill reduced slowly with the increasing of the feeding speed. It was relatively stable when the feeding speed was under 50 kg/h. And the residual rate was on the rise with the increasing of the feeding speed. When the feeding speed was higher than 60 kg/h, the residual rate of shrimp shell increased significantly. The krill with the storage time of less than 120 min could be used for production. Freshness is the most important factor in the quality of shrimp meat. Pre-cooling is an effective way to maintain shrimp quality. Frozen shrimp is not recommended to be used because the yield of shrimp meat will become lower significantly. [ABSTRACT FROM AUTHOR]

Light is one of the key environmental factors that influence the growth, development and survival of aquatic organism. In this study, the effects of different light qualities (red, orange, white, blue, green light and dark setting) and initial stage of lighting (fertilized egg, trochophore, eye spot larvae) on the growth, development and survival of the larvae of Haliotis discus hannai Ino were examined. Experimental results suggested that the hatching rate of larvae under green, blue, and dark setting were all >80% and were significantly higher compared with those under red, orange, or white light (P<0.05). Under red, orange or white light, the abnormality rate of larvae was higher and significant difference was identified if compared to any other light quality group (P<0.05). Under red light, abnormalities occurred in >10% of larvae, which was significantly higher than in any other treatment group (P<0.05). Under blue light, since the trochophore stage, the metamorphosis rate of larvae was significantly higher than any other light quality group. Under red, orange light or in dark setting, the metamorphosis rate of larvae was lower at the initial stage of different lights and no significant difference was identified if compared to any other light quality group (P>0.05). The metamorphosis rate of larvae cultured under blue light since the fertilized egg stage was significantly higher than in any other light quality group lit at the same stage (P<0.05), while the metamorphosis rate among larvae cultured under green or white light was also higher than in the remaining groups, with no significant difference between them (P>0.05). Under blue, green light, the survival rate of juvenile was significantly higher than any other light quality group (P<0.05), but no significant effect on the survival rate of juvenile was identified in the initial stage of different lights (P>0.05). In cultures lit since the fertilized egg stage, trochophore size was significantly larger under blue, green, or dark setting, compared with white or red light (P<0.05), with no significant difference among these blue, green, or dark setting (P>0.05). Under blue, green light, since the stage of trochophore or eye spot larvae, the size of completion of larval shell and metamorphosis was significantly bigger than any other group since the fertilized egg stage (P<0.05). However, the required time of metamorphosis of larvae since the eye spot larvae stage was significantly longer if compared to that of any other group since the stage of fertilized egg or trochophore (P<0.05). Therefore, blue, green light used as light source and lighting starting from the stage of trochophore in the culture and growth of the larvae of H. discus hannai Ino can be highly referential to boost the hatching efficiency of seeds, increase the yield per water body and for the rapid development of the aquaculture industry. [ABSTRACT FROM AUTHOR]

An experimental study on mechanized gutting for Trachurus japonicus was conducted, faced with equipment shortages for the pre-processing of trash fish. A self-developed test platform was employed for slitting Trachurus japonicus to avoid fish damage and increase the gut removal rate in the gutting process. Preliminary studies showed that the parameters of the slitting cutters had a significant effect on the gutting process of trash fish. In addition, the subsequent operations of gutting were directly determined by the slitting process. The various trash fish gutting operations should be equipped with different parameters of slitting cutters to achieve the best gutting effect. The relationships between gutting effect and cutter external diameter, cutter tooth structure, cutter rotation direction, cutter thickness, and cutter rotation speed were studied. The results showed that cutter external diameter, cutter thickness, and cutter rotation speed were the key factors in the gutting process of Trachurus japonicus. Using a toothless disc cutter had the best slitting effect that could achieve a smooth and flat slitting surface and a higher getting proportion. Under the same conditions, converse slitting had a better effect than consequent slitting, while a high rotation speed was better than a low rotation speed. When the slitting cutter's external diameter was 190.0 mm, it had a better acceptability evaluation of 9.68. The getting proportion had no significance when the thickness of cutter was less than 3.0 mm. With the increasing of the cutter's thickness, there was a tendency of growing weight loss of trash fish during the gutting process, which led to a lower getting proportion. An orthogonal test showed that: The best parameters of the gutting process of Trachurus japonicus were: cutter external diameter 190.0 mm, cutter thickness 3.0 mm, and cutter rotation speed 1 100.0 r/min. Under these conditions, the maximum value of acceptability evaluation and getting proportion of gutting effect was achieved, and thus it could meet the needs of the gutting process. The productivity of a mechanized processing method was 8-12 times as much as the productivity of a manual processing method. The study also showed that the gutting effect was closely relevant to the size and body characteristics of the trash fish, so their pre-processing required a heavy workload. However, replacing the manual gutting process with the mechanical gutting process could be achieved through proper size grading and the development of a general fish gutting device with the optimization of slitting cutter parameters. This study can provide reference for the design of gutting equipment for trash fish. [ABSTRACT FROM AUTHOR]