Understanding the hydrodynamic behaviors and fluttering motions of trawl codends is crucial for improving trawl selectivity and controlling fish escape while retaining desired catch. This study investigated factors like mesh size, twine diameter, codend length, knot direction, and twine material on codend fluttering in a flume tank. Fast Fourier Transform (FFT) visualized the Strouhal number, fluttering amplitude, and drag force evolution. Backpropagation (BP) neural networks were used to predict oscillatory characteristics under various conditions. Results showed that empty codends had a waist-to-end hanging ratio > 0.8, while codends with catch had ratios < 1.2. T90 and polyethylene meshes maintained mesh openings better than T0 and nylon. The mean drag force coefficient decreased with Reynolds number and then tended to level off slowly. Extreme fluttering amplitudes occurred at Strouhal numbers between 5.41 × 10⁻⁴ and 7.15 × 10⁻⁴. Drag force amplitude increased with mean drag force coefficient for empty codends, but for codends with catch, it increased with smaller mesh sizes, twine diameters, and higher flow velocities. Positional amplitude increased with lower waist-to-end hanging ratio. BP neural network predictions matched experimental results with over 90

The application of artificial light to attract marine organisms was demonstrated to enhance fishing gear efficiency. This study presented a novel stow net design incorporating noctilucent sticks to optimize catch performance. Specifically, the research examined the impact of different colores of noctilucent sticks on the efficiency of catch in stow nets. The results revealed the use of noctilucent sticks could significantly increase the catch weight of stow nets (p < 0.01). Notably, the color of the noctilucent sticks influenced their effectiveness, with olive green sticks increasing catch weight by 40.65 %, followed by azure sticks (12.57 %) and bluish green sticks (8.88 %). The predominant species caught was the small yellow croaker, whose catch proportion rose from 19.18 % to 22.80 % due to the noctilucent sticks. In addition, a comprehensive analysis was conducted using the generalized additive model (GAM) to assess the impact of noctilucent sticks, lunar phases, and tidal cycles on stow net catch weights, complemented by a backpropagation (BP) neural network for predictive modeling of catch weights. It was confirmed that lunar phase, tidal cycle, and noctilucent stick presence significantly affected stow net catches. While the BP neural network predictions closely matched the measured data, with the accuracy exceeding 89.63 % and 91.72 %. This study provided theoretical guidance for stow net fishing practices in the Yellow Sea.

Artificial light has been shown to enhance the fishing efficiency of fishing gear by attracting marine organisms. This study introduces a novel approach by incorporating noctilucent materials into crab pots and evaluates their effects on catch performance. Based on the crab pots commonly used on the coast, four types of crab pots were tested: ordinary crab pots (Con-pot), ordinary crab pots equipped with noctilucent sticks (Exp-pot 1), crab pots equipped with noctilucent nets (Exp-pot 2), and crab pots equipped with both noctilucent nets and sticks (Exp-pot 3). The results showed that the noctilucent material exhibits 6 h persistent emission in darkness after just 10 min of solar charging. Exp-pot 3 could significantly enhance fishing efficiency, which increased by 63.84% compared to the Con-pot. The proportion of crabs in Exp-pot 3 was the highest (86.35%), and the individual weight of crabs in Exp-pot 3 was the heaviest (61.5 g), which was 38.30% heavier than that in the Con-pot. Notably, Exp-pots 2 and 3 demonstrated superior selectivity with higher W50 values (53.01 g and 54.49 g), narrower SRs (33.04–72.98 g and 32.95–76.03 g), effectively balancing target catch retention with undersized crab release, indicated that noctilucent nets exhibited stronger weight selectivity for crabs compared to noctilucent sticks. These results demonstrate that functional materials have broad potential applications in fishing gear, which could enhance the catch efficiency and individual size of crab caught.

Deep-sea mariculture, particularly copper (Cu) alloy fence mariculture, is increasingly regarded as a sustainable model for future mariculture development. However, limited research has been conducted on its impact on seawater and sediment. To investigate variations in environmental factors induced by large-scale enclosure aquaculture of the large yellow croaker (Larimichthys crocea), a comprehensive quarterly analysis was conducted in the sea area near Dachen Island, China, from 2021 to 2023. This study focused on changes in pH, dissolved oxygen (DO), Cu, chlorophyll a, dissolved inorganic nitrogen (DIN), and labile phosphate ( PO^3-_4 ) in seawater. Additionally, variations in total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) content and pollution levels in the sediment were examined. The Nemerow index was used to assess the quality of both seawater and sediment. In 2021 and 2022, the highest DIN content in seawater was observed during the summer, reaching 0.491 ± 0.161 mg·L−1 and 0.485 ± 0.101 mg·L−1, respectively. Contrastingly, in 2023, the peak DIN concentration occurred in autumn, escalating to 0.597 ± 0.054 mg·L−1. Over the three years, the content of PO^3-_4 in seawater exhibited elevated levels during summer and autumn, with the highest concentration of 0.087 ± 0.009 mg·L−1 observed in autumn 2023. Notably, the Cu content in spring 2023 was 4.09 ± 0.36 μg·L−1, making the highest quarterly value within the three-year period. This data indicated a discernible accumulation trend for DIN, PO^3-_4 , and Cu in seawater. Additionally, TN, TP, and TOC levels in the sediment demonstrated an increasing trend over the three years. The maximum TN content recorded in the sediment was 0.69 ± 0.15 mg·L−1 in 2021, 0.74 ± 0.12 mg·L−1 in 2022, and 0.90 ± 0.15 mg·L−1 in 2023. For TP, the highest content was 0.66 ± 0.17 mg·L−1 in 2021, 0.60 ± 0.18 mg·L−1 in 2022, and 0.85 ± 0.12 mg·L−1 in 2023. The maximum TOC content was 0.74 ± 0.15

To address the dilemma of the stiffness and toughness properties of high-density polyethylene (HDPE) composites, titanate coupling agent-treated CaCO3 nanoparticles (nano-CaCO3) and ethylene–octene copolymer (POE) were utilized to blend with HDPE to prepare ternary nanocomposites via a two-sequence-step process. Meanwhile, a one-step process was also studied as a control. The obtained ternary nanocomposites were characterized by scanning electron microscopy (SEM), Advanced Rheometrics Expansion System (ARES), Dynamic Mechanical Analysis (DMA), wide-angle X-ray diffraction analysis (WXRD), and mechanical test. The SEM results showed one or two CaCO3 nanoparticles were well-encapsulated by POE and were uniformly dispersed into the HDPE matrix to form a core–shell structure of 100–200 nm in size by the two-step process, while CaCO3 nanoparticles were aggregated in the HDPE matrix by the one-step method. The result of the XRD showed that the nano-CaCO3 particle played a role in promoting crystallization in HDPE nanocomposites. Mechanical tests showed that the synergistic effect of both the POE elastomer and CaCO3 nanoparticles should account for the balanced performance of the ternary composites. In comparison with neat HDPE, the notched impact toughness of the ternary nanocomposites of HDPE/POE/nano-CaCO3 was significantly increased. In addition, the core–shell structure absorbed the fracture impact energy and prevent further propagation of micro-cracks, thus obtaining a higher notched Izod impact strength.

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Determination of bar spacing of bycatch reduction devices (BRDs) should consider species composition and morphometric characteristics (particularly width) of target species krill and bycatch. This study conducted a scientific investigation of the finfish bycatch in the Antarctic krill (Euphausia superba) trawl fishery by the fishing vessel SHEN LAN in the waters surrounding the South Orkney Islands from December 24, 2022, to February 20, 2023. The results show that scientific observers sampled 676 individuals of finfish bycatch. Of these, 665 were identified to species (17 species from 8 families), while the remaining 11 specimen were juveniles of the Nototheniidae family that could not be identified to the species level. IRI (index of relative importance) calculations showed three dominant (IRI value greater than 1,000) finfish bycatch species (Champsocephalus gunnari, Pseudochaenichthys georgianus, and C. aceratus from the Channichthyidae family) and four important (IRI value between 1,000 and 100) finfish bycatch species (Electrona carlsbergi and Gymnoscopelus nicholsi from the Myctophidae family, Gobionotothen gibberifrons from the Nototheniidae family, and Notolepis coatsi from the Paralepididae family). Our study provides morphometric data (particularly body width) that is crucial to model the potential for bycatch reduction by use of bycatch reduction devices (BRDs) and to determine the appropriate candidate bar spacings for BRD sea trials. Predictions suggest that a 10 mm (the maximum body width of krill) bar spacing releases a significant amount of dominant and important bycatch species (93.94% of C. gunnari, 53.99% of P. georgianus, 76.25% of C. aceratus, and 100% of G. gibberifrons). Reduced fishing pressure would reduce the risks to dominant and important bycatch species to make the krill fishery sustainable. We recommend that future BRD sea trials should initially test a 10 mm bar spacing. If marked loss of krill is observed, wider spacings (e.g. 15 mm) must be tested.

The beam trawl is one of the primary operational trawls for Antarctic krill, and its beam provides horizontal expansion support for the trawl net. The hydrodynamic performance of the beam significantly affects the vertical expansion and sinking performance of the trawl, as well as impacts the energy consumption of the fishing vessel. In this study, the beam of the Antarctic krill trawl used on the “Shen Lan” fishing vessel served as a prototype. Three types of beams, cylindrical, airfoil, and elliptical, were designed. The hydrodynamic performances of beams with different shapes at different angles of attack were studied using numerical simulation, and the accuracy of the numerical simulation was validated through the flume test. The results show that the cylindrical beam has a higher drag coefficient and a lower lift coefficient, compared to the airfoil beam and the elliptical beam. Under different angles of attack, the cylindrical beam’s drag coefficient is, on average, 49.54% higher than that of the airfoil beam and 59.74% higher than that of the elliptical beam. Its lift coefficient is 87.79% lower than that of the airfoil beam and 85.06% lower than that of the elliptical beam, respectively. At different angles of attack, the hydrodynamic coefficients of the airfoil beam and the elliptical beam are similar, and their trends, with respect to the angle of attack, are generally consistent. The drag coefficients increase with an increasing angle of attack, while the lift coefficients show a trend of initially increasing and then decreasing with an increasing angle of attack. The absolute values of the lift coefficients for the airfoil beam and the elliptical beam both reach their maximum values at an angle of attack of 45°, with values of 0.703 and 0.473, respectively. Compared to the cylindrical beam, the hydrodynamic performances of the airfoil beam and elliptical beam are superior.

Antarctic krill (Euphausia superba) is a key species of the Antarctic ecosystem whose unique ecological status and great development potential have attracted extensive attention. However, the genomic characteristics and potential biological functions of the symbiotic microorganisms of Antarctic krill remain unknown. In this study, we cultured and identified a strain of Brucella sp. WY7 from Antarctic krill using whole-genome sequencing and assembly, functional annotation, and comparative genomics analysis. First, based on 16S rDNA sequence alignment and phylogenetic tree analysis, we identified strain WY7 as Brucella. The assembled genome of strain WY7 revealed that it has two chromosomes and a plasmid, with a total genome length of 4,698,850 bp and an average G + C content of 57.18%. The DNA—DNA hybridization value and average nucleotide identity value of strain WY7 and Brucella anthropi ATCC® 49188TM, a type strain isolated from human clinical specimens, were 94.8% and 99.07%, respectively, indicating that strain WY7 is closely related to Brucella anthropi. Genomic island prediction showed that the strain has 60 genomic islands, which may produce HigB and VapC toxins. AntiSMASH analysis results showed that strain WY7 might produce many secondary metabolites, such as terpenes, siderophores and ectoine. Moreover, the genome contains genes involved in the degradation of aromatic compounds, suggesting that strain WY7 can use aromatic compounds in its metabolism. Our work will help to understand the genomic characteristics and metabolic potential of bacterial strains isolated from Antarctic krill, thereby revealing their roles in Antarctic krill and marine ecosystems.

对捕捞自闽东海域的209尾体质量7.70～66.09 g、体长79.88～150.70 mm的棘头梅童鱼的外部形态、可数性状和可量性状进行了研究,分析了形态特征参数间的相关关系.结果表明:(1)棘头梅童鱼鱼体呈长椭圆形,侧扁,背部呈浅弧形;头大而圆钝,额部隆起;口大,口裂倾斜度大;吻短钝,眼小;头部及体部被薄圆鳞,鳞小;侧线发达,略呈弧形;背侧面灰黄色,腹侧面金黄色,鳃腔上部深黑色;唇橙红色,口腔浅色.背鳍鳍棘部边缘及尾鳍末端为灰黑色,各鳍为淡黄色.(2)全长、肛前长、尾柄长、头长、眼径、头高、体高、尾柄高、眼后头长和体质量与体长存在极显著相关关系(P<0.01),体宽与体长存在显著相关关系(P<0.05).(3)以体长为自变量、各参数为因变量进行拟合处理,结果显示,全长、肛前长、尾柄长、头长、眼径、体高、体宽和眼后头长与体长呈指数相关,而尾柄高、头高与体长呈线性相关,其中体质量(W)与体长(Sl)的拟合方程为:W=4.5065×10-6Sl3.2907(R2=0.9306,P<0.01),b值为3.2907,为异速生长.(4)与体长显著相关的体质量、肛前长、尾柄长、头长、眼径、头高、体高、尾柄高、眼后头长和体宽等10个参数间存在偏相关关系,其中肛前长与尾柄长、头长、眼后头长和体宽为极显著相关(P<0.01),尾柄长和头长与尾柄高存在显著相关关系(P<0.05),与其他参数间存在极显著相关关系(P<0.01).

The purpose of this study was to comprehend the escape intensity and its influencing factors in Antarctic krill (Euphausia superba) that escaped through large mesh located at the front end of commercial trawl nets. Two pocket nets were employed to collect escaped krill that passed through the mesh opening in the first section (400 mm mesh size, without liner) and second section (16 mm mesh size liner) of the trawl body. The results show that krill escape primarily took place in the first section of the trawl body. Meanwhile, there was almost no krill escape observed in the second section of the trawl body, primarily attributable to the presence of a 16 mm mesh size liner. In terms of body length composition, the average PSI (percentage similarity index) was 67.31 (95% CI: 61.86–72.87) for krill from the pocket net on the larger mesh part and the codend. In addition, the PSI was significantly different (p < 0.05) between the day (60.96, 95% CI: 55.68–66.71) and night (83.62, 95% CI: 76.80–89.46). The escape intensity of krill ranged from 20.83 to 213.13 g·m−2 per ton per hour in the area at the front end of trawl body, with a mean value of 76.52 (95% CI: 55.22–101.09) g·m−2 per ton per hour during the daytime, and 144.66 (95% CI: 110.44–180.03) g·m−2 per ton per hour at night. These results indicate that krill can see and avoid contacting the netting easily during the day, particularly for larger individuals. This provides insight into the design of krill trawls, specifically on the arrangement of liners, which should be integrated from the front part of the trawl body.

深远海大型围栏养殖是我国海水养殖业结构调整和产业升级中新兴的养殖模式之一,具有养殖面积大、鱼类活动空间大、养殖环境更近自然和养殖鱼类品质明显提升等特点.本文在介绍围网养殖发展概况、深远海养殖内涵的基础上,重点概述了我国深远海大型围栏养殖发展现状及其研究进展,并对今后的发展方向加以展望,为我国深远海大型围栏智能化生态养殖模式的构建提供参考.

为克服人工规划网口捕捞路线的主观性和滞后性,提高我国南极磷虾捕捞的自动化水平,设计了基于层次分析法的南极磷虾捕捞网口前进路线规划体系.在分析磷虾虾群体积反向散射强度数据图像获得磷虾的局部密度中心位置的基础上,以3次B样条曲线为路径规划器,构造磷虾虾群的路径簇.采用层次分析法建立路线评价模型,评价候选路线的优劣,以经济性和可控性为准则,以捕捞率、路径长度、平均曲率、拐点个数量化各个指标,构造路径择优体系,获得最优路径.在现有实测数据基础上的实验结果表明,本算法磷虾捕捞率为94.33％,比人工规划路线的捕捞率多了9.80％、规划路线平均总耗时为2.5 s,可以满足磷虾捕捞网口前进实时规划的要求,有利于实现瞄准捕捞,提高捕捞效率,降低人工成本.

南极磷虾生物资源丰富,富含蛋白质、虾青素、磷脂等营养成分,磷虾粉是其主要加工产品,保障产品品质和全效利用是业内关注重点.对比了南极磷虾全脂虾粉与脱脂虾粉的生产工艺,对全脂虾粉的营养品质进行了评价,并阐述了南极磷虾粉在虾油提取、水产养殖与高值利用等方面的应用现状及发展趋势.相关研究现状表明,南极磷虾粉营养丰富,但目前我国相关生产加工装备落后、产品品质存在较大差异,南极磷虾粉的潜在价值尚未完全得到利用,应进行针对性工艺优化与系统性装备升级,建立虾粉标准化生产体系,重点开展南极磷虾粉高值利用相关工作.

Antibiotic resistance genes (ARGs) are ubiquitous in nature, especially in the current era of antibiotic abuse, and their existence is a global concern. In the present study, we discovered that Antarctic krill-related culturable bacteria are resistant to β-lactam, tetracyclines, aminoglycosides, and sulphamethoxazole/trimethoprim based on the antibiotic efflux mechanism. In addition, the co-occurrence of ARGs with insertion sequence (IS) (tnpA, IS91) and Intl1 on the isolates and the phylogenetic analysis results of the whole-genome revealed low-frequency ARG transfer events, implying the transferability of these ARGs. These findings provide an early warning for the wide assessment of Antarctic microbiota in the spread of ARGs. Our work provides novel insights into understanding ARGs in culturable host-associated microorganisms, and their ecological risks and has important implications for future risk assessments of antibiotic resistance in extreme environments.

为评价深远海大型围栏养殖大黄鱼(Larimichthyscrocea)海域的沉积物质量状况,通过对大黄鱼不同养殖期围栏养殖区、围栏外围区、网箱外围区和对照区的4次调查,分析评价了调查海域沉积物中的Cu、Zn、有机碳、硫化物等指标的区域分布、含量变化及污染水平,并采用内梅罗指数对调查海域沉积物进行了质量综合评价.结果显示,4次调查大黄鱼围栏养殖区沉积物Cu的含量范围为15～33mg/kg,Zn的含量范围为80～137 mg/kg,有机碳的含量范围为0.14％～1.90％,硫化物的含量范围为0.3～128.0 mg/kg.围栏中心区沉积物有机碳、硫化物的含量比其他区域高,但均符合《海洋沉积物质量》(GB18668-2002)中的一类标准.不同调查区域沉积物Cu、Zn和有机碳的含量差异不显著(P＞0.05),围栏中心养殖区沉积物硫化物含量显著高于对照区(P＜0.05).内梅罗综合评价结果表明,调查区域沉积物质量均为清洁或较清洁状态,沉积物质量符合海水养殖标准.沉积物Cu、Zn和硫化物未表现出明显的累积趋势,沉积物有机碳在本调查时间内有轻微累积的趋势,建议通过加强大黄鱼配合饲料的研发与应用,以缓解目前冰鲜鱼饵料大规模投入的状况,降低饵料系数,从而在一定水平上减轻有机质累积对沉积环境的污染.

深蓝渔业是"养-捕-加"一体化、"海-岛-陆"相联动的全产业链渔业生产体系,是实现"以养为主、三产融合"的战略性新兴产业,也是我国现代海洋渔业转型升级的重要方式和有机载体.其生产体系覆盖我国黄渤海、东海、南海的近海和远海以及大洋极地等海洋空间,将"种-养-捕-加-网"等不同关键环节结合成为一个有机整体,是"蓝色粮仓"的拓展与延伸,对于保障优质蛋白供给、拓展养殖新空间、支撑蓝色经济增长和坚守国家海洋权益等具有重要作用.近年来,伴随着科技工作日益加强与产业化实践不断深入,深蓝渔业发展面临的机遇与挑战逐步涌现.本文综合分析了发展深蓝渔业的战略意义,阐述了其蕴含的主要生产功能,总结了制约发展的突出问题,在针对发展目标的基础上提出了开展深蓝生物遗传资源解析、打造工业化绿色生产模式、高品质捕捞大洋极地资源、研发海陆联动加工技术与装备、构建渔业船联网系统等重点科技任务,凝练了实施科技能力提升工程、出台产业发展扶持政策、打造多元人才聚集高地、建立产业创新示范园区等措施建议,旨在为促进深蓝渔业科技进步和推动产业迭代升级提供借鉴与参考.

Collichthys lucidus (C. lucidus) is an economically important fish species, exhibiting sexual dimorphism in its growth rate. However, there is a lack of research on its underlying sex-related mechanisms. Therefore, small RNA sequencing was performed to better comprehend these sex-related molecular mechanisms. In total, 171 differentially expressed miRNAs (DE-miRNAs) were identified between the ovaries and testes. Functional enrichment analysis revealed that the target genes of DE-miRNAs were considerably enriched in the p53 signaling, PI3K-Akt signaling, and TGF-beta signaling pathways. In addition, sex-related miRNAs were identified, and the expression of miR-430c-3p and miR-430f-3p was specifically observed in the gonads compared with other organs and their expression was markedly upregulated in the testes relative to the ovaries. Bmp15 was a target of miR-430c-3p and was greatly expressed in the ovaries compared with the testes. Importantly, miR-430c-3p and bmp15 co-expressed in the ovaries and testes. This research provides the first detailed miRNA profiles for C. lucidus concerning sex, likely laying the basis for further studies on sex differentiation in C. lucidus.

A V-typed multi-slotted trawl-doors was designed for the bottom trawl fishery, and its hydrodynamic performances was investigated in a wind tunnel. Two different kinds of model with right trapezoid and isosceles trapezoid wings were tested on six-component force balance with the wind speed of 28m/s. Data for measuring the performance of trawl-door included: lift coefficient Cy, drag coefficient Cx, centre of pressure coefficient Cp, pitch moment coefficient Cm. Analysing results showed that the maximum lift to drag ratio of the trawl-doors with the isosceles wings was higher (3.482 at α =22.5°), and the maximum lift coefficient of the trawl-doors model with the right trapezoid wings was higher (2.099 at α =55°). The comparative analysis of pitch moment coefficient showed that the pitch stability of model with the right trapezoid wings is better, the comparative analysis of centre of pressure coefficient showed that the rolling stability of model with the isosceles trapezoid wings is better.