A seasonal survey was conducted at fixed stations in the coastal waters off western Hainan Island from 2023 to 2024. A total of 330 zooplankton species were identified. The relationships between environmental drivers and community structure were systematically disentangled through non-metric multidimensional scaling (NMDS), permutational multivariate analysis of variance (PERMANOVA), redundancy analysis (RDA), hierarchical partitioning (HP), variance partitioning analysis (VPA), and Mantel tests. The results revealed pronounced seasonal divergence in zooplankton community composition, with summer–autumn and winter–spring assemblages forming two distinct ecological clusters. Temperature emerged as the predominant single driver. At the factor-group level, physical properties collectively explained a greater proportion of variance than chemical properties, biological factors, and nutrients. Notably, fish-mediated top-down control and total phosphorus (TP) also exerted significant influences on community structure. Mantel tests further revealed significant covariation between TP and temperature, suggesting that under phosphorus-limited conditions, elevated temperatures may exacerbate the physiological phosphorus demand of phytoplankton, thereby generating a temperature–phosphorus combined physiological bottleneck. Consequently, TP may function not merely as a conventional limiting nutrient but as an ecological threshold variable that modulates the direction of temperature effects. These findings demonstrate that zooplankton communities in subtropical–tropical transition zones are governed by multi-factor interactions with markedly nonlinear response characteristics, rendering them particularly vulnerable to global warming. Therefore, phosphorus–temperature coupling threshold research should be prioritized in future zooplankton community monitoring.

The identification of ecological corridors is crucial for mitigating habitat fragmentation and conserving biodiversity. This study pioneered the use of environmental DNA (eDNA) metabarcoding to identify potential fish ecological corridors in Xiamen Bay, a subtropical semi-enclosed bay in Southeast China, addressing the challenge of delineating marine corridors for mobile species. We collected surface and bottom water samples from 29 sites across 10 transects during winter and summer of 2021. eDNA metabarcoding of the 12S rRNA gene (MiFish-U) revealed distinct seasonal shifts in fish community composition, with 46 and 112 species detected in winter and summer, respectively. The communities were predominantly composed of warm-water and temperate species, with a significant proportion of migratory taxa. Alpha and beta diversity analyses confirmed significant seasonal variations in community structure. Spatial analysis of habitat nodes identified ecological corridors with clear seasonal dynamics. In winter, a primary corridor connected the estuary to the western waters and Tong'an Bay, while a secondary corridor linked the Jiulong River Estuary to the southern waters of Xiamen Island. During summer, both corridors extended eastward, with the primary corridor reaching through the waters around Dadeng Island to the eastern waters and the secondary corridor expanding to the eastern waters of Xiamen Island. These corridors likely facilitate various critical ecological processes. Our findings demonstrate that eDNA metabarcoding is a powerful, spatially explicit tool for identifying ecological corridors in complex marine environments, offering a novel and efficient approach to inform marine spatial planning and conservation strategies.

Global climate change is profoundly altering Arctic marine biodiversity, yet baseline data on fish assemblages in the central Arctic Ocean remain critically scarce. The Chukchi Borderland-a Pacific-Atlantic water confluence zone experiencing the most pronounced sea ice retreat in the Arctic-is a frontline area for assessing fish diversity dynamics under climate change. In this study, we simultaneously conducted bottom trawling and environmental DNA (eDNA) metabarcoding to evaluate their complementarity in characterizing fish diversity and to detect species beyond their previously documented ranges. Trawling at 16 stations captured 72 specimens from 17 species, while eDNA metabarcoding of 69 seawater and sediment samples from 31 stations detected 16 species, of which only two were shared with the trawls, highlighting their complementarity. The detected taxa-including pelagic groups (Myctophidae, Gadidae) and demersal groups (Cottidae, Zoarcidae)-align with the region's biogeographic character. Log-transformed eDNA sequence reads were strongly correlated with species' site occurrence frequency, validating the site-occurrence model for inferring relative abundance in Arctic waters. Notably, six species-Artediellus atlanticus, Lycodes raridens, Zaprora silenus, and the Atlantic-affiliated Lycodes lavalaei, Lycodes gracilis, and Hippoglossoides platessoides-were detected beyond their historically recorded northern boundaries. We interpret these signals cautiously: they may reflect climate-driven northward expansions, but may equally indicate historically under-sampled resident populations given the extreme paucity of baseline surveys in the central Arctic Ocean. This study provides the first paired comparison of eDNA and trawling in the central Arctic Ocean and delivers new evidence essential for filling ecological baseline gaps in this rapidly changing region.

Artificial illumination generated during deep-sea mining may impose physiological disturbances on mesopelagic fishes that have long adapted to extremely dim environments, however, the quantitative relationship between light stress intensity/duration and biological responses remains unclear. In this study, Epinephelus lanceolatus was used as a model species to investigate transcriptomic changes in eye and brain tissues under no light (0 lx), weak light (900 lx), and strong light (2000 lx) conditions, aiming to define the biological thresholds of light-induced effects. The results revealed that the eye was highly sensitive to light exposure, with weak light significantly upregulating genes related to visual signal transduction and energy metabolism, whereas the brain exhibited fewer transcriptional changes and maintained homeostasis, showing a differentiated response pattern of "active eye-stable brain". Short-term exposure (24 h) primarily induced acute stress and rapid metabolic adjustments, while long-term strong-light exposure (72 h) led to circadian rhythm disruption, mitochondrial dysfunction, and persistent metabolic burden, potentially impairing growth and reproduction. Based on these mechanistic insights, we propose a dual-threshold model of "adaptive threshold-stress threshold": ≤103 lx as a low-risk level and ≥ 103 lx as a high-risk level. Accordingly, it is recommended that deep-sea mining operations restrict illumination within the weak-light range (≤103 lx), avoid prolonged continuous exposure, and adopt intermittent, directional, and tiered lighting strategies. Incorporating light intensity, duration, and frequency into environmental risk assessments, alongside noise and sediment plume impacts, will support integrated risk management and help mitigate ecological impacts on mesopelagic nekton.

In recent years, tilapia have become increasingly important in aquaculture in South China. Due to its strong ecological adaptability, the redbelly tilapia (Coptodon zillii) has rapidly established natural populations in many waters of South China, posing a potential threat to the ecosystem structure and function of aquatic realms. However, the genetic information of wild populations of this species have not been well-characterized. In this study, mitochondrial control region sequences were used to analyze population genetic features of wild populations of the redbelly tilapia from Fuzhou, China. A total of 82 redbelly tilapia samples were collected from eight sits in Fuzhou. We also downloaded additional 38 control region sequences of the redbelly tilapia from the GenBank database. Population genetics analyses revealed that only two haplotypes and extremely low levels of genetic diversity were detected in Fuzhou populations, indicating a founder event of this species. Moreover, based on shared haplotype information and phylogenetic topology, our results suggested that the wild redbelly tilapia populations in Fuzhou should be established by at least two introduction events. Our study provides a genetic background for the Fujian populations of the redbelly tilapia. These genetic data and information in this study are essential for further invasion biology studies in the redbelly tilapia, and can provide fundamental materials for invasion management and scientific control of this species.

The international community has reached a consensus to facilitate knowledge of living resources in the Central Arctic Ocean (CAO), where the demersal fishes remain largely unexplored. The Chukchi Borderland is currently one of the few viable areas for bottom trawling within the CAO because it possesses some gentle terrain and has experienced severe seasonal sea ice retreat. In this region, we report an unexpectedly speciose demersal fish fauna with unique zoogeographic patterns based on the most extensive fish surveys conducted by the Chinese National Arctic Research Expedition (CHINARE). Several fish species were recorded here for the first time, which is crucial for updating their geographic ranges and assessing their distribution shifts. Cods (Gadidae), eelpouts (Zoarcidae), and sculpins (Cottidae) were the dominant families, which may have diverse origins and intensified competition that revealed by otolith chemistry and stable isotope analyses. The key species, polar cod (Boreogadus saida), exhibits high mobility and flexible feeding strategies that contribute to its high biomass. Fish assemblages in the Chukchi Borderland have been significantly influenced by sea ice and oceanic inflows, thereby the individual northwards movement and rising biota and nutrients in this region are assumed to increase its fish species richness and biomass. Our findings highlight the importance of scientific monitoring and research in comprehending the impacts of climate change on fish, which is essential for future conservation and sustainable fisheries management in the CAO.

Eelpouts (Zoarcidae) are known for their bipolar distributions and distinctive biogeographic histories. However, limited genomic data have hindered our understanding of their adaptive evolution. In this study, we present a thoroughly annotated chromosome-level genome assembly of pale eelpout (Lycodes pallidus) generated through the integration of Illumina, PacBio circular consensus, and Hi-C sequencing techniques. The final assembly spans 753.4 Mb, with its high quality confirmed by a scaffold N50 of 28.6 Mb and a Benchmarking Universal Single-Copy Ortholog (BUSCO) completeness of 99.3%. In comparison to other eelpouts and related fishes, the L. pallidus genome is larger and exhibits greater repetitive element content, accounting for approximately 45% of its total length. We annotated 21,419 protein-coding genes, a significant proportion of which are involved in signal transduction mechanisms and transcription. These findings provide valuable genetic resources for elucidating the evolutionary mechanisms underlying polar fish adaptation.

Yellow seabream (Acanthopagrus latus), a species of significant economic importance, predominantly inhabits the warm waters of the Indo-Western Pacific. While previous studies have explored the genetic diversity of A. latus using microsatellites and other nuclear markers, a comprehensive understanding of its genetic characteristics and adaptive evolution using whole-genome resequencing (WGR) remains limited. In this study, we collected 60 individuals from six distinct geographic locations and performed WGR, achieving an average sequencing depth of 12.59×, which resulted in the identification of 19,488,059 high-quality single-nucleotide polymorphisms (SNPs). The nucleotide polymorphism (πθ) across all populations was consistent, ranging from 0.003042 to 0.003155, indicating low genetic differentiation among populations. Comparative analyses revealed that populations other than that in Xiamen (XM) have undergone adaptive evolution, potentially linked to traits such as growth and development, feeding, immunity, and movement. This study explores the population genetics and adaptive evolutionary patterns of Acanthopagrus latus at the genomic level, providing an essential foundation for the conservation and management of this economically important species in the future.

Sthenoteuthis oualaniensis is one of the most commercially important marine cephalopod species distributed throughout tropical and subtropical waters of the Indo-Pacific Seas. The Indian Ocean is a main fishing ground for S. oualaniensis with a high population density. To explore the distribution of S. oualaniensis in the east equatorial Indian Ocean, four surveys were carried out using light-lift-net fishing vessels. Meanwhile, marine environmental data were also collected, including the sea surface temperature, sea temperature at 100 m depth, mixed layer depth, sea surface chlorophyll-a concentration, sea surface height, and eddy kinetic energy. Generalized Additive Models were used to analyze the relationship between the catch per unit effort (CPUE) for S. oualaniensis and environmental factors. The results showed that the average CPUE of S. oualaniensis was 14.55 kg/h in the four surveys, which was considerably lower than in the South China Sea and Northwest Indian Ocean. In terms of seasonal distribution, the high-CPUE stations were closer to the continental shelf in spring, while they shifted towards the deeper and offshore water in autumn, demonstrating a seasonal migration trend. Pearson correlation analysis showed that CPUE reflected a significant negative correlation with both sea temperature at 100 m depth and eddy kinetic energy (p < 0.001). The Generalized Additive Models revealed that sea surface height was the most significant factor affecting CPUE with a variance explanation of 30.1%. Furthermore, the optimal CPUE prediction model was established by stepwise regression, which contains two factors, sea surface height and eddy kinetic energy, with a variance explanation of 34.9%. This study provides insights into the environmental factors influencing the distribution of S. oualaniensis, which is essential for the sustainable utilization and management of this species.

Skipjack tuna (Katsuwonus pelamis) (SKJ) is one of the most commercially important marine fish species distributed throughout the world's tropical and subtropical oceans. The Indian Ocean is a main fishing ground for SKJ, whose exploitation rate is just below the maximum sustainable yield. Therefore, SKJ stocks may potentially be significantly affected by climate change. In this study, climatic oscillation indices related to the Indian Ocean, including the Indian Ocean Dipole (IOD), the mean water temperature anomaly in the Eastern Indian Ocean (EIO) and Western Indian Ocean (WIO), the Madden-Julian Oscillation Index at 80 degrees E (MJO80) and the Arctic Oscillation Index (AOI), were associated with SKJ catch per unit effort (CPUE). This study aimed to understand the effect of these five climatic oscillations on SKJ, with the goal of optimizing the utilization of skipjack tuna in the Indian Ocean. We combined gradient forest analysis (GFA) and generalized additive models (GAMs) to evaluate the importance of each climatic index with a 0-5 year lag on the impact of SKJ CPUE and to establish an optimal prediction model. The GFA results show that MJO80 is the most important climatic index influencing SKJ CPUE, followed by MJO80_1, AOI_2, IOD_4, WIO_2, etc. The best GAM model includes MJO80, AOI_2, and WIO_2, which could be related to the recruitment and larval survival of SKJ by influencing water temperature. Meanwhile, there is a significant negative correlation between SST and SKJ CPUE in the tropical regions of the western and central Indian Ocean. Our results suggest that climate oscillations have a 0-2 year lag effect on the SKJ fishery in the Indian Ocean, which can be used to predict resource changes in SKJ over the next 2 years.

Studies on the demersal fish composition of the East Antarctic nearshore region are very scarce due to the harsh physical geography of the East Antarctic region, which is covered in ice and snow year round, leading to a scarcity of scientific surveys. Based on the data from the bottom trawl survey conducted by the 37–38th Chinese National Antarctic Research Expedition (CHINARE) program in the Cosmonaut Sea, East Antarctica, the species of demersal fishes were identified, and the demersal fish composition and the characteristics of depth distribution were examined and analyzed. The basic biological information of highly abundant species was analyzed. The results from 97 individuals sampled within 30–60° E, south of −65° S, indicate that the fishes belong to 5 orders, 11 families, 19 genera, and 23 species. Most of the species are found in Myctophidae and Bathydraconidae, and the most common species is Macrourus whitsoni (Macrouridae). Macrourus whitsoni and Prionodraco evansii have a high abundance in the survey. Macrourus whitsoni has body lengths of 144–662 mm and body weights of 17.3–1425.1 g, and Prionodraco evansii has body lengths of 90.18–134.33 mm and body weights of 4.9–20.7 g. The length–weight relationships for Macrourus whitsoni and Prionodraco evansii are y=0.00002x2.748 and y=0.000006x3.353, respectively. All the Macrourus whitsoni samples were found in waters deeper than 1000 m, with the highest number of individuals captured at depths of 1500–2000 m. Prionodraco evansii was found only at stations less than 250 m deep. These results complement the demersal fish composition and distribution data of the Cosmonaut Sea, East Antarctica. These data can provide valuable basic information for characterizing regional assemblages and delineating zoogeographic boundaries.

Larmichthys crocea (L. crocea) is an economically important fish species mainly distributed off the coast of China. In this study, 11 L. crocea samples of different body lengths were collected from aquaculture cages in the East China Sea to measure the acoustic target strength (TS). Using the Kirchhoff-Ray mode (KRM) model, the directional TS of L. crocea was measured at frequencies of 70 kHz, 120 kHz, and 200 kHz. Furthermore, the relationships between TS and body length were determined using the least squares method and the standard b20 equation. The results showed that the TS of L. crocea varied with tilt angle, frequency, and body length. For tilt angles ranging from (−5°, 15°), the equation for fitting TS and body length using the least squares method were TS = 32.99·log10L − 87.36 (70 kHz), TS = 33.26·log10L − 87.77 (120 kHz), and TS = 39.46·log10L − 95.51 (200 kHz). They were expressed in the standard b20 equation as TS = 20·log10L − 71.16 (70 kHz), TS = 20·log10L − 71.23 (120 kHz), and TS = 20·log10L − 71.24 (200 kHz). For tilt angles ranging from (0°, 10°), the equation for fitting TS and body length using the least squares method is TS = 28.69·log10L − 81.71 (70 kHz), TS = 32.30·log10L − 86.44 (120 kHz), and TS = 45.87·log10L − 103.73 (200 kHz). They were expressed in the standard b20 equation as TS = 20·log10L − 70.88 (70 kHz), TS = 20·log10L − 71.10 (120 kHz), and TS = 20·log10L − 71.48 (200 kHz). Moreover, the 18–300 kHz spectral curve showed a decreasing trend in the frequency range from 18 kHz to 30 kHz, while maintaining relatively stable fluctuations in the other frequency ranges. These findings offer a comprehensive understanding of the scattering characteristics of L. crocea and provide a reliable reference of TS for the fishery acoustic assessment of L. crocea.

Antarctic krill Euphausia superba is a key species in the Southern Ocean ecosystem and has important ecological value. It is also one of the main fishery resources in the Southern Ocean with high economic value. In recent years, with the development of krill fishery and rapid climate change, the conservation and management of krill resources have faced unprecedented challenges. The krill resource is different from the general fishery resources. Due to the krill schooling characteristics, fishery data has some advantages over scientific survey data. Reviewing and analyzing the krill fishery data is necessary. Therefore, in this study, four fishery resource indices (FRIs) were calculated based on Antarctic krill fishery data, and based on the environmental dependence of Antarctic krill, the FRI with the strongest environmental dependence was screened by using the Gradient Forest Model, and the step changes of the FRI with strongest environmental dependence was examined by using the sequential t-test analyses of regime shifts (STARS). The generalized additive model (GAM) to analyze the correlation between the FRI with the strongest environmental dependence and the main environmental factors, and then explore the resource status of Antarctic krill in the study area. The model results showed that the "FRI_hual" had the strongest environmental dependence and was a better indicator of the status of the Antarctic krill in the study area than the others. In the 2009-2010 year, "FRI_hual" had an obvious regime shift. The interaction of environmental factors "ice_area_2" and "SSH_1" has a great impact on "FRI_hual". Methods used and results obtained in the study can provide new ideas and a scientific reference for future work, including integrated stock assessment of krill and krill resource monitoring, conservation, and management based on the ecosystem.

Abstract The melting of sea ice in the Central Arctic Ocean (CAO) is more severe than previously expected. When this physical barrier disappears, fishing vessels without ice-breaking capability may enter the CAO ifprofitable. The international community has repeatedly called for this issue to be considered with the potential of adverse ecological consequences usually caused by unregulated fisheries.In 2021, the Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean , which took nine nations and the European Union years to negotiate, finally entered into force. The Agreement demonstrated the lack of knowledge about CAO fishes and encouraged scientists to conduct surveys. The Scientific Coordinating Group (SCG) of the Preparatory Conference for the Agreement has had several discussions in order to provide the best available scientific information. Therefore, it is necessary to summarize the fish surveys of the Chinese National Arctic Research Expedition (CHINARE) for devoting to establish the fish composition and distribution baselines, because the CHINARE has the largest number of voyages and stations in the region. In the present study, we report a list of 30 fish species in the CAO, including the first occurrence of six fish species.

为了解东山湾及其邻近海域游泳动物群落的年代变化特征,根据2008年11月、2009年5月、2018年4月和11月在东山湾及其邻近海域进行的4个航次底拖网调查数据,对该海域游泳动物种类组成、优势种、多样性特征及群落结构进行研究.结果表明:2008年秋季捕获90种游泳动物,2009年春季捕获67种游泳动物,优势种为中颌棱鳀、林氏团扇鳐、短蛸等;2018年春季捕捞61种游泳动物,秋季捕获87种游泳动物,优势种为中颌棱鳀、林氏团扇鳐及青鳞小沙丁鱼等.多样性结果显示:东山湾及其邻近海域丰富度指数(D)、多样性指数(H')和均匀度指数(J')的变化范围在2008—2009年分别为0.32～4.25、0.58～2.67和0.19～0.99,在2018年分别为0.28～4.08、0.12～2.65和0.11～0.77.2008—2009年数量优势度曲线与生物量优势度曲线呈相交状态,而2018年数量优势度曲线分布于生物量优势度曲线之上,表明2008—2018年间该海域游泳动物群落结构受到外界扰动较多.聚类结果显示,东山湾游泳动物群落分为湾内和湾口2个群组,群组间差异的分歧种存在明显年代变化.研究发现相较于10年前,2018年东山湾游泳动物的资源量有所恢复,但游泳动物群落组成已经发生了较大的变化.本研究结果可为类似海域游泳动物多样性和群落结构研究提供参考,也可为研究海域渔业资源开发、利用与养护等政策的制定提供科学依据.

Based on bottom trawl survey data collected in November 2009 (autumn), February 2010 (winter), May 2010 (spring), and August 2010 (summer), the seasonal variation in the trophic structure of the fish community in Dongshan Bay and adjacent waters was investigated. A total of 114 species of fish were caught in surveys throughout the year. According to their feeding habits, the fish species in the surveyed area were classified into six functional groups, including planktivores (FG1), planktivores/benthivores (FG2), benthivores (FG3), benthivores/piscivores (FG4), piscivores (FG5), and omnivores (FG6). FG3 was the most diverse group, with 43 species, followed by FG4, with 29 species. The biomass of FG3 was the highest among all functional groups throughout the year and in each individual season. FG1 and FG5 had higher biomass proportions in spring than in the other seasons, accounting for 8.02% and 16.72%, respectively. The functional group diversity (HFD) and species diversity (Hs) showed similar variations, reaching their lowest values in winter and highest values in summer. In 2009-2010, the mean trophic position of the fish community in Dongshan Bay and adjacent waters was 3.64. This value was 3.74 in winter (highest), 3.49 in summer (lowest), 3.71 in spring, and 3.63 in autumn. The relationship between the trophic position and the mean body mass indicated that the seasonal variation in the mean body mass of high-trophic-level fish species was the highest in winter, followed by autumn, spring, and summer. In general, with seasonal and temporal changes, large-bodied, high-trophic-level fishes were gradually replaced by small-bodied, low-trophic-level fishes in the fish community of Dongshan Bay and adjacent waters in 2009-2010, and the trophic structure tended to become simplified.

The V3-V4 region of the bacterial 16S rRNA in the intestinal contents of three commercial fish species ( Larimichthys crocea , Larimichthys polyactis , and Trichiurus lepturus ) from the central and southern East China Sea was sequenced in an attempt to understand the intestinal microbial diversity (IMD) and community structure in these populations collected in spring and autumn. Diversity analysis showed that the Shannon index, the Simpson index, the abundance-based coverage estimator (ACE) index, and the Chao1 index of the intestinal samples of the three commercial fish species were all lower in spring than in autumn, indicating that the richness of the intestinal microbiota of these three commercial fish species was lower. At the phylum level, Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota were dominant among the intestinal microbiota of the three commercial fish species. Analysis of the composition and structure of the intestinal microbial community showed that the IMD and the community structure of the three commercial fish species were similar in a given season but differed significantly in different seasons. This study shows that the IMD and community structure of fish were significantly affected by season and feeding habits.

Chiloscyllium plagiosum (Bennett, 1830) is a productive shark species found in the Chinese coastal waters. However, populations of this species have declined due to factors such as increased fishing pressure, habitat loss, and habitat destruction. Therefore, monitoring the genetic signatures of C. plagiosum is an urgent need. Using the coastal waters of Xiamen as the research area, C. plagiosum specimens were collected from 2017 to 2021 to detect changes in their genetic diversity across several years. The genetic diversity of C. plagiosum from the coastal area of Xiamen fluctuated between generations and remained relatively high in general compared to that of fishing waters which is possibly related to the coastal waters of Xiamen being in a protected marine area where C. plagiosum is not affected by fishing pressure. The genetic differentiation between C. plagiosum populations in different years was extremely low, primarily arising from within the population, indicating that the recruitment stock of C. plagiosum in the coastal waters of Xiamen was sufficient for adequate gene exchange. The results of the historical demography revealed that a population expansion of C. plagiosum had historically occurred, and its effective population experienced rapid growth after expansion. The coastal waters of Southern Fujian are the center of the expansion of the ancestral C. plagiosum population along the southern coast of China; therefore, the genetic diversity and genetic structure of this species require further study to understand the changing patterns of its genetic characteristics, prevent the decline of its germplasm resources in the wild, and protect fishery resources.

Aims: The internal structure of the Arctic marine ecosystem is changing and its stability is facing unprecedented challenges due to the influences of climate warming. Since fish are important resources for nutrient transport and transfer in Arctic marine food webs, understanding their feeding habits and interspecific trophic relationships is the key to grasping the changes occurring in the Arctic food web structure and function. This study was carried out to obtain basic biological information about fish in the Bering Sea and Chukchi Sea, as well as to provide reference for subsequent studies on trophic ecology.Methods: We analyzed the stable isotope ratio, trophic level range and trophic niche width and overlap of fish from the Bering Sea and Chukchi Sea using stable isotope techniques based on fish samples obtained from the 6th（2014） and 8th to 11th（2017–2020） Arctic scientific expedition trawl surveys by China.Results: A total of 29 species of 8 families and 21 genera of fish were captured, and the mean δ 13 C value of all fish samples was –19.36‰（–23.88‰ to –15.78‰）, the mean value of the δ 15 N value was 16.16‰（11.80‰–20.37‰）, and the total trophic levels ranged from 2.42 to 4.62, with a mean value of 3.74. The results of the trophic niches indicated that each fish species had some degree of overlap with several other species, but most species did not overlap completely with each other and maintained some singularity. Boreogadus saida had the largest corrected standard ellipse area（SEAc = 5.51）; Artediellus atlanticus had the smallest width of the trophic niche（SEAc = 0.85）. Conclusion: This present study provides basic background information on the trophic ecology in Arctic seas for further study of the food web structure and an in-depth analysis of the response of Arctic marine ecosystems to climate change.