Abstract:C-type lectin （CTL） is an important pattern recognition receptor for recognizing carbohydrate structural domains. In this study we isolated and cloned a Litopenaeus vannamei C-type lectin， named LvCTLE， and analyzed its expression and function. The results of the study show that the full-length sequence of the LvCTLE gene cDNA was 1 231 bp with an open reading frame of 702 bp， encoding 233 amino acids. The LvCTLE amino acid sequence contained a signal peptide structure encoding 17 aa at the N-terminus and a sugar recognition structural domain encoding 134 aa at the C-terminus. The results showed that LvCTLE was distributed in the 9 tissues tested， with higher expression in muscle and gill tissues. After intramuscular injection of Vibrio parahaemolyticus， the expression of LvCTLE gene in both muscle and gill tissues of shrimp showed a tendency of up-regulation followed by a decrease， and the expression reached a peak at 12 h. Prokaryotically expressed recombinant rLvCTLE had Ca²⁺-dependent agglutination activity and could agglutinate Lactococcus garvieae， Escherichia coli， V. parahaemolyticus and V. tubiashii. D-glucose， D-galactose， D-mannose， D-fructose， maltose， sucrose and alginose all had inhibitory effects on the agglutination of rLvCTLE toward E. coli. These results suggested that LvCTLE could be involved in the immune response against bacterial challenge in the innate immune system of L. vannamei.

Abstract:In order to understand the effects of long-term high-temperature on blood-related indexes and tissue structure of Nile tilapia （Oreochromis niloticus）， tail vein blood analysis and microscopic observation techniques were used to compare the hematological parameters and microstructural changes of the spleen and liver of Nile tilapia at normal-temperature （28 ℃） with those at long-term high-temperature domestication （34 ℃）. The results showed that the number of erythrocytes and hemoglobin content of tilapia in the high-temperature group were significantly higher than those in the normal-temperature group； although the morphology of hemocytes did not show any difference between the two groups of temperature conditions， the sizes of erythrocytes， monocytes， and neutrophils tended to decrease significantly in the high-temperature group. In addition， observations of tissue sections showed that long-term high-temperature domestication led to an increase in the number of erythrocytes， an expansion of the red pulp area， a relative decrease in the white pulp area， and an increase in the number of melano-macrophage in tilapia spleen tissues， as well as an intensification of hepatocyte vacuolization and an increase in the number of melano-macrophage in liver tissues. These results indicated that the long-term high-temperature environment had significant effects on blood indices and hematopoietic tissues of Nile tilapia， and it was hypothesized that they adapted to the high-temperature environment by regulating their hematopoietic function and immune response. This study provides an important reference for understanding the physiological adaptation mechanism of Nile tilapia under long-term high-temperature， and also provides a scientific basis for tilapia aquaculture practice in the context of global warming.

Abstract:To investigate the effects of different diets （iced trash fish， expanded diet and powder soft diet） on growth performance， gastric evacuation， and digestive enzyme activity in Takifugu flavidus， a 60-day indoor growth experiment was conducted with three replicates per group， each containing 30 individuals， and the fish in all cages continued to be fed respectively with above three diets to apparent satiation. Gastric evacuation rate experiment was conducted using the same dietary groups （three replicates each）， with sampling of gastric contents at 0， 2， 4， 6， 8， 10， 12， 14， and 16 hours postprandial to determine percentage residual stomach content. Meanwhile， liver and intestinal tissues were collected for analysis of digestive enzyme activitiy variations. The results showed that： （1） From day 20 onward， the average body weight in powder soft diet group was significantly higher than that expanded diet group （P<0.05）， while showing no significant difference from iced trash fish group （P>0.05）. In terms of feeding rate， the expanded diet group was significantly lowest （P<0.05）， while there was no significant difference between the iced trash fish group and the powder soft diet group； （2）In terms of the percentage change of gastric contents after feeding different diets， the gastric evacuation rate was the fastest when feeding powder soft diet， followed by iced trash fish， and the slowest when feeding expanded diet， with the square root model providing optimal fit for all dietary groups. （3） In terms of the theoretical 50% and 80% gastric evacuation times， the gastric evacuation time of the powder soft diet group was the shortest， the iced trash fish group was the second-longest， and expanded diet group had the longest time， the 80% gastric evacuation time was 10.43 h， 11.29 h and 11.44 h， respectively； （4）Live digestive enzymes displayed an "M" type variation trend over time across all diets， while intestine digestive enzymes exhibited initial increase followed by decline. Chymotrypsin and amylase activities in both tissues showed positive correlations with substrate concentrations in respective diets. These results suggest that the physical properties of expanded diets （e.g.， high hardness and delayed softening） may delay gastric evacuation， thereby reducing feeding rate. Coupled with its suboptimal protein content， these factors collectively constrain the growth potential of Takifugu flavidus. This study highlights the urgent to carry out research on the optimal protein requirements of Takifugu flavidus， and further optimize the expanded diet formula to improve the digestion and utilization efficiency.

Abstract:In order to compare the nutrient composition of wild and farmed Thamnaconus septentrionalis， 10 （each as an independent sample） wild （20.0-21.7 cm in length and 120.95-170.66 g in weight） and 10 farmed Thamnaconus septentrionalis （21.0-23.4 cm in length and 124.08-184.85 g in weight） were used in this study， and the morphological indexes， proximate composition， fatty acid profile and amino acid profile were analysed and compared. The results were as follows： the hepatosomatic index and viscerosomatic index of the farmed group were significantly higher than those of the wild group， and there was no significant difference in condition factor. The crude protein content of the muscle of Thamnaconus septentrionalis ranged from 18.5% to 20.2%， and the crude lipid content ranged from 0.8% to 1.1%. The crude protein and crude fat contents of the muscle of the farmed group were significantly higher than those of the wild group， and there was no significant difference in moisture content. The ash content of the whole fish and liver of the farmed group was significantly lower than that of the wild group. The fatty acid composition of whole fish was similar between the farmed and wild groups. Muscle DHA and EPA contents （% total fatty acids） were 20.2%-24.7% and 11.4%-15.8%， respectively. The contents of saturated fatty acids， 20：4n-6 and DHA in muscle were significantly lower in the farmed group compared to the wild group， but the EPA content was significantly higher than that in the wild group； while the differences in the contents of long-chain polyunsaturated fatty acids and EPA+DHA were not significant. A total of 18 amino acids were detected in the whole fish and muscle of wild and cultured Thamnaconus septentrionalis. The amino acid composition of the whole fish was similar between wile and farmed fish， but the total amount of essential amino acids in the muscle of the farmed group was significantly higher than that of the wild group. Among the essential amino acids， the contents of isoleucine， leucine， phenylalanine， and lysine in the muscle of the cultured group were significantly higher compared to the wild group. In conclusion， the nutritional value of Thamnaconus septentrionalis is higher， and the nutritional quality of farmed Thamnaconus septentrionalis is higher than that of wild Thamnaconus septentrionalis， as evaluated by the contents of protein， lipid， EPA and essential amino acids in muscle.

Abstract:This study evaluated the effects of replacing fishmeal with black soldier fly（BSF）larvae meal on the growth performance，physiological metabolism，and muscle quality of hybrid mandarin fish （Siniperca chuatsi ♀ × Siniperca scherzeri ♂）. Juvenile fish with an initial body weight of（11.43±0.54）g were used as experimental subjects，and five isonitrogenous and isolipidic diets were formulated， incorporating BSF larvae meal as a replacement for fishmeal at levels of 0%，10%，20%，30%，and 40%. The results showed that：（1）Replacing 20% of fishmeal with BSF larvae meal significantly enhanced weight gain rate（WGR）and specific growth rate（SGR），whereas growth performance declined markedly when the replacement level reached 30% or higher（P<0.05）.（2）Analysis of tissue texture and proximate composition showed that crude protein and lipid contents in the hepatopancreas of the 20%-40% replacement groups were significantly lower than those in the control group（0% replacement）. Moreover， gumminess，resilience，and chewiness of muscle were significantly reduced in the 40% replacement group compared to the control group（P<0.05）.（3）Serum biochemical parameters indicated that triglyceride and total cholesterol levels decreased significantly with increasing fishmeal replacement，while albumin levels increased significantly（P<0.05）.（4）Serum malondialdehyde（MDA）levels were lowest in the 30% replacement group，while lysozyme（LZM）activity peaked at the 20% replacement group. In conclusion， replacing up to 20% of fishmeal with BSF larvae meal significantly improved growth performance and enhanced the immune-antioxidant capacity of hybrid mandarin fish. However，higher replacement levels adversely impacted growth performance and muscle quality. Therefore，the optimal replacement level of BSF larvae meal for fishmeal in hybrid mandarin fish diets is approximately 20%.

Abstract:In order to explore the effects of different temporary rearing duration indoors on phenotypic characteristics， health status and muscle quality of black carp （Mylopharyngodon piceus）， an indoor feeding trial was conducted. In this experiment， average body mass of （3.30±0.12） kg of pond-raised black carps were used， commercial formulated pellets for black carp （30.05% crude protein） was fed during the trial period， and 28 d of indoor temporary rearing duration was carried out to explore the variations of phenotypic indexes， physiological and biochemical indexes， body color， muscle color， texture property， and contents of conventional nutrients， amino acids， earthy odor substances and volatile compounds in black carps on 0 d （control）， 7 d， 14 d， 21 d， and 28 d， respectively. The results showed that： body brightness and whiteness of black carp decreased significantly （P<0.05）； muscle brightness and whiteness decreased firstly and then increased （P>0.05） during the temporary rearing period； muscle chewiness and elasticity increased significantly （P<0.05） at 14， 21 and 28 d of staging time； contents of muscle essential amino acids increased （P<0.05） at 21 d of staging time； contents of earthy odor substances in muscle and liver decreased （P<0.05） during staging time. Compared with the control group， hepatic steatosis index and serum triglyceride content， HDL content， AST and AST activities were significantly decreased （P<0.05） at 21 and 28 d of staging time； malondialdehyde contents in liver and muscle were significantly decreased （P<0.05） and total antioxidant capacity was significantly increased （P<0.05） at 21 and 28 d of staging time， increased content of pleasant odors and other substances such as 2-heptanone， 1-octen-3-ol， and 2-pentylfuran in muscle at 21 and 28 d of staging time. In conclusion， at 14 d of staging time could reduce the content of earthy substances in black carp. At 21 d of staging time increased the antioxidant activity of the liver and muscle of black carp， and improved the elasticity and chewiness of the fish meat.

Abstract:This study was conducted to investigate the effects of different gradients of Ala-Gln added to fishmeal-free diets on the growth performance， amino acid metabolism and energy budget of juvenile Acipenser schrenckii. In this study， 450 juvenile sturgeon with initial body weight of （21.66±1.02） g were raised in a recirculating water culture facility and randomly divided into 5 groups （3 replicates per group with 30 fish per replicate）. The control group was fed a basal diet， while the experimental groups were fed diets supplemented with 0， 0.25%， 0.50%， 0.75%， and 1.00% Ala-Gln， respectively. The experiment lasted for 56 days. The results were as follows： （1） The final weight and condition factor of sturgeon were significantly higher in the groups receiving 0.50%-1.00% Ala-Gln compared to the control group （P<0.05）. Weight gain rate， feed efficiency， dry matter intake， crude protein， and crude lipid content increased with Ala-Gln supplementation， though these increases did not reach statistical significance （P>0.05）. （2） Fecal energy （F）， excretion energy （U）， showed no significant differences （P>0.05）， but growth energy （G） and metabolizable energy （R） were significantly different from the control group （P<0.05）. （3） The cysteine content of fish supplemented with 0.75%Ala-Gln was significantly higher than that of other groups （P<0.05）. The glycine content of fish supplemented with 0.50%Ala-Gln was significantly higher than that of other groups （P<0.05）. The glycine content of fish supplemented with 0.50%Ala-Gln was significantly higher than that of other groups （P<0.05）. （4） Glutamine and alanine levels in the blood were significantly increased 5 hours after ingestion （P<0.05）. After 0.25%-1.00% Ala-Gln supplementation， glutamine was the most important amino acid affecting the blood metabolic profile. The addition of 0.50% Ala-Gln resulted in significantly higher aspartic acid levels compared to other groups （P<0.05）. Analysis of PLA， a key component of aspartic acid， indicated that glutamine was the most important amino acid influencing the blood metabolic profile. The results indicate that exogenous supplementation of 0.75% to 1.00% Ala-Gln can significantly improve the growth performance of juvenile sturgeon， likely due to increased absorption of Ala-Gln， which elevates the levels of glutamine and alanine in the body， thereby affecting metabolism and promoting protein synthesis.

Abstract:Glyptosternum maculatum is an important cold-water economic fish in Tibet. To explore the differences in nutritional value of wild and farmed Glyptosternum maculatum muscles， the conventional nutrients， amino acids， and fatty acids in the muscles of wild， domesticated， and farmed Glyptosternum maculatum were determined. The results showed that there were significant differences between the conventional nutritional components of wild， domesticated and farmed Glyptosternum maculatum （P<0.05）； the crude fat mass score of wild fish was significantly higher than that of domesticated fish and farmed fish （P<0.05）； the crude protein mass score of domesticated fish was considerably higher than that of wild fish and farmed fish （P<0.05）； the moisture mass score of farmed fish was significantly higher than that of wild fish and farmed fish （P<0.05）. 17 amino acids were detected in wild， domesticated， and farmed Glyptosternum maculatum， among which there were significant differences in total amino acid content between farmed fish and domesticated fish （P<0.05）. The highest farmed fish were followed by wild fish and domesticated fish， and the lowest farmed fish， and the total non-essential amino acid content of wild fish， domesticated fish， and farmed fish was consistent with the total amino acid content. According to the AAS and CS standards， the first restriction amino acids of wild， domesticated， and farmed Glyptosternum maculatum are methionine + cystine， and the second restriction amino acid is valine. The total amount of saturated fatty acids， monounsaturated fatty acids， and polyunsaturated fatty acids content in wild fish was significantly higher than that in domesticated fish and farmed fish （P<0.05）. Among them， C12：0， C17：0， and C18：3n6w are fatty acids unique to wild fish， C22：1n9， C24：1n9， and C22：2n6 are fatty acids unique to farmed fish， and C15：0 and C20：0 are unique to wild fish and farmed fish. Both wild fish and farmed fish DHA+EPA content was significantly higher than domesticated fish （P<0.05）. In summary， the nutritional quality of wild and farmed Glyptosternum maculatum is higher than that of domesticated Glyptosternum maculatum， which provides basic data for the improvement of Glyptosternum maculatum muscle quality.

Abstract:This study aimed to investigate the effects of different levels of dietary choline on the growth， health， and metabolism of Pacific white shrimp （Litopenaeus vannamei） under low-salinity （salinity 3） conditions compared to seawater. An 8-week feeding trial was conducted with diets containing three different levels of choline chloride： 2 500， 5 000， and 10 000 mg/kg. The results showed that under low-salinity conditions， increasing the dietary choline chloride level from 2 500 mg/kg to 10 000 mg/kg did not significantly promote the growth performance of P. vannamei （P>0.05）. However， the 2 500 and 5 000 mg/kg choline group exhibited significantly higher crude lipid content in the shrimp （P<0.05）. Additionally， the 5 000 mg/kg choline diet significantly reduced glucose levels in both serum and hepatopancreas （P<0.05）， while the 10 000 mg/kg choline group showed a significant increase in hepatopancreatic superoxide dismutase activity， enhancing antioxidant capacity （P<0.05）. Moreover， a high level of choline （10 000 mg/kg） significantly decreased the triglyceride content in the hepatopancreas （P<0.05）. The study concludes that a dietary choline chloride supplementation of 2 500 mg/kg is sufficient to meet the growth requirements of P. vannamei at a salinity of 3. However， higher dosages （≥5 000 mg/kg） play a more significant role in regulating lipid metabolism and enhancing antioxidant capacity. These findings provide a scientific basis for optimizing nutritional strategies for P. vannamei in low-salinity aquaculture.

Abstract:Based on water quality data from Litopenaeus vannamei aquaculture ponds in the same aquaculture farm during 2014-2018 and 2021-2024， this study selected key water quality parameters including total nitrogen （TN）， total phosphorus （TP）， active phosphorus （AP）， nitrate nitrogen （NO^-₃-N）， nitrite nitrogen （NO^-₂-N）， total ammonia nitrogen （TAN）， chemical oxygen demand （COD）， temperature （T）， and pH values to develop water quality prediction models for TAN and COD using temporal convolutional network （TCN） and gated recurrent unit （GRU）. A hybrid FC-TCN-GRU model architecture was constructed， which employed TCN for feature extraction and dimensionality reduction of data features， fed the processed data into GRU， and finally maped the results through fully connected layers （FC） to generate predictions. Mean absolute error （MAE）， mean squared error （MSE）， and coefficient of determination （R²） values of the FC-TCN-GRU model for TAN prediction were 0.255， 0.089 and 0.861， respectively， while achieved 1.750， 4.840 and 0.332 for COD prediction. Compared with PCA-LSTM， basic LSTM and basic GRU models， the FC-TCN-GRU model showed better predictive accuracy for both TAN and COD prediction. The model performs superior in TAN prediction， but it still needs improvement in COD prediction.

Abstract:The Zhoushan fishing ground， an important fishery resource area in southeast China， faces potential threats from marine environmental pollutants. This study investigates the concentration， composition， influencing factors， and health risks of polychlorinated biphenyls （PCBs） in aquatic organisms from the Zhoushan fishing ground. We collected and analysed 37 species of aquatic organisms from the area between March and June 2023. Using GC-MS/MS， concentrations and compositional profiles of 41 PCB congeners in their muscle were measured. A univariate analysis was employed to explore the factors influencing PCB accumulation. Additionally， toxic equivalent quantity （TEQ） and health risk assessment models were applied to evaluate dietary risks. The results showed that the ∑₄₁PCBs concentrations ranged from 5.70 to 338.17 ng/g lipid weight （lw）. Pentachlorinated and hexachlorinated compounds were the most abundant. The concentrations of seven indicator PCBs were strongly correlated with total PCB concentrations， with PCB 138 and PCB 153 being the dominant congeners. No significant differences were observed in PCB concentrations or compositions among different species. PCBs accumulation exhibited a parabolic relationship with logK_ow values （with a turning point around 7） and was negatively correlated with lipid content. No significant correlation were observed with body length or weight. The total toxic equivalency of PCBs ranged from ND to 9.42×10^-5 ng TEQ/g. Both non-carcinogenic risk （HI<1） and carcinogenic risk （CRI<10^-4） were within acceptable limits. These findings provide valuable scientific evidence for the protection of aquatic resources and human health in the Zhoushan Fishing Ground.

Abstract:This study aims to investigate the bioaccumulation characteristics and dietary risks of organophosphate esters （OPEs） in aquatic products from the natural environment of the Beibu Gulf. A total of 65 samples from six species were collected from nearshore and estuarine areas during summer and winter. The concentrations of OPEs were quantified using gas chromatography-tandem triple quadrupole mass spectrometry （GC-MS/MS）. The results revealed the presence of 11 OPEs in aquatic products， with concentrations significantly higher in winter [（127±101） ng/g dw] compared to summer [（38.5±28.6） ng/g dw]. Fish exhibited lower concentration of OPEs than benthic organisms across both seasons. Seasonal compositional patterns were consistent， dominated by tris（2-chloroisopropyl） phosphates （TCIPPs） and tris（2-chloroethyl） phosphate （TCEP）. Chlorinated OPEs （Cl-OPEs） exhibited higher bioaccumulation potential than Alkyl-OPEs， with tris（1，3-dichloroisopropyl） phosphate （TDCIPP） and trihexyl phosphate （THP） obviously bioaccumulated in all aquatic products. Key factors influencing bioaccumulation included metabolic capacity， feeding habits， and habitat conditions. Dietary risk assessment showed hazard quotients （Q_h） below 1 for all age and gender groups， indicating low dietary risk. This study advances the understanding of OPEs contamination in the Beibu Gulf aquatic products and provides a scientific basis for ecological protection and food safety management.

Abstract:In order to investigate the pollution situation of microplastic （MPS） in juvenile fish of the Yangtze River Estuary， a total of 508 juvenile fishes of 10 species from the Yangtze River Estuary were collected， and microplastics were ablated and extracted from their gastrointestinal contents， gastrointestinal walls and gill tissues， and then observed and counted， combined with the differences in feeding habits （filter-feeding， carnivorous and omnivorous） of the juvenile fishes and the time nodes before and after the fishing ban， analyzed by the one-way PERMANVOA test analysis of variance. The results showed that microplastics were detected in 99% of the juvenile fish， with an average abundance of （10.13±7.23） items/individual. The distribution of microplastics among tissues was as follows： gastrointestinal contents [（4.10±4.09） items/individual] > gill tissues [（3.12±2.40） items/individual] > gastrointestinal walls [（2.89±2.61） items/individual]. Fiber （65.7%）， transparent （56.4%） and <0.5 mm （58.3%） microplastics accounted for the highest proportion. The microplastic abundance of filter-feeding juvenile fish was significantly higher than that of other feeding individuals （P<0.05）. After the fishing ban in the Yangtze River， the total abundance of microplastics in Coilia nasus juvenile fish was significantly reduced to （5.20±2.53） items/individual （P<0.01）， the proportion of <0.5 mm transparent fiber microplastics decreased， while the <1 mm size still accounted for most of the microplastics （76%）. The study showed that microplastics pollution was common in juvenile fish in the Yangtze River estuary， and filter-feeding fish were more likely to be enriched with micro plastics. The Yangtze River fishing ban policy significantly reduced the microplastic pollution of Coilia nasus juvenile fish， which revealed that the decreasing trend of microplastic pollution in the water environment of the Yangtze River Estuary and in the juvenile fish. This study can provide data support for the research of microplastics pollution in the Yangtze River Estuary basin.

Abstract:The Poyang Lake Basin serves as a critical ecological barrier in the middle and lower reaches of the Yangtze River. Investigating the response mechanisms of phytoplankton communities to the dual stressors of extreme climate events and anthropogenic activities is essential for regional ecological conservation. Our study focused on the dynamic characteristics of phytoplankton dominant species in key aquatic conservation zones of Jiujiang City during the extreme drought of 2022 and the subsequent hydrological recovery period in 2023. Through systematic surveys at 18 sampling sites across dry and wet seasons， we integrated niche breadth， niche overlap index （O_ik）， variance ratio （VR） method， and interspecific association analyses （χ² test， association coefficient AC， and Spearman's rank correlation） to elucidate the mechanisms underlying phytoplankton community stability under hydrological fluctuations. Results showed that： （1） A total of 161 phytoplankton species from seven phyla were identified， with 13 dominant species from three phyla. Bacillariophyta （Aulacoseira granulata and Ulnaria acus） dominated both extreme drought and recovery phases. （2） During the 2022 extreme drought， niche overlap values significantly increased. Generalist species with broad niches formed stable symbiotic networks through complementary resource utilization， resulting in overall positive community associations （VR>1， 51.31% of species pairs positively linked）. （3） The persistent dominance of A. granulata and U. acus was attributed to their morphological adaptability and niche differentiation， which alleviated competitive pressures from high-overlap species pairs （e.g.， O_ik=0.93 with Navicula sp.）. （4） Post-drought recovery reduced mean niche breadth （7.54） while increasing specialist species proportions， indicating hydrological stabilization drove succession toward functionally resilient community structures. Our study pioneers in exploring niche differentiation and interspecific synergy mechanisms of phytoplankton in mid-Yangtze waters under extreme drought， providing baseline data for ecological monitoring in Poyang Lake and the Yangtze Basin， as well as theoretical insights for freshwater ecosystem management under climate extremes.

Abstract:Poyang Lake is the largest freshwater lake in China， which plays an important role in supporting the biodiversity of the Yangtze River. However， fish species diversity in this area has changed significantly in recent years， coupled with taxonomic revisions driven by advancements in molecular biology and taxonomy research. This study aimed to update the fish species list， providing insights for further biodiversity analysis and protection in Poyang Lake. Field surveys of the fishes in Poyang Lake were conducted from 2006 to 2022， and numerous sampling methods like gill nets， cast nets， and cages were employed to collect fish specimens. We incorporated records from survey results， historical records， and online resources fishbase to refresh the fish checklist in Poyang Lake. The type of migration， water column， feeding habits and protection status of fish species were categorized as well. This updated checklist of the freshwater fishes in the Poyang Lake included a total of 128 species belonging to 14 orders， 35 families， and 78 genera. Among them， 124 species are indigenous and four are aliens. Cypriniformes dominate the fish fauna in this area. Xenocyprididae had the highest number of species， followed by the Gobionidae and Bagridae. There are four newly recorded species and all of them are aliens. Twenty-one of the valid species had nomenclatural changes； 98 historically recorded species were excluded. Thirteen documented fish species that are almost belonging to migrators， benthic water column dwellers， as well as omnivores and piscivores， were not collected during these field surveys. In conclusion， this study confirmed and updated the species checklist of fishes from Poyang Lake， providing crucial insights into the biodiversity protection of this area in the future， especially under the increasing impacts of global climate change and human activities while a complete ban on fishing enforced in the Yangtze River.

Abstract:To investigate the larval and juvenile fish resources in channel connecting Poyang Lake and Yangtze River during spring and summer. This study conducted surveys at 27 sampling stations across three areas （Gutang， Huoyanshan， and Duchang） in spring（May to June） and summer（July to August） of 2024. Using a Type I shallow-water plankton net with 10-minute surface horizontal trawls. A total of 24，603 larval and juvenile fish specimens， representing 41 species from 12 families and 7 orders， were collected. The dominant species were Hemiculter bleekeri， Rhinogobius similis， Hemiculter leucisculus， and Hyporhamphus intermedius， accounting for 87.86% of the total catch. In terms of community structure， spatial analysis showed higher diversity in the downstream Gutang area compared to the other two regions. Temporally， diversity and richness indices were higher in spring than in summer， while the evenness index exhibited the opposite trend. Larval and juvenile fish abundance peaked at June. With the highest density recorded in June， where Hemiculter bleekeri was the most dominant species. Environmental factors varied significantly over time and redundancy analysis （RDA） revealed that water temperature， pH， and dissolved oxygen were the most influential environmental factors affecting the distribution of larval and juvenile fish. Coilia nasus and Hyporhamphus intermedius showed significant positive correlations with water temperature and pH， suggesting that suitable temperatures promote gonadal development and that weakly alkaline conditions favor fish growth and reproduction. In contrast， Pseudolaubuca engraulis and Rhinogobius similis were positively correlated with dissolved oxygen， reflecting that sufficient oxygen levels support feeding and reproductive activities. The study demonstrates difference in the species composition of larval and juvenile fishes in the channel connecting Poyang Lake and Yangtze River， and environmental factors significantly influencing the distribution of dominant species.

Abstract:To investigate the otolith morphological characteristics of Collichthys lucidus in the Yangtze River estuary and their relationships with individual growth traits （body length and body mass）， a total of 409 specimens were collected from June 2022 to May 2023. Nine otolith morphometric parameters， including length， width， perimeter， area， maximum radius， minimum radius， minimum bounding rectangle area， aspect ratio and radius ratio were systematically measured on both left and right otoliths. Principal component analysis （PCA） was used to extract the key variables representing otolith shape variation. Subsequently， the relationships between otolith morphological indicators and body length/weight were analyzed and fitted using exponential， linear， logarithmic， power， and polynomial functions. The results indicated high consistency in major morphological parameters between left and right otoliths. However， significant differences （P<0.05） were observed in specific parameters： otolith length （L₁）， length-to-width ratio （L₃）， minimum radius （r）， radius ratio （L₄）， and perimeter （P₁）. PCA revealed that otolith length， minimum bounding rectangle area， and radius ratio were the most influential variables in shape variation. Among them， minimum bounding rectangle area showed no significant difference between sides （P>0.05）， and thus data were pooled for further analysis. Polynomial models best described the relationships between otolith length and rectangle area with body length （R²>0.85， P<0.05）， whereas power function models performed best in fitting their relationships with body weight （R²>0.91）. The radius ratio showed poor correlation with both growth indices.This study demonstrates that otolith length and minimum bounding rectangle area can serve as effective predictors of individual growth in C. lucidus. These findings provide a theoretical basis for understanding the linkage between otolith morphology and fish growth， and offer practical insights for fisheries resource assessment and species management.

Abstract:For exploring the species and genetic diversity of Suaeda plants in Shanghai coastal wetlands， this paper investigated and studied the species resources and genetic diversity of Suaeda plants collected from 11 stations in three coastal wetlands， including the Nanhui east tidal flat in Pudong New Area， Fengxian tidal flat， and Chongming east tidal flat. The results showed that： （1） By the morphological identification and molecular identification based on ITS and matK sequence barcode analysis， the collected Suaeda plants in Shanghai coastal wetlands were two species： Suaeda salsa and Suaeda glauca. （2） In this study， we found only S. glauca distributed in Chongming east tidal flat， and the genetic distance between these seven samples collected was 0， indicating there was no gene exchange between the population and the outside area. （3） According to ITS and matK sequence analysis of S. salsa distributed in Chongming District， Pudong New Area， and Fengxian District， there are 2-3 haplotypes， respectively， and genetic distances （D） between populations of different districts are smaller than 0.05， indicating that most of them are genetic variations within the population. We further found that the genetic diversity of Fengxian S. salsa population was the lowest on ITS and matK sequences （H_d=0.419±0.113， P_i=0.000 9 and H_d=0.133±0.112， P_i=0.000 4）， while the genetic diversity of Pudong S. salsa population was the highest （H_d=0.629±0.086， P_i=0.001 5 and H_d=0.475±0.141， P_i=0.004 3）. There is moderate differentiation between the S. salsa population of Pudong New Area and both S. salsa populations of Chongming District and Fengxian District （0.05<F_ST<0.15， P<0.05； N_m>1）， while there is high differentiation between the Chongming S. salsa population and the Fengxian S. salsa population （0.15<F_ST<0.25， P<0.05； N_m<1）. This study laid a solid foundation for the protection and population restoration of Suaeda plants in Shanghai coastal wetlands.

Abstract:In order to improve the automation and real-time analysis ability of fish resources monitoring in waters， this paper combines YOLOv8X（You only look once version 8 - Extra Large） target detection algorithm， ByteTrack（ByteTrack： a strong baseline for multi-object tracking）algorithm and DIDSON sonar（Dual-frequency identification sonar） data to develop a fast and accurate fish target recognition and counting method. The experimental results show that the combined method of YOLOv8X and ByteTrack is close to the traditional Echoview software recognition accuracy （the deviation rate is only 1.36%）， but the processing time is significantly reduced （ the single line is reduced from approximate 30 minutes to approximate 3 minutes ）， showing strong real-time processing ability and generalization performance. Meanwhile， the stability of the method is verified by repeated experiments， and its reliability in different scenarios is confirmed. The research methods and results of this paper provide reliable technical support for the automatic monitoring of fish resources in waters， and can be widely used in the monitoring and management of fishery resources in a wide range of high frequency.

Abstract:To address potential biases caused by the long-term dependence on fishing data from Japan and Korea for the stock assessment of albacore tuna（Thunnus alalunga） in the Southeast Pacific Ocean， this study constructed an abundance index using Chinese longline fishery data.Based on Chinese tuna longline fishery catch data and marine environmental parameters from 2013 to 2022， generalized additive models （GAM） were employed to standardize catch per unit effort （CPUE）， quantifying the effects of latitude， longitude， year， month， environmental factors， and their interactions. The standardized CPUE trends of Chinese and Japanese longline fisheries were compared using ordinary least squares （OLS） regression models. The results show that the maximum interpretation bias of the model for CPUE was 69.8%， and latitude had the most significant effect on CPUE. The areas with higher index are mainly around 20°S-30°S and 100°W-120°W， and the highest index is in 2016， and the highest month is from April to August. The trends of standardized CPUE and nominal CPUE were mostly the same， and both have obvious seasonal fluctuations. Except for 2020， the standardized CPUE was lower than the nominal CPUE. In most years， the standardized CPUE based on China's fishery data has a similar trend to that of the Japanese longline fishery. This study provides a new abundance index information for the stock assessment of albacore tuna in the Southeast Pacific Ocean， and is valuable for further improving the stock assessment.

Abstract:To address the decline in target detection accuracy caused by blur and color deviation in underwater images and to improve the accuracy and robustness of squid detection in complex underwater environments， this study proposes an underwater squid detection algorithm named DUIE-YOLO based on image enhancement. The algorithm adopts a cascaded framework of “enhance first， detect later” consisting of the DUIE-Net enhancement module and the YOLOv8-HD detection module. The DUIE-Net module significantly improves image quality through color correction， multi-scale feature fusion， feature restoration and enhancement， and dehazing optimization. The YOLOv8-HD detection module combines the FasterNet network， a small-object detection head， the CoordAttention mechanism， and the ShapeIoU loss function to optimize feature extraction and small-object detection accuracy. Experimental results show that DUIE-YOLO outperforms the original YOLOv8n in four key metrics： Precision， Recall， F1-score， and mAP， with improvements of 4.2%， 6.8%， 5.7% and 5.5%， respectively. Joint experiments demonstrate that the combination of DUIE-Net and YOLOv8-HD achieves a 40.3% increase in mAP， a 10.5% increase in Precision， a 53% increase in Recall， and a 31% increase in F1-score compared to the baseline （Raw+YOLOv8n）， proving the algorithm's significant cascaded optimization effect. The study indicates that DUIE-YOLO effectively mitigates the performance degradation caused by poor underwater image quality through the synergistic optimization of image enhancement and detection modules. This research provides a high-precision solution for target recognition in complex underwater environments， offering significant application value for marine biological monitoring and resource development.

Abstract:In order to investigate the response characteristics of the contact behavior of Chinese sturgeon （Acipenser sinensis） in the ovary during the early stage of reproduction to flow velocity in natural water bodies， this study set up ovaries in the Yangtze River estuary in November 2024. The flow velocity was regulated by a push flow pump to form different flow velocity environments， and the intensity of the contact behavior of Chinese sturgeon under different flow velocity conditions was statistically analyzed. The results showed that： （1） Under the condition of moderate flow velocity （0.12-0.20 m/s）， the intensity of contact behavior of Chinese sturgeon was significantly higher than that of natural flow velocity （0.05-0.15 m/s） （P<0.01）， and the increase in contact behavior intensity of Chinese sturgeon in each region reached more than 50%. Among them， the contact behavior intensity in the low and medium flow velocity region B and the high flow velocity region A was the highest， reaching （50.10±2.93）times/h and （47.80±5.61）times/h， respectively. However， when the flow velocity was too high （>1.0 m/s）， the contact behavior intensity of Chinese sturgeon decreased slightly， with the highest decrease of 28.0% in the high flow velocity region. （2） The proportion of contact behavior in the low to medium flow velocity zone B is always the highest， gradually increasing from 29.1% at the initial flow velocity to 35.0% with the increase of flow velocity， and significantly higher than other zones under high flow velocity conditions （P<0.01）. Research has shown that flow velocity has a nonlinear regulatory effect on the contact behavior of Chinese sturgeons. Moderately increasing flow velocity can maximize the stimulation of their contact behavior. At the same time， during the early stages of reproduction， Chinese sturgeons have the ability to autonomously choose water flow， and their contact behavior is more inclined to occur in areas with low to medium flow velocities，This study provides a key theoretical basis for optimizing the velocity regulation of the spawning environment of Acipenser sinensis and repairing the habitat of the natural spawning ground.

Abstract:To investigate the optimal assembly proportions of inner liners in Antarctic krill beam trawls and achieve the goal of green， low-carbon fishing， this study focuses on the beam trawl used by the Antarctic krill fishing and processing vessel "Deep Blue". The trawl model with a scaling ratio of 15 was developed based on the modified Tanaka criterion， and experiments were conducted in a circulating flume tank to investigate the effects of liner net proportions （100%， 90%， 80%） and sinker mass （0.5， 1.0， 1.5， 2.0 kg） on the overall geometry， drag， energy consumption coefficient， and stability of the beam trawl model. The results indicate： （1） A reduction in the liner net proportion led to decreases in drag and energy consumption coefficient， while the net mouth height remained relatively unchanged. Under identical conditions， a 20% reduction in liner net proportion resulted in a 12.02% decrease in drag and a 5.66% reduction in the energy consumption coefficient. （2） With increasing flow velocity， the beam trawl model exhibited a reduction in net mouth height， greater overall contraction and increased drag. （3） Increased sinker mass was positively correlated with drag， net mouth height， and energy consumption coefficient. （4） Reducing the liner net proportion while increasing sinker mass resulted in more stable resistance oscillations with reduced amplitude. Appropriately reducing the liner net ratio and increasing the sinker mass can help reduce trawl drag and energy consumption. This study provides foundational theoretical guidance for optimizing the design of beam trawl gear for Antarctic krill harvesting.

Abstract:To analyze the long-term characteristics of changes in the structure of the fishery ecosystem in the FAO 77 fishing area of the Eastern Central Pacific （ECP）， this study utilized fishery catch data from the ECP FAO 77 area from 1950-2019. Combining multivariate statistical analysis methods， specifically Principal Component Analysis （PCA） and Sequential T-test Analysis of Regime Shifts （STARS）， we identified the regime shift time points for ecosystem functional groups， thermal adaptation groups， and representative indices （Mean Trophic Level， MTL； Mean Suitable Temperature， MST； and Species Evenness， EVE）. The results indicate that the structure of the ECP fishery ecosystem exhibits significant decadal changes， with regime shift nodes primarily concentrated in the late 1950s and mid-1970s. The regime shift occurring in the late 1950s was characterized by an increase in the catches of functional groups such as benthic fish， reef-associated fish， cartilaginous fish， and invertebrates. This was accompanied by a rise in the catches of warm-water species， leading to an increase in the ecosystem's Mean Trophic Level （MTL） and Species Evenness （EVE）， reflecting the utilization of diversified resources during the early stage of fishery development. Another pivotal shift occurred in the mid-1970s. At this time， there was a significant increase in the catches of pelagic fish and cartilaginous fish， while catches of cold-water species also increased. However， the ecosystem's Mean Trophic Level （MTL）， Mean Suitable Temperature （MST）， and Species Evenness （EVE） showed a declining trend. The study indicates that the structure of the ECP fishery ecosystem underwent two major regime shifts over the past 70 years， and the interactive effects of climate change and human fishing activities were key drivers shaping its evolutionary trajectory. This study provides a scientific basis for analyzing the dynamics of the ECP fishery ecosystem and formulating adaptive management measures.

Abstract:Mesoscaleeddies play a pivotal role in oceanic material transport， energy exchange， and climate variability modulation. To understand their impacts on air-sea interactions in the Northwestern Pacific， this study analyzes satellite altimeter and scatterometer data （2006—2009） using eddy identification and composite analysis techniques， focusing on over 30 000 warm and cold eddies.Results demonstrate distinct air-sea parameter anomalies： warm （cold） eddies exhibit positive （negative） anomalies in sea surface temperature （SST， 1.64/-1.58 ℃）， surface wind speed （0.72/-0.58 m/s）， sensible heat flux （19.60/-39.25 W/m²）， and latent heat flux （40.98/-55.03 W/m²）； these atmospheric responses show strong linear coupling with SST anomalies， with maximum coefficients of 0.49/0.50 m/（s·℃） （wind）， 19.57/20.04 W/（m²·℃） （sensible heat）， and 33.61/32.96 W/（m²·℃） （latent heat）. Regional and seasonal variations in anomalies are modulated by background SST gradients and wind fields through vertical heat transport efficiency and surface roughness modification； synergistic mechanisms involving Ekman pumping， mixed layer adjustment， and boundary layer stability further contribute to these patterns. This study underscores the need for eddy-resolving coupled models to quantify mechanistic contributions and provides critical insights for improving air-sea parameter forecasting in eddy-active regions.

Abstract:In order to verify the reliability of GNSS-R technology in soil moisture monitoring in the Arctic coastal areas， the experiment used GNSS-R technology to carry out soil moisture inversion research at Barrow Station in Alaska in summer， and took the soil moisture in the ARM program and SMAP of the US Department of Energy as reference values， respectively， to analyze the variation characteristics of soil moisture at Barrow Station from 2015 to 2023. The results show that the GNSS-R data from 2015 to 2023 have good consistency with the SMAP and ARM soil moisture data in the long-term trend， and the correlation between the interannual results is 0.54-0.76 and 0.54-0.81， respectively， and the root mean square errors are 0.02-0.06 and 0.01-0.06， respectively. From June to September in 2015 to 2023， the soil moisture inverted by GNSS-R is most consistent with the SMAP and ARM observations in the medium-to-high humidity range （0.4-0.6 cm³/cm³ for SMAP and 0.20-0.35 g/g for ARM）. Under low and high humidity conditions， although the GNSS-R inversion results can still capture the rising trend of soil moisture， there is a certain deviation from SMAP and ARM， which may be related to the increase in summer rainfall. This study confirms the reliability of GNSS-R technology in inverting soil moisture along the Arctic coast.