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Introduction: The implementation of the 10-year fishing ban in the Yangtze River has provided a crucial opportunity for the recovery of rare and endangered diadromous species, such as Coilia nasus. Methods: In this study, we utilized electronic length–frequency analysis (ELEFAN) and length-based Bayesian biomass estimation (LBB) method to fit the body length data of C. nasus from the Yangtze River Estuary and its adjacent sea areas before and after the fishing ban (2019-2023), and the resource changes of C. nasus population were evaluated. Additionally, combined the catch production monitoring data from 2020 to 2022, we comprehensively analyzed the impact of the Yangtze River fishing ban on the recovery of C. nasus resources. Results: The results showed that: (1) The proportion of quantity, weight and occurrence frequency of C. nasus in catches showed a significant increasing trend year by year. (2) 4,994 C. nasus were caught from 2021–2023, with body lengths ranging from 13–410 mm. In 2023, the average body length and weight of C. nasus had increased by 39.93% and 133.89%, respectively, from those in 2021. (3) ELEFAN estimated that the growth parameters after fishing ban, including asymptotic length, growth coefficient, and the theoretical age at length zero, were determined to be 42.92 cm, 0.43 year-1, and -0.31 year, respectively. The total mortality rate, fishing mortality rate, and exploitation rate were determined to be 1.47 year-1, 0.79 year-1, and 0.54, respectively. (4) LBB estimated that the relative fishing mortality of C. nasus before the fishing ban increased from 1.22 in 2019 to 2.65 in 2020, while the relative biomass decreased from 0.34 to 0.22. After the fishing ban, the relative fishing mortality decreased from 0.85 in 2021 to 0.06 in 2023, and the relative biomass increased from 0.26 in 2021 to 0.90 in 2023, with a significant increase in 2022, indicating a clear recovery trend in C. nasus resources. Discussion: By quantifying the resource characteristics of C. nasus before and after the 10-year fishing ban on the Yangtze River, this research revealed the impact of the ban and provided a reference for future systematic evaluations of the C. nasus population. [ABSTRACT FROM AUTHOR]

Large-scale intensive feeding triggered reduced growth performance and nutritional value. Exogenous probiotics can promote the growth performance and nutritional value of fish through improving the intestinal microbiota. However, detailed research on the correlation between the intestinal microbiota, growth performance, and nutritional value remains to be elucidated. Therefore, we performed metagenomic and metabolomic analysis to investigate the effects of probiotic addition to basal diet (1.0 × 108 CFU/g) (PF) and water (1.0 × 108 CFU/g) (PW) on the growth performance, muscle nutritional value, intestinal microbiota and their metabolites, and glucolipid metabolism in Coilia nasus. The results showed that FBW, BL, and SGR were enhanced in PF and PW groups. The concentrations of EAAs, TAAs, SFAs, MUFAs, and PUFAs were increased in PF and PW groups. Metagenomic and metabolic analyses revealed that bacterial community structure and metabolism were changed in the PF and PW groups. Moreover, adding probiotics to diet and water increased SCFAs and bile acids in the intestine. The gene expression associated with lipolysis and oxidation (hsl, pparα, cpt1, and acadm) and glycolysis (gck and pfk) was upregulated, while the gene expression associated with lipid synthesis (srebp1, acc, dgat, and elovl6) and gluconeogenesis (g6pca1, g6pca2, and pck) was downregulated in the liver. Correlation analysis displayed that hepatic glucolipid metabolism was regulated through the microbiota–gut–liver axis. Mantel test analysis showed that growth performance and muscle nutritional value were improved by the gut–liver axis. Our findings offered novel insights into the mechanisms that underlie the enhancement of growth performance and nutritional value in C. nasus and other fish by adding probiotics. [ABSTRACT FROM AUTHOR]

The intestinal microbial composition of fish is closely related to their living environment. In order to investigate the origin of of Coilia nasus and Coilia brachygnathus in Poyang Lake, samples were collected from the the main stream of the Yangtze River, Poyang Lake, the Qingcaosha Reservoir in the Yangtze Estuary and the sea area of Shengsi in different months. The intestinal microorganisms of the samples were comparatively analyzed using 16S rRNA high-throughput sequencing technology. The results showed: （1） among the different sampling groups of C. nasus, the abundance of intestinal microorganisms of the samples from the section of Pengze in March was significantly higher than that of the samples from Poyang Lake, Qingcaosha and Shengsi. The richness of intestinal microorganisms of one group from the in Poyang Lake （PC-4） in April and one group from Qingcaosha had a high similarity with those of the samples from Shengsi （SC-3） through PCoA, suggesting that they may migrate from Shengsi. （2） The intestinal flora of Coilia brachygnathus varied greatly in different regions, while the differences between different months in the same region were smaller. But the intestinal flora in Poyang Lake in May was significantly different from the other sampling groups, indicating that they might have migrated from different places. （3） The average abundance and diversity of the intestinal flora of Coilia brachygnathus in Poyang Lake were higher than those of Coilia nasus in Poyang Lake. The above results demanstrated that there may be migratory populations of both Coilia nasus and Coilia brachygnathus in Poyang Lake. [ABSTRACT FROM AUTHOR]

Coilia nasus are an important fish resource in the Yangtze River, and the Yangtze River Estuary is a crucial migration pathway for them. In this study, we used otolith microchemistry to analyze the strontium/calcium (Sr/Ca) ratios and Sr contents in the sagitta otolith of C. nasus from the south branch (SB) and north branch (NB) of the Yangtze River Estuary and obtained the diversity of migration patterns and spawning ground distribution for C. nasus. The results indicate that C. nasus from both branches include two types of habitat history: freshwater (F)–brackish water (B) (Type I) and F-B seawater (S) (Type II), with Type I being dominant at 62.50% in both branches. The C. nasus from the SB comprise six migration patterns, while that from the NB has seven migration patterns. The C. nasus from both branches hatch in F habitats. At the time of capture, the C. nasus from the SB predominantly remain in F, accounting for 62.5%, while C. nasus from the NB primarily stay in B, accounting for 87.5%. Throughout the migration process, C. nasus from both branches switch between different habitats, with C. nasus from the NB exhibiting more frequent transitions between F and B, showing a greater reliance on the estuarine brackish habitat. The radius of the first blue region near the core (Lf) and freshwater coefficient (Fc) of the otolith for C. nasus from both branches are divided into three groups: long-distance freshwater dependence (LD), medium-distance freshwater dependence (MD), and short-distance freshwater dependence (SD), with the LD only appearing in the SB, while the NB is primarily represented by MD. There is a correlation between the differences in Lf among different groups of C. nasus and the differences in the distance from the spawning grounds of C. nasus in different sections of the Yangtze River to the estuary (DYRE), reflecting the distribution pattern of C. nasus spawning grounds in different sections of the Yangtze River. This study provides theoretical guidance for the protection of migration pathways and maintenance of spawning grounds for C. nasus, which have significant practical value in the precise management of C. nasus resources in the Yangtze River Estuary. [ABSTRACT FROM AUTHOR]

The intermuscular bones of fish are closely related to their locomotion; the more athletic the fish is, the greater the number of intermuscular bones and the relatively higher the muscle fat content. In order to investigate whether C. brachygnathus exists migratory ecological taxa in Poyang Lake, samples of C. brachygnathus were collected from different sampling sites of Poyang Lake, such as Qianyanqiao. In addition, samples of C. nasus from Zhoushan Shengsi and Qingcaosha Reservoir at the mouth of the Yangtze River were collected in order to investigate the effect of migration on the formation of intermuscular bones of C. nasus. The morphology, number and muscle protein and fat content of medullary arch ossicles and pulse arch ossicles were compared by anatomical method and conventional measurement method. The results showed that： (1) The number of intermuscular bones of C. brachygnathus was the least in the Poyang Lake which was 100.67±6.34; The number of intermuscular bones in Qianyanqiao was the largest which was 127.67±6.18. (2)The intermuscular bone number of C.nasus in Poyang Lake was 129.60±0.98 which was significantly higher than C. brachygnathus of 110.60±2.97. (3) The number of Poyanghu intermuscular bones of the same species was significantly higher than that of 113.67±3.29 intermuscular bones of the Qingcaosha but lower than that of 147.67±3.09 intermuscular bones of Shengsi ; (4) The protein content of muscle in the C.nasus in Poyang Lake was lower than that of the C. brachygnathus, and the fat content was higher than that of the C.brachygnathus. Suggesting that the C.nasus need to oscillate more in order to fulfil the needs of long-distance migration and to stimulate more intermuscular spine formation. These results are important for the understanding of the difference in the origin of the migratory populations of C. nasus and C. brachygnathus in Poyang Lake, and lay the foundation for the further research on the biology of the migratory populations in Poyang Lake. [ABSTRACT FROM AUTHOR]

Pakistan is bestowed with variety of habitats and climatic conditions which leads to diverse range of avian species. Among avifauna of Pakistan, Birds of prey or raptors are well-known because of their beauty and speed of flight. Falcons, hawks, kites, eagles, and vulture are common birds of prey. They are geographically widespread and common among the vertebrates. Being predatory birds, they are found on the top of food chain. Unfortunately, birds of prey are facing serious threats such as loss of habitat, pollution, poaching and injuries. In order to maintain ecological balance and food chains, this is very important to make strategies for conservation of these predatory birds. However, there is still uncertainty in their taxonomy because these birds are not studied well at genetic level. Morphological identification includes size, color, and body weight etc. which are crude and does not lead to accurate identification at species level. In order to overcome such gaps, the aim of this study was the identification of two broad families of raptors; Accipitridae and Falconidae, at molecular level using mitochondrial ND2 gene. The partial sequence of ND2 gene was submitted to GenBank. The novel SNPs were investigated which serves as marker for identification of Pakistani raptorial species. Two sub species of falcons are also characterized at genetic level for the first time. The study represented the first report on genetic data of raptorial species of the Pakistan. This strategy can be used to identify other species of birds of prey to get diverse genetic data which will be helpful for the conservation planning of these birds. Developed genetic markers of identification will be used for forensic purposes and also play a significant role in maintenance of ecosystems. [ABSTRACT FROM AUTHOR]

Simple Summary: To reveal the effects of waterborne copper stress on gene expression changes, molecular pathways, and physiological functions in Coilia nasus, two libraries were constructed from a copper treatment group (Cu) and a control group (C) and sequenced using Illumina sequencing technology. The present study indicates the main view: copper induces the aberrant expression of immune and metabolic aspects of genes, suggesting that copper causes metabolic disorders and insufficient energy supply in the body, and it induces oxidative stress, which results in reduced immune functions. To reveal the effects of waterborne copper stress on gene expression changes, molecular pathways, and physiological functions in Coilia nasus, juvenile fish were equally divided into two experimental groups, and the copper levels were 1.61 ± 0.03 mg/L (copper-exposed group) and 0 mg/L (control group), respectively. After 4 h, gill tissue samples were collected for transcript sequencing analysis, and two libraries were constructed from the copper treatment group (Cu) and the control group (C) and sequenced using Illumina sequencing technology. The results showed that approximately 40.2–46.0 M clean reads were obtained from each library, and the percentage of uniquely mapped transcripts ranged from 80.57 to 84.93%. A total of 3915 differentially expressed genes (DEGs) were identified under waterborne copper stress, among which 1300 genes were up-regulated, and 2615 genes were down-regulated. Twelve DEGs were randomly selected for quantitative RT-PCR (qRT-PCR) analysis, and the results confirmed that the transcriptome analysis was reliable. Furthermore, the DEGs were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and the results showed that most of the DEGs were involved in metabolic pathways, including steroid biosynthesis, glutathione metabolism, and peroxisome proliferator-activated receptor (PPAR) signaling pathways. Furthermore, due to the waterborne copper levels, gsk-3β was significantly up-regulated, while other metabolism-related genes (tor, pi3k, lpl, aqp7, fabp3) were significantly down-regulated. In addition, the copper-exposed group significantly reduced the expression of some immunity genes (ifn-γ, stat1, cxcl10, and tgf-β), and enhanced the expression of il-1β and tnf-α. In summary, these results indicated that copper causes metabolic disorders and insufficient energy supply in the body, and induces oxidative stress, which results in reduced immune functions. [ABSTRACT FROM AUTHOR]

IntroductionThe implementation of the 10-year fishing ban in the Yangtze River has provided a crucial opportunity for the recovery of rare and endangered diadromous species, such as Coilia nasus.MethodsIn this study, we utilized electronic length–frequency analysis (ELEFAN) and length-based Bayesian biomass estimation (LBB) method to fit the body length data of C. nasus from the Yangtze River Estuary and its adjacent sea areas before and after the fishing ban (2019-2023), and the resource changes of C. nasus population were evaluated. Additionally, combined the catch production monitoring data from 2020 to 2022, we comprehensively analyzed the impact of the Yangtze River fishing ban on the recovery of C. nasus resources.ResultsThe results showed that: (1) The proportion of quantity, weight and occurrence frequency of C. nasus in catches showed a significant increasing trend year by year. (2) 4,994 C. nasus were caught from 2021–2023, with body lengths ranging from 13–410 mm. In 2023, the average body length and weight of C. nasus had increased by 39.93% and 133.89%, respectively, from those in 2021. (3) ELEFAN estimated that the growth parameters after fishing ban, including asymptotic length, growth coefficient, and the theoretical age at length zero, were determined to be 42.92 cm, 0.43 year-1, and -0.31 year, respectively. The total mortality rate, fishing mortality rate, and exploitation rate were determined to be 1.47 year-1, 0.79 year-1, and 0.54, respectively. (4) LBB estimated that the relative fishing mortality of C. nasus before the fishing ban increased from 1.22 in 2019 to 2.65 in 2020, while the relative biomass decreased from 0.34 to 0.22. After the fishing ban, the relative fishing mortality decreased from 0.85 in 2021 to 0.06 in 2023, and the relative biomass increased from 0.26 in 2021 to 0.90 in 2023, with a significant increase in 2022, indicating a clear recovery trend in C. nasus resources.DiscussionBy quantifying the resource characteristics of C. nasus before and after the 10-year fishing ban on the Yangtze River, this research revealed the impact of the ban and provided a reference for future systematic evaluations of the C. nasus population.

Abstract Background Air exposure is an inevitable source of stress that leads to significant mortality in Coilia nasus. Our previous research demonstrated that adding 10‰ NaCl to aquatic water could enhance survival rates, albeit the molecular mechanisms involved in air exposure and salinity mitigation remained unclear. Conversely, salinity mitigation resulted in decreased plasma glucose levels and improved antioxidative activity. To shed light on this phenomenon, we characterized the transcriptomic changes in the C. nasus brain upon air exposure and salinity mitigation by integrated miRNA-mRNA analysis. Results The plasma glucose level was elevated during air exposure, whereas it decreased during salinity mitigation. Antioxidant activity was suppressed during air exposure, but was enhanced during salinity mitigation. A total of 629 differentially expressed miRNAs (DEMs) and 791 differentially expressed genes (DEGs) were detected during air exposure, while 429 DEMs and 1016 DEGs were identified during salinity mitigation. GO analysis revealed that the target genes of DEMs and DEGs were enriched in biological process and cellular component during air exposure and salinity mitigation. KEGG analysis revealed that the target genes of DEMs and DEGs were enriched in metabolism. Integrated analysis showed that 24 and 36 predicted miRNA-mRNA regulatory pairs participating in regulating glucose metabolism, Ca2+ transport, inflammation, and oxidative stress. Interestingly, most of these miRNAs were novel miRNAs. Conclusion In this study, substantial miRNA-mRNA regulation pairs were predicted via integrated analysis of small RNA sequencing and RNA-Seq. Based on predicted miRNA-mRNA regulation and potential function of DEGs, miRNA-mRNA regulatory network involved in glucose metabolism and Ca2+ transport, inflammation, and oxidative stress in C. nasus brain during air exposure and salinity mitigation. They regulated the increased/decreased plasma glucose and inhibited/promoted antioxidant activity during air exposure and salinity mitigation. Our findings would propose novel insights to the mechanisms underlying fish responses to air exposure and salinity mitigation.

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Background: Air exposure is an inevitable source of stress that leads to significant mortality in Coilia nasus. Our previous research demonstrated that adding 10‰ NaCl to aquatic water could enhance survival rates, albeit the molecular mechanisms involved in air exposure and salinity mitigation remained unclear. Conversely, salinity mitigation resulted in decreased plasma glucose levels and improved antioxidative activity. To shed light on this phenomenon, we characterized the transcriptomic changes in the C. nasus brain upon air exposure and salinity mitigation by integrated miRNA-mRNA analysis. Results: The plasma glucose level was elevated during air exposure, whereas it decreased during salinity mitigation. Antioxidant activity was suppressed during air exposure, but was enhanced during salinity mitigation. A total of 629 differentially expressed miRNAs (DEMs) and 791 differentially expressed genes (DEGs) were detected during air exposure, while 429 DEMs and 1016 DEGs were identified during salinity mitigation. GO analysis revealed that the target genes of DEMs and DEGs were enriched in biological process and cellular component during air exposure and salinity mitigation. KEGG analysis revealed that the target genes of DEMs and DEGs were enriched in metabolism. Integrated analysis showed that 24 and 36 predicted miRNA-mRNA regulatory pairs participating in regulating glucose metabolism, Ca2+ transport, inflammation, and oxidative stress. Interestingly, most of these miRNAs were novel miRNAs. Conclusion: In this study, substantial miRNA-mRNA regulation pairs were predicted via integrated analysis of small RNA sequencing and RNA-Seq. Based on predicted miRNA-mRNA regulation and potential function of DEGs, miRNA-mRNA regulatory network involved in glucose metabolism and Ca2+ transport, inflammation, and oxidative stress in C. nasus brain during air exposure and salinity mitigation. They regulated the increased/decreased plasma glucose and inhibited/promoted antioxidant activity during air exposure and salinity mitigation. Our findings would propose novel insights to the mechanisms underlying fish responses to air exposure and salinity mitigation. [ABSTRACT FROM AUTHOR]

Coilia nasus, a migratory fish species found in the middle and lower reaches of the Yangtze River and along offshore areas of China, possesses considerable aquacultural and economic potential. However, the species faces challenges due to significant variation in the gonadal development rate among females, resulting in inconsistent ovarian maturation times at the population level, an extended reproductive period, and limitations on fish growth rate due to ovarian prematurity. In the present study, we combined genome-wide association study (GWAS) and comparative transcriptome analysis to investigate the potential single nucleotide polymorphisms (SNPs) and candidate genes associated with population-asynchronous ovarian development in C. nasus. Genotyping of the female population based on whole-genome resequencing yielded 2 120 695 high-quality SNPs, 39 of which were suggestively associated with ovarian development. Of note, a significant SNP peak on LG21 containing 30 suggestively associated SNPs was identified, with cpne5a determined as the causal gene of the peak. Therefore, single-marker and haplotype association analyses were performed on cpne5a, revealing four genetic markers (P<0.05) and seven haplotypes (r2>0.9) significantly associated with the phenotype. Comparative transcriptome analysis of precociously and normally maturing individuals screened out 29 and 426 overlapping differentially expressed genes in the brain and ovary, respectively, between individuals of different body sizes. Integrating the GWAS and transcriptome analysis results, this study identified genes and pathways related to hypothalamic-pituitary-gonadal axis hormone secretion, extracellular matrix, angiogenesis, and gap junctions involved in population-asynchronous ovarian development. The insights gained from this study provide a basis for a deeper understanding of the molecular mechanisms underlying ovarian development in fish and may facilitate the genetic breeding of C. nasus strains exhibiting population-synchronous ovarian development in the future. [ABSTRACT FROM AUTHOR]

Coilia nasus is a species of anadromous migratory fish, which predominantly lives in the sea. During the breeding season, the reproductive population migrates from the sea to rivers to reproduce and clusters to form a fishing season. The Yangtze Estuary is an important migration channel for this species. In recent years, due to the influence of upstream dam construction, water conservancy projects along the Yangtze River, environmental pollution and overfishing, the populations of this species in the Yangtze River are on the verge of extinction. In order to better protect C. nasus in the Yangtze River, a large number of studies on the conservation and management of its resources, migration habits, genetic structure, and the effects of resource recovery on this species have been conducted. As for the nutritional composition of C. nasus, studies have been conducted on the different sources, ecotypes, breeding methods, and stages of gonad development. These studies have mainly focused on the muscle nutrition of C. nasus from the Yangtze River; however, none have investigated the nutritional composition of different tissues of the reproductive populations from the Yangtze Estuary. This study is the first to determine the nutritional status of the reproductive population that migrates to the Yangtze Estuary with mature ovaries, and to compare and analyze the distribution characteristics of total lipids and fatty acids in different tissues, and provides reference information for ascertaining the nutritional status and reproductive performance of this species in the Yangtze Estuary. In this study, the contents of moisture, total lipid, and fatty acid composition in muscle, liver, and ovary tissues of adult female C. nasus with gonad development stage Ⅳ were measured and analyzed using standard GB methods. The results indicated that: The moisture content declined successively in muscle, liver, and ovary tissues, with measurements of (77.91±1.61)%, (75.01±1.33)%, and (46.77±5.58)%, respectively. The total lipid content of dry matter increased successively in muscle, liver, and ovary tissues, with measurements of (16.21±1.09)%, (21.94±1.23)%, and (55.21±1.35)%, respectively. The saturated fatty acids (SFA) content was (29.89±0.81)%, (37.60±3.06)%, and (18.33±1.61)% in the muscle, liver, and ovaries, respectively, with the highest in the liver and the lowest in the ovaries. There were significant differences in SFA contents among the three tissues (P0.05). The ratio of UFA/SFA in muscle, liver, and ovary tissues was 2.35, 1.67, and 4.49, respectively, and the ratio of n3-PUFA/n6-PUFA in the same three tissues was 4.94, 3.87, and 5.13, respectively. These ratios were highest in the ovary, followed by the muscle, and were the lowest in the liver. In summary, the total lipid, PUFA, EPA, DHA, and n3-PUFA contents and the ratios of UFA/SFA and n3-PUFA/n6-PUFA were highest in ovary tissues, and the distribution characteristics of the corresponding composition in different tissues was closely related to the reproductive habits of this species during gonad development stage Ⅳ. The accumulation of rich lipids and reasonable essential fatty acid nutrition in the ovary can improve the reproductive performance of C. nasus in this stage and provide sufficient nutrition and energy sources for the development of eggs and larvae in the subsequent stage. In this study, it was found that the lipid and polyunsaturated fatty acid nutrition of C. nasus adults with ovarian development to stage Ⅳ selectively accumulated in the ovary, which is an adaptation to the reproductive activities of this species at this stage. The results provide basic data for determining the differences in nutritional demands of C. nasus adults at different ovarian development stages and the mechanisms for the synthesis and transformation of essential fatty acids. Additionally, this study lays a foundation for further exploration of the relationship between ovarian nutritional status and egg quality. Relevant data can enrich the reproductive biology knowledge of this species and provide theoretical guidance for protecting the reproductive population and the maintenance of C. nasus spawning grounds in the waters adjacent to the Yangtze Estuary.

The Japanese grenadier anchovy Coilia nasus Temminck & Schlegel, 1846 belongs to the family Engraulidae of the order Clupeiformes. This species is widely distributed in China, Japan, and Korea and in Northwest Pacific Ocean. In China, C. nasus is found in the Bohai Sea, the Yellow Sea, the East China Sea, and the middle and lower reaches and the estuaries of some main rivers, such as the Liao River, the Yellow River, and the Yangtze River. The life history of C. nasus is diverse and it is found to have three main ecological types (i.e., anadromous migratory, freshwater resident, and freshwater landlocked), indicating its strong adaptability to different habitats. Because of its commercial importance in China, C. nasus has been heavily exploited for years. Due to the significant decline of the wild stocks and the degeneration of freshwater spawning grounds in its distribution region, C. nasus was listed in the IUCN Red List of Threatened Species as "Endangered" category in 2018.Currently, the exact distribution boundary of C. nasus to the southern limit of China is unclear. Based on the fishery surveys in the southern Zhejiang Province for the past 15 years, the adjacent waters of Ou River estuary in Wenzhou are the known southernmost distribution area for C. nasus. The distribution of C. nasus in Fujian waters, both freshwater and seawater was documented from 1960—2008; however, the sampled individuals were very rare. It is impossible to understand the habitat history and life history pattern of C. nasus using traditional fishery survey methods. In this study, three C. nasus individuals were collected by trawl net, set net, and gill net in Fuzhou and Ningde waters in 2017—2019 during various fishery surveys along the coastline of Fujian. To reconstruct the life history of C. nasus in Fujian waters, the X-ray electron probe micro-analysis (EPMA) approach was used to analyze otolith (sagitta) microchemistry patterns of the fish for the first time. Otolith microchemistry is an effective tool for revealing the anadromous pattern and the spatial and temporal distribution of fishes. The otolith Sr/Ca ratios are powerful indicators for identifying freshwater, brackish water, and seawater habitats throughout the life history of fish.The results of this study showed that the Sr/Ca ratios of the otolith core areas of all three C. nasus individuals were less than 3, and the core areas exhibited a blue pattern in the X-ray intensity maps of Sr content. Both results indicated that the three individuals originated from freshwater and hatched in freshwater habitat. Among the three individuals, the individual collected in Fuzhou waters was more dependent on freshwater at its early life stage and did not enter brackish water until it was almost 1-year-old. Combined with the sampling site and the adjacent water of Min River, it is deduced that it might have originated from the pure freshwater habitat of Min River. Two individuals collected in Ningde waters were less dependent on freshwater habitat at their early life stage. Combined with the sampling sites, i.e., the outer water of Sansha Bay, it is deduced that the two individuals from Ningde might have originated from the pure freshwater habitat of Jiao Brook in Ningde, Ou River in Wenzhou, or Min River in Fuzhou. According to the fluctuations of the Sr/Ca ratio from the core to the edge of the otoliths and X-ray intensity maps of Sr content through the otolith core, all three C. nasus individuals were confirmed to be typically anadromous ecological types. The habitat history of the only one C. nasus individual in Fuzhou was a freshwater-brackish type; its hatching and early life stage were also associated with freshwater habitat, and then it entered the brackish water habitat and traveled back and forth between brackish water and freshwater habitats to grow out until it was captured. The habitat history of the other two C. nasus individuals in Ningde was freshwater-brackish-seawater type; their hatching and early life stage were associated with freshwater habitat, and then they entered high salinity habitat and traveled back and forth between brackish water and seawater habitats for growth until captured. Moreover, we found that the higher salinity in the capture waters of the three C. nasus individuals did not correspond to the Sr/Ca ratio at the edge of the otoliths, indicating a certain time delay in otolith responding to the salinity of their most present living habitats.This study not only revealed the diversity of C. nasus life history patterns and habitat histories but also confirmed the current distribution of anadromous C. nasus in Fujian waters. Since February 2019, the Yangtze River, the most important habitat for C. nasus and many endangered fishes and mammals has initiated a new management measure, i.e., a 10-year fishing ban plan. However, there is still a lack of sufficient understanding of the distribution, the locations of spawning grounds and the population size of C. nasus in Fujian waters. Further studies on the key habitats of C. nasus such as spawning ground and ecological type are needed to formulate effective management measures for its natural resource conservation in Fujian waters.

Coilia nasus is an anadromous fish that has been successfully domesticated in the last decade due to its high economic value. The fish exhibits a delayed ovary development during the reproductive season, despite breeding and selection for five to six offspring. The molecular mechanism of the delayed ovary development is still unknown, so the obstacles have not been removed in the large-scale breeding program. This study aims to investigate the key genes regulating ovarian development by comparing the transcriptomes of ovarian-stage IV and stage II brain/pituitary of Coilia nasus. Ovarian stages were validated by histological sections. A total of 75,097,641 and 66,735,592 high-quality reads were obtained from brain and pituitary transcriptomes, respectively, and alternatively spliced transcripts associated with gonadal development were detected. Compared to ovarian Ⅱ- brain, 515 differentially expressed genes (DEGs) were upregulated and 535 DEGs were downregulated in ovarian Ⅳ- brain, whereas 470 DEGs were upregulated and 483 DEGs were downregulated in ovarian Ⅳ- pituitary compared to ovarian Ⅱ- pituitary. DEGs involved in hormone synthesis and secretion and in the GnRH signaling pathway were screened. Weighted gene co-expression network analysis identified gene co-expression modules that were positively correlated with ovarian phenotypic traits. The hub genes Smad4 and TRPC4 in the modules were co-expressed with DEGs including Kiss1 receptor and JUNB, suggesting that ovarian development is controlled by a hypothalamic-pituitary-gonadal axis. Our results have provided new insights that advance our understanding of the molecular mechanism of C. nasus reproductive functions and will be useful for future breeding.

Coilia nasus is a typical anadromous migratory fish found in the lower reaches of the Yangtze River. Every year, C. nasus clusters offshore and swims upstream along the Yangtze River into the tributaries and lakes in the middle and lower reaches of the Yangtze River to breed. In this study, female C. nasus were collected as study subjects from the Chongming section of Shanghai, the Taizhou section of Jiangsu, and the Anqing section of Anhui. Their ovaries were used to examine tissue sections and investigate gene expression, including the follicle-stimulating hormone receptor (fshr), the luteinizing hormone receptor (lhr), kisspeptin-1 (kiss1), and forkhead box l2 (foxl2), which are related to reproductive development, while the serum levels of estrogen (including estradiol, E2) and progestins (including 17α,20β-dihydroxy-4-pregenen-3-one, 17α,20β-DHP) were also analyzed. Our results showed that, first, the growth period of the oocytes was small in stage II of ovarian development, in which both E2 and 17α,20β-DHP levels and gene expression were low. Then, in stage III, the growth period of the oocytes became large, and the yolk granules and oil droplets began to appear. Simultaneously, E2 and the expression of kiss1 and foxl2 were significantly elevated. Finally, stage IV was the period of a large amount of accumulation of nutrients in the oocytes, and 17α,20β-DHP levels and the expression of fshr and lhr were significantly elevated. These results enrich the theoretical study of ovarian development in the natural population of C. nasus, supplementing the biological basis of C. nasus reproduction and scientifically supporting the study of C. nasus population ecology and resource conservation. [ABSTRACT FROM AUTHOR]

The longjaw tapertail anchovy Coilia nasus, which migrates from ocean to freshwater for spawning in spring, is an important anadromous fish with ecological and cultural significance. To determine parasite infection in anadromous C. nasus, a total of 103 fish from the Yangtze River were collected and examined in 2021 and 2022. The overall infection prevalence of nematodes in C. nasus was 100%, with a mean intensity of 13.81 ± 16.45. The mean intensity of nematode infections in 2022 was significantly higher than that observed in 2021 across all sampling sites (p < 0.05). Nematodes were widely detected in the mesentery, pyloric cecum, stomach, and liver, among which the mesentery accounted for the highest proportion, reaching up to 53.52%. A total of eight ascaridoid nematodes belonging to the family Anisakidae and Raphidascarididae were identified by using morphological characters and molecular biological techniques, including two species of Anisakis, five species of Hysterothylacium, and one species of Raphidascaris. A. pegreffii was found as the predominant species, accounting for 48.65% of all identified parasitic nematodes in liver, while Raphidascaris sp. was the most common nematode in the mesentery, pyloric cecum, and stomach, reaching up to 39.81%, 36.21%, and 74.36%, respectively. The present study systematically investigated the parasitic status and community structure of the nematode in C. nasus during its migration in the Yangtze River. This research provides a foundation for studying the impact of nematode parasitism on the reproductive migration and population recruitment of C. nasus, and offers valuable insights for biomarker screening and nematode identification in C. nasus. [ABSTRACT FROM AUTHOR]

Immune-related lncRNAs (LncRNA) play an essential role in tumorigenesis and progression, and sought to develop an immune-related lncRNA signature to assess the value of immune-related lncRNAs to discover their prognostic values. RNA-seq and clinical information were obtained from the Cancer Genome Atlas (TCGA) database, which aims to screen for immune-associated lncRNAs based on constructing a risk scoring formula. Besides, in virtue of univariate and multivariate Cox regression, immune-associated lncRNA signatures formed its structure. In addition, in virtue of gene ontology (GO) and KEGG pathway enrichment analysis genes were given functional identification. In total, there were 102 differentially expressed immune-related lncRNAs which were identified, and there were four genes (USP30-AS1, U62317.1, ZEB1-AS1 and MIR205HR) which were screened from the gene signature to form a prognostic signature model. Based on the survival analysis results, patients with high-risk scores had poor survival outcomes. To conclude, we constructed a predictive signature of four immune-related lncRNAs, which can provide assistance for prognosis prediction and immunotherapy of SKCM. [ABSTRACT FROM AUTHOR]

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Coilia nasus is an endangered fish species in the Yangtze River, and there is urgent need to know the genes related to its reproduction and fertility. The DAZ family including boule, daz and dazl, plays an important role in germ cells development. In this study, the cDNA sequence of boule (Cnbol) and dazl (Cndazl) genes were cloned and their expression patterns were characterized in Coilia nasus. RT-PCR showed that the expression of Cnbol and Cndazl mRNAs was restricted in adult gonads. The section in situ hybridization indicated that the temporospatial expression patterns of Cnbol and Cndazl were significantly different. In the testis, Cnbol was mainly detected in spermatocytes and spermatids, while Cndazl was prominently expressed in s permatogonia. In the ovary, Cnbol and Cndazl were highly expressed in the early stages of oocytes. Interestingly, Cndazl was also concentrated in perinuclear speckle and then localized to the Balbiani body in late stages of oocytes. In addition, Cnbol and Cndazl 3′ UTR can specifically label medaka Primordial Germ Cells (PGCs). According to our results, Cnbol and Cndazl are marker genes of germ cells and may play a vital role in the development and differentiation of germ cells in Coilia nasus.

Coilia nasus is a precious migratory fish typical to the Yangtze River Basin of China. It is locally referred to as the "Three delicious fish of the Yangtze River, " with its fresh meat being particularly delicious and popular. In recent years, wild C. nasus numbers in the Yangtze River Basin have been decreasing due to environmental changes and illegal overfishing, among other reasons. To attenuate the availability of C. nasus, the Shanghai Fisheries Research Institute has successfully established an indoor artificial breeding and pond culture program in 2011. The research and development of C. nasus artificial breeding technologies have steadily progressed, though the artificial breeding yield of C. nasus remains relatively low. In addition, related research on the artificial cultivation of C. nasus is still in its infancy. Research on C. nasus in China and abroad mainly focuses on gonad development, breeding technology, muscle nutrient composition, and growth performance. No reports exist on the effects of brackish water culture conditions on the physiology of C. nasus. Given its economic importance, it would be of great value to evaluate the changes in the digestive, antioxidant, nonspecific immune capacity, and metabolic rates of C. nasus from brackish water (natural seawater in Hangzhou Bay, salinity 8.7~12.5) to freshwater aquaculture, to determine the breeding conditions of C. nasus, and to improve the artificial breeding yield and related technology. To investigate the differences in digestive capacity, antioxidant capacity, nonspecific immune capacity, and metabolic rates of C. nasus in brackish water and freshwater aquaculture conditions, the experiment adopted the pond interbreeding method. Two groups were established: A brackish aquaculture group and a freshwater aquaculture group (control group). Each group was housed in a single aquaculture pond with an area of 0.17 hm2. 500 C. nasus were stocked in each pond and moved to a Takifugu obscurus pond for a seven-month aquaculture experiment. At the end of the experiment, 12 C. nasus were randomly selected from each group and randomly divided into three replicates. Four C. nasus samples were selected from each replicate. The liver, intestine, stomach, and cecum of C. nasus were dissected on an ice plate and carefully removed to prepare a 10% homogenate. The activities of digestive enzymes, antioxidant enzymes, nonspecific immune enzymes, and metabolic enzymes and the total protein content were measured using a kit produced by the Nanjing Jiancheng Bioengineering Institute. The activities of digestive enzymes, antioxidant enzymes, nonspecific immunity enzymes, and metabolic enzymes in brackish water and freshwater aquaculture environments were compared and analyzed in a seven-month aquaculture experiment using the same batch of artificially bred C. nasus. The growth and survival rates of C. nasus cultured in brackish water (hereafter referred to as brackish water C. nasus) were significantly higher than that in the freshwater (hereafter referred to as freshwater C. nasus) (P < 0.05). The digestive ability of protein and starch in brackish water C. nasus was higher than that of freshwater C. nasus, while the digestive ability was weakened. Among them, the activity of amylase (AMS) in the four organs of brackish water C. nasus was higher than those in freshwater, but not significantly so (P > 0.05). The activities of protease in the liver and stomach were significantly higher than those in freshwater C. nasus (P < 0.05), and the activities of lipase (LPS) in the liver and cecum were significantly lower than those in freshwater C. nasus (P < 0.05). The order of AMS and protease activity of brackish water C. nasus was: cecum > intestine > stomach > liver, while the order of LPS activity was intestine > cecum > stomach > liver. The order of AMS, protease, and LPS activity of freshwater C. nasus was: cecum > intestine > stomach > liver. Brackish water had significant effects on antioxidant, nonspecific immunity, and metabolic abilities, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in the liver of C. nasus were significantly increased, while the activity of catalase (CAT) was significantly decreased (P < 0.05). The activities of alkaline phosphatase (AKP) and acid phosphatase (ACP) in the liver of C. nasus in brackish water were significantly lower than those in freshwater (P < 0.05). Brackish water had no significant effect on the activity of aspartate aminotransferase (AST), but it significantly reduced the activity of alanine aminotransferase (ALT). In summary, brackish water aquaculture conditions promoted the growth of C. nasus; increased the survival rate; improved the ability of C. nasus to digest protein and starch; improved the immunity of fish; and reduced the influence of external stresses by decreasing the activities of AKP, ACP, and ALT enzymes and increasing the activities of SOD and GSH-PX enzymes. This study also found that C. nasus living in brackish water, as a result of maintaining the internal osmotic balance, significantly reduced ALT enzyme activity and reduced urea production and emission, thereby reducing the pollution of the direct environment. Therefore, brackish water is more suitable for the aquaculture of C. nasus, and it is recommended that brackish water (salinity of 8.7~12.5) be used for aquaculture of 1+ age C. nasus individuals in the future. The results of this study provide a scientific basis for the improvement of artificial breeding technology, improving the yield of C. nasus, and the development of special compound feed for C. nasus.

Simple Summary: Induction of sperm cell differentiation in vitro is a key technology for conserving germplasm resources. Coilia nasus is an anadromous fish with commercial value found in the Yangtze River in China. Overfishing and deteriorating ecological conditions have almost caused the extinction of the C. nasus's natural resources in the past decade. To preserve the declining population of C. nasus, a stable spermatogonial stem cell line (CnSSC) of C. nasus was obtained. The cell line remained proliferative and maintained stable cell morphology, a normal diploid karyotype, and normal gene expression patterns for over a year. Additionally, the cells could differentiate into sperm. Our research results contribute to further research on endangered fish germplasm resources of significant value. The process by which spermatogonial stem cells (SSCs) continuously go through mitosis, meiosis, and differentiation to produce gametes that transmit genetic information is known as spermatogenesis. Recapitulation of spermatogenesis in vitro is hindered by the challenge of collecting spermatogonial stem cells under long-term in vitro culture conditions. Coilia nasus is a commercially valuable anadromous migrant fish found in the Yangtze River in China. In the past few decades, exploitation and a deteriorating ecological environment have nearly caused the extinction of C. nasus's natural resources. In the present study, we established a stable spermatogonial stem cell line (CnSSC) from the gonadal tissue of the endangered species C. nasus. The cell line continued to proliferate and maintain stable cell morphology, a normal diploid karyotype, and gene expression patterns after more than one year of cell culture (>80 passages). Additionally, CnSSC cells could successfully differentiate into sperm cells through a coculture system. Therefore, the establishment of endangered species spermatogonial stem cell lines is a model for studying spermatogenesis in vitro and a feasible way to preserve germplasm resources. [ABSTRACT FROM AUTHOR]

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Simple Summary: Coilia nasus is a migratory fish species with high nutritional and economic value, and naturally inhabits the middle and lower reaches of the Yangtze River and offshore China. Since the 1970s, the continuous deterioration of the habitat environment and continuous high-intensity fishing have led to a sharp decline in the germplasm resources of the Coilia nasus, which has been listed in the Red List of Threatened Species by the International Union for Conservation of Nature. Artificial farming has gradually become an important way to protect and utilize the germplasm resources of Coilia nasus, but limited germplasm sources and unscientific breeding strategies have put the germplasm resources and genetic diversity of Coilia nasus at risk, which limits its resources protection and utilization. The aim of this study was to assess the germplasm resources of Coilia nasus by analyzing the genetic diversity and genetic structure of its natural and farmed populations. In conclusion, the present study provides a reference for germplasm conservation and breeding strategy optimization in Coilia nasus, and contributes to the healthy development of Coilia nasus aquaculture. Coilia nasus is a threatened migratory species in the Yangtze River Basin. To reveal the genetic diversity of natural and farmed populations of C. nasus and the status of germplasm resources in the Yangtze River, the genetic diversity and structure of two wild populations (Yezhi Lake: YZ; Poyang Lake: PY) and two farmed populations (Zhenjiang: ZJ; Wuhan: WH) of C. nasus were analyzed using 44,718 SNPs obtained via 2b-RAD sequencing. The results indicate that both the wild and farmed populations had low genetic diversity, and germplasm resources have undergone varying degrees of degradation. Population genetic structure analyses indicated that the four populations may have come from two ancestral groups. Different amounts of gene flow were identified among WH, ZJ, and PY populations, but gene flow among YZ and other populations was low. It is speculated that the river–lake isolation of Yezhi Lake is the main cause of this phenomenon. In conclusion, this study revealed that genetic diversity reduction and germplasm resource degradation had occurred in both wild and farmed C. nasus, suggesting that conservation of its resources is of great urgency. This study provides a theoretical basis for the conservation and rational exploitation of germplasm resources for C. nasus. [ABSTRACT FROM AUTHOR]

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This study was designed to generate the full-length transcriptome of Coilia nasus using single-molecule long read isoform sequencing (SMRT-seq) technology. RNAs of brains, ovaries, and testes of C. nasus conditioned in both seawater and freshwater except for gut which was only from the fish conditioned in freshwater, were isolated. All the RNAs were pooled together equally for SMRT sequencing. One SMRT cell produced 64.18 Gb clean data, including 765,184 circular consensus (CCS) reads and 616,126 full-length non-chimeric (FLNC) reads. Finally, 93,793 non-redundant transcripts were obtained after clustered and polished. Structural analysis of the 93,793 non-redundant transcripts predicted 8242 alternative splicing events, a total of 229,825 SSR and 72,037 complete CDS. A total of 8437 lncRNA were identified. 84,617 transcripts were annotated in NR, Swissprot, GO, COG, KOG, eggnog, Pfam and KEGG database totally. This is the first full-length transcriptome of Coilia nasus, including transcripts appeared in the case of seawater, which will facilitate exploration of genetic data and life story of Coilia nasus.

In the protection of migratory species, Coilia nasus has always been a research topic of very high interest in various countries because of the high economic value and the serious decline of resources. In this study, C. nasus were collected from the Shengsi Sea area, the Yangtze River estuary, the Taizhou section of the Yangtze River and Poyang Lake. By using 2b-RAD simplified genome sequencing technology, 63,110 SNP sites were screened, and the genetic diversity of each population was analyzed with SNP markers. The results showed that (1) the genetic purity of the four groups of populations was not high, with the need to further increase levels of genetic purity; (2) the genetic diversity in the four populations was high, indicating that they had strong adaptability to environmental changes and could easily expand their distribution and resource growth; (3) the FST values (0.112–0.142) of the four populations were higher, indicating that there was moderate genetic differentiation, but no independent population was formed. This study speculated that these migratory species may have the same spawning grounds and pointed out that the gene purity of C. nasus may have been polluted, and it is urgent to improve the purity in the protection of migratory C. nasus. [ABSTRACT FROM AUTHOR]

The estuarine tapertail anchovy (Coilia nasus) is a high-value commercial fish. Estimating the spawning site or hatchery origin and habitat is essential for its conservation. This study aimed to determine the habitat use and life history characteristics of C. nasus from the Changjiang River Estuary. We investigated the environmental signatures of strontium (Sr) and calcium (Ca) in the otoliths of the collected specimens using electron probe microanalysis; additionally, we examined their gonadal maturity stage. Our results indicate that the 31 adult C. nasus specimens used in this study could be classified into two types based on their otolith Sr:Ca concentration ratios and their gonadal maturity stage. The long freshwater early life history type (Type LF) had wider central region in the otolith with low Sr:Ca concentration ratios ranging from 1.24±0.62 to 1.92±0.78 and a bluish pattern of low Sr content level. These fish are of riverine origin and had a relatively long early life history in freshwater and low gonadal maturation when captured. The short freshwater early life history type (Type SF) had a shorter central region in the otolith with low Sr:Ca concentration ratios ranging from 1.35±0.5 to 2.82±0.97 and a correspondingly bluish pattern. These fish also had a relatively short-term early life history in freshwater and high gonadal maturation when captured. The results of the otolith microchemical analysis indicated that Type LF and Type SF originated in spawning/hatching sites far from and close to the estuary, respectively. The mature gonads of Type SF fish indicated that they may breed in areas close to the estuary, whereas the immature gonads of Type LF fish indicated that they may breed in areas far from the estuary. This study is the first to reveal that the Changjiang River Estuary contains stocks of anadromous C. nasus originating in different spawning sites during the same season. The estuarine habitat plays a critical role in the connectivity between freshwater recruitment and the marine resources available to adult spawners of this commercially valued species. From a conservation perspective, this study provides important information for identifying anadromous C. nasus stocks originating in different spawning sites in the Changjiang River Basin. [ABSTRACT FROM AUTHOR]

The estuarine tapertail anchovy Coilia nasus is distributed throughout the Dayang River. However, the life history and habitat use of this fish remain unknown. Here, the microchemistry patterns of Sr and Ca in 23 otoliths collected from the lower reaches of the Dayang River were analyzed using an X-ray electron probe microanalyzer. The anchovies were divided into two patterns: (1) with low Sr/Ca ratios (<3.0) and a single bluish Sr concentration map, indicating that it only experienced a freshwater habitat during its whole life, and (2) with Sr/Ca ratios fluctuating between low and high (>3.0) phases and Sr concentration maps showing various colors, including blue, green, yellow, and red, from the core to the edge of otoliths, whose larvae hatched in freshwater and spent their first winter in brackish or sea waters. The juveniles then stayed in estuarine water areas for further growth and feeding until sexual maturity, when the mature adults returned to the spawning grounds in the river. The co-existence of freshwater residents and anadromous C. nasus in the Dayang River has been studied for the first time, and its possible spawning ground was discovered. These findings provide essential information to effectively protect this species and guide its rational, sustainable utilization. [ABSTRACT FROM AUTHOR]

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Coilia nasus was once an economically important fish in the Yangtze River estuary, but overfishing and other anthropogenic factors have severely depleted its population. To conserve and restore C. nasus , there is an urgent need to determine its precise spatiotemporal distribution. However, as a typical anadromous species, C. nasus seasonally uses estuarine habitats, resulting in a very high proportion of nulls in some seasons and posing a great challenge to predicting abundance. This study compared three commonly used tree methods (gradient boosting machine (GBM), random forest (RF), and conditional random forest (CRF)) to predict the abundance of C. nasus in the Yangtze River estuary using trawl resource monitoring survey data from 2013 to 2018. Based on the survey data, 16 explanatory variables, including temperature, salinity, pH, and chemical oxygen demand, were used as predictors, and the coefficient of determination (R2), root mean square error (RMSE), and root mean square logarithmic error (RMSLE) were used to evaluate the performance of the three tree methods. Three metrics were used to assess the performance difference between interpolation and extrapolation for the three tree methods when modeling by season and combining seasons. The results showed that (1) compared with combined modeling, seasonal modeling could accurately determine the high- and low-abundance regions in interpolation, and the quarterly model greatly improved the extrapolation prediction accuracy. (2) Almost all metrics indicated that the interpolation RF model had the best performance, while CRF and GBM were significantly worse than other methods for some indicators, and the RF model had better robustness and could be applied to the abundance of all seasons. (3) The model performance in extrapolation was significantly lower than that of interpolation, RF was also the best method, and RF could still identify high-abundance areas when the amount of data was much smaller than that used for interpolation. The findings of our study can be generalized to species distribution modeling of other migratory species in the Yangtze River estuary or estuarine ecosystems in the Northwest Pacific Ocean. • Seasonally zero-inflated abundance data are derived from differences in species ecology. • Seasonal modeling is more suitable for anadromous species that use estuaries periodically. • RF demonstrated superior performance in both interpolation and extrapolation. • Accurate spatiotemporal distribution predictions of C. nasus improve the evaluation of estuarine protected areas. [ABSTRACT FROM AUTHOR]

【Objective】The study aimed to find out the lipid nutrition status and the rule of changes in fatty acid composition 0+ age young fish Coilia nasus high-density cultured in pond, and evaluate whether the C. nasus young fish cultured under high density mode was oppressed by the crowded environment.【Method】Using C. nasus young fish(0+ age)cultured by high density mode(7216 ind/667 m~2) in pond, the fatty acid composition and content of C. nasus 0+ age young fish in different growth stages(July to November) were detected and analyzed by biochemical analysis methods. 【Result】Fish body moisture of C. nasus 0+ age young fish decreased linearly with the growth, the value decreased from 82.27% in July to 76.17% in November, in the early stages of cultivation(Jul. 26 to Aug.7), the total lipid contents of the fish body dry sample decreased slightly with the growth, in the middle of cultivation(Aug.7 to Oct. 5), the fish body moisture accumulated rapidly, however, at the later stage of cultivation(Oct. 5 to Nov. 1), due to bait competition, the accumulation of the fish body moisture slowed down. The top three fatty acids of C. nasus 0+ age young fish body in different growth stages were C16:0, C18:1 n9 c and C16:1, the ranges of percent content were 21.21%-29.76%, 23.56%-28.90% and 8.71%-14.29%, respectively. Except for July, the percent contents of the C16:0 and C16:1 decreased significantly with the growth of C. nasus 0+age young fish. The percent content of the C18:0 increased first and then decreased with the growth of C. nasus 0+age young fish(P<0.05), the highest point(7.62%-7.76%) appeared in August and September, while the percent contents of the C22:6 n3(DHA), C20:5 n3(EPA), ∑PUPA and∑n3 PUPA decreased first and then increased(P<0.05), the lowest point all appeared in September, the highest point all appeared in November. The lowest point of the∑n3 PUPA/∑n6 PUPA ratio(3.58) appeared in September, the highest point(5.35) appeared in November, this accords with the migration law of C. nasus young fish from fresh water to sea water. At the later stage of high-density cultivation(Oct. 5 to Nov. 1), the crowding stress was more pronounced with the growth, in order to cope with the crowding stress, C. nasus 0+age young fish needed to consume more MUFA(especially C18:1 n9), which led to a rapid decrease in ∑MUFA and C18:1 n9 c contents of C. nasus young fish body from 44.42% and 28.90% in October to 35.29% and 23.56% in November, respectively. 【Conclusion】Therefore, C. nasus young fish cultured in high density pond may have been stressed by overcrowding. It is suggested to reduce the stocking density of C. nasus 0+age young fish in pond. [ABSTRACT FROM AUTHOR]

At present, the resources of anadromous fish in the world are drastically reduced and one of the solutions to promote its recovery may be to identify and protect its feeding grounds. To determine whether the feeding grounds of anadromous Coilia nasus in the Yangtze River are still in the sea area, the quantitative line analysis of Sr and Ca contents (Sr/Ca ratios) and the area distribution analysis of Sr content in the otoliths of C. nasus in three water areas (Poyang Lake, Yangtze River estuary and Shengsi Sea area) were carried out by electron probe microanalysis (EPMA) to analyze the habitat use and the migratory patterns of different estuarine C. nasus. These results showed that the Sr/Ca ratios of all otoliths fluctuated significantly. By comparison, it was found that C. nasus of Yangtze River might exist in the Shengsi Sea area, and the Shengsi Sea area might be one of the feeding grounds of migratory C. nasus. Therefore, it is urgent to carry out a comprehensive investigation on the distribution of related groups in the Shengsi Sea area and the influence of potential threat factors, such as fishing and harsh habitat, to effectively protect the resources and habitats of C. nasus in the Shengsi Sea area. [ABSTRACT FROM AUTHOR]

The estuarine tapertail anchovy, Coilia nasus, is a migratory fish with high economic value in China. We collected fish from the Changjiang River (the Yangtze River) estuary, the Qiantang River estuary, and the southern Yellow Sea, and studied their relationships using otolith elemental and stable isotopic microchemistry signatures to assess the population connectivity of C. nasus. Results show that, in addition to Ca, other elements were present in the otolith core. The δ18O, Na/Ca, Fe/Ca, and Cu/Ca values of the Qiantang population were significantly higher than those of the others, whereas its δ13C and Ba/Ca values were found to be significantly lower. Otolith multi-element composition and stable isotope ratios differed significantly between the Qiantang and Changjiang estuary groups (p < 0.05); however, no difference was observed between the latter and the Yellow Sea group. Cluster analysis, linear discriminant analysis, and a self-organizing map strongly suggest possible connectivity between the fish populations of the Changjiang estuary and Yellow Sea, while the population of the Qiantang River estuary appears to be independent. Notably, results suggest a much closer connectivity between the fish populations of the Changjiang River and the Yellow Sea. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian Ocean University is the property of Journal of Dalian Ocean University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Anisakidae nematode larvae is one of the most common parasites in wild anadromous Coilia nasus. This study aims to explore the mechanism of the C. nasus immune response to the parasitism of Anisakid nematode larvae. Results found that Anisakid nematode larvae parasitism caused liver injury as evidenced by histomorphology results as well as high levels of aminotransferase and aspertate aminotransferase. Furthermore, Anisakid nematode larvae parasitism induced an immune response in the host, which was characterized by the elevated populations of macrophages and neutrophils in the liver and head‐kidney in the Anisakidae‐infected group compared to the noninfected group. The expression of immunoglobulin IgM and IgD in the liver and head‐kidney was also increased in the Anisakidae‐infected group. The Anisakidae‐infected group showed higher activity of antioxidant enzymes catalase and superoxide dismutase, which indicates severe oxidative stress, and increased production of pro‐inflammatory cytokines, TNF‐α, IL‐6 as well as MCP‐1 in the liver compared with the noninfected group. As a result of inflammation, livers of hosts in the Anisakidae‐infected group showed fibrosis, and elevated expression of associated proteins including α‐smooth muscle actin, fibronectin, collagen type I and type III compared with the noninfected group. We demonstrated that Anisakid nematode larvae parasitism results in injury and fibrosis in the liver, and triggers immune cell infiltration and inflammation in the liver and head‐kidney of C. nasus. Altogether, the results provide a foundation for building an interaction between parasite and host, and will contribute to C. nasus population and fishery resource protection. [ABSTRACT FROM AUTHOR]

Abstract Background Coilia nasus (C. nasus) is an important anadromous fish species that resides in the Yangtze River of China, and has high ecological and economical value. However, wild resources have suffered from a serious reduction in population, attributed to the over-construction of water conservancy projects, overfishing, and environmental pollution. The Ministry of Agriculture and Rural Affairs of the People’s Republic of China has issued a notice banning the commercial fishing of wild C. nasus in the Yangtze River. Wild C. nasus populations urgently need to recover. A better understanding of C. nasus migration patterns is necessary to maximize the efficiency of conservation efforts. Juvenile C. nasus experience a simultaneous effect of increasing salinity and cold stress during seaward migration, and the brain plays a comprehensive regulatory role during this process. Therefore, to explore the early seaward migration regulation mechanism of juvenile C. nasus, we performed a comparative transcriptome analysis on the brain of juvenile C. nasus under salinity and cold stress simultaneously. Results Relevant neurotransmitters, receptors, and regulatory proteins from three categories of regulatory pathway play synergistic regulatory roles during the migration process: neuronal signaling, the sensory system, and environmental adaptation. The significant differential expression of growth-related hormones, thyroid receptors, haptoglobin, and prolactin receptors was similar to the results of relevant research on salmonids and steelhead trout. Conclusions This study revealed a regulatory network that the brain of juvenile C. nasus constructs during migration, thereby providing basic knowledge on further studies could build on. This study also revealed key regulatory genes similar to salmonids and steelhead trout, thus, this study will lay a theoretical foundation for further study on migration regulation mechanism of anadromous fish species.

Mass stock enhancement and release are excellent ways to recover Coilia nasus resources. However, it is challenging to evaluate stock enhancement effectively, and it is important to establish a method suitable for estimating C. nasus populations. We explored the effectiveness of marking otoliths in these fish with strontium by immersing C. nasus in hexahydrate strontium chloride solutions. We used laser ablation inductively coupled plasma mass spectrometry to measure the strontium content of otoliths and fish bodies. The larvae (40 d post hatch) were reared in five different concentrations of strontium (0, 12, 24, 48, and 60 mg/L) for 7 d, followed by treatment in non-additive water for 3 wk. The results showed that the cumulative mortality rate was not significantly different between treatment and control groups (P>0.05), except in the group treated with 24 mg/L strontium. The swimming and feeding behaviors did not change significantly, indicating that strontium did not negatively affect survival in this species. The strontium/calcium ratios of otoliths in the control group were stable (1.78–2.32 mmol/mol), whereas those of the experimental (marked) groups ranged widely (4.47–61.02 mmol/mol). The strontium/calcium ratios increased with increasing strontium concentration, but gradually returned to baseline values, resulting in a 100% success rate of marking with strontium. Following immersion in 12 mg/L strontium, strontium levels in the body returned to normal after 24 d. In summary, a treatment of 12 mg/L strontium for 4 d was identified as viable for marking. We confirmed the feasibility of strontium marking for the mass marking and release of C. nasus. This marking method does not affect the physiology of the fish and may provide a new approach for reasonable and scientific stock assessment of C. nasus post hatch.

Coilia nasus is one of the anchovy species that exclusively lives in freshwater environments, which has been increasing, and its distribution range has been gradually expanding in the Three Gorges Reservoir Region since it was first identified in 2015. Up to now, there was still no research on the resource status, ecological effects, adaptation strategies, and risk assessments concerning Coilia nasus in the Three Gorges Reservoir Region. In order to investigate age and growth characteristics of Coilia nasus in the Three Gorges Reservoir Region, 459 individuals were collected from Penxi River, Meixi River, Caotang River and Daning River from July to December 2019. The results showed that the age of Coilia nasus ranged from 1 to 6, and sexual maturity was reached at the age of 1. The proportion of individuals aged from 1 to 3 years old was 90.85%. The average body length and average weight of sampled individuals were (16.57±0.21) cm (mean±SE) and (19.14±0.78) g (mean±SE), respectively. The relationship between body weight and body length could be expressed as W=0.0038L2.957 (R²=0.987). The Von-Bertalanffy growth equations of female and male Coilia nasus were Lt=38.567[1--e--0.196(t+0.985)], Wt=183.029[1--e--0.196(t+0.985)]2.938 (♀) and Lt=34.711[1--e--0.26(t+0.603)], Wt=143.599[1--e--0.26(t+0.603)]2.995 (♂), respectively. The growth inflection points of body weight were 4.62 (♀) and 3.62 (♂). Moreover, these results indicated that Coilia nasus from the Three Gorges Reservoir Region belonged to a small individual population, which had simple age structure, upward trend in population number, high proportion of females, and abundant reproductive potential. Therefore, in order to protect the safety and stability of the aquatic ecosystem, further studies on the influences and risk assessments of Coilia nasus on the aquatic ecosystem of the Three Gorges Reservoir Region should be carried out. [ABSTRACT FROM AUTHOR]

Salinity changes will threaten the survival of aquatic animals. However, osmoregulatory mechanism of Coilia nasus has not been explored. Oxford Nanopore Technologies (ONT) sequencing was performed in C. nasus gills during hypotonic and hyperosmotic stress. 23.8 G clean reads and 27,659 full-length non-redundant sequences were generated via ONT sequencing. Alternative splicing, alternative polyadenylation, transcript factors, and long noncoding RNA were identified. During hypotonic stress, 58 up-regulated differentially expressed genes (DEGs) and 36 down-regulated DEGs were identified. During hypertonic stress, 429 up-regulated DEGs and 480 down-regulated DEGs were identified. These DEGs were associated with metabolism, cell cycle, and transport. The analysis of these DEGs indicated that carbohydrate and fatty acid metabolism were activated to provide energy for cell cycle and transport during hypotonic and hypertonic stress. Cell cycle was also promoted during hypotonic and hypertonic stress. To resist hypotonic stress, polyamines metabolism, ion absorption and water transport from extra-cellular to intra-cellular were promoted, while ion secretion was inhibited. During hypotonic stress, glutamine, alanine, proline, and inositol metabolism were activated. Ion absorption and water transport from intra-cellular to extra-cellular were inhibited. Moreover, different transcript isoforms generated from the same gene performed different expression patterns during hypotonic and hypertonic stress. These findings will be beneficial to understand osmoregulatory mechanism of Coilia nasus.

Himalayan ibex (Capra ibex sibirica) is a subspecies of Capra ibex, and is evenly distributed throughout the upper comparatively dry mountains of Gilgit-Baltistan, Pakistan. It is categorized as a Least Concern species globally as well as in Pakistan, however its presence in the Karakorum mountain plays a significant role in the economy of the region as dozens of trophy hunting of this specie takes place in the region every year and generates handsome money to the local inhabitants of the mountainous community. The characteristic habitat analysis and preference was important as the ibex move downwards during winter to cope the fodder shortage after heavy snowfall. This may expose the ibex to potential threats of predation by predators, poaching and competition for food with livestock during winter season. Therefore, the study was conducted to analyze the characteristic habitat feature and preference of Himalayan ibex during winter season in Hushe valley of Karakorum range. [ABSTRACT FROM AUTHOR]

Abstract Background Fish immunity is not only affected by the innate immune pathways but is also triggered by stress. Transport and loading stress can induce oxidative stress and further activate the immune inflammatory response, which cause tissue damage and sudden death. Multiple genes take part in this process and some of these genes play a vital role in regulation of the immune inflammatory response and sudden death. Currently, the key genes regulating the immune inflammatory response and the sudden death caused by stress in Coilia nasus are unknown. Results In this study, we studied the effects of the Glo1 gene on stress, antioxidant expression, and immune-mediated apoptosis in C. nasus. The full-length gene is 4356 bp, containing six exons and five introns. Southern blotting indicated that Glo1 is a single-copy gene in the C. nasus genome. We found two single-nucleotide polymorphisms (SNPs) in the Glo1 coding region, which affect the three-dimensional structure of Glo1 protein. An association analysis results revealed that the two SNPs are associated with stress tolerance. Moreover, Glo1 mRNA and protein expression of the heterozygous genotype was significantly higher than that of the homozygous genotype. Na+ and sorbitol also significantly enhanced Glo1 mRNA and protein expression, improved the fish’s antioxidant capacity, and reduced the immune inflammatory response, thus sharply reducing the mortality caused by stress. Conclusions Glo1 plays a potential role in the stress response, antioxidant capacity, and immune-mediated apoptosis in C. nasus.

Air exposure, as a stressor, can cause death of most fish species in aquaculture. However, little has been known about the responses to the stress caused by air exposure. In the present study, the influence of addition of salt on mitigating the stress caused by air exposure was investigated in Coilia nasus juveniles for the first time. Five experimental groups (control (C), air exposure group without addition of salt (FAF), addition of salt after air exposure (FAS), addition of salt before air exposure (SAF), and addition of salt both before and after air exposure (SAS)) were analyzed in an acute air exposure stress model. The results showed that air exposure triggered high mortality; antioxidase activities and total antioxidant capacity were decreased; malondialdehyde (MDA) and lipid peroxide (LPO) were increased; and Caspase 3 expression was activated. The expression of genes associated with mitochondrial apoptosis (Caspase 9, Apaf1, Bax, Bcl-2), endoplasmic reticulum apoptosis (CHOP, PERK, ATF4), and death receptor apoptosis (CFLAR, TRADD) was activated after air exposure. Compared to FAF, mortality was decreased by 5-fold in the SAS group. Additionally, antioxidant activities were increased, and MDA and LPO levels were decreased. SAS could also inhibit expressions of the genes related to apoptosis. These results indicated that high mortality, oxidant stress, and apoptosis were caused by air exposure, but the addition of salt both before and after air exposure could significantly reduce mortality, inhibit oxidant stress and apoptosis. Our data demonstrated that the addition of salt both before and after air exposure would be an effective method to mitigate air exposure stress in C. nasus juveniles.

Spatial-temporal distribution of marine fishes is strongly influenced by environmental factors. To obtain a more continuous distribution of these variables usually measured by stationary sampling designs, spatial interpolation methods (SIMs) is usually used. However, different SIMs may obtain varied estimation values with significant differences, thus affecting the prediction of fish spatial distribution. In this study, different SIMs were used to obtain continuous environmental variables (water depth, water temperature, salinity, dissolved oxygen (DO), pH, chlorophyll a and chemical oxygen demand (COD)) in the Changjiang River Estuary (CRE), including inverse distance weighted (IDW) interpolation, ordinary Kriging (OK) (semivariogram model: exponential (OKE), Gaussian (OKG) and spherical (OKS)) and radial basis function (RBF) (regularized spline function (RS) and tension spline function (TS)). The accuracy and effect of SIMs were cross-validated, and two-stage generalized additive model (GAM) was used to predict the distribution of Coilia nasus from 2012 to 2014 in CRE. DO and COD were removed before model prediction due to their autocorrelation coefficient based on variance inflation factors analysis. Results showed that the estimated values of environmental variables obtained by the different SIMs differed (i.e., mean values, range etc.). Cross-validation revealed that the most suitable SIMs of water depth and chlorophyll a was IDW, water temperature and salinity was RS, and pH was OKG. Further, different interpolation results affected the predicted spatial distribution of Coilia nasus in the CRE. The mean values of the predicted abundance were similar, but the differences between and among the maximum value were large. Studies showed that different SIMs can affect estimated values of the environmental variables in the CRE (especially salinity). These variations further suggest that the most applicable SIMs to each variable will also differ. Thus, it is necessary to take these potential impacts into consideration when studying the relationship between the spatial distribution of fishes and environmental changes in the CRE. [ABSTRACT FROM AUTHOR]

Commercial fishing of estuarine tapertail anchovy (Coilia nasus), an important anadromous fish species in the Yangtze River of China, has been prohibited due to the serious damage overfishing has caused to the wild population. Research regarding the energy metabolism is important for migratory fish to ensure the continuation of their existence. In this study, we performed, for the first time, a comparative transcriptome analysis of the liver of C. nasus subjected to long-term starvation stress. The results indicated that the damaging effects involved downregulation of the antioxidant capacity and immune response. The positive response to starvation involved upregulation of the anti-allergy and anticancer capacity, which supports the function of starvation in cancer inhibition, as has also been determined for human beings. This study revealed regulatory pathways, differentially expressed genes (DEGs), and mechanisms leading to damage of the liver in C. nasus affected by starvation. This research contributes information for the further study of the energy metabolism mechanism of C. nasus and provides a theoretical reference for starvation metabolism research of other fish species and even human beings.

Loss of valued diadromous fishes and their habitats is one of the most critical problems in aquatic habitat connection and resource management worldwide. In China, the Poyang, Dongting, Gaobao, Gucheng, Dongping, and Taihu lakes were known to be historical migratory spawning sites of the anadromous estuarine tapertail anchovy Coilia nasus. However, except for Poyang Lake, it is believed that these lakes are no longer used by anadromous fish owing to overfishing, water pollution, and loss of connectivity. To confirm this assumption, we used an electron probe microanalyzer to analyze elemental strontium (Sr) and calcium (Ca) microchemical patterns in the otoliths of C. nasus individuals sampled from these lakes, in accordance with our previous analysis of the otolithic patterns of the same species sampled from habitat areas characterized by different salinity gradients. The results of line transect analysis of Sr/Ca ratios and Sr X-ray intensity maps of the otoliths indicated that all individuals from Dongting, Gaobao, Gucheng, Taihu, and Dongping lakes were characterized by a freshwater-resident life history. In contrast, individuals from Poyang Lake exhibited both freshwater-resident and anadromous life histories. The findings of this pilot study suggest that anadromous C. nasus can be found in Poyang Lake but are unlikely to be found in Dongting, Gaobao, Gucheng, Dongping, or Taihu lakes, despite these lakes being historical distribution areas or even spawning sites. This anchovy can possibly be used as a good model species for understanding the aforementioned global problem. Given that C. nasus is a commercially important species, restoration of its natural habitats and maintenance of their connections are recommended for its management and conservation.

Coilia nasus is a rare anadromous fish species found in China’s Yangtze River and is a precious commercial commodity. The anti-stress mechanism of C. nasus has become the focus of research due to the animal’s strong stress responses. Salinity has been reported to weaken the C. nasus stress response. Nrf2 is an important anti-stress transcription factor that plays key regulatory roles in mediating salinity stress. In the present study, we cloned the full-length sequence of C. nasus Nrf2 for the first time and evaluated its differential expression in tissues. We also investigated the regulatory role of Nrf2 in osmoregulation, antioxidation and immunopotentiation in C. nasus under salinity stress. The results indicate that the C. nasus Nrf2 sequence is highly conserved. C. nasus Nrf2 is activated and plays a coordinated osmoregulatory role together with AQP1 under salinity stress and stimulates the activity of downstream antioxidant enzymes, including superoxide dismutase, glutathione peroxidase and so on. Nrf2 also triggers immunopotentiation via stimulation of lysozyme activity and an elevation of white blood cell counts. All of these C. nasus constructed adaptive Nrf2 regulatory networks act in response to salinity stress. This study lays a theoretical foundation for further research on the anti-stress mechanisms of C. nasus and will provide a reference for the further optimization of the C. nasus breeding mode.