Abstract:Based on the fishing vessel data obtained from VⅡRS (Visible Infrared Imaging Radiometer Suite) payloaded on SNPP (Suomi National Polar-orbiting Partnership satellite), this paper studies the temporal and spatial distribution of fishing vessels and its variation in East China Sea and Yellow Sea. The results show that:(1) Fishing vessel data can reflect the temporal and spatial distribution of fishing activities and fishery resources in East China Sea and Yellow Sea, for example, the distribution of fishing vessels in the north fishing region has been greatly reduced because of weather and the Spring Festival in February and the distribution range and number of fishing vessels which are affected by the supplement of fishery resources in current year and the concentration of coastal feeding groups reach the peaks in the south fishing region in August and in the north fishing region in October, respectively. Moreover, the temporal and spatial distribution of fishing vessels and the change of their barycenter also indicate the influence of Yellow Sea Warm Current, Taiwan Warm Current, Coastal Current, and Changjiang Diluted Water on the distribution of fishery resources. (2) The effects of fishery policy are well reflected in the fishing vessel data. During the closed fishing season, the sailings have obviously decreased, but fishing activities have not completely disappeared, and illegal fishing may still exist. (3) The annual sailings in the south fishing ground decrease and the barycenter in the north or south fishing grounds generally move westward, which might be related to the alternations of fishery resources. The quality of remote sensing data will be impacted by cloud cover and other factors, but SNPP/VⅡRS night light remote sensing data can still provide support for the monitoring of the light-fishing industry in the coastal regions of China.

Abstract:We evaluated the effects of high-density stress on gene expression in the intestine, muscle, and brain by measuring Nrf2-Keap1 signaling pathway signaling molecules following different exposure times (30, 60, 90 days) of Megalobrama amblycephala (average initial weight 2.33 g±0.13 g) were reared at two different initial densities (low density group[LD], 534 fish/m³ and high-density group[HD], 1073 fish/m³) for 90 days. At the end of the trial, the results showed that the HD group exhibited increased mRNA levels of Keap1 and Bach1 in the muscle, Bach1 mRNA in the brain, and SOD mRNA in the intestines on day 30 compared to in the LD group. However, the HD group showed significantly decreased mRNA levels of NOX2, Nrf2, and Keap1 in the intestines, NOX2 in the brain, and NOX2, Nrf2, SOD, and CAT in the muscle compared to the LD group. On day 60, the HD group showed increased mRNA levels of NOX, Nrf2, SOD, and CAT in the intestines, NOX and SOD in the muscle, and NOX2, Nrf2, Keap1, Bach1, SOD, and CAT in the brain, but significantly decreased mRNA levels of Bach1 compared to the LD group. On day 90, the HD group showed increased mRNA levels of Nrf2 in the intestines, NOX, Nrf2, Bach1, SOD, and CAT in the muscle, and Nrf2, Keap1, and SOD in the brain, but significantly decreased mRNA levels of Keap1, Bach1, and SOD in the intestines compared to the LD group. Thus, the HD group (1073 fish/m³) in IRAS exhibited increased expression of various stress-related genes in the muscle and brain on day 60. Crowding induced the expression of antioxidant Nrf2-Keap1 signaling molecules to protect the tissues from oxidative stress. However, on day 90, high-density (1073 fish/m³) stress may reduce the mRNA levels of SOD, causing oxidative stress in the intestine and affecting fish growth.

Abstract:is a commercially important fish species that is valued for its nutritive value and is used as a delicacy. It is widely distributed in the Yangtze River, coastal waters of China and Korea, and Ariake Sound in Japan. is highly responsive to stress, which often causes tissue damage, apoptosis, and ultimately death during loading and transport, hampering the development of this industry. Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors belonging to the nuclear receptor superfamily. Like other nuclear receptors, PPARs consist of four domains that have distinct functions. The A/B domain, located in conserved N-terminus, is responsible for ligand-independent transcription activity. The C domain, which is the DNA-binding domain (DBD), contains two zinc finger structures. The D domain, the hinge region, connects the DBD with the ligand-binding domain (LBD) and is involved in the conformational changes of PPARs. The E/F domain is an LBD. Transcriptional activation by PPARs requires the presence of PPAR response elements (PPREs) in the promoter of the target gene. PPARs bind PPREs as heterodimers with retinoid X receptor. Three isoforms of PPARs, , have been cloned in various mammals and fish. is involved in many processes such as ontogenesis, lipid metabolism regulation, peroxisome biogenesis, immune functions and inflammation, and oxidative stress. The aim of this study was to investigate the stress response and expression of PPARγ cDNA was obtained, which contained 1951 base pairs with an open reading frame of 1470 base pairs, encoding 489 amino acids. PPARγ has four functional domains, A/B region, DBD, hinge region, and LBD. Real-time quantitative PCR was used to detect the expression of in different tissues and under transport stress. The results showed that was expressed in all tissues, with the highest expression observed in the liver, relatively high expression detected in the brain, intestine, heart, kidney, head kidney, and muscle, and low expression in the gill and spleen. During transport stress, <0.05), peaked at 4 h, and was then significantly down-regulated. High expression of may increase lipid metabolism and relieve inflammation and apoptosis. plays an important role in lipid metabolism and stress responses. During embryonic development, shows the highest expression in the fertilized egg stage, after which its expression is rapidly decreased and then remains at a lower level. Lower expression of may down-regulate lipid metabolism and transportation. This study provides information regarding the theoretical basis of stress regulation.

Abstract:The objectives of this study were to investigate the expression pattern of Cyprinus carpio), to lay the foundation for studying and understanding the molecular regulation mechanism of fat deposition in common carp. In this study, a full-length cDNA sequence of gene in common carp was cloned by reverse transcription PCR and rapid-amplification of cDNA ends (RACE) technology, and the expression pattern of gene in different tissues of common carp and during its different developmental stages. cDNA of the gene of common carp was 3379 bp, with an open reading frame of 2079 bp, 5' untranslated region was 230 bp, 3' untranslated region was 1067 bp, encoding 693 amino acids. Multiple sequences alignment revealed that the amino acid sequences of Paralichthys olivaceus, and , respectively. It was determined that the sequence differences were mainly concentrated on the C-terminal polypeptide sequence between different species, and the structural analysis of proteins showed that the protein contains three functional domains with lipase activity, acetyl hydrolase activity, and hydrolase activity, respectively. Real-time quantitative PCR showed that the gene was expressed in all tested tissues, and the relative expression level was the highest in visceral fat, followed by abdominal muscles, and lowest in the blood. Its expression declined during the development of embryo; it was the highest in the 8-cell stage, followed by the late blastula stage. It was the lowest in the feeding period. The mRNA expression in different fat tissues negatively correlated with adipose tissue in the abdominal cavity; the highest and the lowest expression levels differed significantly (<0.01). The expression also positively correlated with dorsal muscle but it was not significant ( gene highlights its function and molecular regulation mechanism of fat development in common carp.

Abstract:The swimming crab , an important marine economic animal widely distributed in China, belongs to Crustacea, Decapoda, Decapoda, is an aquatic crustacean with wide tolerance to salinity (13.7-47.7). Salinity is one of the most important environmental factors affecting the growth and development of . Ingestion, molting, growth, metabolism, immunity, and other processes in are greatly affected by salinity. Therefore, it is important to study the mechanism of salinity adaptation to breed improved salt-tolerant varieties of . In this study, random amplification of cDNA ends technology was used to clone the crustacean cardioactive peptide (CCAP) gene. The full-length CCAP gene was 606 base pairs (bp) long, including an open reading frame of 426 bp, 5' untranslated region of 72 bp, and 3' untranslated region of 108 bp, with a poly A structure. Amino acid sequence analysis showed that the CCAP gene encodes 141 amino acids with a predicted molecular weight of 15.6 kD and isoelectric point of 9.55. Homology analysis showed that the homology between CCAP of Callinectes sapidus was higher at 85% and 82%, respectively. Phylogenetic analysis showed that were clustered first, followed by . Tissue expression analysis revealed that the relative expression of the CCAP gene was highest in the in thoracic ganglia, followed by in the brain and eye stalk. Analysis of the expression pattern of the CCAP gene during low-salinity stress showed that low salinity significantly altered the expression pattern of CCAP in the thoracic ganglia; CCAP gene expression in the experimental group was significantly higher than that in the control group at 24, 48, and 72 h ( < 0.05) with values 1.73-, 2.16-, and 2.19-fold higher than that in the control group, respectively. P. trituberculatus under low-salinity conditions and the activities of Na⁺/K⁺-ATPase and V-ATPase were significantly increased. The results demonstrate that CCAP plays a protective role in under low-salinity conditions by regulating osmotic pressure and may be associated with increased Na⁺/K⁺-ATPase and V-ATPase activities to modulate the osmotic pressure balance in .

Abstract:Cold stress causes physiological dysfunction, tissue damage, and finally death in fishes, and increasing studies have suggested that epigenetic mechanisms play essential roles in the cold stress response in fishes. Our previous study showed that cold stress induced the production of reactive oxygen species (ROS) in zebrafish -derived ZF4 cells in a temperature and time-dependent manner and that the genomic DNA methylation level was increased under short-term (18℃ for 5 days) cold exposure and decreased under long-term cold exposure (18℃ for 30 days). However, the relationship among DNA methylation, ROS production, and cold acclimation in fishes remains poorly understood. In the present study, zebrafish ZF4 cells were exposed to short-term (18℃ or 10℃, for 3 or 5 days) and long-term (18℃ for 30 days) cold stress, and then the global DNA methylation level was detected by digestion with the methylation-sensitive enzyme I. The results showed that short-term cold stress caused remarkable growth arrest and cell death in ZF4 cells, and cold acclimation was observed under long-term cold stress. Additionally, global DNA methylation increased remarkably under short-term cold stress ( < 0.05). Co-treatment of ZF4 cells with -acetylcysteine inhibited global DNA methylation induced by short-term cold stress ( < 0.05), suggesting that ROS affects short-term cold stress-induced global DNA methylation levels. Co-treatment of ZF4 cells with the ataxia telangiectasia mutated (ATM) inhibitor KU-55933 also inhibited the induction of global DNA methylation under short-term cold exposure, indicating the involvement of DNA damage repair pathways in this process. Our data indicate that short-term cold stress resulted in ROS production and ataxia telangiectasia mutated activation, which then up-regulated global DNA methylation in ZF4 cells. The present study improves our understanding of the role of DNA methylation under cold stress in fishes.

Abstract:Environmental stresses can regulate gene expression patterns by modulating histone activity. However, the effect of low-temperature stress on whole-genome histone modification in fish has not been reported. To explore the effect of low-temperature stress on histone modification in zebrafish () cells, the experimental conditions for chromatin immunoprecipitation (ChIP) were established and optimized. The optimum NP-40 concentration for lysing cells was 0.2%. The optimal time of sonication with a Covaris S220 to break the chromatin was 20 min. Primers targeting the -actin promoter region were used to perform routine PCR to verify the preliminary ChIP experiment results. Optimized experimental conditions resulted in a very low background, with nearly no IgG band in the agarose gel. Moreover, the lack of H3K27me3 in the -actin promoter region, accompanied by enriched H3K4me3 and H3K27ac, was observed as predicted. Zebrafish embryonic ZF4 fibroblasts cultured under normal condition (28℃) and cold-acclimated ZF4 cells under long-term cold exposure (18℃ for 30 days) were evaluated with the optimized ChIP protocol. The effect of cold acclimation on the expression of tumor necrosis factor tnfb promoter was detected by qPCR and ChIP-qPCR, respectively. The qPCR and ChIP-qPCR results showed that was upregulated after cold acclimation and that H3K4me3 and H3K27ac were enriched in the promoter region of , while enrichment of H3K27me3 showed no significant change. This suggests that cold pressure regulates expression by affecting H3K4me3 and H3K27ac levels in the promoter region of . In conclusion, the established and optimized ChIP method can be used to study histone modification in ZF4 cells and provides a foundation for further analysis of the effect of low-temperature stress on whole-genome histone modification in zebrafish cells.

Abstract:In order to understand the physiological role of the growth axis (GH/IGF axis) in embryonic development and early growth of , a quantitative PCR method was used to study the differential expression patterns of five key growth factors (GH, GHR1, GHR2, IGF-I, and IGF-Ⅱ) along the growth axis during early life stages. The results showed that these five growth factors could all be genetically inherited from parents, and they all exhibited significantly higher paternal expression levels, except for GH. GH mRNA was detected in all embryonic development stages, but the highest expression level was observed at the 2-cell stage and hatching stage. GHR1 and GHR2 mRNA levels showed similar expression patterns during embryonic development stages, and there were significantly higher expression levels of GHR1 mRNA than that of GHR2 during all embryonic development stages, except in the morula and gastrula stages. IGF-I and IGF-Ⅱ mRNA were both detected during all embryonic development stages, and the highest expression level of IGF-I mRNA was observed at the hatching stage. IGF-Ⅱ mRNA levels peaked at the embryo encircling 2/3 of yolk sac and hatching stages. During the larval and juvenile development stages, GH mRNA expression level increased significantly from 3 d post hatching and peaked at 6 d. The GHR1 mRNA expression level increased significantly from 6 d and reached the maximum level at 30 d. GHR2 mRNA level significantly increased at 3 d, then gradually decreased to a lower expression level at 15 d, but then showed a significantly higher level from 20 d to 30 d, and also at 60 d. The expression level of IGF-I mRNA was the highest in 3 d larvae, and for IGF-Ⅱ mRNA, there was significantly increased expression from 6 d, which was maintained at a high level until 45 d. The IGF-Ⅱ mRNA level was significantly higher than that of IGF-I during the larval and juvenile stages. Correlation analysis showed that these growth factors play positive synergistic or negative antagonistic regulatory roles in the embryonic development and early growth stages. The results showed that the GH/IGF axis plays an important physiological role in regulating the embryonic development and early growth of , and provide new clues and materials for better understanding the role of the GH/IGF axis in fish growth.

Abstract:In order to explore the difference in embryonic muscle development between an intermuscular bone (Imb) deficiency mutant and wildtype zebrafish, we used a qRT-PCR method to analyze the expression of 5 muscle-specific genes, including , in the development stages blastula (3 hpf, hours post fertilization), gastrula (6 hpf), segmentation (12 hpf), pharyngula (24 hpf), and hatching period (72 hpf), and discussed the impact of Imb's deficiency on muscle development during embryonic development. Furthermore, the differences in fertilization rate, hatching, and abnormal rate of larvae were assessed. The results showed that the expression of genes were elevated in the gastrula stage, and downregulated in the segmentation and pharyngula stages; the expression levels of in the blastula and gastrula stages were extremely low, and were upregulated significantly in the segmentation and pharyngula stages before being downregulated in the hatching period. The results also showed that there were no significant differences in 5 muscle-specific genes' expression between the wildtype zebrafish and its Imb deficiency mutant. Additionally, no significant difference in fertilization rate, hatching, and abnormal rate occurred between the two Imb phenotypes. In summary, the deletion of Imb do not impact muscle development or the survival of embryos during embryonic development of zebrafish.

Abstract:is a freshwater fish with high economic value and is endemic to East Asia. Some studies have shown that mandarin fish exhibit different movement modes, feeding behavior, and nutritional demands during the larvae and juvenile stages. In this study, the morphological ossification characteristics of the skulls, vertebrae, and appendages of larvae[1-35 days post hatching (dph)] were described using a cartilage bone clearing and staining technique to provide information on the larval and juvenile organ structure development and functional adaption. The results showed that the preopercle of the skull began ossification at 14 dph. The upper and mandibular structure, which showed a relative length change, was ossified at 15 dph. At 17 dph, the jaw teeth, articular, and hyomandibular began to ossify, while the interopercle, angular, opercle, branchiostegal ray, and frontal structures were ossified at 19 dph. At 20 dph, the quadrate, subopercle, and supplementary maxilla were ossified; most of the skull was completely ossified by 35 dph. Ossification of the vertebrae began at 15 dph from the anterior to the posterior and was completely ossified by 29 dph. The dorsal rib and ventral rib began to ossify from the base to the outside at 20 dph. The haemal arch, haemal spine, neural arch, and neural spine from the front to back and the base to the distal end were ossified. Ossification of the haemal spine and neural spine occurred later than that of the corresponding vertebrae. The ossification order of the appendages was from the pectoral fin to the dorsal fin, anal fin, pelvic fin, and caudal fin. The cleithrum of the pectoral fin was ossified at 16 dph, while the coracoid and scapula were ossified at 25 dph. The dorsal fin and anal fin were ossified at 18 and 20 dph, respectively. The pelvic fins were ossified from the middle to both ends at 23 dph and the ossification pattern was opposite to that of the pectoral fin. The urostyle and hypural of the caudal fin began to ossify at 25 dph. The appendicular skeleton was fully ossified at 35 dph. The results showed that the early skull ossification of larvae and juveniles is closely related to their feeding and defense behavior, while ossification of the vertebrae and appendages are closely related to their movement and avoidance of the enemy.

Abstract:In the present study, female Japanese eels () with an average body weight of (592.5±52.5) g were fed with a commercial diet supplemented with two Chinese herbs Lam at a water temperature of (21±1)℃ for 90 d. Then, the structure of ovarian development; changes in serum 11-KT and E2 levels; mRNA expression levels of liver vitellogenin (), and ovarian aromatase (tissue section staining, immunoenzymatic assays, semi-quantitative PCR, and gas chromatography, respectively. The results showed that the gonadosomatic indices (GSIs) and the hepatosomatic indices (HISs) in the Japanese eels fed with diets containing Lam. were significantly higher than those in the control group (<0.05); the treated group also showed ovaries filled with advanced perinucleolar follicles and increased numbers of oil droplets, and significantly higher serum 11-KT and E2 levels ( mRNA was elevated in the liver of the treated group; however, mRNA levels were extremely low in the ovaries of both the control group and the treated group, and the expression of mRNA was not detected in the livers of the two groups. Total fatty acid levels, including saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and highly unsaturated fatty acids (HUFA), in muscle were significantly higher in the Japanese eels fed with diets containing Lam than in the control group fish (<0.05); particularly, the levels of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were higher in the treated group. These findings indicated that the two Chinese herbs, Lam., induced early ovary development by increasing oil droplets of previtellogenic oocytes and promoted vitellogenin accumulation in the liver of parental female Japanese eels. Moreover, Lam. accelerated absorption of fatty acids, particularly HUFA, from diets, and subsequently their accumulation in the muscle, to prepare for vitellogenesis and further development of oocytes.

Abstract:Soybean antigen proteins (soybean glycinin and -conglycinin) are the main anti-nutritional factors in soybean meal. Recent studies showed that a high level of glycinin and -conglycinin in soybean meal can disrupt the intestinal tissue structure, resulting in digestion and absorption disorders, stunted growth, and allergic reactions with a variety of non-specific and specific immune responses in aquatic animals. In recent years, fermented soybean meal has been increasingly used in aquatic animal feed. Compared to soybean meal, anti-nutritional factors, particularly soybean antigen proteins in fermented soybean meal, are drastically reduced. This study was conducted to compare the effects of soybean meal (SBM) and fermented soybean meal (FSBM) on the growth, serum biochemical indices, gene expression, and oxidative status in and evaluate whether the effects were caused by soybean antigen protein. Practical diets (T15, TF) and purified diets (AP0, AP5) were formulated for the feeding trial. Compared to T15 (21.5% FM, 15.45% SBM, 15% FSBM), the soybean meal was completely replaced with fermented soybean meal in TF, while AP0 and AP5 were semi-purified diets containing approximately the same content of soybean antigenic protein as TF (nearly 0% soybean antigen proteins) and T15 (approximately 5% soybean antigen proteins), respectively, with soybean antigen proteins included as the sole anti-nutritional factor. Giant river prawns with an initial average body weight of (0.17±0.02) g were cultured in net cages in a fixed indoor cement tank and fed the above four diets for 64 days. The results showed that as soybean antigen proteins were reduced, trypsin activity was decreased for both series of diets. The practical diet groups showed a significantly decreased growth rate, while the purified diet groups did not, demonstrating that 5% soybean antigen protein did not affect the growth of . In contrast, a significant reduction in soybean antigen protein in the practical diet was not conducive for growth. A certain amount of soybean antigen protein increased trypsin activity to promote digestion of the feed, which in turn had a positive impact on growth. In the practical diet groups, there was no significant difference in the serum malondialdehyde content and expression of nuclear factor-κB mRNA in the gills. Superoxide dismutase activity in the serum was significantly higher in TF, while expression of the Toll-like receptor in the gills and HSP70 mRNA in the hepatopancreas was significantly decreased. In the purified diet groups, there was no significant difference in the serum superoxide dismutase activity, malondialdehyde content, and HSP70 mRNA expression in the hepatopancreas, while expression of the Toll-like receptor and nuclear factor-κB mRNA in the gills was significantly higher in the AP0 group. The results showed that fermented soybean meal scavenged free radicals by synthesizing antioxidant enzymes and reducing oxidative stress in the hepatopancreas, which may not be directly related to the reduction of soybean antigen protein content. Soybean antigen proteins and a variety of anti-nutritional factors together likely stimulate the body's immune system and promote immunity by decreasing Toll-like receptor and nuclear factor-κB mRNA expression levels. Total protein in the serum was significantly decreased in the practical diet groups, and aspartate aminotransferase activity was significantly increased. However, total protein and albumin levels were significantly decreased in the purified diet groups. The results demonstrated that this concentration of antigen proteins improved the health of the hepatopancreas and the body's amino acid and protein synthesis metabolism. In addition to a more sensitive immune response, the T15 group showed better growth performance in the practical diet groups. In conclusion, was tolerant to 5% of soybean antigen protein, which was beneficial for its growth and health. A synergistic effect between soybean antigen protein and other anti-nutritional factors likely occurred. Low levels of soybean antigen proteins in the feed led to reduced protein synthesis and metabolism in the hepatopancreas and decreased growth. These results suggest that fermented soybean meal and soybean meal can be mixed together in an appropriate proportion under normal feeding conditions.

Abstract:Antarctic krill () is a key species in the Southern Ocean ecosystem, and knowledge regarding its biomass is essential to understand the ecology and distribution of krill. The acoustic data was collected across extensive gradients in the South Orkney Islands on the commercial fishing vessel . Krill targets were identified in acoustic data using a multi-frequency identification window and converted to krill density using the Stochastic Distorted-Wave Born Approximation target strength model. The average krill length was (33.01±4.06) mm, with a maximum length of 49.21 mm and a minimum length of 25.50 mm. There was no significant difference between male and female krill length. The whole ecogram could be divided into 1338 integration units, of which 586 units were in daytime and 752 units were at night. The maximum krill density was 554.07 g/m² and the minimum density was 0 g/m². The Antarctic krill were mainly aggregated, with 87.90% integration units having no biomass. There was no significant difference in diurnal NASC and values of the 9 transects, which suggested that the diurnal vertical movement had no effect on the estimation of krill biomass. The average krill density was 71.01 g/m² and the total biomass was 1.77×10⁶ t in this area. The krill were mainly aggregated in a 60-180 m water depth range in the daytime, and gradually moved upwards or downwards at night. Light intensity is one of the factors that influence the krill diurnal vertical movement. However, a proportion of the Antarctic krill sunk to deeper waters at night, which may be to prey on the deep-water food. The results of this study provide abundant information on krill distribution in this area and basic data for current feedback on the krill resource management of CCAMLR. In future, the research on the correlation between krill biomass and external factors (environmental factors, predators) can help us understand the population structures more accurately and predict the distribution of krill resources.

Abstract:Population differentiation and structure are important topics of evolutionary biology, and morphology and genetics are the main methods of researching these topics. migrates annually from the overwintering field to the spawning ground, and for a long time, it has been thought that the breeding period of its inshore populations was as long as two months. In addition, during the grouping period, the specification of arriving in different stages showed a decreasing trend with arrival time. Thus, the objectives of this study were to characterize the population structure and clustering phenomenon in over time, and discover why the parental specification diminished during spawning of the mature animals in Qingdao. The morphological characteristics and genetic differentiation during three different migratory periods (early, middle, and late) of inhabiting the coastal waters of Xuejia Island were analyzed using morphology and DNA markers. The results showed that the cumulative contribution rate of the first three principal components was 60.067% in the principal component analysis (PCA), which was lower than 85%. The discrimination accuracy ranged from 66.7% to 82.1% in the discriminant analysis (DA). The scatter plots of PCA and DA showed a similar result, which is the species was not clearly dispersed among these three migratory periods. Analysis based on microsatellite markers indicated that genetic distances () ranged from 0.12 to 0.16 and the genetic differentiation index ( from the three different migratory periods. The optimal number of theoretical groups was 1 according to the genetic structural analysis. These findings suggested that there was no obvious population differentiation among early, middle, and late migratory periods of in Qingdao, owing to the low values of morphological differences, genetic distances, and genetic differentiation, although the population showed a large difference in mantle length and body weight in specifications. The differences in the swimming ability of small and large individuals may be the main reason behind the long period of 's clustering and the decrease of its specification over time. It is undeniable that the differences in morphology and genetics among populations of marine cephalopods populations of fish are unpredictable yet significant. Macroscopic identification methods, such as morphological studies, are vulnerable to the influence of living environment, and at the same time, marine fish with good dispersal ability usually exhibit very low genetic differentiation within a wide geographic range. Therefore, the strong athletic ability of may also lead to a similar genetic structure of its populations.

Abstract:This study aimed to investigate the community characteristics of major nekton based on the catch survey data from Yiwan Bay of Taizhou (27.9°N-28.6°N and 121.1°E-121.9°E) in October 2016 and April 2017, through analysis of functional groups along with the niche of and probability of interspecific encounter (PIE) between species. The results showed that there were 13 and 11 species of major nekton in spring and autumn, respectively, most of which were the short-distance migratory species or settler species, with low seasonal turnover rates. In addition, the benthivores/piscivores feeding functional group (FG4) was dominant among the major nekton in spring and autumn, with low trophic levels. Additionally, the total PIE between the major nekton in spring and autumn were 0.66 and 0.76, respectively, and that in autumn was higher than that in spring. There were significant differences in the niche breadth, both in spring and autumn. Specifically, there were four broad niche species, seven meso niche species, and two narrow niche species in spring; conversely, there were five broad niche species, four meso niche species, and two narrow niche species in autumn. In addition, the niche breadth (Portunus trituberculatus) was associated with the highest PIE and maximum niche breadth in both seasons, along with the strongest abilities of competition and resource utilization. Moreover, the interspecies niche overlap values in spring and autumn were 0.14-0.88 and 0.21-0.91, respectively, indicating uneven degrees of interspecies overlap in the two seasons. In summary, small seasonal variation was observed in the composition of major nekton in the studied sea area, and a single functional group had taken the dominant place, most of which belonged to the low and middle trophic species, with a large niche breadth and PIE. Thus, this might result in the fluctuations in community numbers, as well as a decline in the structure and functional stability of the communities.

Abstract:is one of the important commercial fish in the Yangtze River, and the section between Yichang and Jingzhou is an important spawning ground and habitat of . In order to study its population status in this area, 470 samples were collected from the annual survey of H. molitrix has a relatively complex age structure, which contains 7 age classes ranging from 1 to 7. The preponderant age class was comprised of 3-5 year-old individuals, making up 72.7% of the total. Body-length range of the population was 18.2-93.8 cm, mainly between 40.0-70.0 cm (77.2%). The relation between body length and body weight was estimated as =0.9297, =470), for non-uniform motion pattern; Von Bertalanffy equations and the corresponding growth curves were calculated as W_{; growth parameters were estimated as =4.2753 kg growth inflection was 5.43 years, and inflection point length and inflection point weight were =4.2753 kg, respectively. The results showed that the population structure of was complex, but the growth performance had declined. Conservation of the population and habitat of this species should be prioritized.}

Abstract:Based on the fishery production sampling data obtained from the coast of Jiangsu Province in 2014, the production and spatial distribution characteristics of different horsepower gillnet fishing vessels were analyzed. The results show that different horsepower fishing boats differ in terms of production time; the main production time of the majority of vessels is after the closure of the summer fishing period. The rate of fishing of small horsepower vessels is high not only after the closure of the fishing period, but also in the months towards the end of the year. The overall fishing production has obvious seasonal characteristics:at the beginning of the year, from January to March, the number of fishing vessels was the least; after the Ching Ming Festival and before the closure of the fishing period, from April to May, there was a small peak in the number of boats setting out for fishing; after the closure of the fishing period, the number of fishing boats was the greatest. The spatial distribution characteristics varied among different horsepower fishing vessels. The small horsepower vessels are fewer in the outer waters, and production is more likely in the waters further west and north, in terms of increasing horsepower. The distribution of fishing vessels in different months is different:the production waters occurred towards the northern area and close to inshore waters from January to March; the production waters tended to be offshore and in northern waters in April and May, same in latitude range of the pre-period; the production of the boats tended to be inshore and in northern waters in August and September; the production waters tended to occur in the southern and offshore waters from October to December. Additionally, there was a positive correlation between the size of the vessel and the catches per unit of effort (CPUE), and the relationship is estimated as CPUE=5.3428e^{(0.0062xPower)}; this can provide an important reference for the evaluation of the fishing intensity of Jiangsu gillnet fishing vessels. Finally, based on the research results, the corresponding management suggestions are proposed according to spatial and temporal characterization of gillnet production.

Abstract:Tilapia is an important aquaculture species world-wide, and China is the largest producer of farmed tilapia. In recent years, alongside the rapid development of tilapia aquaculture in the world, diseases in this fish have become a great concern, including viral diseases caused by beta Nodavirus, herpes simplex virus, and tilapia lake virus, which lead to huge economic losses. So far, research studies on tilapia viral pathogens are dependent on the E-11 cell line derived from grouper and tilapia primary brain cells; thus, a cell line derived from the host of tilapia needs to be urgently established for applications. Therefore, in the present study, by using tissue explant techniques, a novel cell line (designated TiK) derived from the kidney of tilapia (), was established and fully characterized. The TiK cell line are fibroblast-like cells, which have been stably subcultured for more than 50 passages. The optimal growth conditions for the TiK cell line are DMEM medium, 28℃, and 15% FBS. Under the optimal conditions, the doubling time of TiK cells is about 45.8 h. After 6 months of cryopreservation in liquid nitrogen, TiK cells exhibit a viability of about (89.84±3.48)%, as measured by trypan blue staining. Chromosome analysis of TiK cells showed that the number of chromosomes ranged from 20 to 66, and the modal number is 48 at the 32^th passage. The TiK cell line was infected with tilapia virus isolated by our laboratory, and showed typical cytopathic effects, demonstrating that the TiK cell line was susceptible to infection by tilapia viruses. The establishment of the TiK cell line will contribute to research on the control of tilapia viral diseases.

Abstract:is a common conditional pathogen in aquaculture, which is widely distributed in the world. Rapid detection of the pathogen is necessary for the prevention and control of the diseases caused by the bacterium. Aptamers exhibit great advantages in the detection of microorganisms owing to their high affinities and specificities. In the present study, was detected based on its aptamer and its selection products following various steps, such as binding, washing, separation, amplification, and electrophoresis. The results showed that the aptamer and the selection products could superiorly detect and its inactivated form. The lowest detection limits were 10 cfu/mL of cfu/mL of inactivated by the selection products. The system of detection had better affinity and specificity for from other aquatic pathogens such as , and therefore shows good application potential in the detection of pathogens in aquaculture.

Abstract:is an important bacterial fish pathogen that can cause vibriosis extensively in economically-important fish including Anguilla anguilla, and in China. In our previous studies, we have carried out the epidemiological work of O1, O2, and O3 serotype strains are prevalent in marine fish farms. Vaccination is proven to be a safe and efficient route to prevent and control vibriosis. However, no commercial vaccine is available in China. In this study, the antibody persistence and immune protection duration of a inactivated bivalent vaccine based on O1 and O2 serotype strains were evaluated in turbot ( formalin-inactivated bivalent vaccine was prepared using O1 serotype VAM003 and O2 serotype VAM007 strains. Groups of turbot were injected intraperitoneally with three dosages of vaccine preparation, i.e, 10⁷ cells/ind, 10⁸ cells/ind, and 10⁹ cells/ind. At 3 d, 7 d, 14 d, 30 d, 60 d, 90 d, 120 d, and 150 d after injection, each immunized fish group was evaluated for their serum-antibody titers against VAM003 and VAM007 using a serum-agglutination test, and the relative percent survival (RPS) was evaluated by challenge with a 10 LD₅₀ (50% lethal dose) of VAM003 or VAM007. The results showed that specific antibodies against VAM003 and VAM007 were noticeably induced in the immunized fish as early as 7 d post-immunization, and an RPS of 27%-60% was detected in these fish. Specifically, the induced VAM003 antibody persisted in three dosage fish groups for at least 90 d for 10⁷ cells/ind, 150 d for 10⁸ cells/ind, and 150 d for 10⁹ cells/ind, respectively, while anti-VAM007 persisted in each of three dosage fish groups for more than 150 d. The immune protection duration for each of the three dosage groups all exceeded 150 d. With an RPS of more than 75% as an effective immune protection, the effective immune protection duration against O2 serotype cells/ind fish group, 14-120 d for 10⁸ cells/ind group, and 14-150 d for 10⁹ cells/ind group, respectively, while the effective immune protection duration against O2 serotype were 14 d-60 d for 10⁷ cells/ind group, 14-120 d for 10⁸ cells/ind group, and 14-120 d for 10⁹ cells/ind group, respectively. We also analyzed the relationship between serum antibody titer and RPS of bivalent vaccine. When the serum antibody titer was over 1:40 for the O1 serotype and 1:160 for the O2 serotype, the corresponsive RPS to O1 or O2 serotype were all over 75%. These results suggest that the inactivated bivalent vaccine could provide effective immune protection for turbot, and the data of antibody persistence and immune protection duration obtained in this study will provide support for clinical trials of this vaccine.