Abstract:To explore the role of inducible nitric oxide synthase (Nos2) in fish growth regulation, we generated nos2a deficient (nos2a^-/-) zebrafish using CRISPR/Cas9 technology for the first time. By monitoring their growth process,we found the growth trend of nos2a^-/-zebrafish was slower than nos2a^+/+zebrafish, and the adult body size of nos2a^-/-zebrafish was smaller than that of nos2a^+/+zebrafish (P<0.01):the mean length and weight of nos2a^+/+zebrafish were 29.53 mm and 512.8 mg, respectively,that of nos2a^-/-zebrafish was 26.34 mm and 394.4 mg. Additionally, there was no notable difference in the density of muscle fibers (P=0.718) and sectional area of vertebrae (P=0.548)between nos2a^+/+ and nos2a^-/-zebrafish. Moreover,compared with nos2a^+/+zebrafish at 8 dph (days post hatching), the mRNA level of growth hormone (gh1, P<0.01) and insulin-like growth factor-1 (igf1, P<0.001) of nos2a^-/-zebrafish at 8 dph were lower significantly; and it was the same as that at 68 dph:gh1, P<0.000 1; igf1, P<0.000 1. These findings indicate that the defect of nos2a negatively affected zebrafish growth, and the reduced gene mRNA level of growth hormone was the potential factor.

Abstract:As one of the important members of interleukin, interleukin-11(IL-11) plays a pivotal role in many biological processes, including wound healing, cancer cells migrating, immunity regulating, and so on. To study the transcription regulatory mechanism of il-11b, the 3 000 bp promoter of an interleukin-11b (il-11b) in zebrafish (Danio rerio) was found through bioinformatics analysis, and we obtained 2 908 bp, 2 000 bp, 1 000 bp and 500 bp different fragments after deletion processing. These promoter sequences were amplified through PCR method and reconstructed into pGL3-enhancer empty plasmid to form reporter gene vectors. We used dual-luciferase reporter assay system to detect the activity of these promoters in HEK293T cell line. Bioinformatics results indicated there are about 3 promoter regions and 7 CpG islands in the sequence of il-11b promoter, and 60 binding sites including Adf-1, Krox-24, Sp1, CACCC-box, Egr-1, ICSBP, c-Jun, COUP, GR, RAP1, NF-kappaB, REV-Erbalpha, ER, RAR-alpha1, RXR-beta, SRF, Oct-1, Oct-2, Pit-1a, GCN4, HNF-1, TBP, C/EBPalpha, HNF-1C, Oct-2.1, USF, etc. The fragment sizes of all recombinant plasmids were consistent by double enzyme digestion, and the sequences were correct. Compared to control group, the results of luciferase showed the activity of pGL3-il-11b, pGL3-il-11b-Δ1, pGL3-il-11b-Δ2, pGL3-il-11b-Δ3, pGL3-il-11b-Δ4, pGL3-il-11b-Δ5 were about 1.94, 14.92, 5.33, 9.11, 0.75, 1.32 folds, respectively. These results may provide a tool to investigate the immune signals in which cytokines are involved.

Abstract:RNA interference assays of three types of MrTLRs in Macrobrachium rosenbergii were conducted using specific short-interfering RNAs (siRNAs) with doses of 0.4, 0.8, and 1.2 μg/g, and the relative expression levels of three Toll-like receptor genes in gills were analyzed with relative quantitative real-time PCR. The result showed that 1.2 μg/g was the optimal dose of siRNA for RNA interference assay of MrTLRs in the present study. In the RNA interference assay of MrTLR1, the expression of Myeloid differentiation factor 88 (MyD88), Crustin and anti-lipopolysaccharide factor (ALF) in MrTLR1-silenced prawns obviously declined at 24 h and 48 h post injection, whereas the MrTLR2 expression was significantly upregulated. Furthermore, the expression levels of MyD88 and Crustin significantly decreased in MrTLR2-silenced prawns, and the silencing of MrTLR3 induced remarkable upregulation of the expression of immune deficiency (IMD) and ALF in M. rosenbergii. Additionally, there was no significant difference of prophenoloxidase (proPO) expression between MrTLRs-silenced groups and scrambled-siRNA group. These results suggested that MrTLR1 and MrTLR2 might be involved in the regulation of antibacterial peptides expression, and MrTLR3 exhibited regulatory effects on the Toll signaling pathway as well as IMD signaling pathway in M. rosenbergii.

Abstract:This experiment studied the changes in serum biochemical characteristics, intestinal microstructure, intestinal microbial flora diversity, and species abundance of carp under the conditions of rice fields.In Liannan Yao Autonomous County from June to August 2019, paddy fields and ponds were selected, and carp juveniles of the same size were stocked for 3 months without feeding. After the test, sampling and testing were performed uniformly. The results showed that paddy field environment significantly incresased the body length and weight of the carp, significantly reduced the carp serum alanine aminotransferase(ALT) activity and intestinal microvilli height (P<0.05); the content of serum complements C3 and C4 showed an upward trend, but there was no significant difference (P>0.05). In terms of intestinal microorganisms, the environment significantly increased the diversity of carp intestinal flora, and significantly increased the abundance of Verrucomicrobia and Proteobacteria at the phylum level (P<0.05), significantly reducing the abundance of Fusobacteria (P<0.05); At the genus level, the abundance of Cetobacterium, Plesiomonas, Bacteroides and Aeromonas was significantly reduced (P<0.05). The experimental results confirmed that the paddy environment changed the intestinal microbial diversity and the abundance of functional genes related to metabolic capacity, reduced the abundance of some conditional pathogens, reduced the probability of disease outbreaks, and helped to maintain liver function stability.

Abstract:In order to study the effects of dietary lipid sources on growth performance, antioxidant capacity and fatty acid composition of abdominal muscles of juvenile red swamp crayfish Procambarus clarkii. Six isonitrogenous and isoenergetic experimental diets were formulated with palm oil, fish oil and soybean oil as lipid sources. 252 juvenile P.clarkii with initial weight of(5.26±0.10) g were selected and cultured for 120 days. They were randomly assigned to 6 groups(3 replicates in each group, 14 individuals in each replicate).The results showed that the specific growth rate(SGR) and survival rate(SR) of juvenile shrimps decreased with the increase of palm oil addition level in the feed. SGR of juvenile P.clarkii in F3 and F4 groups was significantly higher than that of other groups. Survival rate of juvenile P.clarkii in F4, F5 and F6 was significantly higher than that in F1 and F3. There was no significant difference between F4, F5 and F6. The total antioxidant capacity (T-AOC) in hepatopancreas of single lipid source groups (F1, F5 and F6) was significantly higher than that of mixed lipid source groups(F2, F3 and F4). Among all feed treatments, the activity of CAT in hepatopancreas in F4 was the lowest, and the content of malondialdehyde (MDA) in F5 was the highest. There was no significant difference of ∑SFA in juvenile P.clarkii muscles of each feed group. 18 kinds of fatty acids were detected in the muscles of each group, ∑PUFA > ∑SFA > ∑MUFA, n-3/n-6 ∑PUFA values ranged from 1.44 to 1.84.Results indicated only palm oil, fish oil and soybean oil as feed lipid sources have negative effects on the growth performance and antioxidant capacity of P. clarkii,and the mixture of fish oil and soybean oil as lipid source was beneficial to SR and SGR of P.clarkii.

Abstract:The present study was conducted to investigate the effects of marine animal protein hydrolysates inclusion on growth performance and feed utilization of hybrid grouper, Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂. Seven isonitrogenous and isolipidic diets were formulated with the diet with 60% and 40% fish meal as the positive control (PC) and negative control (NC), respectively. Five diets were formulated with the supplementation of crystal amino acid (CAA), fish soluble (FS), shrimp paste (SP), squid paste (SUP) or the mixture of the above three marine proteins (Mix, 1:1:1). Results showed that the specific growth rate of grouper was significantly reduced in the NC and CAA groups compared to the PC group. However, the supplementation of marine protein hydrolysates significantly neutralized the negative effects on SGR induced by high fishmeal replacement. The fish in the NC group obtained the lowest feed intake (FI), while no significant difference was observed among other treatments. The feed efficiency ratio (FER) and protein efficiency ratio (PER) followed the similar patterns to those of FI. In conclusion, the inclusion of fish soluble, shrimp paste, squid paste and their mixture in low-fish meal diets can significantly improve the growth and feed utilization of hybrid grouper, indicating that the supplementation of marine animal protein hydrolysates can elevate the nutrition value of low fish meal based diets.

Abstract:The present study investigated the incomings and outgoings budget of dissolved oxygen (DO) in juvenile Chinese mitten crab (Eriocheir sinensis) culture ponds. The research was conducted in six juvenile crab farming ponds in Maogang Town, Songjiang District, Shanghai from July to October in 2019. The DO production from photosynthesis, respiratory oxygen consumption by Alternanthera philoxeroides, juvenile crab, pond sediment, and oxygen consumption of aquatic respiration were measured. The DO incomings from deploying aerators, and oxygen exchanges between water and atmospheric were calculated based on measured values by the subtraction method. The DO production from photosynthesis was less than the water respiratory oxygen consumption during the test period, only the DO production from photosynthesis in the surface water column was significantly greater than the water respiratory oxygen consumption, and the DO production from photosynthesis in the middle and bottom water layers were almost zero. There was no significant difference in the respiratory oxygen consumption by different water layer. Mechanical aeration was the main factor contributing to the DO incomings, accounted for 72.32% of the total DO incomings; this is followed by oxygen exchanges between water and atmosphere 24.02%, and DO production from photosynthesis 3.66%. Alternanthera philoxeroides is the main factor of DO outgoings, accounting for 80.51% of the total DO outgoings. The respiratory oxygen consumption of Alternanthera philoxeroides is about 21 times that of DO production from photosynthesis. Benthic respiration, juvenile crab respiration and aquatic respiration accounted for 4.19%, 4.81% and 10.49% of total oxygen outgoings, respectively. The results show that in the juvenile crab ponds, regular cleaning of Alternanthera philoxeroides and control of the aerators operating time are important means to maintain the balance of DO.

Abstract:In order to explore the significant effects of new rice-fish culture modes on rice growth and yield,the practice of a new rice-fishing culture model was carried out in Guangming Fishing Village, Helan County, Yinchuan City, Ningxia Hui Autonomous Region. Rice paddy irrigation patterns affect rice growth and yield under different conditions. The experiment divides the fish pond water once every 5 days, irrigates the fish pond water every 7 days and does not irrigate the fish pond water.Rice planting variety is "Jihong 6". The average yield per mu of rice is 1089.93/667m². The overall yield per mu is higher than that of paddy fields. The irrigation period is 5 d for irrigation once>7 d for irrigation once > no irrigation of fish pond water. The upper part of the biomass is larger than the paddy field. There were different degrees of correlation between rice yield and yield components, and the overall correlation of gray correlation was from 0.576 to 0.907. the correlation between The root stem constituent factors and rice yield from strong to weak is:root length (0.907)> stem base outside diameter (0.863)=panicle base outside diameter (0.863)> stem length (0.846)>Plant height (0.829)> panicle length (0.776), the root stem constituent factor with the highest correlation with rice yield is root length, and the smallest correlation is the length of the stem; the correlation between rice yield component and rice yield is from strong to weak. The order of ordering is:effective panicle number (0.869)> grain number per ear (0.847)> biomass (0.813)> seed setting rate (0.806)> thousand grain weight (0.759)> hills per hectare (0.715)> root dry weight (0.625)> panicle setting rate (0.576), the yield component with the highest correlation with rice yield is the effective panicle number, and the smallest correlation is the panicle setting rate.

Abstract:The objective of the present study is to screen and identify potential antagonistic bacteria against aquatic pathogenic Citrobacter freundii, and to evaluate its safety. Using crab-pathogenic C. freundii C1 as the indicator and the diameter of inhibition zones as the evaluation index, the good Bacillus isolate with antagonistic activity was screened, and was identified by phenotypic identification and 16S rRNA gene analysis. The safety of the isolated antagonist was assessed by assaying virulence gene, antibiotic resistance, inhibitory effect on Chlorella sp, and pathogenicity for zebrafish and Chinese mitten crabs. Isolate PNB3 with good antagonistic activity was screened from the aquaculture sediment which reached 99.99% after co-culture with C. freundii C1 for 120 h at 1.0×10⁵ CFU/mL, and was identified as Bacillus licheniformis based on phenotypic characterization and 16S rRNA gene analysis. It did not contain virulence genes including haemolysin BL gene, enterotoxin Nhe gene, enterotoxin T gene, enterotoxin FM gene, cytotoxin K gene, vomiting gene, multiple regulatory factors, and exhibited high sensitivity to compound sulfamethoxazole, ampicillin, norfloxacin, kanamycin, polymyxin B, florfenicol, gentamycin, enoxacin, cefradine, penicillin, and displayed a growth-promoting effect on Chlorella sp., and showed no pathogenicity for zebrafish and Chinese mitten crabs. In conclusion, B. licheniformis PNB3 is a potential safe antagonist against C. freundii, and has the safe potential in the biocontrol of C. freundii infection in Chinese mitten crabs.

Abstract:Qingcaosha Reservoir, located in the Yangtze Estuary, is the largest estuary reservoir built and was put into use at the end of 2010. In order to grasp the trend of fish community structure changes after the completion of Qingcaosha Reservoir, a five-year fish survey was conducted quarterly from January 2015 to December 2019. The results show that 5 158 fish samples were collected and 51 species were identified, belonging to 9 orders 16 families 41 genera; Cyprinids account for the highest proportion, 87.1%; the proportion of migratory fish, anadromous migratory fish, estuarine fish decreased year by year from 2015 to 2019, and the proportion of freshwater settled fish increased year by year; silver carp, bighead carp and crucian carp are dominant species in all survey years, and the dominance of crucian carp is increasing year by year; Cluster clustering analusis results show that the community structure was similar in 2015 and 2016, and similar in 2017, 2018 and 2019. Combined with the annual changes of Margalef, Pielou and Shannon Wiener index values, it shows that the disturbance degree of the community structure of Qingcaosha Reservoir is on the rise. At present, freshwater fishes are dominant in Qingcaosha Reservoir, and migratory and estuarine fishes gradually disappear from the reservoir. The fish composition is getting closer and closer to the characteristics of freshwater lakes in the lower reaches of the Yangtze River, which is different from the fish community structure in the peripheral Yangtze River estuary.

Abstract:To study the gonad development of spotted knifejaw (Oplegnathus punctatus), this study focuses on the development and differentiation process of spotted knifejaw gonads with histological methods. The results showed that O. punctatus is a differentiated gonochorist. Its spermary is lobular in the structure.Its development can be divided into six stages. Under the culture at 24-26℃, the full length of fish 120 days after hatch ranged from 56.1 to 64.5 mm, and spermaduct formed, indicating the beginning of testis differentiation. Seminal lobule formed 180 days after hatch, indicating the accomplishment of anatomical differentiation of testis. Meanwhile, the appearance of primary spermatocyte indicated the beginning of cytological differentiation of testis. The development of female gonads can be divided into six stages. Under the culture at 24-26℃, the full length of fish 90 days after hatch ranged from 30.4 to 49.5 mm, and clusters of oocytes appeared, indicating the beginning of anatomical differentiation of ovary. Ovarian cavity was observed in presumptive ovary 150 days after hatch. The appearance of primary oocyte 180 days after hatch indicated the beginning of cytological differentiation of ovary. This study showed that the anatomical differentiation timing of ovary was earlier than that of testis in O. punctatus; while the cytological differentiation of ovary and testis was synchronized.

Abstract:The number, histological characteristics, types and distribution of mucus cells in the pyloric caecum of Siniperca chuatsi at different developmental age were observed and described by histology sectioning, H.E and AB. PAS stainings. The results showed that at 15 days after hatching, there was a cluster of pyloric caeca began to develop on the left ventral side between the stomach and intestine. At 20 days after hatching, there was a cluster of pyloric caeca that developed on the right ventral side below the intestinal tract, and at 25 days after hatching, there was a cluster of pyloric caeca that developed on the right ventral side between the stomach and intestinal side, and the left ventral side below the intestine, respectively. At the age of 20, 30, 40, 50 and 60 days, the number of pyloric caeca was (25±2), (75±2), (123±4), (155±7) and (190±5), respectively. The number and the length of the folds and the thickness of the muscular layer of pyloric caecum increased with development age. The pyloric caecum was clustered by multiple branches, each of which produced two sub-branches in the middle section. Ⅱ type of mucous cell was widely distributed in the pyloric caecum, followed by type Ⅳ, there was no Ⅰ type mucous cell. The number of mucous cells on the base pyloric caecum was higher than the top part.

Abstract:Nine conical reactors were divided into three groups according to the stirring intensity:low speed group (300 r/min), medium speed group (600 r/min) and high speed group (900 r/min).After 21 days of culture, mature and stable bioflocs were formed, then rapid transformation test and Biolog-ECO test were carried out. The results show that the biofloc structure of low speed group is loose and the edge is fuzzy; the biofloc structure of medium and high speed groups is compact and the edge is neat; the biofloc size decreases with the increase of shear force, and the biofloc size and proportion are inversely proportional to the shear force.In the process of biofloc culture, the water quality changes and rapid transformation test showed that each group had a good removal effect on NH₄⁺-N and NO₂^--N.Biolog-ECO test showed that the microbial community diversity of biofloc was better than that of the other two groups at low speed. In terms of carbon preference, the utilization rate of amino acids was the highest and that of phenolic acids was the lowest in each group. In addition, there were 19 carbon sources with more than 0.5 correlation coefficient of principal component 1. There were 13 kinds of carbon sources with more than 0.5 correlation coefficient of principal component 2. α-D-lactose, β-methyl-d-glucoside, γ-hydroxybutyric acid, itaconic acid and phenylethylamine can be used specifically by microorganisms in different treatment groups.

Abstract:Taking a typical square chamfered aquaculture pond as the research object, a numerical model of the liquid-solid two-phase flow field was established,and the influence of the slope of the pond bottom surface and hydrodynamic conditions on its water purification efficiency was analyzed. Studies have shown that as the internal pressure of the aquaculture pond decreases, the forces on the particulate matter decrease and the sediment concentration increases; When the rotation speed of the flow is constant, the separation efficiency of the particles increases with the increase of the bottom slope; when the rotation speed of the flow is 0.25 rad/s and the bottom slope is 12 °, the water purification efficiency of the aquaculture pond is the highest; The numerical calculation results are in good agreement with the experimental data, verifying the effectiveness of the numerical calculation method. The research results have important scientific significance and engineering application value for the optimal design of the pond water circulation aquaculture system, the evaluation of the hydrodynamic conditions of fish survival, the solution to the problems of low water circulation efficiency and low efficiency of sewage collection.

Abstract:In this study, optical images of 7 microalgae were sampled. Based on the experience and knowledge of experts at home and abroad on identification of marine microalgae, an image data set labeled with algae names was made and data enhancement was carried out.With the help of the principles and methods of deep learning, the AlexNet model based on the structure of convolutional neural network was designed and trained.The 5-fold cross validation method was applied to ensure the stability of the model.The results showed that the average training accuracy of the model can reach 97.86%±1.63%and the average testing accuracy can reach 85.86%±0.80%. By using the parameters obtained from AlexNet model training, the reserved 280 sample images were actually tested.The average accuracy, average recall rate and average F1 Score of the 7 algal species were 83.2%,84.4% and 83.3%, respectively.It was indicated that the deep learning method is an effective way to identify marine toxic algal species.

Abstract:The impact of ocean acidification on the changes of marine species abundance is a hot topic. East Bering Sea is rich in fishery resources and the sea area is at greater potential risk from ocean acidification. This study explored the 70 species' abundance variations (including fishes, crustaceans and mollusks) and its relationship with bottom seawater pH in this area by dynamic regression model. Results showed that 27.78%, 36.84% and 33.33% of the species abundance of fish, mollusks and crustaceans were affected by the changes of pH respectively. The responses of species abundance to pH decrease were different, including three kinds, i.e. up, down, and up first, then down. These responses could be result from the change of habitat environment or suitable habitat range under pH variations. Our results indicated that it is not enough to analyze the species abundance only by pH. Ocean acidification would have different types of impact on the abundance of fishery species. This study could provide a reference for the sustainable development and utilization of fishery species under future ocean acidification.

Abstract:Sea turtles are at the top of the marine ecosystem and have been regulating the diversity and stability of marine ecosystems. Based on the data by scientific observer surveys in high seas of the tropical Atlantic Ocean (15°S-15°N, 15°W-45°W) by the pelagic tuna longline fishery targeting bigeye tuna from 2009 to 2019, the total 108 sea turtles were observed and analyzed.The result showed that incidental sea turtles were classified as 3 species, namely loggerhead (Caretta caretta), olive ridley turtle (Lepidochelys olivacea) and leatherback (Dermochelys coriacea). There were 32 sea turtles of mortality after capture. The annual catch rate ranged from 0.001 6 per thousand hooks to 0.069 3 per thousand hooks. And the interactions between fishing gear and sea turtles showed that most sea turtles bycatch in longline are caused by hooked mouth and branch line entanglement.Seasonal differences were found in sea turtles bycatch,and BPUE(bycatch per unit effort)occurred mainly from October to May in next year. BPUE in the north of the equator exhibited interannual variations, but the overall extents were not large. However,in the south of the equator,BPUE varied greatly, even in some years there were no bycatch reports,especially from 2009 to 2013. However, since 2013, the growth trend of BPUE in southern area appeared obviously, and the maximum value occurred in 2015, then southern BPUE gradually decreased to the minimum value in 2019.There was a great difference in BPUE between the bright moonlight and moonless night, especially at full moon or near full moon, the BPUE increased significantly. Different species of bycatch sea turtles occurred in a certain temperature range. Leatherback turtles were more often caught when the water temperature ranged from 24 to 26℃, while olive ridley turtles were easier incidentally caught between 26 and 27℃. In addition, this research explored the factors affecting the increase of sea turtles bycatch survival rates about Chinese longline fleet in recent years, and suggestion was also made to adjust the management plan of sea turtles bycatch mitigation in high seas of the tropical Atlantic Ocean in real time according to the difference of fishery area, target species and environmental conditions.

Abstract:Antarctic krill (Euphausia superba) is a key species in the Southern Ocean ecosystem, and the main target specie of the Southern Ocean trawl fishery. The size of Antarctic krill is small, the body of a krill trawl is usually lined with a small mesh netting to prevent krill from escaping. The length and assembly position of the liner netting vary from country to country, depending on operation habits and captain's preferences, and some make up more than two-thirds of the body net length. The catch data are often used in the assessment of krill resources, so it is of practical significance to understand the selectivity and influencing factors of large mesh body net of Antarctic krill trawl net for the accuracy of krill resource assessment using fishery data. To this end, the authors attached a 0.2 m×0.2 m small mesh net to the first section (2a=400 mm, without liner netting) and the second section (2a=200 mm, lined with 16mm mesh size liner netting) of body net of the krill trawl used by krill factory trawler "LONG TENG" of the China National Fishery Corporation Ltd, to collect the krill that passed through the large mesh during conducting the survey at the northern waters (FAO statistical area 48.1) of the Antarctic Peninsula. We employed the logistic curve equation to study the selectivity index 50% selection body length (L₅₀) and selection range (SR) based on the body length composition of krill from the above attached fine-mesh net and codend. The results showed that the selectivity of the trawl used by "LONG TENG" trawler mainly occurs-red at the first section of the trawl body with large mesh, but there was almost none-selectivity in the second section of the trawl body due to the inner netting with small mesh size. The probability (P_c) of Antarctic krill contacting the first section of the trawl body ranged 5.85%~69.52%, the average was 23.17%±14.80%, and there was no significant difference between daytime and night (P>0.05). The L₅₀ range was 25.05~47.74 mm, the average was (32.68±4.92) mm, but L₅₀ was (30.06±2.23) mm at daytime, significantly (P<0.05) lower than was (35.81±5.48) mm at night. The SR range was 2.07~19.08 mm, the average was (7.65±4.02) mm, and the SR was (7.11±4.41) mm at daytime, slightly lower than (8.30±3.53) mm at night. This study focused on the selectivity of net body parts, and considered the difference in krill selectivity between day and night, which could provide scientific basis for scientific evaluation of krill resources and development of ecologically friendly krill trawl.

Abstract:With the fluid simulation software (Ansys Fluent) and turbulence module (large eddy simulation, LES), we have simulated the flow field effects of four different types double layer cross-airfoil artificial reef. To quantify the flow field parameters, including the volume of upwelling and wake vortex, and the transport flux by upward waters, we adopt the method of concrete volume ratio to obtain the optimal structure of artificial reef, in order to provide a scientific basis for the design and selection of artificial reef. The simulation results show that the double layer cross-airfoil artificial reef with roof has faint effects on flow field, the relative volume of upwelling and wake vortex become smaller. While the artificial reef with side plate has obvious effects on flow field, the relative volume of upwelling and wake vortex increase gradually. Similarly, the flow effects of upwelling and wake vortex of D-type reef with full-side plate are most strongest, and the relative volume of the upwelling can reach 13.50-25.48 times of the B-type reef without side plates, the relative volume of the wake vortex can reach 1.40-1.61 times; the maximum transport flux value of upward waters appears at 1 times height of the reef, and about half of the maximum value appears at 2 times height of the reef. The result also shows that there is no evident difference in the flow field effect of D-type reef when changing the upstream angle, which indicates that this type of reef has a good adaptability to the flow direction in the natural sea area.

Abstract:Ommastrephes bartramii is a kind of short-lived species which is one of the economic cephalopods in the Northwest Pacific. Optimizing the resource abundance prediction model can provide a scientific and effective basis for fishery production. This study used the fishing data of neon flying squid from 1998 to 2016. Firstly,GM (1,1) models are established for resource abundance (CPUE) sequences of different time lengths. The CPUE sequence with the smallest relative error and variance is selected to perform grey correlation analysis with the environment and climate factors of the spawning and fattening grounds, including Pacific Decadal Oscillation Index (PDO), average sea surface temperature at spawning ground (SGSST), average sea surface temperature at fattening grounds (FGSST), average chlorophyll concentration at spawning ground(SGC), average chlorophyll concentration at fattening ground (FGC)to evaluate the importance of environmental factors. And based on the results, we established 6 grey prediction models of different orders[GM (0, N) model and GM (1, N) model]. Finally,we selected the model with relatively small fitting errors and prediction errors as the best model to predict the abundance of neon flying squid resources. The results show that the average relative error of the GM (1,1) model of the 8-year CPUE sequence is the smallest (6.28%). The prediction accuracy of the GM (0, N) models is generally higher than that of the GM (1, N) models. The GM (0,5) model 4 which included SGSST in February, FGSST in October, FGC in August, and PDO in October have the best model effects. Its relative error of fitting is 3.87%, and the relative error of prediction is 1.18%.Therefore,we suggested that this model can be used to forecast the resource abundance of neon flying squid.

Abstract:Todarodes pacificus(T. pacificus) is an important fishery species around the world. In order to scientifically manage and exploit this fishery resources, mitochondrial COⅠgene and Cytb gene sequences were assessed to explore the level of genetic structure and variation of T. pacificus from the northwestern Pacific Ocean.465 bp(COⅠ) and 404 bp(Cytb) gene sequences were obtained and a total of 18 and 21 haplotypes were defined, which had been derived from 90 individuals in three sites. The results showed that the haplotype diversity of COⅠ gene and Cytb gene sequences were 0.493 and 0.479, respectively.The nucleotide diversity of COⅠgene and Cytb gene sequences were 0.001 3 and 0.001 4, respectively. It was also found that genetic differentiation coefficient (F_st) were negtive(F_st<0.05), the tremendous gene flow (Nm) values were approximate infinity. However, molecular biological variance analysis (AMOVA) showed that the genetic variation observed within populations were 100.82% and 99.57%, respectively.There sults of Tajima's D based on COⅠand Cytb gene sequences of T. pacificus were -2.341 2 and -22.643 0 (P<0.01), respectively. In summary, all these results revealed that the genetic diversity of T. pacificus population in the northwest Pacific Ocean was extremely low, and there was no genetic differentiation among the three geographic groups. Besides, the genetic variation mainly came from individuals within the species. And the population expansion occurred about between 12 000 and 15 000 years ago.Therefore, it is suggested that T. pacificus should be regarded as an integration management unit in fishery management.

Abstract:β-cyclodextrin was used as the wall material, bergamot essential oil and Litsea cubeba essential oil were used as the core material, β-cyclodextrin-bergamot essential oil and and L. cubeba essential oil micro-capsules Langbergen were prepared by the method of cyclodextrin embedding. Essential oil microcapsules were dispersed as antibacterial agents in a water-absorbing pad and encapsulated to prepare active antibacterial fresh-keeping pads loaded with essential oil microcapsules. The effect of the active fresh-keeping pads on the preservation of grass carp was investigated. The results showed that compared with non-functional absorbent pads, for the absorbent pads packed with β-cyclodextrin-essential oil microcapsules packaged grass carp, total viable counts (TVC), total volatile basic nitrogen (TVBN) pH and thiobarbituric acid(TBA), were significantly lower than that in the blank group (P <0.05), there by reducing the changes in the texture of grass carp meat hardness, elasticity and resilience. It shows that the sustained release of the essential oil in the microcapsules has a positive effect on the preservation of grass carp. Compared with the blank group, under the condition of (4 ±1)℃ cold storage, the active preservation pad of the experimental group can effectively delay the spoilage of grass carp, and can extend the shelf life of grass carp by 2 to 3 days, and the extension time can reach 50% of the original shelf life.