Abstract:In sampling of Siniperca fishes from Poyang Lake and Dongting Lake in the middle Yangtze River, 48 intermediate individuals with partial morphological features of S. chuatsi and S. kneri (Main feature:The posterior edge of the cleft mouth is below the posterior edge of the eye, the eye size and the anterior ridge of head are between the S. chuatsi and S. kneri) were collected. In order to clarify their taxonomic relationship, the quantitative morphological parameters and species-specific microsatellite loci were screened for identification. Results showed:(1) there was significant difference in head length/eye diameter and (snout length+eye diameter)/fissure length between S. chuatsi and S. kneri. Head length/eye diameter in S. chuatsi is from 5.286 to 7.157, (snout length+eye diameter)/fissure length is from 0.811 to 0.999, they are from 3.306 to 5.106 and 1.040 to 1.166 in S. kneri, respectively. Among 48 intermediate individuals, 5 individuals were identified as S. chuatsi, and the remaining 43 individuals were still unable to be identified. (2) Five speices-specific loci (T103, T063, T089, T135, W19517) were screened from 28 pairs of microsatellite markers. In genetic analysis and identification of intermediate types of individuals using these five loci, 16 were inter-species hybrid progeny, and 9 of them were identified as backcross progeny (F₁×SK). The results indicated that inter-species introgressive hybridization between S. chuatsi and S. kneri existed in the middle Yangtze River, and it is necessary to strengthen genetic monitoring and management of mandarin fish resources in the Yangtze River.

Abstract:The mitochondrial Cytb genes were sequenced and analyzed of W. pigra Whitman from three wild geographical populations including Gaoyou Yangzhou, Zhangjiagang Suzhou and Hailing Taizhou. The results showed that Cytb sequence of W. pigra was 1 146 bp, and the average contents of A, G, T and C were 27.57%, 15.77%, 43.49% and 13.17%, respectively. The A+T content (71.06%) was higher than that of G+C(28.94%).Among examined 77 individuals, 96 polymorphic sites and 58 parsimony information sites were detected. Besides,47 haplotypes were found and there was only one shared haplotype. The total haplotype diversity, nucleotide diversity, and the average nucleotide difference were 0.978 1, 0.013 3, and 15.20, respectively. The Hailing Taizhou population has the highest haplotype diversity (0.987 7) and nucleotide diversity (0.013 1). The genetic differentiation index F_st of the three populations ranged from 0.065 1 to 0.175 6, and the difference was significant (P<0.05), which indicated that there was a certain genetic differentiation among different populations. The analysis result of molecular variance (AMOVA) showed a higher percentage of 88.87% within-population variation than that of 11.13% among-population variation. The haplotype neighbor-joining (NJ) tree with individuals of different geographical groups radiated showed no phylogeographic structure among three populations. Neutral test and mismatch distribution analysis revealed that the overall size of the three populations of W. pigra remained relatively stable, with no significant population expansion.

Abstract:The differences in culture performance and nutritional composition of adult Chinese mitten crab (Eriocheir sinensis) were investigated through continuous sampling and biochemical analysis. Growth performance, puberty molting rate, hepatosomatic index (HSI), gonadosomatic index (GSI), meat yield (MY), total edible yield (TEY), condition factor (CF), and nutritional composition were compared for the three edible tissues of adult Eriocheir sinensis. The results illustrated that:(1) Regardless of females or males, the power function model was found between body mass and carapace length or carapace width, and liner function was discovered between carapace length and carapace width. The mean body mass of females was always lower than that of males, and there was significant difference from July to September (P<0.05). No significant difference was found in WGR and SGR between females and males (P>0.05). (2) The females had slightly earlier puberty molting than males, and the peak of puberty molting appeared between August and September. All adults completed molting until mid-September. From August to October, a significant upward trend emerged in GSI of adults, while the HSI decreased (P<0.05). Higher proportion of female body mass was observed in 60.00-99.99 g, while males were in the range of 100.00-139.99 g in September. (3) The GSI and TEY of females were significantly higher than those of males, however, MY and CF of males were higher in October (P<0.05). The protein and lipid contents of female edible tissues were higher than those of males, but males had higher moisture content. No significant difference was found in ash content. Above all, the peak of puberty molting of adults in pond was observed between August and September. The total edible yield of female and male adults was 46.47% and 44.81%, respectively. Therefore, the edible tissues had higher nutritional value.

Abstract:By nitrifying bio-floc system to culture Litopenaeus vannamei, and by setting different stocking density, the influence of nitrifying bio-floc systems was explored at different culture density on growth performance and quality of Litopenaeus vannamei. Some healthy Litopenaeus vannamei in same size[body length (4.80 + 0.25) cm, body mass (0.98 + 0.16) g] were selected to culture 45 days at five different stocking density treatments. The results showed that:In the range of 80-610 ind/m³ density, the nitrifying bio-floc system can control the Un-ionized ammonia and Nitrite-N near the warning concentration (0.2 mg/L),which improves the environment for health growth of Litopenaeus vannamei and ensure the survival rate of culture, and in addition,appropriate sewage discharge at the system can avoid the Nitrate-N concentration accumulation too fast in high density culture; In the range of 80-610 ind/m³ density, the survival rate of Litopenaeus vannamei declined with the increase of density,but the yield increased with the increase of density.

Abstract:Comparison of the survival rates of different transport modes and temperature for the Pinctada fucata juveniles was made so as to provide references for the transportation. Three-month-old P. fucata juveniles were used as experimental materials, and three methods of dry transport, water transport and oxygen transport were used to simulate transportation at temperature of 5, 13, 21 and 29℃ respectively. One group of experimental juveniles was taken from each group of transport conditions every 3 h, and transferred to a normal environment for temporary recovery, and the survival rate was calculated after 48 h. Nonlinear parameter curve fitting between transportation time and survival rate, and calculated lethal time (T₀), semi-lethal time (T_0.5) and total lethal time (T₁) for each group of transport conditions, two-way analysis of variance were used, and the Duncan method was used to compares the average of the three modes of transport and the four temperatures. The results showed that:the survival rates of oxygen transport mode is higher than the other two transportations, and the water transport is better than dry transport. The survival rates of temperature at 13℃ and 21℃ are highter than that of the other two temperatures, and the temperature from 17.60℃ to 20.05℃ is the optimal temperature for the P. fucata juveniles transportation.

Abstract:To explore the liver fat accumulation and its possible reasons of grass carp (Ctenopharyngodon idellus) fed with broad bean, liver samples of grass carp fed with broad bean (treatment group) and artificial feed (control group) were collected. The pathological feature, fat accumulation and hepatic structure were observed by H&E, oil red O staining and transmission electron microscopy method, respectively. The expression leads of genes associated with fatty acid synthesis were further analyzed. Additionally, some biochemical indexes were also detected both in liver and serum. The results showed that:hepatic steatosis was observed accompanying the abnormal morphology and decreased number of mitochondria in the treatment group; Triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum of treatment group were significantly higher than those of the control group (P<0.05); TG, TC and hydrogen peroxide (H₂O₂) in the liver of treatment group were extremely higher than those of the control group (P<0.01), but catalase (CAT) activity and glutathione (GSH) were extremely lower (P<0.01); The mRNA expression levels of fatty acid synthesis (acc and fas) in treatment group were extremely higher than those in the control group (P<0.01). The results demonstrated that long-term feeding broad bean could cause fat accumulation in the liver of grass carp, which may be related to the increase of fatty acid synthesis, oxidative stress and collapse of mitochondrial structure. This study would provide scientific data for nutritional regulation of crisp grass carp and prevention from fish hepatic steatosis.

Abstract:The survival mechanisms of seeds and seedlings of Scirpus mariqueter under the effect of salinity and flooding time were studied to provide an important scientific basis to the ecological restoration of coastal wetlands in the Yangtze Estuary. Different flooding time (8 h/d, h/d 10, 12 h/d, 14 h/d) and salinity (0,5,10,15) were controlled through the simulation of tidal, then the impact of physiological indexes, such as germination rate, germination index, chlorophyll, superoxide dismutase (SOD) and malondialdehyde (MDA) were analyzed. Among them, salinity had the greatest influence on germination rate, germination index and MDA of seedling. Chlorophyll and SOD were mostly influenced in the interaction between salinity and submergence. The results showed that the germination rate reached to the highest when the salinity at 0, and the flooding time at 8 h/d. The critical salinity of the seed germination was 15‰, and the number of turns was the highest at 10‰ and 12 h/d. Chlorophyll was the highest under the interactive treatment of salinity at 0‰ and flooding time of 12 h. What's more, the total activity of SOD was the highest at 10‰ of salinity and 8h/d of flooding time, and MDA was the lowest at 10‰ and 12 h/d. The results showed that the Scirpus mariqueter was most adaptable to moderate salinity (5, 10) and moderate flooding time (10 h/d, 12 h/d).

Abstract:The Predicated No Effect Concentration (PNEC)of norfloxacin in the freshwater sediment was derived by the Species Sensitivity Distributions(SSDs) method and distribution equation model with collected and calculated chronic toxicity data. Those data collected were fitted in 5 different models by SSDs method,the model of log-normal was fitted best. The PNEC of norfloxacin in freshwater sediment was 1 612.82 ng/g. Also, ecological risk assessment of existing research of the sediment in different freshwater areas were conducted by risk entropy. The results show that, in China, the ecological risks of known statistics of the concentration of NFLX in sediment, were between medium and low and some sample sites showed high risk, which probably had potential hazard to freshwater ecology system.

Abstract:The vertical distribution and changes during day and night of Coilia nasus larvae and juveniles depending on flood tide and ebb tide in the southern branch of Yangtze River estuary. According to the tidal changes, monthly 4 flood trawls and 4 ebb trawls were set at two stations (surface layer and middle layer) from May to September in 2017 using a larval net (1.3 m mouth-diameter, 0.5 mm mesh-aperture) againsting to the current at every station. A total of 369 individuals of Coilia nasus were collected,with developmental stages from pre-flexion larva to juvenile. The average density in the surface layer was 0.851 ind./100 m³ which was higher than 0.145 ind./100 m³ in the middle layer.The average density at pre flexion larva and flexion larva is higher in the surface than in the middle layer, at flood tide than at ebb tide,in the daytime than in the night time. While the average density at post flexion larva in the daytime is lower than that in the night time, at flood tide than at ebb tide. At flood in the daytime, the average density of juveniles is 0 in the surface and 0.14 ind./100 m³ in the middle layer. At ebb tide in the daytime, the average density of juvenile is 0.14 ind./100 m³ in the surface and 0 in the middle layer. The results show some tendency that pre flexion larva and flexion larva trend to the surface and post-flexion larva and juvenile trend to the middle layer. At flood tide in the daytime,post-flexion larva and juvenile trend to the middle layer. At ebb tide in the daytime, post-flexion larva and juvenile trend to the surface. The average density of post-flexion larvae and flexion larvae is higher in the daytime than in the night time.

Abstract:To explore the gut microbiome composition and community structure, we collected 4 amphipod species sampled from four sampling sites were collected including Mariana Trench, Marceau Trench, the East of New Britain Trench and the Center of New Briton Trench. The gut microbiome communities of the amphipods were analyzed by 16S rRNA-RFLP (restriction fragment length polymorphism) method to compare the gut microbial community between the different sampling sites. The diversity index and rarefaction curves showed significant differences among these four sampling sites. For Hirondellea gigas sampled from Mariana Trench, Psychromonas sp. and uncultured bacterium were the dominant bacterial communities with the ratio of 37.05% and 18.52%, respectively. For the Scopelocheirus schellenbergi sampled from Marceau Trench, Uncultured Mollicutes bacterium and Uncultured deep-sea bacterium were the dominant communities with the ratio of 62.50% and 25.0%, respectively. For Alicella gigantean sampled from the East of New Britain Trench, the dominant communities were Uncultured Mollicutes bacterium (50.0%) and Uncultured Mycoplasmataceae bacterium (44.44%). As for the A. gigantean sampled from the Center of New Britain Trench, the dominant communities were Psychromonas sp. (39.29%), Uncultured Mollicutes bacterium (32.14%), Uncultured Mycoplasmataceae bacterium (14.29%) and Uncultured bacterium (10.71%). Uncultured Mollicutes bacterium possess different ratios among four sampling sites, 62.50% for S. schellenbergi from Marceau Trench, 50% for A. gigantean from the Center of New Britain Trench, 32.14% for A. gigantean from the East of New Britain Trench, and 3.70% for H. gigas from Mariana Trench. There existed great differences between the the gut microbiome composition of the hadal amphipods sampled from four sites. H. gigas sampled from Mariana Trench possessed the highest diversity and complexity, followed by S. schellenbergi from Marceau Trench, and A. gigantean from the New Britain Trench was the least.

Abstract:According to the investigated data of fishery resources and habitats of comprehensive survey on Wen-Tai fishing ground in four seasons in 2015-2016, using normal distribution function respectively the sea bottom temperature (SBT), sea bottom salinity (SBS), water depth, and by the relative density of resources suitability index (SI) were built, and by used the least squares parameter model, based on different weight arithmetic average method (AWM), the habitat suitability index(HSI) model was also built. According to the data of resource density, bottom temperature, bottom salinity and depth, the boosted regression tree (BRT) was also built used to evaluate the weight of each environmental variable in the HSI model, and the model accuracy was tested by cross validations. It was found that there was a significant normal relationship between environmental factors and SI. Larimichthys polyactis optimal habitat has an obvious seasonal change of habitats.The whole-year high value appeared in spring and summer, followed by autumn and winter, the spring high value area is located in east of 122°30'E, north of 28°30'N summer strip of south high value area, autumn high value area is located at 122°00'E, 28°00'N, winter high value area north is located 123°00'E, 29°00'N. The results showed that the model can positively reflect the distribution and variation of the habitat of the Larimichthys polyactis in the warm stage after considering the weight in the HSI model.

Abstract:Based on the catch data of purse seine fishery of China from 1998 to 2015 and Japanese Resource Assessment of Chub mackerel and economic data, the Pella-Tomlinson model was used to calculate the Maximum Sustainable Yield (MSY), Bio-economic Equilibrium (BE),Maximum Economic Yield (MEY) and their corresponding fishing efforts. Taking into account different factors of biology, economy and society, 10 different fishing schemes was designed to compare the biological, economic and social benefits for 5 years,10 years and 20 years. The results show that the resource abundance of the Chub mackerel in East China Sea and the Yellow Sea decreased year by year; Increaseing investment in fishing effort will have a serious impact on economic,output and resources. The study determined that considering the biological, economic and social factors, Option 10 is the optimal fishing strategy, i.e. the weights of f_MSY,f_BE and f_MEY are 0.25, 0.25 and 0.50. The accumulated profit and output of 5 years under this strategy will be 3.019 billion yuan and 1 320 200 tons, and the resources will be 867 300 tons 5 years later.

Abstract:According to the squid samples collected from 2010, 2015 and 2016, the mantle length, body weight and beak morphometrics of annual and sexual differences were analyzed, and the monthly beak growth rate was calculated, combined with the distribution of monthly sea surface temperature (SST) and Chlorophyll a (Chl.a) to study the potential influential factors on the beak morphology and growth. The results showed that the mantle length and body weight had significant difference between years, the largest beak morphometrics was the individuals in 2016, and the smallest was in 2010. The growth parameter b in 2010 was the largest, and that in 2015 was the lowest. The growth rate during August to September in 2010 had the highest beak morphometrics growth rate, and had lowest in 2015. The distribution status of SST and Chl.a, the SST during August to September in 2015 was lower than that in the other years, the distribution of Chl.a during August to September was dispersed, but the high concentration (>0.7mg/m³) had a large proportion; the beak and mantle were relatively larger in 2016 than in other years due to the suitable SST and Chl.a. The beak morphology had significant difference between different years, and the variation of SST and Chl.a during August to September is one of the main factors that affect the beak morphometics.

Abstract:Vessel monitoring system (VMS), as a comprehensive application system integrating global satellite positioning, electronic map, network communication and database technology, aims to acquire the ship's position and operating status information in near-real time, and transmit them to the onshore monitoring center to realize the information interaction. More than sixty thousand fishing vessels have installed VMS so far. The VMS data mainly contains time, position, speed, direction and rate of turn with a temporal resolution of 3 minutes and a spatial resolution of 10 meters which can be analyzed deeply using data mining technology to identify the status of vessels, calculate fishing effort, search fishing ground and so on. DBSCAN is a density-based spatial clustering algorithm designed to find high-density regions segmented by low-density. Compared with distance-based clustering algorithms, it can identify noise data and find clusters of arbitrary shapes. In this paper, we used VMS data of Zhelinyu 12870 and Zhesanyu 66666 in 2017 and DBSCAN to extract the hauls of set gillnet. The speed of hauling gillnet is quite different from that during tracking or setting the net, so they could be extracted them by threshold. Firstly, we obtained the speed threshold of vessel's fishing condition by the statistics of navigational speed and extracted the points whose speed is in the range of threshold value. Secondly, the time difference of adjacent points was carried out to obtain time interval between hauls. Thirdly, the DBSCAN algorithm was used to cluster the fishing points around the set gillnet, which determines the starting time and the ending time of each fishing haul. The difference of the starting time and the ending time of each haul between clustering result and fishing log were calculated, and 15 minutes were token as a reasonable error-tolerant range. The comparisons showed that the accuracy of the hauls was above 80%.

Abstract:Due to the negative influence of human activities, the living environment of aquatic wildlife in the Yangtze River basin has been deteriorating, biodiversity continues to decrease, and some species are critically endangered. On the basis of literature review, the study carded the status of endangered aquatic wildlife species in the Yangtze River basin and discovered that the natural population number of many species has been extremely low and some of them have been endangered or extinct. They need to be protected immediately. Corresponding protection and management measures have been adopted by the Chinese government, and a relevant legal system for aquatic wildlife protection has been initially formed with some achievements. But the overall condition is still not optimistic. The factors that lead to the aquatic animal crisis in the Yangtze River are systematically studied in this article. Based on the analysis, corresponding protection measures are proposed:①put more emphasis on the protection of the entire ecosystem, and promote an integrated watershed protection model; ②improve existing laws and regulations, and promulgate the Yangtze River Protection Law as soon as possible; ③put major focus on local protection, with ex situ conservation as an auxiliary measure;④call for the demolition of some water conservancy facilities, and the establishment of special compensation;⑤strengthen related law enforcement supervision; ⑥increase investment in scientific research on the protection of endangered aquatic wildlife; ⑦encourage public participation and strengthen citizens' awareness of protection, in order to promote the development of endangered aquatic wildlife protection in the Yangtze River basin.

Abstract:Inland fisheries are mostly subsistence fisheries. Taihu's gillnet fisheries are typical subsistence fisheries. The main fishing villages in the Taihu Lake area were investigated. The results of the survey of 58 gillnet fishing vessels show that:(1) More than 80% of gillnet fishing fishermen are older than 45 years old; (2) The highest education level of gillnet fishing fishermen is junior high school, and more 60% of the fishermen have received education at the primary school level.(3) Of the fishing vessels surveyed, 98% are profitable, but the average profit of low-power fishing boats (6.468 kW) and high-power fishing boats (8.820 kW) is significantly different.Fishermen have poor economic conditions, and they can not afford to discard capture fisheries in the face of losses. Therefore, a livelihood fishery management system should be established from the sustainable subsistence fisheries to safeguard the society of Taihu capture fisheries,economic stability and society harmony.

Abstract:To meet the requirements of eco-civilization construction, it is an urgent demand to enhance fisheries surveillance for better fisheries resource conservation.How to well relocate the fishermen who have quitted fishing owing to the reduction of fishing capacity and the expansion of no-fishing zones has become an important project. This paper analyzes the necessity of fishermen's participation in fisheries surveillance from the theory of public participation in social governance, the actual demand of fisheries management and the relocation demands of fishermen who quit fishing; its feasibility was analyzed from legal grounds, the result of survey on fishermen's will and advantage of fishermen' ability as well as the existing practice. After, analyzing the institutionalization of forest ranger and auxiliary police, in order to promote fishermen's participation in fisheries surveillance, the following suggestions were made:(1) clarify the legal status and responsibilities of fishermen participating in fisheries surveillance; (2)set the number of participants according to the state of water area and fishermen as well as the difficulty of patrol;(3)set a uniform recruitment standard; (4) establish a unified regulatory agency; (5) strengthen pre-job training and on-the-job training; (6) establish review system based on training and work performance; (7) establish a multi-angle supervision system; (8) incorporate part of the funding into the government budget to ensure the stability of investment, and safeguard the basic rights and interests of fishery patrol officers.

Abstract:The extraction of polysaccharides from Grateloupia livida (GLP)was optimized using one-factor-at-a-time method and response surface methodology.Solid-to-solvent ratio, temperature and time were used as independent variables while polysaccharide yeild was used as response variable.The antioxidant activity of GLP was investigated by measuring scavenging activities against 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH) and hydroxyl radicals(·OH).The results showed that the optimum extraction conditions were found to be extraction at 100℃ for 4 h with a solid-to-solvent ratio of 1:37 g/mL, while polysaccharide yeild was 15.23%. GLP possessed strong antioxidant activity with half inhibitory concentration(IC₅₀) for scavenging of DPPH and hydroxyl radicals. 12.61 mg/mL and 2.05 mg/mL,respectively.