Abstract:The black rockfish (Sebastes schlegelii) is an important economic fish species widely distributed across the coastal areas of northern China. It has been widely studied due to its special viviparous reproductive strategy and long-term sperm storage characteristics. Although there are some previous reports about multiple paternity in S. schlegelii, the spatial distribution pattern of paternity in the ovary has not been studied. In this study, the multiple paternity in different regions of the ovary was investigated by applying six polymorphic microsatellite markers to genotype 9 cultured pregnant females and 291 of their offspring in different regions (the proximal part from the cloacal orifice, the middle part, and the distal part) of the ovary in S. schlegelii. The results showed that: (1) Multiple paternity was detected in 8 of 9 (88.89%) cultured female fish, which was similar to the findings of reports of the previous two scholars whose work focused on cultured and wild black rockfish. However, the average number of copulations was 3.56 times, which was higher than that reported in previous studies. The reason for this phenomenon might be the higher group density (7–8 fish/m3 ) than in previous studies. Furthermore, four broods were significantly skewed from equal paternal contributions (50%, B>0); (2) the results of one-way ANOVA showed that the proportions of paternal offspring did not significantly differ in the different regions of the ovary in females; and (3) the chi-square uniform distribution test results showed that the paternal offspring in each family had no significant bias in different ovary regions, indicating that multiple paternity in S. schlegelii is randomly distributed in the ovary due to a degree of sperm mixing in the female’s ovaries after mating to some extent. Considering that the ovaries of female fish are not yet mature in S. schlegelii during the mating period, the sperm from different males may be completely mixed in the immature ovary and then stored in it. The differences in males’ sperm number and sperm activity may be the important reasons for the bias of paternity contribution rate. These results may provide a scientific basis for the enrichment of reproductive biology research on S. schlegelii.

Abstract:According to the Red List of Threatened Species by the International Union for Conservation of Nature (IUCN) (www.iucnredlist.org), almost all sturgeon species are at risk of extinction, being identified as the most endangered species in the world. The ship sturgeon (Acipenser nudiventris) is classified as critically endangered. However, unlike the rapid decline of wild populations, sturgeon farming is rapidly increasing in the China Mainland, being the country with the largest sturgeon aquaculture with a production amount of approximately 97,000 tons in 2018. This figure is greater than 80% of the total amount of aquaculture production globally. The ship sturgeon is a large sturgeon with good egg quality and high caviar price, and the controlled propagation of this species is of great significance to conservation biology and aquaculture. The ship sturgeon is the only native sturgeon species that lives in the Ili River Basin of Xinjiang in China. The wild sturgeon populations in the Ili River have sharply decreased in recent decades, similar to the decline seen in other areas. It is a national second-class protected wild animal in China and a first-class protected wild animal in the Xinjiang Uygur Autonomous Region. Collecting wild individuals to implement controlled propagation technology under domestic conditions is the best strategy to save this species. In this study, 13 juvenile fish were collected from the Ili River and farmed in flowing ponds for many years. Among them, two females and three males reached stage IV gonadal maturity, and the controlled reproduction, embryonic development, and fry breeding of these fish were studied. LHRH-A2 was used to successfully induce spawning and insemination, and 120,000 eggs were collected. The fertilization rate was about 50%. Under the incubation conditions of 15–17 ℃, the larvae hatched for approximately 5–7 d, and more than 25200 newly hatched larvae were obtained, with a survival rate of 42%. The successful controlled propagation of A. nudiventris in the Ili River has laid a solid foundation of technology and experimental materials for conservation and population retrieval.

Abstract:With many fish stocks subject to over-fishing and marine fisheries in decline around the world, marine ranching is rapidly growing in China as an alternative method to re-establish coastal fisheries and conserve aquatic biodiversity. In China and East Asia, marine ranching has concentrated on a concept of aquaculture-based, artificial habitat-based marine ranching (e.g., buoyant rafts and artificial reefs) and rehabilitation-based marine ranching (e.g., seaweed beds and seagrass). Studies reported that some species of fish feed primarily on zooplankton, which may play an essential role in the future development of marine ranching. To evaluate the effects of facilities associated with marine ranching on zooplankton communities, a case study was conducted in Xiangshan Bay investigating the spatial heterogeneity of zooplankton communities in four different areas: an artificial reef, a kelp (Laminaria japonica)-suspended farming area, a Kumamoto oyster (Crassostrea sikamea)-suspended farm, and a neighboring natural rock reef habitat (control area). The results demonstrated that there were significant differences among the zooplankton communities in different areas. Both the Pielou’s evenness index (J′) and Shannon–Wiener diversity index (H′) in the artificial reef area were lower than those in the control area, while an approximately 134% increase in zooplanktonic numerical abundance was observed in the artificial area compared with that in the control area. The abundance of Centropages abdominalis (Copepoda) in the artificial reef area was 2.28 times higher than in the control area. The artificial reef area was characterized by a dense distribution of eggs and larvae of the Dotted gizzard shad (Konosirus punctatus) and Blackhead seabream (Acanthopagrus schlegelii), which indicated that the artificial reefs did have a positive role in promoting the enhancement of the above species. A decrease in nutrient concentration and an increase in chlorophyll a were detected in the kelp farming area. The concentrations of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphate (DIP) were significantly lower in the kelp farming area than in control area, which indicated that kelp farming was an effective measure to lessen eutrophication. No measurements of diversity or total zooplankton abundance exhibited significant differences between the kelp farming and control areas. However, a significant regional difference in zooplankton community composition was found. The abundance of Amphipoda (Gammaridae sp. and Caprellidae sp.) was higher in the kelp farming area compared with those of the control area, whereas ichthyoplankton abundance was low in kelp farming. Since oyster cultivation increased the concentration of both DIN and DIP, eutrophication tended to be elevated in the oyster farming area. The abundance of copepods, particularly that of C. abdominalis, was low in the oyster farming area; consequently, the total zooplankton abundance was low. However, the abundances of Caprellidae sp. and Blackhead seabream larvae and eggs were higher in the oyster farming area than in the control area.

Abstract:为了解长江湖口段四大家鱼卵的资源现状和产卵场位置与产卵规模, 本研究于 2019 年 4 月 19 日至 8 月 5 日利用浮游生物网对湖口江段设置的 4 个采样断面进行逐日调查。调查结果显示: 采集到家鱼卵 93 粒, 其中以鲢为绝对优势, 占家鱼卵总数的 80.65%。本次研究采集到的受精卵瞬时发育时期共 9 期, 主要是尾芽出现期、囊胚期和原肠早期, 分别占总家鱼卵数的 32.26%、24.73%和 15.05%, 结合水流情况, 推算出四大家鱼产卵场分布于湖口江州、武穴龙坪和黄冈蕲州 3 个江段附近, 产卵规模分别为 0.49×10⁸ ind、0.68×108 ind 和 0.38×10⁸ ind, 与历史资料相比其位置无明显变化, 但产卵规模显著下降。研究期间, 1 号断面的鱼卵平均日丰度为 1.52 ind/1000 m3, 显著高于 2 号(0.88 ind/1000 m3)和 3 号断面(0.43 ind/1000 m3)。运用 Pearson 检验分析表明, 四大家鱼卵日丰度与水流量日上涨率呈极显著正相关(P<0.01), 与水位日上涨率和流速呈显著正相关(P<0.05)。时隔 50 余年, 本研究再次报道了长江中下游衔接水域四大家鱼产卵场位置与产卵规模, 为四大家鱼资源保护提供基础资料。

Abstract:Trachurus murphyi is a pelagic fish species, the resource abundance and distribution of which are significantly affected by variations in the marine environment. Accordingly, analyses of the influence of key environmental variables on the fishing grounds of T. murphyi are of particular importance in gaining an understanding of how fishing grounds are altered in response to changes in environment. In this study, we collected fishery data for Chilean T. murphyi from March to August, obtained during the period between 2013 and 2017, from the National distant-water fisheries data center of Shanghai Ocean University, along with data relating to the following 12 environmental factors: mixed layer depth (MLD), sea surface height (SSH), sea surface salinity (SSS), and water temperature at different depths (0, 25, 50, 100, 150, 200, 300, 400, and 500 m). Using these data, we examined monthly variations in the potential habitat of Trachurus murphyi based on a maximum entropy model. The key environmental factors in each month were selected according to the proportional contribution of each environmental variable, and the suitable range of key environmental factors was determined on the basis of the response curves of these factors. We also examined monthly variations in the key environmental variables. The results revealed that the spatial changes in potential habitat were essentially consistent with the actual fishing locations, and that habitat hotspots gradually shifted northward during the months from March to August. In March, the potential habitat hotspots were distributed in the waters between 42°S and 47°S, and extended to regions north of 30°S in August. The contribution of environmental variables in each month indicated monthly differences in the key environmental factors, as well as in the suitable environmental ranges. The key environmental factors were identified as Temp 400 m, Temp 500 m, and SST in March; Temp 400 m, Temp 500 m, and MLD in April; Temp 500 m, SST, and Temp 400 m in May; SST, Temp 500 m, and Temp 50 m in June; SST, Temp 300 m, and SSH in July; and SSH, Temp 300 m, and Temp 100 m in August. In addition, water temperature was identified as an important factor affecting the spatio–temporal distribution of the fishing grounds, and the suitable water temperature layer in different months was found to be consistent with the migration characteristics of T. murphyi. With the northward movement of the habitat, the contribution rate of SSH gradually increased, which may be related to the distribution of currents off the Chilean coast.

Abstract:The small yellow croaker (Larimichthys polyactis) is an important fishery species in China that plays an important role in the marine ecosystem of the Yellow Sea. Species distribution models (SDMs) can be used to forecast the distribution of fishery species by establishing the relationships between the spatio–temporal distribution of a population and environmental factors. In this study, we used an SDM to analyze the spatio–temporal distribution of small yellow croaker and its relationships with environmental factors. Spatio–temporal distribution was determined based on data collected from seasonal bottom trawl surveys in southern waters off the Shandong Peninsula from 2016 to 2017. Environmental factors were initially selected based on Pearson correlation analysis to determine whether these were significantly correlated, and to ensure that the variables used in the model were independent, with the best model being determined based on a minimum Akaike information criterion (AIC). The results revealed significant seasonal variations in the spatial distribution of small yellow croaker, the highest and lowest abundances of which occurred in summer and winter, respectively. The pattern of spatial distribution showed a clear seasonal variation, with relative abundance being high in the southern area (near 35°N) during spring; contrastingly, in summer and autumn, the highest relative abundance was found in the northern coastal waters (36°N), and in winter in the shallow inshore waters of less than 50 m in depth. Generalized additive model analysis indicated that depth and sea bottom temperature have a significant influence on the distribution of small yellow croaker. Relative abundance increased with depth, with the highest abundance being located in the waters close to the 50 m isobath. Within a given temperature range, the abundance of small yellow croaker showed a seasonal correlation with sea bottom temperature, with the highest relative abundance being correlated with a temperature of approximately 18–20℃. The calculated optimal temperature ranges for small yellow croaker were 8–10℃ in spring, 10–14℃ in summer, 16–20℃ in autumn, and 9–12℃ in winter. These results conceivably reflect migration of the small yellow croaker, as well as the variable and complex hydrological environment of the Yellow Sea. Furthermore, there are certain changes in dietary preference during the life history of the small yellow croaker; thus, in addition to environmental factors, prey source and predators may represent factors contributing to the observed distribution of this species.

Abstract:Species diversity is one of the most important characteristics of biological communities and an important factor affecting the function and stability of ecosystems. The variation in diversity has been a topic of great interest in ecological research for many years, whereas β diversity, an important aspect of species diversity, has been studied in terrestrial ecosystems and freshwater ecosystems more than in marine ecosystems. Haizhou Bay is a traditional fishing ground in the Yellow Sea and historically has had rich fishery resources. However, the fishery resources in Haizhou Bay have seriously declined in recent years due to overfishing, environmental pollution, and human activities. The purpose of this study was to understand the temporal and spatial variation in β diversity of the fish species in Haizhou Bay to provide a scientific basis for the conservation of fishery resources and the construction of protected marine areas. The data in this study were collected from fishery resource surveys conducted in Haizhou Bay in the autumn of 2011 and 2013–2019 using bottom trawl. Non-parametric methods, including the Chao’s and Bootstrap approaches, were used to estimate the number of fish species, namely species richness, in the entire area of Haizhou Bay and in each sampling station. On this basis, β diversity was calculated according to the additive principle with a variety of measurement methods, including Sorenson’s index and Cody’s index, which reflects the similarity of species composition between the two groups and the substitutability between groups, respectively. To evaluate the spatial variation in β diversity, survey stations were divided into two groups along the 20 m isobath roughly by K-Means Cluster. The results of this study showed that the richness and β diversity of the fish species in Haizhou Bay decreased significantly in recent years, the Cody’s index decreased, and the Sorenson’s index increased slightly. The result reflected biotic homogenization in the marine ecosystem and it also indicated a remarkable difference in the trend of β diversity between deep water and shallow water. The decline in biodiversity has become a common phenomenon, which is closely related to human activities, especially long-term overfishing. In addition, environmental factors, especially the rise of sea water temperature, also contribute significantly to biotic homogenization. In summary, our research indicated that the abundance and β diversity of the fish species in Haizhou Bay decreased substantially from 2011 to 2019, and these changes were associated with the life history of fish species and their adaptability to the environment. These changes were also closely related to human activities, such as overfishing, environmental pollution, habitat destruction, and the water temperature increase caused by climate change. The driving mechanism remains to be further explored. In-depth studies on β diversity are helpful for understanding the fluctuation of marine fish communities, managing and protecting fishery resources, and providing a reference for constructing marine protected areas, which have great significance to the sustainable use of fishery resources and the protection of biodiversity.

Abstract:To explore the bacterial community structure on the surface of healthy and diseased seedlings of Saccharina japonica during a temporary rearing period and their relationships with seawater, in this study, sequences of 16S rRNA from healthy kelp (HS), diseased kelp (DS), seawater from healthy kelp breeding areas (HW), and seawater from diseased kelp breeding areas (DW) were analyzed using Illumina sequencing technology. The results showed that 32 phyla, 77 classes, 398 families, 797 genera, and 1772 operational taxonomic units (OTUs) were identified. At the phylum level, the dominant bacteria in the kelp samples were Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The relative abundances of Bacteroides, Actinobacteria, and Firmicutes in the HS and DS samples were 19.91%, 10.79%, 15.52%, 37.31%, 1.65%, and 5.92%, respectively, showing substantial differences. At the family level, the relative abundances of Flavobacteriaceae and Rhodobacteraceae in the HS samples were 10.7% and 12.55%, respectively, which was lower than those in the DS samples (33.47% and 21.17%, respectively). The diversity analysis showed that the Ace and Chao indexes between HS and DS samples showed no significant differences (P>0.05), whereas the Shannon and Simpson indexes showed significant differences (P<0.05). The SIMPER analysis showed that the four OTUs (OTU1169, OTU1111, OTU1351, and OTU1353) from the three bacterial families in the diseased kelp provided a difference rate of 35.88%. In summary, the relative abundances of dominant epiphytes in healthy and diseased kelp were significantly different, as was the distribution between species (P<0.05), but there was no significant difference in species richness. OTU1169 and OTU1111, belonging to the flavobacteria, were the main indicators for the diagnosis of diseases in kelp. This study analyzed the interaction between epiphytes and vegetative kelp diseases from the perspective of community structure and diversity and provided a scientific reference for revealing the mechanism of vegetative kelp diseases in the future.

Abstract:The offshore waters of southern Zhejiang are rich in fishery resources and marine species; however, with the influences of overfishing, environmental pollution and other factors, fishery resources have been sharply reduced. Information on fatty acid content and composition can be used to evaluate the nutritive value of a species.In addition, because of the biological specifificity of fatty acids, essential fatty acids are transmitted stably between species and can track food sources and indicate trophic relationships among species. There are many studies analyzing the fatty acid contents of marine species, but there are few reports on the fatty acid contents of marine species specifically along the coast of Zhejiang Province, and few species have been involved. The purpose of this study was to provide references for consumers to choose seafood reasonably, as well as to provide basic data for the construction of food webs in the offshore waters of southern Zhejiang by exploring the characteristics of fatty acids in common marine species from these waters. This included an analysis of the nutritional value of fatty acids and exploring the relationship between fatty acid content and dietary habits. A total of 31 marine species were collected, including 20 marine fishes, 9 types of crustaceans, and 2 types of cephalopods. Three samples were randomly selected from each species for a total of 93 samples. Fatty acids were extracted using Folch’s method (chloroform-methanol solution, V : V = 2 : 1), were methyl esterified, and were then separated and detected using gas chromatography-mass spectrometry. Differences in the composition of the total lipids (TFA), saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-6 series of polyunsaturated fatty acids (n-6 PUFA), n-3 series of polyunsaturated fatty acids (n-3 PUFA), docosahexaenoic acid (C22:6n3, DHA), and eicosapentaenoic acid (C20:5n3, EPA) were analyzed. The results showed that the total lipid content of the marine fishes, crustaceans, and cephalopods ranged from 18.74–153.90 mg/g, 24.65–62.81 mg/g, and 37.23–92.18 mg/g respectively; the ranges of DHA+EPA content were 4.32–38.31 mg/g, 7.22–22.86 mg/g, and 12.48–49.61 mg/g, respectively. The contents of n-3 PUFA, EPA, and DHA in the 31 marine species from the offshore waters of southern Zhejiang were positively correlated with the content of TFA (P<0.01). There were significant differences among the 31 species of marine organisms in the offshore waters of southern Zhejiang. The average DHA/EPA ratios in marine fish and crustaceans in this study were 4.20 and 1.45, respectively. Additionally, the contents of DHA and EPA in crustaceans were relatively similar, whereas the content of DHA in marine fish was higher than that of EPA. DHA has been shown to be more effective than EPA at regulating blood pressure; thus, a higher intake of marine fish may help prevent cardiovascular disease. The mean ratios of SFA, MUFA, and PUFA in marine fish, crustaceans, and cephalopods (Uroteuthis duvauceli and Octopus variabilis) were 1.25 : 0.84 : 1, 1 : 0.67 : 1.75, 1 : 0.18 : 1.56, and 1 : 0.32 : 1.47, respectively; compared with the recommended ratio of 1 : 1 : 1, the content of MUFA was low. Therefore, consumers should consume a variety of seafood products to ensure a balanced intake of fatty acids. In addition, the results showed that the percentages of PUFA and n-3 PUFA were related to the dietary habits of the species, revealing that the species that mainly prey upon phytoplankton and benthic algae expressed higher contents than those of species that mainly prey upon swimming animals, such as fish.

Abstract:In the study of fish biology, stomach content analysis is the most common and important method to evaluate the feeding habits of fish species. In a fishery independent survey, stomach samples were generally collected randomly at different stations. The feeding habits of a predator within a certain area were estimated by calculating the arithmetic mean value of the predator’s diet information from different stations. This method is simple but ignores the spatial variation of the predator. Based on a fishery resources survey in the offshore waters of southern Zhejiang, a total of 750 stomach samples from Bombay ducks (Harpadon nehereus) were collected from March to November, 2019. Combined with the catch per unit effort (CPUE) difference in H. nehereus at different stations, the diet composition, feeding intensity, seasonal variation, and ontogenetic shift of H. nehereus were examined. Since each haul provided us with a group or “cluster” of H. nehereus for a given station, as in a cluster sampling design, this study introduces “cluster sampling estimators” to calculate the feeding habits of H. nehereus. The results showed that the prey items of H. nehereus included 11 prey categories and more than 40 prey species, with the index of relative importance percentage indicating that fishes (IRI%=82.29%) and shrimps (IRI%= 15.77%) were the dominant prey categories. Other categories included cephalopods, crabs, euphausiids, stomatopods, amphipods, etc. The dominant prey species were Benthosema pterotum, Apogon lineantus, H. nehereus, and Acetes chinensis. The main prey items were similar to those found in previous studies from the Yangtze River estuary, Yellow Sea, and other areas in the East China Sea; however, the dominant prey species varied in different sea areas. Obvious seasonal variations were indicated for the feeding habits of H. nehereus in this study: whereas fish were the most important prey group in all seasons, with higher than 85% for IRI% in spring and autumn, the proportion of shrimp consumed by H. nehereus in summer and winter was higher than that in other seasons. The seasonal variation in prey abundance among habitats is one of the main reasons for the seasonal variation in fish feeding habits. The feeding intensity of H. nehereus was higher in spring and autumn and the lowest in winter. The ontogenetic shift of H. nehereus was revealed in this study. With the increase in the body length of H. nehereus, its main prey items transitioned from small-sized items (such as small shrimp) to large-sized items (such as fish). This feeding characteristic is in accordance with the “optimal foraging theory.” With the development of feeding organs, the predation ability of H. nehereus is greatly enhanced, with the phenomenon of cannibalism mainly occurring in the larger group.

Abstract:The Spanish mackerel (Scomberomorus niphonius) is widely distributed in the China Seas. It is a commercially important marine fish species, which has maintained a high yield in China for many years. With the recent decline in fishery resources, S. niphonius has played an increasingly important role in Chinese capture fisheries. Therefore, it is of great significance to analyze the status of fishery resources for the sustainable utilization and rational management of S. niphonius. Catch per unit effort (CPUE), commonly used as an index of the relative abundance of fish populations, is one of the most important data sets used for fishery stock assessment. Fishery-dependent monitoring programs are a common source for collecting data for stock assessment and fishery management, as it is more cost-effective and may collect data on a larger spatio-temporal scale compared with that of fishery-independent survey programs. However, the nominal CPUE calculated based on the fishery-dependent survey data is usually influenced greatly by various factors, such as temporal (e.g., year and month), spatial (e.g., longitude and latitude), and environmental (e.g., sea surface temperature) factors. It is essential to standardize the CPUE before it is used in fishery stock assessment. Generalized additive models (GAM) are commonly applied to standardize CPUE data. Based on the logbook data of monitoring fishing vessels in Shandong Province in 2012–2018, the CPUE and variations in the barycenter of fishing grounds for S. niphonius pair trawler fishery in the Yellow and Bohai Seas were studied. The GAM model was used to analyze the relationship between the nominal CPUE of S. niphonius and the spatio-temporal and environmental factors, such as sea surface temperature, and to standardize the CPUE. The results showed that the nominal CPUE and barycenter of the fishing grounds of S. niphonius had clear monthly and annual changes; the nominal CPUE showed a fluctuating downward trend from 2012 to 2018, and the maximum appeared from September to November each year. The monthly changes in the barycenter of the fishing grounds included a spatial shift from the southeast to the northwest and then to the southeast throughout the year, which was consistent with the migration patterns of S. niphonius. The barycenter of the fishing grounds showed yearly variation, and the variation in longitude was opposite to the trend of sea surface temperature change, whereas the variation in latitude was the same as the trend of sea surface temperature change. The results of the GAM model showed that year, sea surface temperature, longitude, and latitude had an extremely significant effect on nominal CPUE, among which the year had the most significant effect on nominal CPUE. The nominal CPUE showed an increasing trend with sea surface temperature. The standardized and nominal CPUEs had similar variation trends, but the fluctuation range of the standardized CPUE was small, and its value was lower than that of the nominal CPUE.

Abstract:In order to determine the pathogen and pathogenic characteristics of diseased blunt snout bream (Megalobrama amblycephala) in a farm in Hubei Province, as well as to analyze the virulence and drug-resistance characteristics of the pathogen through the whole genome, a strain of pathogenic bacteria (LHW39) was isolated from the liver lesions of the diseased blunt snout bream. Based on 16S rRNA identification and physiological and biochemical characteristics, LHW39 was identified as Aeromonas hydrophila. Multi-sequence typing showed that LHW39 belongs to the ST251 clonal group, the epidemic strain group causing the outbreak of motile Aeromonas septicemia (MAS) in China and the USA. Artificial infection tests confirmed its pathogenicity to blunt snout bream. The median lethal concentration of LHW39 to zebrafish (Danio rerio) was 1.55×105 CFU/fish, suggesting that LHW39 is highly virulent. Drug susceptibility tests demonstrated that LHW39 was resistant to cephalothin. Whole genome sequencing results showed that strain LHW39 contained a chromosome of 5,099,855 bp with an average G+C content of 60.80% and 4,572 coding sequences (CDS). Its complete genome has been deposited at GenBank under the accession number CP050012. Genomic comparative analysis suggested that the virulence genes of LHW39 are plentiful and highly similar to those of other ST251 strains. LHW39 also contains a type VI secretion system (T6SS). In addition, a heat map suggests that the evolution of the virulence-related genes of strains in the ST251 clonal group might be related to the geographical locations or the infected hosts of the isolates. A complete prophage named phAhLHW39 (30.2 kb) is presented in the LHW39 genome, which is highly conserved among ST251 strains and is unique to ST251. Analysis of drug-resistance genes showed that LHW39 contained resistance genes related to antibiotics such as sulfonamides, quinolones, tetracyclines, cephalosporins, and carbapenems, all of which were highly conserved among ST251 strains. In this study, pathogenic and genome-wide comparative analysis of the pathogenic A. hydrophila strain LHW39 was carried out, which provides references for the prevention and control of fish diseases caused by A. hydrophila.

Abstract:The rapid development of China’s aquaculture industry is inseparable from the development and promotion of the facility aquaculture industry, which is also an important guarantee for the development of environmentally friendly aquaculture in China. To fully grasp the development trend of the facility aquaculture industry, the overall situation of global patents, patented technology life cycles, patent technology field, innovative entities, and key patents was analyzed using bibliometric methods. Patent application data were used for analysis, and the retrieval time was December 8, 2020, on the PatSnap platform, based on the keywords and international patent classification (IPC) numbers. Invention patents were the main patent type (56.61%). The number of patent applications in China was the largest, accounting for 79.49% globally, followed by Japan (6.42%), Korea (4.82%), and the United States (3.03%). However, the number and layout of core patents were relatively small in China and were mainly dominated by the United States, Israel, Australia, the Netherlands, and other countries. At present, the research and development of patented technologies in the field of facility aquaculture are in a phase of rapid development. China entered this rapid development stage in 2011. During this time, the number of patent applications by enterprises has increased rapidly and has significantly exceeded those submitted by scientific research organizations, including universities and scientific research institutes. Thus, enterprises have become the most important innovation entity in the field of facility aquaculture in China. The main innovation entities in other countries and regions globally have been dominated by “enterprises”, and the main patent applicants in the past two decades have also been “enterprises”. Technical research and development in the field of facility aquaculture in China is mainly concentrated in A01K63 (containers for live fish, such as aquarium tanks) and A01K61 (aquaculture of, for example, fish, mussels, crickets, lobster, sponges, and pearls), which account for 28.96% and 28.69% of patent applications, respectively. In other countries and regions, A01K61 (52.28%) was the main technical field, followed by A01K63 (36.64%). These two technical fields are current global technological hotspots. This study showed that the development and innovation of China’s facility aquaculture patent technology has promoted the development of China’s facility aquaculture industry. Enterprises have become the main subject of innovation. The innovation of China’s facility aquaculture patent technology has gradually been effectively integrated into the market, which will have a beneficial impact on the industrialization of China’s facility aquaculture. In the future, we should attach great importance to the innovative research and development of patented technologies in this field and track high-quality patents in a timely manner. Furthermore, we should strengthen the patent layout of core technologies on a global scale and occupy the core advantage area of the global facility aquaculture industry. Through the above analysis, we have elucidated the development status and existing shortcomings of our country’s facility aquaculture technology, which is a reference for the development of our country’s facility aquaculture in the future.

Abstract:Resveratrol (RES) is a type of polyphenolic defense compound that is widely found in many plants, such as grapes, knotgrasses, and blueberries. RES has been used as a new green feed additive in the aquatic industry due to its biological activities, such as anti-oxidation, anti-inflammation, anti-bacteria, and immune regulation. The physicochemical properties, bioavailability, biological activities, and regulatory mechanism of RES are summarized in this article, and the application of RES in aquatic production is also summarized. The results showed that appropriate concentrations of RES were beneficial to the production performance, immune health, and fat metabolism regulation in aquatic animals. In addition, RES could effectively prevent bacterial pathogens from infecting aquatic animals. However, the mechanism underlying its biological activities is still not fully understood, and there is a lack of basic research on the appropriate dose for different aquatic animals. In-depth research should be carried out as soon as possible in order to provide reference for further promoting the application of RES to aquatic animals.