Abstract:Turbot (Scophthalmus maximus) is an important economic species extensively cultured in China. In this study, we exerted acute high temperature stress on turbot to identify the expression characteristics of four candidate genes including UBE2H, p53, ZNF469, and MAGI2 genes in the liver, gill, spleen and skin. These genes are derived from the QTL related to high temperature resistance located at high-density genetic linkage maps. The relative expressions of UBE2H, p53, ZNF469, and MAGI2 mRNA in four experimental groups (temperature 20℃, 23℃, 25℃ and 28℃)and one control group (temperature 14℃) were tested using real-time quantitative PCR. Data analysis demonstrated that the four genes were expressed in all tissues, and the expression levels were tissue and temperature specific. The relative expression of UBE2H mRNA firstly increased and then decreased in four tissues. The expression levels in the liver, spleen, and skin tissues increased rapidly at 20℃ and reached a peak value, and peaked at 23℃ in gill tissue. The expression of P53 mRNA increased first and then decreased in four tissues. However, the expression of p53 increased sharply at 28℃ and peaked significantly. It was speculated that the tissue was severely damaged and the cells are heavily apoptotic. ZNF469 and MAGI2 were abundantly expressed at 20℃ in four tissues, than other temperatures. Therefore, we think that both can serve as biomarkers for response to high temperature stress in turbot.

Abstract:Fishery-independent survey is commonly used for collecting high quality biological and ecological data and provides vital parameters for fish stock assessment and management. For fishery-independent surveys, low cost and high precision as a result of reduced sample size may lead to a much greater reduction of survey mortality for the already depleted fishery populations and the ecosystem of fragile estuarine habitats, so that optimization of sampling design is essential for acquiring cost-effective sampling efforts. Computer simulation is usually applied to evaluating sampling designs in identifying an optimal sampling effort to achieve the goals of a survey program. In this study, the effect of sample size on estimation of abundance index was examined for fishery species including Cynoglossus joyneri, Pholis fangi, Chaeturichthys stigmatias, Loligo sp., Oratosquilla oratoria, Charybdis japonica and small-sized fish species in Clupeidae and Engraulidae in a cluster sampling survey based on the data collected from bottom trawl surveys conducted in August, October 2013 and February, May 2014 in the Yellow River estuary and its adjacent waters. The relative estimation error (REE), relative bias (RB), coefficient of variation (CV), and accuracy change rate (ACR) were used to measure the performances (accuracy and precision) of different sampling efforts. In general, these indices including REE, CV and ACR showed similar trends, decreasing with sample size initially and then becoming stable after certain sample sizes during all the four seasons. Most of RB did not show consistently increasing or increasing trends with sampling size. The absolute value of RB of C. japonica, O. oratoria and P. fangi etc showed an obvious increase when the sample size reduced from 3 to 1. The optimal sampling efforts were different for the selected species because the target species had different spatial variabilities. The effects of reducing sampling effort on the precision of abundance index estimation were low when the species had low spatial variabilities. Therefore, the optimal sampling effort for multiple species fishery resources surveys should consider the spatial and temporal distribution patterns of the target species.

Abstract:Drug metabolizing enzyme CYP3A65 is the only member of Danio rerio CYP3A subfamily. Our study was conducted to select appropriate D. rerio developmental stage, by investigating the expression of CYP3A65 and its its upstream nuclear receptor (PXR and AHR2) during developmental stages.The zebrafish in different growth stages were raised, and the whole fish tissues, liver tissues and intestinal tissues were taken. The relative expression levels of CYP3A65, PXR and AHR2 were measured, and the correlation between nuclear receptors and metabolic enzyme mRNA was compared to confirm the regulating effect of nuclear receptors.In whole fish, liver and intestine tissues, the mRNA levels of CYP3A65, PXR and AHR2 were the highest in 144 hpf larvae and 75 dpf juvenile D. rerio. The change trends of metabolic enzyme and nuclear receptors gene expression were consistent, and affected by the proportion of liver and intestine relative to whole fish. The 144 hpf and 75 dpf D. rerio may be in the juvenile stage and throughout the growth phase, and are most suitable for CYP3A65 metabolism studies. There were significant correlations between CYP3A65 and PXR、CYP3A65 and AHR2 mRNA expression, and correlation between CYP3A65 and AHR2 was better. In our later work, the enzyme activity and protein expression will be further investigated during D. rerio development, which would provide more information for the model organism D. rerio.

Abstract:In the paper, the characters of tension in the mooring lines of a single HDPE gravity cylindrical cage under water are studied by experimental tests. The prototype of cage has a perimeter of 40m and a net height of 10m. Based on the Dixon rule of gear tests, two scales are chosen for the experimental model, i.e. λ=10 and λ_a=λ_d=2. The horizontal projections of the front mooring lines are in the same direction of current or incident waves. Uniform current is produced in the whole basin at a velocity of 0 cm/s, 5 cm/s, 10 cm/s and 15 cm/s. Regular waves with a period within the range of 1.3 s to 2.2 s and a height varying from 10 cm to 30 cm are generated. Tensions in the mooring lines are measured. The following conclusions might be drawn from the analysis of measured data. (1) Under the actions of current only, the average tension in the front main cable is greater than that of other lines. Under the actions of waves only, the maximum tension in the rear side main cable is greater than that of other lines. The maximum tension is linearly related to the wave height. The maximum tension of the front main line decreases with the increase of the period. (2) Under the combined effects of waves and currents, the maximum tension in the front main line is greater than that of other lines under high flow velocity, low wave height and high wave period; the maximum tension in the rear side main line is greater than that of other lines under low flow velocity, high wave height and low wave period. (3) Under the combined effects of waves and currents, the maximum tension of each line increases with the increase of the wave height, the increase of the flow velocity, and the decrease of the wave period.

Abstract:In order to identify and characterize the lactate dehydrogenase (LDH) gene and investigate its expression and activity alterations in response to seawater acidification stress in sea urchins, we used database data mining and rapid amplification of cDNA ends (RACE) to identify a novel LDH gene in the sea urchin Strongylocentrotus intermedius (here designated SiLDH). The full-length cDNA of SiLDH was 1 499 bp, including a 1 017 bp open reading frame encoding 338 amino acid residues. Sequence analysis indicated that the predicted SiLDH protein was similar to the LDH homolog in the sea urchin S. purpuratus. Quantitative real-time PCR analysis showed that SiLDH was ubiquitously expressed in coelomic fluid, gonad, tube foot and intestine of healthy adult S. intermedius, with the highest level of expression identified in the gonad. Total LDH enzyme activity in different tissues of S. intermedius from high to low was as gonad > tubefoot > coelomic fluid > intestine. Both SiLDH mRNA expression profiles and total LDH enzyme activity were altered in the coelomic fluid, gonad, tube foot and intestine after 60-day seawater acidification treatments (Control:natural seawater; OA₁:△pH=-0.3; OA₂:△pH=-0.4; OA₃:△pH=-0.5). Our results provide more information about the characteristics and biological functions of the LDH homolog in sea urchins.

Abstract:The net performance of tuna purse seine is influenced by mesh size, leadline weight, flow velocity and other factors. Most of the purse seine fishing vessels in China are used vessels. The age of the vessels is high and the equipment is old. The settling performance of the nets is hardly improved by increasing the weights of the leadline. In order to understand the effect of mesh size on the sinking performance, enclosed effectiveness and net shape, the authors based on our previous research results, net performance measurement at sea and the opinion of the captain, enlarged the mesh size from 260 mm to 390 mm (equivalent to 50%) of the low one third of the main body of the tuna purse seine currently used by the Shanghai Ocean Fishery Co., Ltd. Two model nets with different mesh sizes in the main body were made by the Tauti rule and the comparative tests were conducted through three shooting patterns at 8 cm/s and one at still water in a professional purse seine test tank of Nichimo Co., Ltd. of Shimonoseki Research Institute. The results show that:both the sinking depth and sinking speed of the experimental net with bigger mesh size (45 mm) are greater than that of the control net with smaller mesh size (30 mm)(Sinking depth increased by an average of 1.6%, and sinking speed increased by an average of 1.1%), indicating that increasing the mesh size can improve the sinking performance of purse seine. The pursing time of the experimental net was 14.3% less than that of the control net, and experimental net also kept a good form. The opening areas surrounded by the floatline at the end of shooting are almost identical for both the experimental net and control net; however, at the end of pursing, the opening area surrounded by floatline of experimental net was 1.33 times that of the control net and the opening area of the leadlline was 1.79 times that of the control net, indicating that the bigger mesh netting can provide bigger areas for fish school swimming.

Abstract:Integrated culture of pearl mussel Hyriopsis cumingii and planktivorous fishes, such as Hypophthalmichthys molitrix and Aristichthys nobilis is widely used in commercial freshwater pearl mussel farming. Previous studies reported that stocking Ctenopharyngodon idella and Carassius auratus gibelio in an integrated system comprising H. cumingii, H. molitrix and A. nobilis and feeding C. idella and C. auratus gibelio with formulated feed could increase pearl production and mussel growth. At present, the integrated system of pearl mussel, C. idella, C. auratus gibelio, H. molitrix and A. nobilis has been widely used as a model for freshwater H. cumingii farming. However, the suitable stocking density of C. idella and C. auratus gibelio remains to be determined. Generally, increasing density of the fishes fed with formulated feed can increase either fish production or waste output, and the increased accumulation of toxic inorganic nitrogen (ammonia and nitrite) and organic matters can negatively affect health and growth of the farmed H. cumingii and fishes. Although microbial products have been recognized as a potential technique to alleviate the environmental impact and enhance the production performance in aquaculture practices, knowledge about application of microbial products in Hyriopsis cumingii farming is scarce. In the present study, a 93-day experiment was conducted in land-based enclosures to evaluate the effect of stocking density of the fishes (C. idella and C. auratus gibelio) fed with formulated feed and effective microorganisms (EM) on structure and function of phytoplankton community in an integrated system of H. cumingii, C. idella, C. auratus gibelio, H. molitrix and A. nobilis. Four treatments abbreviated as LF0 (20 C. idella + 10 C. auratus gibelio + 40 mussel + 8 H. molitrix + 2 A. nobilis), LFA (20 C. idella + 10 C. auratus gibelio + 40 mussel + 8 H. molitrix + 2 A. nobilis + EM supplementation), HF0 (40 C. idella + 20 C. auratus gibelio + 40 mussel + 8 H. molitrix + 2 A. nobilis), and HFA (40 C. idella + 20 C. auratus gibelio + 40 mussel + 8 H. molitrix + 2 A. nobilis + EM supplementation) were established. The pearl mussel included 20 grafted mussel and 20 non-grafted mussel. Each treatment was three replicated, and total 12 enclosures were used. During the experiment, species and biomass of phytoplankton were monitored at the intervals of four weeks, and chlorophyll a (Chl.a) and primary productivity were measured at the intervals of two weeks. Results showed that more than 81 phytoplankton species that belonged to 7 phyla, 32 families and 73 genera were identified. Microcyslis sp. and Scenedesmus sp. dominated in phytoplankton community at the early stage of the experiment, and Microcyslis sp., Merismopedia sp. and Coelosphaerium sp. dominated at the later stage. The phytoplankton biomass ranged from 3.2×10⁸ to 38.3×10⁸ cells/L. No significant differences were found in the species composition of phytoplankton among treatments LF0, LFA, HF0 and HFA. The increase of stocking density of C. idella and C. auratus gibelio resulted in the increase of phytoplankton biomass and community respiration and the decline of the primary productivity. EM supplementation did not significantly affect species composition and diversity of phytoplankton, but resulted in the decrease of the ratio of blue-green algae to phytoplankton biomass and the increase of the primary productivity. This study reveals that the fishes (C. idella and C. auratus gibelio) fed with formulated feed should not be stocked at high densities in the mussel-fish integrated system.

Abstract:In order to explore the selectivity of different mesh size codends for Larimichthys polyactis, the traditional selective method (cover net method) was adopted, and a selection experiment was carried out with 5 different mesh sizes (35 mm, 45 mm, 55 mm, 60 mm, 65 mm) codends on canvas stow net in the middle of Zhoushan fishing ground. The Logistic selection model was used to fit the selectivity curve of L. polyactis and the model parameters were estimated by the maximum likelihood method. The results showed that:① during the experiment, the main catch target was L. polyactis, the number and weight accounted for 66.94% and 84.48% respectively. The body length range was 71 to 190 mm, and the average body length was 124 mm; ② with the increase of mesh size, the dominant body length of L. polyactis in the codend was larger than that of the cover nets; ③ when the mesh size for L. polyactis was 35 mm, 45 mm, 55 mm, 60 mm and 65 mm, its L₅₀ was 80.425 mm, 103.496 mm, 119.711 mm, 122.676 mm and 137.026 mm, its SR was 50.202 mm, 52.540 mm, 61.120 mm, 41.730 mm and 63.560 mm, respectively. L₅₀ showed a gradual increase trend; ④ the relationship between the codend mesh size (m) of L. polyactis and L₅₀ needs to be enlarged, and L₅₀:L₅₀=L₅₀=1.776 m+20.300 (R²=0.980); ⑤ the number escape rate of 5 mesh size were higher than the weight escape rate, when the mesh size of codend ≤ 45 mm, escape rate in number and weight of L. polyactis was less than 5%, when the mesh size of codend ≥ 55 mm, escape rate in number and weight of L. polyactis more than 10%, even up to 50%. Comprehensive analysis shows that the mesh size of 55 mm can effectively release juvenile fish of L. polyactis, but the mesh size still needs to be enlarged.

Abstract:Total 720 Takifugu fasciatus (initial weight 39.84 ±3.09 g) were fed with four isonitrogenous and isoenergetic semi-purified diets for eight weeks:control diet (T0) with hydrolysable tannin-free protein sources (containing 43% fish meal) and three experimental diets supplemented with 0.25%, 0.75%, and 1.25% hydrolysable tannin (called T1, T2, and T3, respectively). In experimental diets, crude protein content was balanced by casein when fish meal level decreased, and the ratio of casein to tannin was nearly equal to that of protein content to tannin content in rapeseed meal (16.8:1).The results showed that the weight gain rate was not influenced, while feed coefficient ratio decreased significantly with increasing tannin level; the muscle crude lipid of T2 was significantly higher than those of T0 and T1, and the amino acid level of T0 was significantly higher than other groups; for liver antioxidant index, the activity of catalase (CAT) in T0 was significantly lower than other groups, while total antioxidative capacity (T-AOC) in T0 was significantly higher than other groups, the activity of superoxide dismutase (SOD) and the content of malonaldehyde (MDA) in T3 was significantly higher than other groups; for serum antioxidant index, the activity of SOD showed no significantly difference (P > 0.05), while the content of MDA in T0 was significantly lower than other groups, and the activity of catalase (CAT) decreased with increasing tannin level; for serum biochemical indices, the activity of ALT first increased, and then decreased at T2, paralleling the result of ALT in liver, the content of album (ALB) in T1 was higher than T3 (P > 0.05) and T1 was significantly higher than T0 and T3 groups, the total protein (TP) content of T1 was higher than T0, and T1 was significantly higher than T2 and T3; the activity of intestinal amylase in T1 and T2 groups were significantly higher than T0, the activity of protease increased with increasing tannin level in both stomach and intestine, the activity of lipase decreased in stomach; the expression of T2R1mRNA in T3 was significantly higher than T0 both in tongue and intestine(P<0.01); the expression of HSP70 mRNA in liver in T0 was significantly higher than T3. Furthermore, the preference decreased with increasing tannin level before feeding test, while after 8-week domestication, the fish preferred to diet containing 0.75% tannin in all groups. In conclusion, feeding obscure puffer with diet containing no more than 1.25% supplemental hydrolysable tannin would not decrease growth and feed coefficient ratio, while it would change the digestion of protein, lipid, carbohydrate and anabolism of protein, and when the amount of supplemental hydrolysable tannin was up to 1.25%, antioxidant ability and anti-stress ability were both damaged.

Abstract:Cyprinid herpesvirus 2 (CyHV-2) is an emerging pathogen of the crucian carp, Carassius carassius, which has caused huge economic losses in China and appears to be spreading worldwide. The objective of this study was to produce and characterize new polyclonal antibodies against CyHV-2 ORF121 that were suitable for diagnostic use and the investigation of ORF121 function. The open reading frame (ORF) of 121 was amplified from the culture supernatant of the CyHV-2. ORF121 was subcloned into the pGEX-4T vector and recombinant protein was expressed in Escherichia coli. The purified recombinant protein ORF121 was used to immunize mice and polyclonal antibodies were obtained. The recombinant protein ORF121 was purified under urea conditions then used to 6-week-old BALA/c mice to prepare its polyclonal antibody. Western Blot and indirect fluorescence assay (IFA) assay were used to validate the ORF121 polyclonal antibody. We found the recombinant protein ORF121(rORF121) could be expressed in E. coli. aggregated in the form of inclusion body. The specificity of the anti-ORF121 polyclonal antibody was confirmed by Western Blot. IFA with anti-ORF121 polyclonal antibody for the detection of CyHV-2 infected RyuF-2 cells was developed in this study. In conclusion, the anti-ORF121 polyclonal antibody will be a valuable tool in further studies to elucidate the mechanisms of viral infection and CyHV-2 diagnosis.

Abstract:Ningde area is the main producing area of Larimichthys crocea in China. It is a useful reference for revealing the morphology, digestive structure and quality characteristics of cultured L. crocea in Ningde, and for the deep processing and sustainable breeding of L. crocea. In this paper, the biological parameters and food physicochemical analysis, the shape parameters of L. crocea, the proportion of each part and the rate of meat yield, the organ parameters of the digestive tract, the diameter of myofibrils, texture, color, cooking loss rate, water loss rate, pH, amino acid composition and taste, fatty acid composition, etc. were measured and analyzed. The results showed that the condition factor of L. crocea in Ningde area was 2.25%, the fish fillets accounted for 57.32% of the body weight, and the meat yield was high; the fish head, skeleton and fish tail accounted for 27.35% of the body weight. In the digestive system, the fish stomach is more developed, there are 15 ring pyloric caeca, and the length of the fish intestine is moderate, which reflects the digestive characteristics of the feed of cultured L. crocea. Its internal organs accounted for 10.73% of body weight, while the liver accounted for 36.65% of the visceral weight. The fish maw was thicker, accounting for 15.74% of the visceral weight. The liver and fish maw were worthy of deep processing. The cultured L. crocea has white muscle color, pH 6.66-6.74, muscle fiber diameter of 104.21μm. The muscle fiber density is 153.13 per square millimeter. The fish meat is tender. Its amino acid type is complete, and essential amino acids account for 41.93% of the total amino acids, and the content of lysine is higher, the umami amino acid accounts for 45.92% of the total amino acid, and the fish meat is fresh and sweet. The fatty acids in muscle are mainly unsaturated fatty acids, accounting for 62.04% of the total fatty acids, of which essential fatty acids account for 28.45% and EPA and DHA account for 20.01% of the total content. It is a high-quality food supplement for essential fatty acids and high unsaturated fatty acids.

Abstract:To study the fish community structure in islands area, a fishery-independent survey was conducted in August and December of 2016, February and May of 2017. The cluster analysis, nonmetric multidimensional scaling (nMDS) and biological environment correlation analysis (BIOENV) were used to study the composition of fish community in our study area. A total of 96 species were collected, which belonged to 77 genera, 47 families and 12 orders. The Perciformes has maximum ratio, which accounted for more than 50% of their biomass and abundance. Harpadon nehereus was the dominant species throughout the year. In addition, the dominant species in spring were Psenopsis anomala, Collichthys niveatus, and Cynoglossus robustus; the dominant species in summer were Larimichthys polyactis, Trichiurus lepturus, and Chaeturichthys hexanema; the dominant species in autumn and winter were Collichthys lucidus and Coilia mystus. The fish community in the Ma'an Archipelago and its eastern waters can be divided into group I (the sites sorrounding island and reef), group Ⅱ (the sites adjacent to reef), and group Ⅲ (the sites far off island and reef). There were significant differences in species composition between groups, and seasons (R=0.651~0.977), except the spring group I and group Ⅲ, group Ⅱ and group Ⅲ. BIOENV analysis showed that the bottom water temperature had the most significant impact on the fish community compared to bottom salinity and water depth.

Abstract:In order to estimate the fish resources and distribution of spawning grounds of the four major Chinese carps of early life history stages, we collected samples of fish eggs and larvae at Huangshi section during May to July in 2015 and 2016. A total of 67 fish eggs and 23 948 larvae were collected during the survey, Hypophthalmichthys molitrix and Ctenopharyngodon idella accounted for 77.0% and 18.1% of the total numbers, respectively. In 2015 and 2016, we estimated there were 0.20×10⁸ and 4.69×10⁸ eggs of the four major Chinese carps drifting through the Huangshi section, respectively; while there were 19.40×10⁸ and 13.65×10⁸ larvae, respectively. The spawning grounds of the four major Chinese carps are located in Lijiazhou, Ezhou, Daijiazhou and Daoshifu sections. Compared with the historical data, the location of spawning grounds had no significant change. It is suggested that enhancement and releasing is needed and the spawning habitat of the four major Chinese carps should be well-protected in the channel regulation project.