• ISSN 1000-0615
  • CN 31-1283/S
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Effects of different water temperatures and dietary phosphorus levels on the production performance, tissueand water phosphorus content of Macrobrachium nipponense
SUN Miao, HE Chaofan, ZHANG Ling, JIANG Guangzhen, LIU Wenbin, LI Xiangfei
In Press  doi: 10.11964/jfc.20201212554
[Abstract](51) [FullText HTML](24) [PDF 2368KB](2)
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Water temperature and dietary phosphorus levels are crucial for the growth of crustaceans. However, the interactions between both factors are still poorly understood in crustacean culture, as brings difficulties in advancing the feed utilization. This experiment was conducted to explore the effects of different temperatures and dietary phosphorus levels on the production performance, tissueand water phosphorus content of M. nipponense. Using a 3×3 factorial design, nine groups (respectively named 20/1.1, 20/1.5, 20/1.9, 25/1.1, 25/1.5, 25/1.9, 30/1.1, 30/1.5, 30/1.9)were divided, including three water temperatures (20, 25 and 30 °C) and three dietary phosphorus levels (1.1%, 1.5% and 1.9%). Each diet was tested by 4 replicates. Prawns were held in the indoor circulation systems for 8 weeks. The results showed that, in terms of water temperatures, the final body weight (FBW), specific growth rate (SGR) and weight gain rate (WGR) of the 30 °C group were all significantly higher than those of the 20 °C, but showed no statistical difference with those of the 25 °C. However, the opposite was true for feed intake and feed conversion rate (FCR). In addition, the phosphorus retention efficiency (PRE) and plasma phosphorus levels of the 30 °C group were both significantly higher than those of the other two groups, meanwhile the hemolymph phosphorus level of this group was significantly higher than that of the 25 °C group, but showed no significant difference from the 20 °C group. In terms of dietary phosphorus levels, the FBW, WGR, PRE and plasma calcium level of the 1.9% phosphorus level group were all significantly lower than those of the other groups, while phosphorus intake and FCR showed the opposite trend. The SGR of the 1.9%phosphorus level group was significantly lower than that of the 1.5% group, but showed no statistical difference with that of the 1.1% group. Besides, the whole-body phosphorus contents of the 1.1% group was significantly lower than that of the other groups, and the hemolymph calcium content of this group was significantly higher than that of the 1.9% group, but there was no significant difference from the 1.5% group. Plasma alkaline phosphatase (AKP) activities of the 1.5% group was significantly higher than that of the 1.1% group, but showed no statistical difference with those of the1.9% group. Furthermore, feed intake, phosphorus intake, PRE, hemolymph phosphorus level and plasma AKP activities were all significantly affected by the interaction between water temperature and dietary phosphorus level with the maximized values observed in the 20/1.1, 25/1.9 and 30/1.9, 30/1.1, 30/1.9, 25/1.5 group, respectively. Additionally, water phosphorus levels increased significantly with increasing sampling times, while the water phosphorus level of the 20/1.5 group was significantly higher than those of the 25/1.1 and 30/1.1 groups. Overall, M. nipponense in the 30/1.1 group obtained the best growth performance and feed efficiency coupled with low phosphorus emission.
Effects of threonine supplementation in poultry by-product meal (petfood grade) replacement diet on growth performance, intermediary metabolism and immunity response in largemouth bass (Micropterus salmoides)
XU Yujue, WANG Wenqiang, YANG Peng, HE Chaoqun, QIN Yawen, SONG Fei
In Press  doi: 10.11964/jfc.20201112498
[Abstract](78) [FullText HTML](34) [PDF 2453KB](0)
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In order to investigate the effects of different dietary threonine levels on growth performance, glucose and lipid metabolism, immunity and utilization rate of poultry by-product meal (petfood grade) of largemouth bass(Micropterus salmoides). Three isonitrogenous and isolipid diets were designed using M. salmoides with an initial body weight of (4.16±0.06) g as the research subjects: (TC diet: threonine control group, LH diet: low threonine group and TS diet: threonine supplementation group) were cultured for for 8 weeks. Present results showed that compared with the TC diet, the LH diet significantly decreased the growth performance, feed efficiency and body nutrient composition, threonine addition could promote those differential effects caused by fishmeal totally substituted by poultry by-product meal. Moreover, the LH diet also suppressed the concentration of plasma nutrients and free amino acids than the control diet. TS diet had significant effects on elevating the plasma free amino acids concentration and made no notable difference compared to the TC diet. The mRNA expression level demonstrated that threonine supplementation markedly ameliorated the inhibition of anabolism, aggravation of catabolism and cellular inflammatory which caused by complete replacement of fishmeal with poultry by-product meal. Studies have shown that appropriate threonine supplementation could promote the growth performance by improving nutrient anabolism and immune response and inhibiting catabolism in M. salmoides.
Effects of temperature and feeding rate on postprandial metabolic response in juvenile Percocypris pingi
PU Deyong, DING Yuxiao, LIU Xiaohong, PU Yingmei, GU Haoran, HE Xingheng, WU Yi, WANG Zhijian
In Press  doi: 10.11964/jfc.20200912390
[Abstract](59) [FullText HTML](22) [PDF 7466KB](0)
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The marked increase in the metabolic rate that occurs following feeding is commonly referred to as specific dynamic action (SDA). Previous studies on SDA in animals have found that the meal type, temperature, body size, feeding frequency, fasting and feeding rate all have significant effects on SDA. The study of postprandial metabolic response in Percocypris pingi has not been reported. To investigate the effects of temperature and feeding rate on postprandial metabolic traits in juvenile P. pingi, the experimental fish [body weight: (38.35±0.49) g, body length: (14.22±0.10) cm] were fed with loach (Misgurnus anguillicaudatus) (feeding rates: 1%, 2%, 4% body mass at 15 °C; 1%, 2%, 4% and 6% body mass at 25 °C) for 4 weeks as diet acclimation at 15 °C and 25 °C in indoor recirculating aquaculture systems. After that, the oxygen consumption rate was detected and parameters related to postprandial metabolic were calculated. Results showed that at the same feeding rate, resting metabolic rate, peak metabolic rate, total energy expenditure on SDA and SDA coefficient of 25 °C acclimation group were significantly higher than those of 15 °C acclimation group. The SDA duration of 25 °C acclimation group at 2% and 4% feeding rate was significantly shorter than that of 15 °C acclimation group. At the 25 °C, fish of higher feeding rates (4% and 6%) presented significant higher peak metabolic rate, factorial metabolic scope, SDA duration and total energy expenditure on SDA than those of lower feeding rates (1% and 2%) at 25 °C, and times to peak metabolic rate of 4% and 6% feeding rate were significantly earlier than those of 1% and 2% feeding rates as well. However, the SDA coefficient showed an opposite situation: higher feeding rate presented significant lower values. At the 15 °C, Peak metabolic rate, factorial metabolic scope, SDA duration and energy expended on SDA of 4% feeding rate group were significantly higher than those of 1% and 2% feeding rates. Nevertheless, no significant difference in the time to peak metabolic rate and the SDA coefficient among all feeding rates were observed at 15 °C. All the above information suggested that the water temperature of 25 °C is more beneficial to the rapid food digestion and absorption by juvenile P. pingi; and the fish may fulfill the increased energy demand during digestive process by means of increasing peak metabolic rate and prolong SDA duration with the increase of feeding rate. The results of this study provide important reference data for the breeding practice and species protection of P. pingi.
Dietary arginine requirement and effects of dietary arginine levels on the metabolism of Scophthalmus maximus
FU Fengshun, LIU Chengdong, WANG Xuan, ZHOU Huihui, MAI Kangsen, HE Gen
In Press  doi: 10.11964/jfc.20210312693
[Abstract](53) [FullText HTML](22) [PDF 2293KB](2)
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The purpose of this study was to investigate the arginine requirement and effects of dietary arginine levels on the growth and metabolism of turbot (Scophthalmus maximus). Turbots with an initial body weight of (43.07±0.10) g were selected as the research object. Five isonitrogenous and isolipid diets (51% crude protein and 12.5% crude lipid) were formulated with casein and gelatin as the main protein sources and fish oil and soybean lecithin as the lipid sources. The arginine contents of the diets were 1.92%, 2.65%, 3.40%, 4.17% and 4.88% of dry matter by adding crystalline amino acid mixture, respectively. (The corresponding diet number was 1, 2, 3, 4 and 5, respectively). The group fed 1.92% arginine level diet served as control group. Each treatment was set to 3 repetitions, each repeating 12 fish, and the breeding period was 10 weeks. The results showed that 3.40% to 4.88% arginine (6.66% to 9.52% of dietary protein) significantly improved the growth performance and feed utilization of turbot compared with the control group. According to the broken line regression analysis based on specific growth rate (SGR), the optimal dietary arginine requirement of turbot was estimated to be 3.17% of dry matter (6.21% of dietary protein). Appropriate dietary arginine levels significantly increased body protein content and plasma total protein level, while significantly decreased plasma glucose level. In addition, appropriate dietary arginine levels significantly enhanced the expression of genes related to fatty acid synthesis, fatty acid β-oxidation, glycolysis, tricarboxylic acid (TCA) cycle and oxidative phosphorylation, while significantly decreased the expression of genes associated with amino acid degradation in liver. The results demonstrated that 3.40% to 4.88% arginine (6.66% to 9.52% of dietary protein) can regulate the nutrient metabolism and promote the growth of turbot.
Preliminary analysis on regional differences of fishing habits of marine fishing vessels in Zhejiang Province–taking double trawlers as an example
LIU Yong, CHENG Jiahua, CHEN Ting
In Press  doi: 10.11964/jfc.20200412247
[Abstract](423) [FullText HTML](186) [PDF 6051KB](10)
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Marine fishing vessels are now under localized management, but their offshore production has the characteristics of operating in waters under cross-regional jurisdiction. Traditionally, local fishing vessels generally have significant local characteristics because they follow local fishing experience and traditional fishing habits in inshore waters. However, with the steelization and large-scale of fishing vessels, the operating space of marine fishing continues to expand, so to understand and grasp whether the current marine fishing has regional characteristics differences, it has indispensable scientific and theoretical guiding significance for fishery sampling statistical survey and accurate fishery management. In this paper, the double-towing fishing vessels in Zhejiang, a major marine fishery province, are selected as the research object. Through a large sample random sampling survey, the annual production data of double-towing fishing vessels in three prefecture-level regions of Zhejiang Province are obtained, and the regional differences of fishing capacity (CPUE, catch per unit of effort) and catch structure are analyzed. The results show that except for September, there are significant regional differences in fishing capacity among the three regions, and Ningbo is relatively close to Taizhou, and there are significant differences in catch structure among the three regions in the whole year. Taizhou area is relatively independent and has its own category, while the similarity between Ningbo and Zhoushan is relatively high. Considering the interaction between fishing capacity and catch structure, the difference among the three regions is more significant. Although the production activities of China’s marine fishing vessels are wider and more flexible than those of 40 years ago, the differences in regional characteristics of fishing operations are still obvious, indicating that China’s marine fishery management should be more accurate. in order to continuously improve the level of spatial scientific management of marine fisheries in China.
Evaluation of suitable body size for tagging and releasing of yellowfin seabream (Acanthopagrus latus)
LÜ Shaoliang, LIN Kun, ZENG Jiawei, ZHANG Shenzeng, CHEN Zhijie, WANG Xuefeng
In Press  doi: 10.11964/jfc.20200412224
[Abstract](488) [FullText HTML](243) [PDF 5862KB](19)
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The data obtained by tag-recapture method are commonly used to evaluate the fish population dynamics and the effect of stock enhancement. However, to ensure the accuracy of the recapture data, it is necessary to choose the appropriate fish size for tagging. Acanthopagrus latus was employed to conducted two indoor experiments. In the first experiment, the effects of T-bar anchor tags on growth, survival and tag retention of A. latus from four size groups (average body length: 5 cm, 7 cm, 11 cm, and 14 cm, respectively) were examined and the size-dependent effects on survival and tag retention were tested. In the second experiment, different mix ratios of tagged fish and untagged fish from two size groups (average body length: 7 cm and 14 cm, respectively) were set for simulated catching and the catching results were resampled. The differences in catching results between groups were compared, the differences between catching result and resample result were also compared. The results show that: ① there was no significant difference in the specific growth rate between 7 cm, 11 cm and 14 cm groups. ② the survival rate was size-dependent. All the tagged fish of 5 cm group died in the first week after tagging. The survival rate of other size groups was 77.5%, 92.5% and 100%, respectively. The relational expression of logistic regression between body length and the probability of survival was: P=exp(0.099X-6.900)/[1+exp(0.099X-6.900)]. ③ the tag retention rate was high (97.5% in 7 cm group, 100% in 11 cm and 14 cm group) but seemed to be unrelated with fish size. ④ there was no significant effect of fish size on the catching result and the resampling result but significant effect of mix ratio of tagged and untagged fish on it. In summary, it is recommended that study objectives and cost should be considered when choosing the appropriate fish size for tagging stocking fishes like A. latus. If the probability of survival needs to be >50%, the tagged individuals with body length should be >7 cm. If >75%, the body length should be >8 cm. If >95%, the body length should be >10 cm. And it is worth further study to know about the appropriate proportion of tagged fish for tagging and releasing.
Relationship between spatial distribution of Oratosquilla oratoria and environmental factors in Shandong offshore based on optimized BP neural network model analysis
LI Pengcheng, ZHANG Chongliang, REN Yiping, XU Binduo, XUE Ying
In Press  doi: 10.11964/jfc.20200712336
[Abstract](406) [FullText HTML](268) [PDF 1623KB](22)
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As a common machine learning method, BP neural network model is widely used in species distribution models to analyze the relationship between biological distribution and environmental factors. Compared with the traditional regression models, this model can flexibly deal with the nonlinear relationship between variables. However, there are substantial uncertainties in parameter setting as result of its complex structure, which may affect the prediction and application of this model. This study considered there approaches to optimize the model parameters, including the group method of data handling, genetic algorithm and adaptive algorithm, to improve initial weights and the number of hidden nodes of the model, respectively. Seven combinations of optimized BP models were implemented based on the survey data obtained from fishery resources and environment in Shandong offshore between 2016 and 2017. Our results showed that there were significant differences in the predictive performance of the seven optimization models. The predictive performance of the one-way and two-way optimization models was approximately the same. The root mean square error and the square of residual error were 0.35 and 1.94 respectively, which were smaller than the initial model's 0.52 and 2.40, and the maximum correlation coefficient was 0.45, indicating that the optimization effect of the model was the best. After the comparison and optimization, it was found that the resource density of Oratosquilla oratoria was basically different with the increase of bottom salinity while the resource density of O. oratoria was significantly different with the increase of bottom temperature. In addition, the increase of water depth in the optimal model compared with the initial model was a key environmental factor,which had an important effect on the resource density of O. oratoria. In this study, the parameter optimization method of the BP neural network model was further developed, which proved that the parameter optimization had important effect on the prediction performance of the BP model, and the model optimization was of great significance for the analysis of the relationship between resource density and environmental factors.
Research progress on aquaculture and feeding regulation mechanism of mandarin fish
LI Songlin, HAN Zhihao, WANG Xiaoyuan, CHEN Naisong
Accepted Manuscript  doi: 10.11964/jfc.20200812371
[Abstract](543) [FullText HTML](314) [PDF 5996KB](70)
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Mandarin fish (Siniperca sp.) is a valuable freshwater economic fish in China, and its production has been approached 330000 tons in 2019. The manuscript introduced aquaculture situation of this fish from three aspects, including aquaculture status, aquaculture mode and selective breeding. The feeding habit of this fish is unique, which relies on prey fish for all lifetime. For many years, prey fish are mainly used to feed mandarin fish, and the way of raising fish by fish not only causes the waste of fishery resources, but also aggravates the damage to environment and resources. Thus, the manuscript also summarized the external factors affecting feeding characteristics of this fish species from environmental factors and feed properties, and analyzed the internal factors from the aspects of feeding sense organs and feeding regulation factors. This may be helpful to adjust the feeding habits of this fish through artificial intervention, and provide necessary basis for its conversion to eat formula feed. Meanwhile, it is necessary to strengthen the research on the feeding regulation mechanism and nutritional physiological demand characteristics, so as to achieve the breakthrough of compound feed and promote the green and healthy development of its aquaculture industry.
Effects of Chaetoceros muelleri and Rhodotorula sp. on the development, growth and survival of the planktonic larvae of sea cucumber (Holothuria leucospilota)
YU Zonghe, HUANG Wen, MA Wengang, HUO Da, LIU Wenguang, XU Qiang
Accepted Manuscript  doi: 10.11964/jfc.20200512277
[Abstract](433) [FullText HTML](191) [PDF 5967KB](12)
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The sea cucumber Holothuria leucospilota is an edible sea cucumber species, which is widely distributed in the shallow water of tropical and subtropical Indo-Pacific Ocean. Nowdays, the H. leucospilota has become an important fishery resource owing to the continuously increasing market demand, however, overfishing activities will put this species at risk of extinction in the future. Artificial breeding of H. leucospilota is considered as a useful strategy to solve this problem. The use of suitable substitute diets is an economical and efficient approach for breeding of planktonic larvae of sea cucumbers. In this study, the microalgae Chaetoceros muelleri and Rhodotorula sp. were fed to planktonic larvae of sea cucumber H. leucospilota, either singly or in combination, to evaluate their nutritional quality. The C. muelleri and Rhodotorula sp. were mixed in 4: 0, 3: 1, 2: 2, 1: 3 and 0: 4, by volume, and they were labeled as groups A, B, C, D and E, respectively. Results showed that larvae in group A, which fed solely on C. muelleri, exhibited the fastest growth and development among the five groups, larvae could develop to the auricularia stage on the 10th day and the doliolaria stage on the 18th day; meanwhile, survival of the larvae in group A was the highest, and the survival rate in this group was 58.73%±2.75% at the end of the experiment. By contrast, the larvae in groups D and E always stayed in the early auricularia stage, and individuals in these two groups could not form the hyaline spheres during the whole study period. The larvae in group E exhibited a negative growth during the whole study period, and survival rate of this group was only 22.22% ± 5.50% at the end of the experiment. In general, negative effects on the development, growth and survival of the planktonic larvae of H. leucospilota were found with the increase in the proportion of the Rhodotorula sp. in the diet, and therefore Rhodotorula sp. was not a suitable substitute diet for breeding of H. leucospilota.
Embryonic development and morphological characteristics of larvae a ndjuvenile of cobia (Rachycentron canadum)
KUANG Jiehua, CHEN Gang, MA Qian, HUANG Jiansheng, ZHANG Jiandong, SHI Gang, WANG Zhongliang, TANG Baogui
Accepted Manuscript  doi: 10.11964/jfc.20200812389
[Abstract](503) [FullText HTML](231) [PDF 6480KB](24)
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Cobia(Rachycentron canadum) is a highly prized recreational specie worldwide as well as a promising candidate for aquaculture because of its rapid growth rate, strong disease resistance and high quality flesh. Studying the morphometrics and physiology of embryos, larvae and juveniles to obtain information about their early life history is the first step and key to the successful aquaculture of a fish species. In order to find out the characteristics and rules of the early development stage of cobia, the morphological characteristics and developmental characteristics of embryo, larvae and juvenile were studied by microscopic observation. The fertilized eggs obtained by artificial spawning were spherically shaped and buoyant, there was an oil globule in the central, with an egg diameter of (1.245±0.065) mm and an oil globule diameter of (0.325±0.027) mm. The fertilized eggs hatched 26 h 30 min after fertilization in the sea water at 27.0±0.5℃, salinity of 29 and pH of 8.3. The embryonic development process was divided into 7 stages, including fertilized egg stage, the cleavage stage, the blastocyst stage, the gastrula stage, the neurula stage, the organogenesis stage and the hatching stage (total 24 developing periods). The total length (TL) of newly hatched larvae was (3.254±0.096) mm. The larvae opened their mouths and exhibited blackened eyes at 3 days post hatching (dph) with a TL of (4.453±0.267) mm, meanwhile, the yolk-sac decreased in volume by approximately 80%. The yolk-sac and oil globule completely absorbed at 5 dph (TL of 6.007 mm±0.171 mm) and 7 dph (TL of 8.173 mm±0.317 mm) respectively, and the larvae completely entered the exogenous nutritional stage. The intestine of the newly hatched larvae was thin, short, and straight, and the intestinal physiological curve formed at 9 dph when the larvae were (10.053±0.594) mm in TL. The larvae started to develop into juvenile at 14 dph (TL of 19.933 mm±1.118 mm) when the development of the dorsal fin, pectoral fin, anal fin and caudal fin was completed. At 22 dph, the juvenile with a TL of (41.140±3.779) mm, there were some scales on the caudal peduncle formed. The 46 dph juvenile reached (116.667±5.916) mm in TL, the whole body surface covered with cycloid scales and their general appearance was similar to that of the adults, except for the shape of caudal fin. These results indicated that the fertilized egg diameter and newly hatched larvae size of cobia were both larger, and its early developmental characteristics had certain adaptability to the ecological behaviors. The present study could provide basic knowledge for investigating biology and artifical propagation of cobia.
Accumulation of nitrite and responses of energy metabolism exposed tonitrite stress in Litopenaeus vannamei
LI Zhongshuai, MA Shen, SHAN Hongwei, WANG Teng, XIAO Wei
Accepted Manuscript  doi: 10.11964/jfc.20201112474
[Abstract](466) [FullText HTML](208) [PDF 12257KB](19)
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Litopenaeus vannamei is one of the most important breeding economic varieties in the world because of its fast growth, strong environmental adaptability, and short growth cycle. Along with the intensive culture model of L. vannamei popularized rapidly, large quantities of harmful substances accumulate in the culture environment which seriously affect the growth and health of L. vannamei. Nitrite enters through gills and accumulates in tissue, which has severely toxic effects on cultured shrimp. In the present study, to explore the accumulation of nitrite and changes in enzymes activities related to energy metabolism exposed to nitrite in L. vannamei [body length (6.8 ± 0.3) cm, weight (4.0 ± 0.6 g)], shrimps were exposed to four nitrite concentrations of 0 (control), 0.8 (11.2 mg/L NO2-N), 4 (56 mg/L NO2-N) and 8 mmol/L (112 mg/L NO2-N) for 96 h and then recovered for 12 h. Each experimental treatment included six replicates. Three replicates were used for sample collection, and the other three replicates were used to calculate the cumulative mortality of the shrimp. At 0, 6, 12, 24, 48 and 96 h of the nitrite stress, the hemolymph, hepatopancreas, muscle, gill and intestinal of 9 shrimp in each group were randomly selected for the determination of the index. Additionally, shrimp death number were recorded every 12 h. The results indicated that the shrimp mortality rate increased with nitrite concentrations. At the end of nitrite stress, shrimp mortality in control group, 0.8 mmol/L group, 4 mmol/L group and 8 mmol/L group were 10.7%, 32.0%, 42.7% and 52.0%, respectively. Within 6 hours of exposure, nitrite accumulated significantly in the gill, hemolymph, intestine, hepatopancreas, and muscle tissues of shrimp, and was positively correlated with stress concentrations. The maximum accumulation of nitrate in gills, hemolymph, hepatopancreas, intestine and muscle were 50.1 mg/kg, 43.2 mg/L, 20.7 mg/kg, 33.5 mg/kg and 14.9 mg/kg. In the same stress concentration group, nitrite accumulated the most in gill and the least in muscle, and the accumulation in gill was about 3 times than that in muscle. The activity of Na+-K+-ATPase in hepatopancreas and muscle of shrimps were significantly increased at 0.8 and 4 mmol/L, but significantly decreased in muscle of 8 mmol/L during the exposure period. The activity of AMPK in the hepatopancreas in the stress groups increased compared to the control group, and showed a positive correlation with the stress concentration. During the recovery period, except for hemolymph (8 mmol/L group), 1-hour recovery rate of nitrite in shrimp tissues in the stress groups were above 50%, and the hepatopancreas and gill showed the highest recovery efficiency exceeding 74%. The recovery time of hemolymph, gill and intestine were the shortest within 6 hours. In addition, the content of nitrite in water increased significantly. This study indicates that nitrite can be accumulated to shrimp tissues in a short time and accelerate the process of energy metabolism. Nitrite would excrete from the body rapidly during recovery in order to reduce the toxic effects.
Guiding out-migrating juvenile grass carp Ctenopharyngodon idella by pulsed direct current electricity with different electric parameters at different flow velocities
SHI Xunlei, HU Cheng, DA Wa, NI Ma, WANG Qingfu, SHI Xiaotao, LIU Guoyong
Accepted Manuscript  doi: 10.11964/jfc.20200712354
[Abstract](479) [FullText HTML](214) [PDF 6270KB](10)
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The necessity for fish to migrate safely is a key requirement for the existence of many fish populations. Anthropogenic constructions, such as dams and weirs, that block rivers make it difficult, if not impossible, for fish to reach their upriver spawning grounds. Also, these constructions are also very dangerous for fish moving down the river because dams are built associated with hydroelectric power station plant intakes where fish are injured or killed on the gratings, pump screens, and in turbine chambers. Mild fields of pulsed, direct current (DC) electricity have been used extensively in deterring invasive fish species as well as in reservoir fishery, but directional fish guidance using electric deterrence arrays to guide fish toward desirable passage locations or away from dangerous areas has received little attention. The effectiveness of the electric barriers is quite variable and testing is often lacking for a variety of water velocity conditions. To explore the effects of different electric parameters of electrical barriers on the avoidance behavior of the juvenile grass carp C. idella with body length of (10.22±2.01) cm and body mass of (34.25±3.62) g, a double-row type of electrical barrier based on pulsed direct current electricity was established and orthogonal designed experiment of three factors, including pulse voltage, frequency and width, four levels was adopted to optimize the blocking performance of the electrical barrier under the static water condition. To explore the effects of water flow conditions on the blocking efficiency of electric barriers using the optimized electric parameters recommended for static water conditions, three flow conditions at a generalized model of fishway entrance were utilized to test the attractive efficiency of fishway entrance. The results showed that, under static water conditions, the working condition 7 had the highest blocking rate (88.67±1.10)% and lower average stupefaction rate and that the factors affecting blocking efficiency are pulse voltage, pulse frequency and pulse width respectively. Determined by analysis of variance and multiple comparison, the optimal electric parameters under static water conditions for blocking efficiency were the pulse voltage of 160 v/m, the pulse frequency of 6 Hz and the pulse width of 16 ms. Under the optimal electric parameters, the experimental fish had minimal injuries when subjected to electric barriers. By employing the optimum electric parameters recommended for static water conditions, the active electric barrier can dramatically boost the aggregation rate and average retention time ratio at the fishway entrance when the channel velocity was 0.15 m/s. When the channel velocity was 0.25 m/s and 0.35 m/s, the aggregation rate and average retention time ratio with the active electric barrier were not enhanced significantly than that in the inactive electric barrier. Therefore, the recommended electric conditions for optimal blocking effect is to set the pulse voltage of 160 v/m, the pulse frequency of 6 Hz and the pulse width of 16 ms under static conditons. The attractive effects of fishway entrance could be enhanced by the active electrical barriers with the best flowing water velocity being 0.15 m/s. These results will have important reference significance for the practical engineering of the electrical barrier arrangement. The pulsed direct current electric systems have the potential to improve fish passage at anthropogenic barriers. Additional research should investigate the effectiveness under variable electric field voltage and various water flow velocities for fish of various size and shape depending on the species and its ethology.
Genomic analysis of Bacillus velezensis LF01 strain and the biocontrol effect of its secondary metabolites
ZHANG Defeng, GAO Yanxia, KE Xiaoli, WANG Yajun, REN Yan, SHI Cunbin
Accepted Manuscript  doi: 10.11964/jfc.20201012442
[Abstract](567) [FullText HTML](240) [PDF 8191KB](9)
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Bacillus velezensis is a novel species in the Bacillus genus which exhibits a broad spectrum of antimicrobial activities due to it produces various secondary metabolites. The current research on B. velezensis mainly focuses on its use for the promotion of the growth of animals and plants, for antagonizing pathogens, and on investigating its gene cluster which play significant roles in biological control, drug research and development, and food fermentation. The aims of this study are to explore the gene clusters related to antagonistic substances of B. velezensis LF01 strain based on the whole genome sequencing, and to evaluate the biological safety and biocontrol effect of the antagonistic substances of the LF01 strain. In this study, the whole genome of the LF01 strain was sequenced based on the third generation Nanopore sequencing platform, and its taxonomic status was identified based on ANI and DDH online analysis, and the genetic evolution at genome level. The gene clusters related to antagonistic substances of the LF01 strain was analyzed based on antiSMASH software. The hydrolysis activity of the LF01 strain to carbohydrate was analyzed based on CAZyme database. The toxicity of the antagonistic substances of LF01 strain to Oreochromis niloticus and Danio rerio was evaluated by intraperitoneal injection. The biocontrol effect of the antagonistic substances of LF01 strain to O. niloticus was evaluated by artificial infection after 5 d of feeding O. niloticus. The complete genome of LF01 strain was a total length of 3974023 bp and the GC content was 46.56%, and it contains 3843 coding genes. Compared to B. velezensis, the ANI and DDH values of LF01 strain were ≥97.66% and ≥80.10%, respectively. Furthermore, the genomic evolution analysis showed that LF01 strain was clustered with B. velezensis. These results indicated that LF01 strain was identified as B. velezensis at the genomic level. The LF01 strain contains nine gene clusters related to antagonistic substances, including bacillaene, bacillibactin, bacillomycin D, bacilysin, difficidin, fengycin, macrolactin H, plantazolicin and surfactin, which accounts for 8.83% of the total genome sequences. In addition, LF01 strain contains a large number of CAZymes related to the degradation of cellulose, hemicellulose, starch, chitin, pectin, peptidoglycan and glucan. The antagonistic substances of the LF01 strain showed high biological safety to O. niloticus and D. rerio, and they were significantly enhanced the resistance of O. niloticus against S. agalactiae infection. In conclusion, the LF01 strain contains large number of gene clusters for biosynthesis of secondary metabolites related to antagonistic substances. The antagonistic substances were found to be safe for O. niloticus and D. rerio, and feeding O. niloticus with them significantly improved the diseases resistance of fish. Therefore, the antagonistic substances of LF01 strain have a broad development and application prospect as biocontrol agents to improve bacteria diseases control in aquaculture.
Effect of dietary choline level on growth performance, body composition and serum antioxidant activity of juvenile largemouth bass (Micropterus salmoides)
ZHOU Yue, WANG Weilong, LI Songlin, LYU Hongyu, ZHANG Song, CHEN Naisong, HUANG Xuxiong
Accepted Manuscript  doi: 10.11964/jfc.20200812380
[Abstract](670) [FullText HTML](321) [PDF 6523KB](50)
Abstract:
An experiment was conducted to investigate the effects of dietary choline content on growth performance, body composition, and serum antioxidant activity of juvenile largemouth bass, Micropterus salmoides. Graded choline chloride levels of 0, 700, 1 400, 2 100 and 2 800 mg/kg were supplemented to basal diet to formulate five isonitrogen and isoenergy practical diets containing choline of 2 369.57 (control group), 2 716.90, 2 993.49, 3 443.60 and 3 799.05 mg/kg, respectively. Each diet was randomly assigned to triplicate cages of 20 fish with an initial average weight of (20.00±0.10) g for 56 days. The results showed that the weight gain rate (WGR) and specific growth rate (SGR) of the fish first increased and then decreased with the increase of dietary choline chloride, and reached the maximum when the dietary supplementation was 2 100 mg/kg, which were significantly higher than those of the control group. The survival rate (SR), hepatopancreas somatic index (HSI), viscera somatic index (VSI), and condition factor (CF) of the fish were not significantly affected by dietary choline chloride supplementation. When the dietary choline chloride supplementation reached 2 100 mg/kg or above, the lipid contents in muscle and liver of the fish were significantly decreased than those in control. Compared with the control group, the total antioxidant capacity, superoxide dismutase and catalase activities were significantly increased and the content of malondialdehyde in serum was significantly decreased in the groups which were dietary supplemented 1 400 mg/kg, 2 100 mg/kg and 2 800 mg/kg choline chloride. The maximum of lysozyme activity and minimum of aspartate aminotransferase activity appeared in the group treated with dietary choline chloride of 2 100 mg/kg the dosage was, which were significantly different from those of the control group. All these results indicated that the suitable dietary choline chloride supplementation could significantly improve growth performance, reduce liver fat content, and enhance the serum's antioxidant capacity. Regression analysis showed that the recommended amount of choline chloride in the practical diet of juvenile largemouth bass was 2 008.50 ~ 2 398.16 mg/kg (the dietary choline content was 3 432.09 ~ 3 530.23 mg/kg).
Characteristics of formation related genes (PyMFG) of monospores and analysis of differential expression in Pyropia yezoensis
SONG Shanshan, DING Hongchang, YAN Xinghong
In Press  doi: 10.11964/jfc.20190311710
[Abstract](932) [FullText HTML](345) [PDF 2804KB](29)
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In our study, a complete open reading frame of PyMFG was obtained by RT-PCR based on the sequence of differentially expressed genes (Contig-21827) screened by transcriptome sequencing of Pyropia yezoensis. Sequence analysis showed that the ORF of the PyMFG was 1 224 bp in length and encoded a polypeptide fragment of 407 amino acids with a molecular weight of 46.24 ku, and theoretical pI of 9.08. Domain analysis revealed that the protein contains a conserved TEA domain and a YAP domain, which belongs to the TEA-ATTS superfamily domain. We found that the protein and fungal conidia forming proteins clustered into one large branch with close genetic relationship through multiple sequence alignment and phylogenetic analysis. In addition, the comparison of the ability of releasing monospores and qRT-PCR analysis between different strains indicated that the expression trend of PyMFG in PY26W and PY26W' was highly consistent with macroscopic statistical results, while the trend in PY26R and PY26R' were exactly existed difference. By inference, the gene type and molecular mechanism regulating the formation and release of monospores in the parental (PY26W) and partial parental strain (PY26W') and the female parental (PY26R) as well as partial female strain (PY26R') existed certain difference, leading to the divergence between the macroscopic statistical results of monospores and the qRT-PCR results.
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2021, 45(8): 0-0.  
[Abstract](0) [FullText HTML](0) [PDF 29718KB](0)
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2021, (8): 1-2.  
[Abstract](0) [FullText HTML](0) [PDF 221KB](0)
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Molecular cloning and functional study of mannose receptor gene in Epinephelus coioides
ZHANG Menglan, QIN Zhendong, LU Zhijie, ZHAO Lijuan, PAN Gan, LIN Li
2021, 45(8): 1279-1295.   doi: 10.11964/jfc.20200812385
[Abstract](169) [FullText HTML](81) [PDF 7269KB](7)
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Mannose receptor (MR), also known as CD206, is an endocytosis receptor involved in pathogen recognition and antigen presentation. As a link between innate immunity and adaptive immunity, MR plays an important role in immune response. Viral nerve necrosis (VNN) caused by nerve necrosis virus (NNV) is a highly contagious neuropathological disease, which has caused the death of more than 50 important farmed juvenile fishes worldwide. At the same time, NNV is also one of the main viral pathogens causing huge economic losses to the Epinephelus coioides culture industry. Innate immunity can recognize pathogens by combining pattern recognition receptor (PRR) with pathogen-associated molecular pattern (PAMP). C-type lectins belong to PRR. MR as a member of C-type lectins family, is of great significance to study whether MR has immune function in NNV. Most of the studies on MR in fish are focused on the antibacterial activity of MR, but the relationship between MR and antivirus in fish is unknown. In order to study the immune function of EcMR gene against red grouper nerve necrosis virus (Red-spotted grouper nervous necrosis virus, RGNNV), EcMR gene was cloned and expressed. The results showed that the EcMR cDNA full length sequence was 4 877 bp, and its open reading frame encoded 1446 amino acids. The protein domain of EcMR was composed of a signal peptide, an extracellular ricin-like β-type clover domain (RICIN), a fibronectin type Ⅱ domain (FN Ⅱ), eight tandem C-type lectin-like domains (CLECTs) and a transmembrane domain. The results of real-time quantitative PCR (qRT-PCR) showed that EcMR gene widely existed in 8 examined tissues and the relative expression of mRNA was in the following order of gill > head kidney > brain > spleen > liver > peripheral blood > heart > muscle. The results showed that RGNNV could proliferate rapidly in GF-1 cells and significantly activate the expression of EcMR gene at 6 h and 24 h after infection. In order to further explore the effect of RGNNV on GF-1 cells, the apoptosis of GF-1 cells infected by RGNNV was detected by the Alexa Fluor® 488 annexin V/Dead Cell Apoptosis Kit. The results showed that RGNNV infection could promote the apoptosis of GF-1 cells, and the apoptosis rate increased with the prolongation of infection time. At the same time, the results of qRT-PCR and enzyme activity assay showed that RGNNV infection could significantly promote the transcription level of apoptosis-related genes, and the expression of inflammatory cytokines and the enzyme activity levels of Caspase-3, Caspase-8 and Caspase-9. To sum up, this study successfully cloned the EcMR gene and revealed its correlation in the process of RGNNV invasion. The results of this study will provide some basic theoretical reference for the prevention and control of grouper viral diseases.
Cloning and expression of ASDIGIRR and ASTRAF6 genes of Acipenser sinensis
ZHANG Lifeng, TANG Dongdong, ZHENG Chuwen, DENG Dan, GUO Huizhi, ZHANG Shuhuan, ZHANG Wenbing, XU Qiaoqing, LI Ningqiu
2021, 45(8): 1296-1306.   doi: 10.11964/jfc.20200812383
[Abstract](575) [FullText HTML](255) [PDF 6298KB](37)
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Acipenser sinensis is one of the ancient and rare fishes in China between teleost fish and cartilaginous fish, but it is vulnerable to different diseases in the process of artificial reproduction and culture, so it is necessary to deeply study the immune regulation of A. sinensis to provide theoretical basis for its prevention of diseases. A single Ig-IL-1R-related molecule (SIGIRR) and tumor necrosis factor receptor-associated factor 6 (TRAF6) are two important signal transduction elements in the signal transduction pathway of toll-like receptors. In this study, homologues of SIGIRR and TRAF6 of A. sinensis, named ASDIGIRR and ASTRAF6, were identified, and their expression levels in normal tissues and Poly (I:C) induced expression were investigated. Results show that ASDIGIRR and ASTRAF6 were expressed in 10 tissues of healthy sturgeon, and the highest expression was found in intestinal tract and head kidney, respectively. After incubating A. sinensis spleen cells with Poly(I:C), the expression of ASDIGIRR was significantly down-regulated at 3 h, and returned to the normal level at 6 h, then increased to the highest level at 24 h and then decreased, and at 48 h still higher than the control group. While the expression of ASTRAF6 reached the highest level at 6 h, and maintained till 24 h, then decreased to the lowest level at 48 h. The results show that ASDIGIRR and ASTRAF6 play an important role in the immune defense of A. sinensis against pathogen invasion.
Genetic structure analysis of Megalobrama terminalis, Culter alburnus, Chanodichthys mongolicus and their hybrids based on genotyping by sequencing
LIU Kai, FENG Xiaoyu, SHEN Yubang, MA Hengjia, LI Jiale, GUO Wei, XIE Nan
2021, 45(8): 1307-1316.   doi: 10.11964/jfc.20200712319
[Abstract](456) [FullText HTML](194) [PDF 5837KB](12)
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Distant hybridization is an essential means of breeding among aquatic animal species, genera, subfamilies, and even families, combining parents’ dominant traits to obtain excellent new hybrid varieties. Previous studies on Megalobrama and Culter’s distant hybridization show that Megalobrama and Culter’s hybrid offspring have significant heterosis. However, the analysis of the genetic structure of the fish hybridized from Megalobrama and Culter is still relatively limited, and there is little research on single nucleotide polymorphism markers (SNPs). This study aims to analyze the genetic structure of Megalobrama terminalis, Culter alburnus, Chanodichthys mongolicus, and their hybrids by high-quality SNPs obtained by genotyping by sequencing (GBS) technology. In the study, the total DNA extracted from the fin strips of 6 individuals that included M. terminalis, C. alburnus, C. mongolicus, and their hybrids (F1), was double digested. Simplified genome sequencing was performed using Stacks software to construct a reference genome for SNP comparison. As a result, six individuals produced 7.01 GB of clean data, with an average of 1.17 GB per sample. All samples were used as a group to detect SNP mutations. A total of 399 145 SNP sites were detected. After quality control filtering, 97 911 SNP sites were obtained. SNP analysis indicated that, of parents and their hybrids, the average observed heterozygosity was 0.339 4. The average expected heterozygosity was 0.285 3. The average polymorphic information content was 0.273 7, average nucleotide diversity was 0.372 7, the average minimum allele frequency was 0.247 2, and the average genotyping rate was 93.94%. The principal component analysis (PCA) showed that M. terminalis, C. alburnus, C. mongolicus, and their hybrids clustered at different points, but the clustering points of the two hybrids of M. terminalis and C. alburnus were close. The PCA’s result indicated apparent genetic differentiation among M. terminalis, C. alburnus, C. mongolicus, and their hybrids. Based on the genetic differentiation index and genetic distance between different populations, the results show that the differentiation indexes between M. terminalis, C. alburnus, C. mongolicus, and their hybrids are 0.309 6-0.894 0, and the genetic distance is 0.370 5-2.244 3. The phylogenetic tree constructed using the maximum likelihood (ML) method shows that M. terminalis, C. alburnus, C. mongolicus, and their hybrids are distinguished. C. mongolicus firstly formed a new branch. M. terminalis (♀) × C. mongolicus (♂) was separated as a single branch. However, M. terminalis, C. alburnus, and their hybrids formed a broad branch. In this big branch, M. terminalis first differentiated and formed a separate branch. M. terminalis (♀) × C. alburnus (♂) differentiated again. Finally, M. terminalis (♂) × C. alburnus (♀) differentiated. The genetic structure diagram further supports the analysis results of the phylogenetic tree. The three parents are divided into three subgroups. The hybrids of M. terminalis and C. alburnus are obtained by crossing M. terminalis and C. alburnus. In comparison, the hybrids of M. terminalis (♀) × C. mongolicus (♂) are obtained by crossing M. terminalis (♀) and C. mongolicus (♂). This study will provide more genetic data for the hybrid breeding of M. terminalis, C. alburnus, and C. mongolicus, such as providing SNPs for constructing a high-density genetic map and screening SNP s associated with traits.
Comparative analysis of skin and eye transcriptome in the Gobiopterus lacustris
LI Xueyou, XIE Minghua, HUANG Chengqin, WANG Chun, WANG Zhongduo, GUO Yusong, DONG Zhongdian
2021, 45(8): 1317-1326.   doi: 10.11964/jfc.20200912401
[Abstract](627) [FullText HTML](265) [PDF 6655KB](25)
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Gobiopterus lacustris is a kind of small fish with strong adaptability to salinity and easy to raise in laboratory. It is an ideal model organism and environmental indicator species, whose body is transparent and its organs can be seen through naked eyes. In order to explore the cause of the transparent body color of G. lacustris, the transcriptome analysis of skin and eye of G. lacustris was carried out. A total of 103 686 unigenes were obtained by de novo splicing. The N50 and average length were 1 456 and 2 490 bp, respectively. In Nr, Nt, KO, SwissProt, PFAM, GO and KOG databases, 57 380, 37 343, 31 700, 51 277, 47 020, 47 555 and 25 604 unigenes were annotated respectively. KEGG enrichment showed that tyr, tyrp1 and tyrp2 were significantly down regulated in melanin production pathway. In addition, the results showed that there were 8 113 differentially expressed genes (DEGs) in the skin and eyes of G. lacustris, of which 3 174 were up-regulated in the skin and 4 939 in the eyes. The verification of 10 DEGs by qPCR confirmed that the RNA-Seq analysis was correct. This study enriches the body color research of G. lacustris, provides data for the utilization of G. lacustris genetic resources, and also provides a reference for further study on the formation mechanism of gorgeous body color of fish.
Expression analysis of CYP2J3-like gene at different growth rates of Litopenaeus vannamei
HUANG Shiyu, ZHANG Lili, WANG Guodong, WANG Yilei, LU Xiqin, HUANG Yongyu, YANG Zhangwu
2021, 45(8): 1327-1339.   doi: 10.11964/jfc.20200912407
[Abstract](482) [FullText HTML](250) [PDF 12920KB](34)
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As the most important cultured shrimp in China, Litopenaeus vannamei constitutes about 70% of the world's cultured shrimp production, and has high commercial value. With the development of culturing technology, high-density farming has become a trend. In order to obtain a commercial size in a short time, it is necessary to cultivate some varieties that grow fast. Single nucleotide polymorphisms (SNPs) brought genetic diversity research into a new stage. SNPs widely existed in genome, and they serve as suitable markers for linkage map, genome wide association studies (GWAS), and marker assisted selection (MAS) of target traits. There were few researches to discover SNPs of important phenotype in L. vannamei, and therefore there was still insufficient information of SNPs available for genetic diversity studies of L. vannamei. Especially, the discovery of growth-related SNPs by transcriptome sequencing was rarely reported in L. vannamei. With the development of next generation sequencing (NGS), the cost of sequencing has greatly fallen, which makes SNPs identification feasible in non-model species. RNA-seq based on NGS has been used widely, and it can identify SNP markers efficiently, because it focuses on the functional information in the genome with expression level of functional gene. In this study, SNPs of a P450 gene and its potential transcriptional factors were detected in different growth rate individuals by RNA-seq. We hope to give an example for the effective use of transcriptome data and a way for the accumulation of genetic and breeding data of shrimp. The inbreeding and crossbreeding offspring of four L. vannamei strains with diverse genetic backgrounds were cultured in net cages of ponds. The top five fastest growing individuals or top five slowest growing individuals in each net cage were put into a pool, respectively. The two kinds of RNA pools (rapid-growing group, RG; slow-growing group, SG), which were sequenced by RNA-seq, were used to find different expression genes and SNPs. The target DNA fragments, which were amplified from two kinds of DNA pools (RG and SG) by PCR, were sequenced by NGS to find SNPs. A different expression P450 gene, which was selected by comparing transcriptomes of two RNA pools of L. vannamei, was named LvCYP2J3-like with a 1 488 bp open reading frame encoding a protein of 495 aa and an integral P450 domain, which might be involved in the inactivation of ecdysones. Six transcription factors of LvCYP2J3-like were predicted by bioinformatics. They are TATA-box-binding protein (TBP), TBP1, TATA element modulatory factor (TMF), pancreas transcription factor (PTF), PTF1A and PTF1A1. The variance analysis of the 7 gene by q-PCR showed there was significant difference of expression levels in tissues, development stages and molting cycle. LvCYP2J3-like was detected in all tissues samples. The expression levels from high to low were eyestalk, gill, intestinal tract, muscle, hepatopancreas and haemocytes. Multiple comparisons showed that there were significant differences between the two groups (P < 0.05). The expression pattern of PTF1A was similar to that of LvCYP2J3-like, with the highest expression in eyestalk and the second in gill (P < 0.05), but no expression was detected in other tissues. LvCYP2J3-like had significantly different expressions in five development stages, with the highest in mysis larva stage (P < 0.05). The expression pattern of PTF and PTF1A was similar to LvCYP2J3-like in development stages. LvCYP2J3-like had a similar pattern with TBP in molting cycle, and there was the highest expression level in premolt stage D1 (P < 0.05). The expression level of LvCYP2J3-like, PTF and TBP in SG were higher than that in RG (P < 0.05), but PTF1A1, TBP1 and TMF had higher expression levels in RG (P < 0.05). There were 4 and 11 SNPs with significant difference of allele frequency (P < 0.05), in sequences of LvCYP2J3-like and its predictive transcription factors, respectively. The expression pattern of LvCYP2J3-like implied that it played a role in development and molting cycle. Its expression level was closely related to environmental stress. The results suggested that genetic diversity of these genes was related to their activities and expressions, which affects the growth rate of shrimp. This study will provide useful data for the genetic and breeding research of L. vannamei.
Redescription and phylogenetic analysis of Myxobolus tricostatus (Myxozoa: Myxobolidae)
LIU Xinhua, WENG Meiqi, SONG Rui, ZHAO Yuanli, LI Aihua, ZHANG Jinyong
2021, 45(8): 1340-1349.   doi: 10.11964/jfc.20200712343
[Abstract](529) [FullText HTML](279) [PDF 6239KB](14)
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Myxobolus tricostatus was found initially to infect the gills of grass carp in the late 1970s with simple and insufficient taxonomic data, so the taxonomic validity was problematic. In order to supplement description and verify the validity of M. tricostatus, we redescribed M. tricostatus collected from Lake Tangxun in Wuhan city, Hubei Province, using the integrative taxonomic approach of combining myxospore morphology, molecular data and ecological information of host and infection site, which has been widely accepted for the taxonomy of Myxozoa. Here, the plasmodia, tissue tropism and molecular data of M. tricostatus are first provided. The morphological features of the concerned species are as follows: whitish plasmodia infecting the gills measured (2.4±0.3) (2.1-2.7) mm in length and (0.8±0.1) (0.6-0.9) mm in width; mature spores encapsulated by a transparent mucous envelope were ovoid in frontal view and fusiform in sutural view, measuring (10.3±0.4) (9.4-11.0) μm long, (9.5±0.5) (8.7-10.9) μm wide, and (7.4±0.5) (6.4-8.0) μm thick; no "V"-shaped folds were observed on the posterior end of the spore; three parallel ridges could be observed in sutural view; two equal polar capsules were pyriform and coiled with 7-8 turns of polar filament. Histological observation showed that the plasmodia dwelled between the gill filaments, and no serious inflammation was found in the surrounding tissues. BLAST search indicated that M. tricostatus was most similar to M. elegans with the similarity of 89.58%, which was definitely below the intraspecies similarity range. Phylogenetic analysis revealed that M. tricostatus branched with M. elegans from the gills of Leuciscus idus and Rutilus rutilus with high support values within the clade of Cyprinidae gill-infecting Myxobolus spp. including M. enoblei, M. minutus and M. bibullatus from the gills of Catostomidae fish. The present phylogenetic results further confirmed that host affinity and tissue tropism provide strong evolutionary signal for tissue-infecting Myxobolidae. In conclusion, we provided here supplemeemtary morphological, histological and molecular data of M. tricostatus, and verified the validity of its classification.
Effects of sexual maturity and body size on statolith shape of Sthenoteuthis oualaniensis in the Northwest Indian Ocean
WANG Honghao, HE Tao, LU Huajie, LIU Kai, CHEN Xuanyu, HE Jingru, CHEN Xinjun
2021, 45(8): 1350-1360.   doi: 10.11964/jfc.20200712348
[Abstract](428) [FullText HTML](260) [PDF 6242KB](21)
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In this paper, the effects of sexual maturity and body size on the statolith shape of Sthenoteuthis oualaniensis in the northwest Indian Ocean were studied, the growth inflection points of statolith shape were evaluated, which would provide a basis for the subsequent studies on the population identification and life history of S. oualaniensis. Statolith, which is mainly composed of dorsal dome, lateral dome, rostrum dome and wing region, is one of the most important hard tissues of Cephalopods to study the age, growth, population structure and life history. According to the samples of S. oualaniensis totaled 1 009 in number collected in the northwest Indian Ocean from February to May of 2019 by the Chinese light falling-net fishery fleets, the total statolith length (TSL), lateral dome length (LDL), wing length (WL) and maximum width (MW) are considered as the indicators of external form growth, and the ratio of MW to TSL is considered as the indicator of changes in statolith shape. The external form growth and statolith shape changes affected by sex, gonad maturity and individual size are analyzed by the analysis of variance (ANOVA) and Least-significant difference (LSD). The results indicated that the changes of TSL, LDL, WL and MW between different sexes were statistically significant. For both female and male samples, the changes of TSL, LDL, WL and MW between different gonad maturity and different mantle length ranges were also statistically significant. However, changes of ratio of MW to TSL in different sexes showed no significant differences but changes in different gonad maturity and different mantle length ranges showed very significant differences. The study showed that sexual maturation and size of S. oualaniensis had an obvious effect on its statolith growth in both males and females. Stage III gonadal maturity and 300-500 mm mantle length are the growth inflection points of statolith shape of female individuals, while there is no distinct inflection point in male individuals. The characteristic parameters of statolith increased rapidly with the growth of gonad and mantle length before the inflection point, while increased slowly after the inflection point.
Spatial autocorrelation of Priacanthus spp. resources in the northern South China Sea
LIU Yuxi, WANG Xuefeng, LÜ Shaoliang, ZENG Jiawei, CHEN Guobao
2021, 45(8): 1361-1373.   doi: 10.11964/jfc.20200512256
[Abstract](448) [FullText HTML](191) [PDF 11258KB](17)
Abstract:
Understanding the spatial autocorrelation characteristics of the distribution of economic fish is helpful to reveal the distribution pattern of its habitat and the formation mechanism of fishing grounds, which provides a basis for the evaluation and rational exploitation of the resources. Due to long-term overfishing, the fishery resources in the northern South China Sea have declined seriously, especially in the shallow area of 100-m isobath. As an important fishing target of bottom trawling in the South China Sea, the resources of Priacanthus spp. are under great pressure, so exploring the pattern characteristics of the spatial distribution of the resources can provide a certain reference basis for the sustainable utilization and scientific management of the resources. However, some studies denied that the spatial autocorrelation was affected by the spatial scope of the study area, and the spatial autocorrelation varied greatly under different analysis scales, thus weakening the actual effect of fishery resources assessment and scientific management. Therefore, based on the data of bottom trawl fishery in the northern South China Sea by a fishery information network from 2009 to 2014, this study used the methods of global spatial autocorrelation and local spatial autocorrelation to analyze the dynamic changes of spatial autocorrelation of Priacanthus spp. resources. And the incremental spatial autocorrelation analysis was added to improve the accuracy of the research results. The results were as follows: ① the results of global spatial autocorrelation analysis showed that in the whole study area, the interannual resources of Priacanthus spp. were mainly in low-density area and less in high-density area. ② according to the incremental spatial autocorrelation analysis, the resources of Priacanthus spp. showed a strong spatial autocorrelation within the scale of 76-87 km, and showed a significant aggregation distribution pattern. ③ the local spatial autocorrelation analysis showed that the distribution of hot and cold spots of Priacanthus spp. resources varied greatly from year to year, and the hot spot fishing areas were mainly concentrated between the 50-m and 100-m isobath in the middle part of the study area. The cold spot fishing areas were concentrated in the sea area near the 50-m isobath. In this paper, the incremental spatial autocorrelation method was introduced to explore the spatial autocorrelation of Priacanthus spp. resources, which provided a new idea for mining the temporal and spatial distribution characteristics of fishery resources.
Fish community structure and biodiversity in the offshore waters of Zhoushan Islands in spring and autumn
YU Nanjing, YU Cungen, XU Yongjiu, ZHENG Ji, LIU Kun, ZHANG Peiyi
2021, 45(8): 1374-1383.   doi: 10.11964/jfc.20200612287
[Abstract](450) [FullText HTML](203) [PDF 8060KB](20)
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In order to understand the species composition, spatial distribution, biodiversity, and community structure characteristics of fish resources in the waters off the Zhoushan Islands, a trawl survey was conducted in the waters off the Zhoushan Islands in April (spring) and October (autumn) 2018. Studies have shown that: (1) there are 106 species of fish in the waters off Zhoushan Islands, belonging to 12 orders, 47 families and 80 genera, including 63 species in spring, belonging to 12 orders, 34 families and 49 genera, and 85 species in autumn, belonging to 12 orders, 45 families. (2) the number of fish species in this survey is 63 in spring and 85 in autumn. Compared with the historical survey results, the total number of fish species significantly reduced in spring, but slightly increased in autumn. This may be due to the previous use of beam drag shrimp nets, and bottom trawl nets were used in this investigation. The difference in nets may cause differences in the main fishing targets, or it may be due to the different layout of survey stations; (3) the dominant fish species in the two seasons changed. Obviously, the dominant species in spring are Lophius litulon, Lepidotrigla japonica and Apogon lineatus, while in autumn the dominant species are L. litulon and A. japonicum; (4) The value of fish biodiversity index is greater in autumn than that in spring, and the evenness index (J') of spring and autumn is relatively small compared to diversity index (H') and richness index (D), and the value of biodiversity index in spring and autumn basically increases with the increase of water depth, and the water depth interval is higher than 80 m. In spring and autumn, the horizontal distribution of D, H', and J' values is lower in the western part of the survey sea area and lower in the sea area near the island. The open sea area far from the islands in the south is greater. However, since there are only 1 and 3 stations with a water depth greater than 80 m and less than 50 m, and it is also related to factors such as seasonal fish activities, and the water depth in the outer waters The degree of impact on biodiversity and the specific reasons need to be further explored; (5) through cluster analysis and non-metric multi-dimensional scaling analysis, it can be obtained that 3 communities are divided into 3 communities at a similarity level of 35% in spring and 45% similarity in autumn. It is divided into two communities at 45% level. The species similarity in autumn is higher than that in spring, and the biomass and species level in spring are lower than those in autumn. The composition of fish communities in waters where the depth gradient does not change greatly depends on temperature. The changes in water temperature caused changes in the dominant species and dominance of fish in the sea, and the migration of migratory fishes caused changes in the concentration of fish populations, which may be one of the main reasons affecting the stability and changes of fish communities in the waters off Zhoushan Islands. (6) the ABC curve shows that the spring fish community structure outside the Zhoushan Islands is undisturbed, which may be caused by the small temperature difference between different stations in the sea area in spring and the relatively stable environment. The biomass dominance curve in autumn has always been below the abundance dominance curve, which indicates that fish individuals are generally small, mainly small fishes, and some large individuals with obvious biomass dominance are almost non-existent. They are perennial and large in size. There are very few fishes, and the fish communities off the Zhoushan Islands are seriously disturbed. There is a large number of supplementary groups in autumn, which has a certain impact on the size of fish communities. Therefore, the ABC curve to determine the stable state of the community needs further discussion.
Niches of four large crustacean species in Laizhou Bay
LI Fan, CONG Xuri, ZHANG Xiaomin
2021, 45(8): 1384-1394.   doi: 10.11964/jfc.20200812378
[Abstract](399) [FullText HTML](193) [PDF 6216KB](14)
Abstract:
Niche theory explains mechanisms of interspecific coexistence and competition in communities. Chinese shrimp (Fenneropenaeus chinensis), swimming crab (Portunus trituberculatus), Japanese stone crab (Charybdis japonica), and Japanese mantis shrimp (Oratosquilla oratoria) are all large-bodied commercially exploited crustacean species in Laizhou Bay, China, with similar food habits. Populations of two of these species, F. chinensis and P. trituberculatus, are also regionally enhanced. Study of the community status, interspecific associations, and spatial niche characteristics of these four crustacean species is warranted to guide stock enhancement and fishing quota management. Data for analysis of community status and spatial niche were collected by bottom-trawl surveys at 20 stations in summer from 2010 to 2019. Representative samples of these four crustacean species, and their potential food sources were collected in 2010, 2011, 2018 and 2019. Using stable carbon and nitrogen isotopes we analyze trophic levels, nutritional niches, and diets of these crustaceans. Average F. chinensis biomass (51.0 g/h) was lowest, followed by P. trituberculatus (107.0 g/h). In most years, O. oratoria and C. japonica were most dominant, and F. chinensis and P. trituberculatus were typically important species in the community. Associations between these four species are not strong, with a significant positive association occurring mainly between F. chinensis and the other three species. The niche width of C. japonica is greatest (2.45), followed by O. oratoria (2.13), F. chinensis (1.92), and P. trituberculatus (1.93). A high niche overlap is apparent between F. chinensis and the other three species; trophic levels of each are similar, ranging 3.02-3.28. The total niche area of F. chinensis is the greatest, while that of P. trituberculatus is similar to those of C. japonica and O. oratoria. Nutritional niche overlaps between P. trituberculatus and C. japonica are relatively high. Proportionally more bivalves are ingested by F. chinensis than any of the other species, for which diets are more homogeneous. Although populations of P. trituberculatus and F. chinensis have expanded through enhancement, the crustacean community structure in Laizhou Bay has not changed greatly. On the basis of community status, inter-species connectivity, spatial niche width and overlap, trophic level and nutritional niche, and the diets of these four crustaceans, F. chinensis is least competitive with other taxa, and P. trituberculatus is more competitive with C. japonica and O. oratoria. To maximize benefits of regional crustacean enhancement, we suggest consideration be given to competition between species, and niche similarities, to determine appropriate release sites and quantities.
Analytical research of spatial distribution of fish larvae and juveniles in summer and autumn in the eastern Chongming, Yangtze River Estuary
LIU Huan, CHEN Jinhui, WU Jianhui, ZHONG Junsheng, HAN Mengting, ZHAO Chen
2021, 45(8): 1395-1405.   doi: 10.11964/jfc.20200412230
[Abstract](650) [FullText HTML](272) [PDF 6473KB](28)
Abstract:
The CEB (Chongming Eastern Beach) is located on the crestal plane of the diluted water at the mouth of the Yangtze River. Under the action of strong currents and tides, it forms a wealth of food and provides a unique place for growth and development of fish larvae. To investigate the distribution and diversity of fish larvae, using big larval net (mesh size of 0.5 mm) to conduct 10 min horizontal trawl, while collecting real-time data of environmental parameters of the water column including temperature (SST), salinity (SSS), depth (DEP), turbidity (TUR), and chlorophyll a (Chl). A total of 10 925 fish larvae and juveniles, belonging to 52 species, 14 families, were collected. Among them, the most abundant were freshwater fish of 22 species (42%), followed by estuarine fish of 19 species, accounting 37% of total, coastal fish of 7 species (13%) and 4 species of offshore fish (8%). Whereas the most common species were Cyprinidae family, consisting of 14 species (27%); Gobiidae family had 12 species (23%); the families of Engraulidae and Osmeridae had both 5 species (10%). The dominant species were (Coilia mystus, 21.51%), (Colia nastus, 18.11%), (Hemiculter bleekeri, 16.34%), (Pseudolaubuca sinensis, 10.82%)and (Acanthogobius ommaturus, 9.38%), respectively. In all, the fish larvae of pre-flexion comprised 76.49% of the total catch, 11.94% of the flexion stage, 8.01% of the post-flexion stage, 3.43% of the juvenile stage. However, the density of fish larvae in the stages of pre-flexion and flexion had a declining tendency, while the density of fish larvae in the stage of post-flexion rose, as the season changed. The number of species, bio-diversity and the density of fish larvae were higher in the summer season than those in the autumn season. The Non-metric Multi-dimensional Scaling and the Cluster Analysis demonstrated that the fishes can be classified as two groups, rich in the freshwater type, followed by the estuary type. Based on the results of this research and other surveys of Coilia family larvae, it shows that there is a significant difference in the spatial distribution of Coilia nasus and Coilia mystus at the larval stage of the Yangtze River. This research showed that the Gobiidae was distributed in a scattered manner, and traces of the larvae and juveniles were found in the southern branch, northern branch of the Yangtze River Estuary and Dongtan water area. Like many estuaries in the world, the Gobiidae have special living habits, which enable them to adapt to the huge runoff and sedimentation of the estuary. At present, many nets and fyke nets for eel fishing have been set up along the Yangtze River Estuary. There is no effective method to assess the damage to larvae and juveniles. In addition, the feeding of larvae and juveniles and the protection of nurseries are the key to the protection and restoration of fishery resources. The CEB of the Yangtze River estuary is a buffer water area for Chinese sturgeon juveniles to descend and migrate to the sea. The density of larvae and juveniles in this water area will significantly affect the species preservation and continuation of Chinese sturgeon. Therefore, it is urgent to develop effective and systematic long-term tracking.
Effect of an obstacle on swimming kinematics in juvenile silver carp, Hypophthalmichthys molitrix
SHI Xiaotao, JIANG Zewen, TU Zhiying, LUO Jinmei, TAO Yu, LEI Qingsong, KE Senfan
2021, 45(8): 1406-1414.   doi: 10.11964/jfc.20200812369
[Abstract](475) [FullText HTML](218) [PDF 5904KB](14)
Abstract:
Weirs and dams affect the hydraulics and geomorphology of natural rivers, greatly modifying fish habitat, in some cases, creating barriers that prevent fish swimming upstream. Typical engineering methods to mitigate dam effects on movements of fish include fishway construction and riverbed reconfiguration. Among these measures, it is common to use obstacles to increase bed roughness and create microhabitat that slows flow velocity and helps fish ascend fishways. Obstacles create a complex flow environment in fishway. Understanding swimming behavior in complex flow environment is critical to improving the effectiveness of fishways. A stationary obstacle within a fish passage can be either beneficial or detrimental to fish depending on the direction and magnitude of flow velocity and the ability of the fish to maintain stability. Flow velocity in relation to energy expenditure is critical when considering the effect of obstacles on locomotory behavior. We also discovered how silver carp (Hypophthalmichthys molitrix) alter their locomotory behavior in response to turbulent flow caused by varying flow velocities around obstacles. Silver carp is an important native commercial species in China. Silver carp tend to inhabit fast-flowing streams with structurally complex flow environments. No quantitative kinematic studies have described the locomotory behavior of silver carp in unsteady flow. In this study, the swimming kinematics of juvenile silver carp holding station and moving forward under obstacle conditions were analyzed at different flow velocities (1, 3 and 5 BL/s) (body length per second). Metrics used to quantify kinematics were tail-beat frequency, tail-beat amplitude, ground swimming speed, swimming acceleration, and ground stride. Compared to free stream swimming at flow velocity of 3 BL/s, silver carp holding station behind the obstacle showed a significant decrease in tail-beat frequency and significant increase in tail-beat amplitude; silver carp moving forward behind the obstacle showed a significant decrease in tail-beat frequency, ground swimming speed, swimming acceleration and ground stride, and significant increase in tail-beat amplitude. This result showed that the obstacle help fish to save energy at 3 BL/s. In the obstacle-placed currents, tail-beat frequency of the holding station behavior increased with flow velocity. Tail-beat frequency, tail-beat amplitude and swim acceleration of moving forward behavior increased with flow velocity, while ground stride decreased with flow velocity. At flow velocity of 3 BL/s, we found that silver carp held a preferential position from 5-30 cm downstream of an obstacle where fish might adopt Karmen gait, and residence time accounted for 92.5%. At flow velocity of 1 BL/s and 5 BL/s, silver carp did not hold an evident preferential position in the flume. Silver carp often swam close to the wall, and there was no obvious position preference. Our results indicate that a certain combination of obstacles and flow velocity will create flow refuge for fish. The results may provide important reference for fishway design.
Evaluation of on competitiveness of China’s provincial recreational fisheries and our suggestions
ZHAO Qilei, CHEN Xinjun
2021, 45(8): 1415-1429.   doi: 10.11964/jfc.20200712339
[Abstract](381) [FullText HTML](184) [PDF 18321KB](20)
Abstract:
The development of leisure fisheries is an important part of promoting the construction of modern fisheries, and also an important measure to implement the strategy of rural revitalization and to build a strong marine economy. Considering the blank of the current research on the evaluation of the competitiveness of Chinese provincial recreational fisheries, the existing evaluation methods cannot take into account both the ambiguity and randomness of indicators. This study introduced the concept of competitiveness and the normal cloud model method, and evaluated the competitiveness of 30 provinces (except Tibet) of China's provincial-level administrative units for leisure fishery competitiveness by constructing a Chinese provincial leisure fishery competitiveness evaluation index system. The results showed: (1) The overall level of competitiveness of China’s provincial recreational fisheries is not high and the development is uneven. Two thirds of the provincial competitiveness results is in the level Ⅰ (weak) state, lacking the competitiveness of level Ⅳ (relatively strong) provinces; (2) Water resources area per capita, market distance index of source area and market size are common shortcomings of the competitiveness in most provincial units, and the total retail sales of social consumer goods and transportation accessibility indicators are generally highly competitive; (3) Level Ⅰ and Ⅲ provincial competitiveness results have less volatility, level Ⅱ provincial competitiveness results have greater volatility, and level Ⅴ provincial competitiveness results have the most stable results. This study can provide reference for enriching leisure fishery evaluation methods and making industrial development decisions.
ROUNDUP
Advances of immune-related microRNA research in teleost fish
WANG Xiaodong, JIN Shengzhen, ZHAO Xin, XIONG Shuting, XIAO Tiaoyi
2021, 45(8): 1430-1437.   doi: 10.11964/jfc.20200312202
[Abstract](634) [FullText HTML](324) [PDF 5710KB](60)
Abstract:
MicroRNAs, which are small non-coding RNAs with 18-25 nt, play important roles in immune response of teleost fish. Recently, more and more differentially expressed miRNAs (DE miRNAs) associated with immune response have been identified through high-throughput sequencing and RT-PCR technology. It is assumed that if the same miRNAs are detected as DE miRNAs in several species of teleost fish challenged with different viruses/bacteria, they are likely to be evolutionarily conserved miRNAs involved in the regulation of immune gene networks in the hosts. Based on the above assumption, ten miRNAs were discovered as responding to viral challenge, and eight miRNAs were described in response to bacterial challenge. In addition, the functional study of miRNA has also attracted attention with marked progress. It has been identified that miRNAs are involved in many immune response processes, such as in preventing the virus replication, in regulating interferon response, inflammation and cell apoptosis.
Lipid metabolism and its physiological and ecological effects of sharks
LI Yunkai, XU Min
2021, 45(8): 1438-1450.   doi: 10.11964/jfc.20200912397
[Abstract](580) [FullText HTML](219) [PDF 6442KB](11)
Abstract:
As the key species, sharks play an important role in regulating the structure and function of the food web of marine ecosystems. In recent decades, due to the continuous increase of global shark catches, the resource status is not optimistic. Eighty percent of marine species are assessed as near endangered by International Union for Conservation of Nature. However, the lack of knowledge on the basic biology, physiology, ecology and other important life history processes of sharks hinders the effective regulation and protection of shark resources. In this paper, we summarized the lipid metabolism pathways of sharks and its effects and the differences of lipid metabolism between sharks and teleosts, in order to further understand the life history of sharks. Shark’s liver is the primary organ where the lipid storage and synthesis, fatty acid oxidation and ketone body formation occur. Digestion and absorption of lipids from diet is the exogenous pathway and lipid synthesis in liver is the endogenous pathway of lipid accumulation of sharks. The lipid metabolism pathways in shark are unique compared with those of the teleost fish. The free fatty acids in shark’s blood are transported by binding with lipoproteins, while those in teleost are carried by albumin and usually have adipose tissues. The oxidation of fatty acids in extrahepatic tissues is limited, which is more dependent on the metabolic capacity of the ketone body which plays a limited role and is only used as alternative sources in the teleost fish. Triacylglycerol and free fatty acid in shark’s liver are the main energy sources, and squalene can provide additional buoyancy. During reproduction, female sharks provide nutrients for their offspring with yolk sac. The fatty acid profiles in the liver and muscles can be used to investigate the trophic ecology on ecological roles, resource partitioning and nutritional physiology of the shark species. Understanding the lipid metabolism pathways of sharks is of great significance for revealing their evolutionary process, understanding their mysterious life history and making effective management strategies for shark conservation.

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