Abstract:The waters in Southwest China are rich ecological environments that provide fishery resources, with many endemic fish species. However, owing to ecological environment destruction and overfishing, such fishery resources in Southwest China have been greatly reduced in recent years. To improve and repair its resources, stock enhancement activities were recorded between 2016 and 2019 according to the Guidance on Doing a Good Job in the stock enhancement of Aquatic Organisms during the 13^th period of the 5-year plan in Southwest China. The results showed the following: (1) in Southwest China, from 2016 to 2019, a total of 56 stock enhancement activities were carried out in rivers, lakes, and reservoirs, involving 95 species of hydrobionts, including 92 species of fish, one species of amphibian, and 54 turtle genera. (2) From 2016 to 2019, a total of 53890.15 × 10⁴ fish were released, most of which were Cyprinidae, with an investment of ￥27128.1600 × 10⁴ . (3) Hypophthalmichthys molitrix, Aristichthys nobilis, and Ctenopharyngodon idellus constituted the main hydrobionts used in stock enhancement. Myxocyprinus asiaticus represented the main rare and endangered hydrobiont. (4) Most of the released individuals measured 1–15 cm, and the release period was concentrated in late autumn and early winter. (5) From the quantity of the total released individuals in Southwest China between 2016 and 2019, the purpose of the releases can be assumed to be for promoting fishermen’s income and biological water purification. The purpose of releasing the specific species was to protect endemic fish populations. This research shows that the selection, time, specification, effect evaluation, and social publicity of released species in stock enhancement activities in Southwest China from 2016 to 2019 need to be further improved. In view of the above problems, we put forward some suggestions to better carry out stock enhancements, to provide a reference basis for China to carry out future stock enhancements.

Abstract:Haemulidae fish, belonging to the suborder Percoidei of the order Perciformes, are important commercial marine fish species in China. Morphologically, classification controversies still exist among the genera and species of this family. To clarify such controversies, in this study, partial mitochondrial cytochrome b sequences of 66 Haemulidae species and their related families/genera were determined and analyzed. Combining this with AFLP marker information, the molecular phylogenetic relationships of Haemulidae and related species were then constructed and investigated. The phylogenetic trees were constructed based on the Cyt b gene sequences using the maximum likelihood method and based on AFLP markers using the UPGMA method. The results showed that in the Cyt b gene, 739 bp homologous sequences from 66 species were obtained, with 243 amino acids encoded; in the AFLP fingerprints, based on six primer pairs, a total of 669 clear polymorphic bands were obtained, with a polymorphic ratio of 100%. Genetic distances among Haemulidae and related families/genera (Terapontidae, Scolopsis, Hapalogenys) calculated by MEGA 7.0 revealed that the distance values between Haemulidae and Terapontidae (Cyt b: 0.191–0.275; AFLP: 1.268–1.683), Haemulidae and Hapalogenys (Cyt b: 0.180–0.297; AFLP: 1.225–1.556), and Haemulidae and Scolopsis (Cyt b: 0.208–0.290; AFLP: 1.097–1.553) were all larger than the Haemulidae intra-genera genetic distance values (Cyt b: 0.024–0.243; AFLP: 0.690–1.362), indicating their distant relationship with Haemulidae. The phylogenetic trees constructed by Cyt b genes and AFLP marker information revealed similar topologies. In the phylogenetic tree the following was found: 1) Haemulidae species were divided into two major groups, seven genera (including Pomadasys, Haemulon, and Anisotremus) were clustered into the Haemulinae group and three genera (namely, Plectorhinchus, Diagramma, and Parapristipoma) were clustered into the Plectorhynchinae group; 2) the genera Hapalogenys and Scolopsis were not clustered together with the Haemulidae group. Hapalogenys formed a separate branch and Scolopsis was clustered together with family Nemipteridae; and 3) species of family Terapontidae were not clustered with Haemulidae. Terapontidae showed a close relationship with the families Kyphosidae and Oplegnathidae. Our study supported the view that Haemulidae comprised two subfamilies, Haemulinae and Plectorhynchinae; and Terapontidae. Hapalogenys and Scolopsis may not be classified into Haemulidae. The present study revealed the phylogenetic relationships within Haemulidae and related families/genera, which provide molecular evidences for analyzing and clarifying the controversies regarding their morphological classifications.

Abstract:The multivariate linear model is a powerful tool for examining associations between a single nucleotide polymorphism and multiple related phenotypes. To improve the computational efficiency of this complex correlation analysis, we spectrum-transformed multiple correlated phenotypes to mutually independent “super traits” by using the mixed model association analysis method of a single trait. The sum of these statistics was used to infer pleiotropic nucleotide genetic loci that control multiple related phenotypes. The multivariate linear mixing model of GEMMA software and the phenotypic orthogonalization method proposed in this study were used to analyze the genome-wide associations (GWASs) of three traits in turbot (Scophthalamus maximus): body length, body mass, and caudal peduncle width. The results showed that 11 QTNs were detected on chromosome 1, 5, 6, 8, 12, 16, 20, 21, and 22 by the multivariable linear mixed model method. However, our method detected a total of 14 QTNs on chromosome 1, 3, 5, 6, 8, 12, 16, 20, 21, and 22, among which nine QTNs were detected jointly by the two methods. Compared with that of GEMMA, our method exhibited higher power to detect QTNs of multi related traits, which provides a convenient and efficient strategy for multi-trait GWAS research and the genetic breeding of other aquatic species.

Abstract:The basic characteristics of Palaeminidae mitogenomes were revealed by the comprehensive mitogenome analysis of 14 Palaeminidae species. The results showed that the lengths of the 14 mitogenomes varied from 15396 bp to 15967 bp. The content of A + T ranged from 58.97% to 69.09%. Compared with the gene order of a Decapoda ancestor, the gene arrangement order of the Macrobrachium had not changed, but the gene arrangement order of Palaemon, Anchistus, and Hymenocera changed to varying degrees. Furthermore, gene deletion was detected in the mitogenome of Anchistus. The Ka/Ks ratios of 13 protein coding genes (PCGs) in Palaemon and Macrobrachium was much lower than one, indicating strong purification. In addition, the codon usage of the 13 PCGs in Palaeminidae showed that the encoded amino acids had similar preferences. Among the two rRNA genes and 13 PCGs identified the mitogenome, the analysis of the different sites between Palaemon and Macrobrachium showed that the genes nd5, nd4, and nd2 were ideal molecular markers. The phylogenetic trees based on the 13 PCGs showed that Palaemon and Macrobrachium were sisters, and Anchistus and Hymenocera were gathered together into a large branch. Finally, according to the estimation results of the molecular clock, it is speculated that Palaeminidae species may have originated in the Permian, before further differentiating into a species with modern characteristics. This study provides a reliable molecular marker for the rapid identification of Palaeminidae species and a theoretical basis for analyzing the genetic diversity of Palaeminidae species.

Abstract:The whiteleg shrimp, Litopenaeus vannamei, is an introduced species in China; the genetic relationship and genetic background among introduced populations in China are not clear. To analyze the effects of these unknown parent groups (UPG) in the basic population of L. vannamei, three populations with different growth rates and survival rates were collected as founder populations and were established as the base population by the diallel-cross design. Four models, namely, the Best Linear Unbiased Prediction based on Pedigree (pBLUP), the pBLUP with genetic groups (pBLUP-GG), the Single Step Genomic BLUP (ssGBLUP), and the ssGBLUP with Metafounders (ssGBLUP-MF), were used to estimate variance components for the body weight of the base population. The effects of UPG on genetic parameters and breeding value across the four models were compared and analyzed by cross validation. The results showed that the highest additive genetic variance (22.58 ± 4.39) and heritability (0.91 ± 0.10) were obtained using the pBLUP model. The pBLUP-GG, ssGBLUP, and ssGBLUP-MF models decreased additive genetic variance by 16.25%–61.20% and heritability by 15.38%–46.15% compared with that of the pBLUP model. The 5-fold cross validation for genotyped and ungenotyped individuals indicated that the accuracy of the pBLUP model was the lowest (0.64–0.68) of all estimates, and the accuracies of the other three models increased by 7.25%–10.53% compared with that of the pBLUP model. The prediction bias of the other three models decreased by 2.83%–7.56% compared with that of the pBLUP model (1.06–1.19). In conclusion, the models considering UPG effects could avoid the overestimation of additive genetic variance components for body weight in the basic population of L. vannamei.

Abstract:Scallop Pationopecten yessoensis is the mainly bottom culture species in Northern coastal of China. To know it moving characteristics after seeding will helpful to improve return catch rate and to select suitable releasing site. In this paper, the pressure sensor-force gauge is used to measure the force production of scallop Pationopecten yessoensis and their escape response to predator starfish, in order to understand the movement behavioral characteristics of the scallop. According to the shell length, the scallops were divided into 3 experimental groups: big size (82.71±3.49) mm, middle size (65.76±4.20) mm and small size (32.36±2.38) mm. 15 individual of each size of scallops were measure the force production for 3 min and then to measure the force response to starfish next day. The results showed that (1) the clap rates (time/s) of big, middle and small size scallop were 0.7±1.6, 1.1±0.5 and 0.6±0.4, respectively, and the maximum contraction force (F_max, N) were 11.4±5.2, 5.9±1.3 and 1.8±0.6, respectively. The phase and tonic contractions of scallops alternated, and there were significant differences between different sizes. The larger the size, the stronger the closing force. (2) When stimulated by starfish, the F_max, clap rate, total contraction force and tonic contraction force of 3 size scallops increased significantly. Among which, the maximum contraction force (F_max, N) of big, middle and small size scallop increased to 17.1±2.8, 8.3±2.3, 2.6±0.5, respectively. However, there was no significant difference between the phase contraction force (Fphasic) with and without starfish stimulation, and there was no significant interaction between the size and the presence or absence of starfish stimulation. The force gauge method quantified the ability of the tonic contraction of scallop. In the future, it will be combined with video recording and other methods to further understand the jump or swim away speed from the predator and movement behavior characteristics of the scallop.

Abstract:The Yesso scallop, Patinopecten yessoensis, is a large-scale fine marine cultured shellfish and is currently the most economically valuable cold-water species in the scallop family in the world. Since it was introduced to China in the 1980s, it has been mainly cultivated in the northern waters. Zhangzi Island is China’s largest scallop bottom sowing base, where the scale of cultivation has increased from 600,000 mu in the 1980s to 1.3 million mu in 2017. However, the rapid development of Zhangzi Island Marine Ranch has seen the large-scale death of Yesso scallops, and the bottom sowing industry is facing extremely severe challenges. We aimed to strengthen systematic research on the environmental effect of mariculture and investigate the sustainable development of bottom-seeded multiplication marine ranches. The existing methods for evaluating the ecological capacity of the Yesso scallop on Zhangzi Island include the parameter index method and the numerical model method. In this study, we used Ecopath with Ecosim 6.5 (EwE) software to construct the Ecopath model of the Zhangzi Island sea area and analyzed the trophic structure and energy flow characteristics of the Zhangzi Island sea ecosystem, as well as evaluated the ecological capacity of the bottom sowing and proliferation of Yesso scallops. The results indicated that 1) the trophic level of the Zhangzi Island marine ecosystem was between 1 and 4.365. The lowest trophic level of one was occupied by phytoplankton and organic debris. The highest trophic level was the stingray functional group with a trophic level of 4.365. The average conversion efficiency between the trophic levels of the grazing food chain was 6.268% and the average conversion efficiency between the trophic levels of the detritus food chain was 7.698%. The energy flow of the system was predominantly the detritus food chain. The total system conversion efficiency was 6.923%, and the Lindemann conversion efficiency was lower than 10%. The system connection index was 0.219, the system omnivorous index was 0.174, the system Finn cycle index was 7.790, and the average path length of the Finn system was 2.674, indicating that the energy of the system was not fully utilized and there was a case of energy transmission blocking. Comparing our results with those of previous Ecopath model data for Zhangzi Island ecosystem, it was found that these values have increased annually, indicating that the ecosystem is in a state of continuous development. 2) The ecological capacity of the Yesso scallop estimated by the model was 36.805 t/km2 , 17.5 times higher than that of the existing stock; the total primary production/total respiration of the Zhangzi Island ecosystem before and after reaching ecological capacity exhibited little (0.26) change, the system omnivorous index and the system connection index did not change significantly and, thus, did not have a significant effect on the stability and nutritional structure of the Zhangzi Island ecosystem. Therefore, there is still great potential for the growth of the Yesso scallop population on Zhangzi Island.

Abstract:To improve the spatial and temporal resolution of fishery forecast models and the resource utilization and economic benefits of Pacific saury (Cololabis saira), a generalized additive model (GAM) was used to fit the suitability index between the catch per unit effort (CPUE) and marine environmental variables, based on Chinese saury fishery and environmental data from the high seas of the northwest Pacific Ocean during July and November from 2013 to 2016. Weighted analysis was also conducted using boosted regression tree models to develop monthly habitat suitability index (HSI) models. The results indicated that the GAM can be reliably used to fit relationships between the suitability index and environmental variables and can obtain optimal environmental variable values. Weighted analysis showed that the three important environmental variables affecting CPUE were sea surface temperature gradient, sea surface temperature, and mixed layer depth. The weight of the sea surface temperature gradient was the highest during September to November (autumn). The overall accuracy of the HSI model test and evaluation stages were 82.0% and 73.2% respectively, reaching 87.7% and 77.9% in autumn, respectively. Furthermore, forecast accuracy was 89.4% in October during the main fishing season. The high-HSI areas were consistent with the fishing grounds of Pacific saury. Thus, the results show that the HSI model is suitable for forecasting the saury fishery and has a significant advantage in daily forecasting.

Abstract:To study the protein function of Tilapia Lake Virus (TiLV) ORF10, the TiLV ORF1 0.coding region was amplified from the cDNA of spleen and kidney tissues of TiLV-infected tilapia.The eukaryotic expression vector pEGFP-ORF1 0.and recombinant expression vector pET3 2.a-ORF1 0.were then constructed.pEGFP-ORF1 0.was transfected into Epithelioma papulosum cyprini (EPC) cells for fluorescence microscopy observation.Green fluorescence signals were observed in the nuclei of EPC, indicating that TiLV ORF1 0.was localized in the nucleus.The recombinant vector pET3 2.a-ORF1 0.was transformed into E.coli DE 3.for protein expression analysis, and the results showed that His-TiLV ORF1 0.was successfully expressed in the supernatant form.Furthermore, the fusion protein His-TiLV ORF1 0.was purified by Ni-NTA affinity chromatography and was subsequently used to immunize Balb/C mice to prepare polyclonal antibodies.Western blot analysis showed that mice antibodies can specifically recognize His-TiLV ORF10.To further analyze the protein content of TiLV ORF1 0.in the muscle, spleen, liver, and kidney tissues of TiLV-infected tilapia, the polyclonal antibodies were used for western blot detection.The results revealed differential protein contents of TiLV ORF1 0.in the muscle, spleen, liver, and kidney tissues.The highest expression was observed in the liver and kidney tissues, followed by the spleen.The lowest expression was found in the muscle tissues.The subcellular localization, polyclonal antibody preparation, and tissue expression analysis of TiLV ORF1 0.in this article provide an important preliminary basis for the further study of the function of the ORF1 0.protein.

Abstract:Acute hepatopancreatic necrosis disease caused by Vibrio has brought huge economic losses to the shrimp farming industry in many countries. Owing to restrictions on the application of antibiotics in aquaculture and the demand for green and healthy aquatic products in the market, microbial control technology has shown great application prospects in the prevention and control of shrimp diseases. Pseudoalteromonas piscicida 2515 (strain 2515) is a broad-spectrum Vibrio antagonistic bacterium that has probiotic potential in aquaculture. To investigate the antagonistic effect of strain 2515 against Vibrio in shrimp farming, the antimicrobial effect between strain 2515 and neomycin was compared using the Oxford cup test method, with V. anguillarum as the indicator. The antagonistic effect of V. anguillarum was evaluated by co-culture with strain 2515 at concentrations of 10⁴ CFU/mL, 10⁵ CFU/mL, 10⁶ CFU/mL, and 10⁷ CFU/mL. To study the application effect, the total number of bacteria and Vibrio in the aquaculture water and shrimp intestines were analyzed after strain 2515 was administrated by oral and immersion at concentrations of 10³ CFU/g, 10⁵ CFU/g, and 10⁷ CFU/g in the feed and 10³ CFU/mL, 10⁵ CFU/mL, and 10⁷ CFU/mL in the water body, respectively. The relative percent survival (RPS) against V. parahaemolyticus in each group was compared. The results showed a corresponding relationship between the number of strain 2515 and the quality of neomycin under the same effect as against V. anguillarum. Strain 2515 concentrations of 10⁶ CFU/mL and 10⁷ CFU/mL showed strong antibacterial effects when co-cultured with V. anguillarum. Strain 2515 concentrations of 10⁵ CFU/g and 10⁷ CFU/g in shrimp feed could significantly increase shrimp survival rate and reduced the number of Vibrio in shrimp intestines (P < 0.05). The optimum concentration was 10⁵ CFU/g, which exhibited the lowest mortality (43.3±5.8)% and the highest RPS (53.7±6.2)% against V. parahaemolyticus. The results indicated that strain 2515, added in feed or water in appropriate concentrations, could improve the ability of shrimp resistance to V. parahaemolyticus and reduce the number of Vibrio in shrimp intestines.

Abstract:As a new type of green farming mode, internal-circulation pond aquaculture (IPA) adopts the concept of “fish farming in ponds and water purifying outside ponds” and relatively closed self-repairing technology to achieve the requirements of sustainable development of fisheries. However, little is known about the effect of this farming mode on fish muscle nutritional quality. To investigate the difference in muscle quality of Ictalurus punctatus reared from internal-circulation pond aquaculture and traditional pond aquaculture (TPA), the texture and fiber characteristics of muscle were determined by texture analyzer and the nutritional components of three parts of muscles (back, abdomen and tail) were determined by biochemical analysis. The results showed that the crude protein content of tail muscle in IPA group was significantly higher than that in TPA group (P<0.05) and the crude fat content of back and tail muscle in IPA group was significantly lower than that in TPA group (P<0.05). The total amount of amino acids, essential amino acids and fresh amino acids in back muscle of IPA group were significantly higher than those in TPA group (P<0.05). Besides, the total amount of essential amino acids and fresh amino acids in abdominal muscle of IPA group were significantly higher than those in TPA group (P<0.05). Among the 17 fatty acids identified, significantly lower myristic acid and higher EPA were found in the three parts of muscles of IPA group than that in TPA group (P<0.05). The total amount of PUFA in back and abdominal muscles in IPA group were significantly higher than those in TPA group (P<0.05). In terms of the texture profile, the hardness, springiness, chewiness and resilience in muscle of I. punctatus in IPA group were enhanced significantly compared with those in TPA group (P<0.05), and the muscle fibers in the IPA group had the characteristics of small diameter and high density. Overall, these results suggested that I. punctatus reared from IPA model has greater advantages in muscle quality and nutrition.

Abstract:The catch performance of tuna longlines was evaluated across two aspects: the catch rate of the target species and the bycatch rate of bycatch species. The aim of this review was to provide references for modifying the longline gear and fishing method, to improve the capture efficiency of target fish species and reduce bycatch rate. Based on the time series, we review the literature on the catch performance of tuna longlines; summarize the research progress of tuna longline catch performance from influence factors of longline fishing gear selectivity, hook depth, bait selectivity, environmental factors, and fishing gear soaking time; and present the existing drawbacks and suggestions for future research. The findings of previous studies are as follows: (1) the optimal operation depth and soaking duration of longline gear differ between different species; (2) larger circle hooks can reduce bycatch rate; (3) artificial bait exhibits selectivity, and fish bait and blue dyed bait can reduce bycatch rate; and (4) the environmental factors of the specific water layer significantly influences catch performance. Based on this review, we suggest that future study on the performance of tuna longline fishing gear should (1) determine the optimal sinking speed and depth of the hook; (2) establish a catch performance prediction model for different species in different water layers; (3) explore the optimum hook type and size for the targeted species; (4) focus on species selectivity by different odors and colors of natural and artificial bait; and (5) consider the potential synergistic effect of bait type, hook type and size, fishing gear soaking duration, bycatch rate, mortality rate, and post-release survival rate of the bycatch species.