ROUNDUPS

• Exploration of ecological theoretical framework for the creation of artificial reef habitat in marine ranching

  YUAN Huarong, ZHANG Shouyu, LIN Jun, FENG Xue, WANG Zhenhua, TONG Fei, WANG Kai, CHEN Yuxiang, CHEN Pimao

  2025,49(1):019501-019501, DOI: 10.11964/jfc.20240114312

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  Abstract:

  Marine ranching in China has been a pivotal strategy for developing the "blue granary" and restoring depleted nearshore fishery resources. The industry has seen significant growth, yet it is not without its challenges, such as unclear goals, ill-defined habitat functions and scales, and an incomplete understanding of the habitat systems, particularly due to a weak theoretical foundation. The construction of artificial reefs, a critical component of marine ranching, is essential for sustaining the growth and reproduction of target species. However, current practices in China have predominantly focused on physical suitability and engineering feasibility, often overlooking the ecological adaptability of target organisms, leading to insufficient ecological functionality. The purpose of this study is to address the ecological insufficiency in the construction of artificial reefs within China's marine ranching by establishing a theoretical framework that emphasizes the ecological adaptability of target species. This framework aims to guide the construction of artificial reefs that are not only physically suitable but also ecologically functional. The study reviews the development history of marine ranching both domestically and internationally, and discusses the physical and biological environments of artificial reefs in China's marine ranching. It innovates the basic structure of artificial reef habitats in China's marine ranching and explores the ecological theory underlying their construction. The research has developed a theoretical framework centered on target species, emphasizing the conformity of habitat structure and function, as well as the consistency between scale and effect. This framework provides a reference for the ecological sustainability of artificial reef habitats in China's marine ranching. The study concludes that a theoretical framework focusing on target species is essential for the ecological sustainability of artificial reef habitats in marine ranching. It is significant as it provides a scientific basis for improving the ecological functionality of artificial reefs, which is crucial for the long-term success of marine ranching initiatives. The recommendations include integrating ecological adaptability into the design and construction of artificial reefs, ensuring that habitat structures and functions align with the needs of target species, and maintaining a balance between scale and ecological effects. This approach is expected to enhance the ecological sustainability of China's marine ranching, contributing to the conservation and restoration of nearshore fishery resources. Furthermore, the study suggests that the future of marine ranching should be guided by technological innovation and ecological sustainability, leading to more efficient use of ocean resources while safeguarding marine ecosystems. The integration of digital monitoring tools and the development of advanced environmental monitoring and early warning systems are highlighted as key areas for future development.

PAPERS

• Proteomic analysis between fresh and freeze-thawing semen in Acipenser schrenckii

  CHEN Zhangfan, DING Lanqing, CHENG Peng, HU Mou, ZHANG Tingting, HUANG Hongtao, DU Hejun, CHEN Songlin

  2025,49(1):019602-019602, DOI: 10.11964/jfc.20231114215

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  Acipenser schrenckii, commonly known as the Amur sturgeon, is a vital species in China's sturgeon industry due to its significant economic value. Cryopreservation of sperm is a crucial technique for conserving and utilizing sturgeon germplasm resources, facilitating long-term storage of viable sperm. Previous studies have optimized the extender formulas, assessed antioxidant activities, examined enzyme functions related to energy metabolism, and compared sperm ultrastructure. However, there remains a paucity of research on the molecular changes occuring during sturgeon sperm cryopreservation. Addressing this gap, a recent study utilized 4D label-free quantitative proteomics to discern differentially abundant proteins between fresh and freeze-thawing A. schrenckii semen, post-thawing at 24 h. Proteins were extracted using SDT lysis buffer (4% SDS, 100 mmol/L Tris-HCl pH 7.6, 0.1 mol/L DTT) and sonication, followed by centrifugation for collection, identifying a total of 1 859 proteins. Employing a threshold of a 1.5-fold difference factor (FC) and a significance level (P-value) less than 0.05, 200 differentially abundant proteins were delineated, including 92 down-regulated and 108 up-regulated. Subcellular mapping revealed protein localization across various cellular compartments, while GO and KEGG enrichment analyses unveiled involvement in diverse biological processes, cellular components, molecular functions, and signaling pathways. Notably, Fas-activated serine/threonine phosphoprotein kinase 1 (FASTK1) was up-regulated in freeze-thawing semen for 48.81-fold, indicating a role in cell proliferation regulation for self-protection. Conversely, the down-regulation cold inducible RNA-binding protein (CIRP) suggested its involvement in cell proliferation, which ultimately affected the motility of free-thawing semen. Up-regulated Nup proteins potentially contributed to membrane protein conformation changes , destabilizing intracellular environments. Down-regulated DNAH-9 was linked to flagellum membrane disruption and fracture. Changes in proteins associated with energy metabolism and antioxidant response, including CK, SDHC, 26S proteasome, CAT and SOD, may elucidate the decreased motility of sturgeon semen after freeze-thawing process. These molecular alternations may impact sperm viability and function, possibly explain reduced fertilization successpost-cryopreservation. The identified proteins could serve as candidate markers for A. schrenckii semen quality during the freeze-thawing process, guiding the development of improved cryopreservation protocols. This research lays a valuable foundation for deeper exploration into the molecular mechanisms of sturgeon sperm cryopreservation, crucial for the conservation and sustainable utilization of this vital fish resource.

• Genetic diversity and adaptation mechanism of Ctenopharyngodon idella in Asian by whole-genome resequencing

  XIE Lingli, SHEN Yubang, GUI Lang, XU Xiaoyan, LI Jiale

  2025,49(1):019103-019103, DOI: 10.11964/jfc.20230313950

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  This study examines the genetic diversity and adaptive evolution of Ctenopharyngodon idella populations across Asia, aiming to enhance our comprehension of the molecular evolution mechanisms and immune adaptations in C. idella. We conducted whole-genome resequencing of C. idella populations from four Chinese provinces (Hunan, Chongqing, Tianjin, Guangdong) and three Asian countries (Nepal, Vietnam, India). Employing population genetics methodologies, we analysed population structure, performed principal component analysis, constructed phylogenetic trees, assessed genetic differentiation, and conducted selective sweep analyses. The Wanzhou population displayed the highest genetic diversity, whereas the Nepal population exhibited the lowest. Cluster analysis revealed significant genetic similarities among the five populations in Vietnam and China. A total of 6 548 523 SNP sites were identified, predominantly in intergenic regions and enriched in signaling pathways such as cell adhesion molecules, hematopoietic stem cells, and DNA recombination repair. Selective sweep analysis highlighted genes enriched in pathways related to immune response regulation, cardiomyocyte regulation, and sodium ion channel activity. Utilizing SNP annotation data, we identified gimap8 in Indian and Nepal populations, crucial for T cells and B cells development. C. idella populations in Anxiang, Yuanjiang, and Wanzhou in China, are genetically diverse, while those in Nepal and India show significant differentitation from other populations. We preliminarily identified the potential adaptive genes gimap8. Concurrently, mutations in gimap8's base affected the gene's structure in three populations. This study lays a foundation for further exploration of the molecular evolution mechanism of C. idella in various habitats, reflecting the molecular mechanisms by which C. idella populations adapt to different environmental stresses. The results reveal the differences in the molecular mechanisms of adaptive immunity in different C. idella populations. These findings not only deepen our understanding of C. idella's adaptive evolution in diverse environments but also provide a significant theoretical basis for C. idella breeding and offer new insights.

• Integrated analysis of transcriptome and miRNA expression in Hypophthamichthys nobilis individuals with different body shapes

  DENG Yujie, ZHU Wenbin, FU Jianjun, LUO Mingkun, WANG Lanmei, LIANG Zhengyuan, DONG Zaijie

  2025,49(1):019604-019604, DOI: 10.11964/jfc.20240514529

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  To explore the molecular mechanisms affecting the body shape differences in Hypophthamichthys nobilis, morphological different H. nobilis individuals with normal body shape (CK group) and with shortened body (PG group) were collected for transcriptome and miRNA sequencing analysis in this study. The results showed that a total of 25 327 unigenes and 8 325 miRNAs were obtained. 930 differentially expressed genes (DEGs) and 146 differentially expressed miRNAs (DEMs) were identified, including 473 up-regulated genes and 457 down-regulated genes, as well as including 44 up-regulated miRNAs and 102 down-regulated miRNAs, respectively. By comparing the DEGs and target genes of DEMs, 140 overlapped genes were obtained, which were mostly enriched in cell cycle (ko04110), DNA replication (ko03030), adhesion plaques (ko04510), and ECM receptor interaction (ko04512) signaling pathways. Additionally, 16 overlapped DEGs were identified to be involved in bone formation and development, such as exo1, mcm4, ccna2, smc2 and ccna2, which were hypothesized to be associated with H. nobilis body shape differences. In addition, through mRNA-miRNA interaction network analysis, DEGs including apob, tgfbr2a and col2a1b as well as DEMs including miR-34a-5p, miR-252a and miR-6547-5p were detected as core members in the network; these DEGs and DEMs may play important roles in regulating and maintaining the morphologically in H. nobilis. Validation experiments using qPCR revealed that the trends of relative expression differences between CK with PG groups were consistent with the RNA-Seq and sRNA-Seq data. These DEGs, DEMs, and enriched metabolic pathways identified in this study may be associated with H. nobilis body shape difference. This study may provide basic data for further exploration of the molecular mechanisms affecting body shape differences in H. nobilis.

• Differential expression patterns of gdnfa and gdnfb in the testis of medaka (Oryzias latipes) and their regulation by retinoic acid and 11- ketotestosterone

  QU Ximei, WANG Yuan, ZHAO Changle, LIU Lei, TAO Wenjing, WANG Deshou, WEI Jing

  2025,49(1):019105-019105, DOI: 10.11964/jfc.20230213894

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  Glial cell line-derived neurotrophic factor (GDNF) is a key factor mediating the self-renewal and maintenance of spermatogonial stem cells (SSCs). Our previous research indicated that there were two gdnf genes in medaka (Oryzias latipes), namely gdnfa and gdnfb, both of which were expressed in the testis and play important roles in the spermatogonial stem cell line SG3. However, the cellular expression patterns of gdnfa and gdnfb in the testis, as well as regulation of their expressions by retinoic acid (RA) and androgen, remain unclear. In this study, the cellular expression patterns of medaka gdnfa and gdnfb in the testis were detected using fluorescence in situ hybridization (FISH). Furthermore, the regulation of RA and 11-ketotestosterone (11-KT) on the expression of gdnfa and gdnfb was investigated at the tissue, cell, and molecular levels through real-time quantitative polymerase chain reaction (qRT-PCR) and transcriptional activity analyses of their 5′ upstream sequences. These results indicated that in medaka testicular sections, gdnfa was primarily expressed in somatic cells, while gdnfb was expressed in both germ cells and somatic cells. In testicular organ culture and somatic cells MTS1 derived from adult medaka testis, RA and 11-KT at different concentrations significantly down-regulated the expression of gdnfa, whereas up-regulated the expression of gdnfb. moreover, RA and 11-KT treatment reduced the luciferase activity of different truncated 5′ upstream sequences of gdnfa, but enhanced the luciferase activity of different truncated 5′ upstream sequences of gdnfb. Collectively, medaka gdnfa and gdnfb exhibit differential cellular expression patterns in the testis and are differentially regulated by RA and 11-KT at the tissue, cell, and molecular levels. This study deepens our understanding of the cellular expression patterns and regulation of medaka gdnfa and gdnfb, and lays an important foundation for further research on their biological functions.

• Molecular cloning of AUF1 gene from large yellow croaker (Larimichthys crocea) and analysis of its TNF-α mRNA decay-promoting activity

  HE Zhiqiao, WANG Huijuan, GUO Shengquan, ZHANG Xiaolin, YAN Xiaojun, SHEN Wang

  2025,49(1):019406-019406, DOI: 10.11964/jfc.20240114353

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  Hyperinflammation, induced by the overproduction of inflammatory cytokines, is a key pathogenesis in infectious diseases of cultured fish, such as hemorrhagic septicemia. Therefore, the biosynthesis of inflammatory cytokines is precisely regulated by transcriptional and post-transcriptional mechanisms to ensure tight control of the production. The importance of AU-rich element-binding factor 1 (AUF1), a ubiquitously expressed mRNA binding protein also known as heterogeneous nuclear ribonucleoprotein D0 (hnRNPD0), in maintaining the balance of inflammatory response has been well demonstrated in mammals, which it decreases the production of inflammatory cytokines by promoting mRNA decay. However, the regulatory effect of AUF1 on the expression of inflammatory factor mRNA in teleost fish remains unknown. To investigate the regulation of fish AUF1 on the mRNA expression of inflammatory factors, the full-length cDNA of an AUF1 homologue, LcAUF1, was cloned by rapid amplification of cDNA ends (RACE) from large yellow croaker (Larimichthys crocea), and its tissue-specific expression pattern and temporal expression in the spleen and kidney following Vibrio parahaemolyticus infection were investigated by real-time quantitative polymerase chain reaction (RT-qPCR). Additionally, the regulatory effect of LcAUF1 on TNF-α mRNA expression was detected by overexpression of LcAUF1 in RAW264.7 cells using a tetracycline-regulated expression system. The full-length cDNA of LcAUF1 was 1 413 bp in length, containing a 266 bp 5′ untranslated region (5′UTR), a 294 bp 3′UTR, and a 954 bp open reading frame (ORF) encoding a polypeptide of 317 amino acids. Multiple alignment revealed that the amino acid sequences and typical functional domains of mammalian AUF1s are highly conserved in LcAUF1, and LcAUF1 clusters with its homologues from other teleost fishes in the phylogenetic tree. In healthy large yellow croaker, Lcauf1 transcripts were detected in all 9 tested tissues, with the highest level found in the muscle tissue. Upon V. parahaemolyticus challenge, the expression levels of Lcauf1 were significantly down-regulated at 2 h (0.51-fold, P<0.01) and 12 h (0.58-fold, P<0.001) post-infection in the kidney, and at 24 h (0.39-fold, P<0.001) in the spleen. In RAW264.7 cells, overexpression of LcAUF1 significantly decreased the expression level of TNF-α mRNA at 0.5 (0.84-fold, P<0.01), 3.0 (0.70-fold, P<0.001) and 6.0 h (0.77-fold, P<0.01) post LPS challenge. After inhibition of transcription by actinomycin D, overexpression of LcAUF1 in RAW264.7 cells significantly increased the degradation rate of TNF-α mRNA, but had no significant effect on the degradation rate of β-Actin mRNA. These results collectively indicated the structure and function of AUF1 are highly conserved in vertebrates, and LcAUF1 decreases the mRNA expression levels of inflammatory cytokine by promoting mRNA decay, suggesting that LcAUF1 may be an important regulator of inflammatory responses during infection. This study provides reference data for further exploring the role of LcAUF1 in the regulation of inflammatory cytokine expression and the application of LcAUF1 in the prevention and control of infectious diseases in the large yellow croaker industry.

• Cloning and functional study of interferon regulatory factor 3 of Apostichopus japonicus

  JIANG Jianyang, LI Hongyang, WANG Chengyang, LI Chenghua, SHAO Yina

  2025,49(1):019407-019407, DOI: 10.11964/jfc.20240214358

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  Interferon regulatory factor 3 (IRF3) is an important member of the interferon regulatory factor family and plays an important role in defensing against pathogen infection. To investigate the function of the IRF3 gene in Apostichopus japonicus, we obtained the full-length cDNA sequence of the IRF3 gene in A. japonicus by cloning and sequence splicing using RACE technology, and named it AjIRF3. The full-length sequence of AjIRF3 gene is 2 023 bp and encodes 441 amino acids. Sequence analysis revealed that the C terminus of AjIRF3 contains an IAD domain. Phylogenetic tree analysis indicated that AjIRF3 is a new member of the IRF3 family and is more closely related to the invertebrate mollusc Littorina littorea. Tissue distribution analysis showed that AjIRF3 is expressed in all tissues, with the highest expression in muscle, followed by intestine, and the lowest expression in coelomocyte. Furthermore, the expression of AjIRF3 in coelomocyte was significantly up-regulated under Vibrio splendidus infection and reached its highest level at 6 h, which was 3.64-fold higher (P<0.05) than that of the control. Moreover, AjIRF3 mRNA expression levels peaked at 48 h after lipopolysaccharide (LPS) and poly(I:C) infection, increasing by 3.20-fold (P<0.01) and 8.57-fold (P<0.01), respectively, compared with the control. Subcellular localization studies showed that AjIRF3 is distributed in the cytoplasm, but it is mainly translocated from the cytoplasm to nucleus after V. splendidus infection. Additionally, we found that the apoptosis rate of coelomocyte was significantly decreased by 16% (P<0.01) following AjIRF3 interference. More importantly, our result showed that the number of intracellular bacteria in the si-AjIRF3 group was significantly increased by 19.83-fold (P<0.05) compared with NC group after V. splendidus infection. Collectively, these findings suggest that AjIRF3 plays important roles in innate immunity and regulates apoptosis to resist pathogen infection.

• Observation on the embryonic and post-embryonic developmental characteristics of blue round scad (Decapterus maruadsi)

  ZHANG Xiaoxiao, YANG Shaosen, ZOU Cuiyun, ZHANG Yong, HUANG Jinxiong, GAN Songyong, QIN Zhendong, HUANG Weiping, CHEN Yongnan, WU Jinhui, LIN Li

  2025,49(1):019608-019608, DOI: 10.11964/jfc.20240614591

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  Blue round scad (Decapterus maruadsi) is an economically significant fish species in China. Wild juveniles of D. maruadsi have been caught and are being cultured in net cages in China. However, the lack of artificial seedlings has limited the cultural scale of D. maruadsi in China. To date, there have been no reports on the propagation of D. maruadsi. To explore artificial breeding techniques for D. maruadsi, fertilized eggs were obtained by injecting HCG. The embryonic and post-embryonic development processes were observed and imaged using stereomicroscopy, and the characteristics of each stage from fertilized egg to juvenile fish were described. The results showed that D. maruadsi fertilized eggs were spherical, buoyant, and colorless, with an average diameter of (763.4±27.6) μm, containing a single oil globule. Under conditions of hatchery with temperature of 22.10–25.17 °C , salinity of 32.56–33.91, dissolved oxygen of 4.85–5.95 mg/L , and pH of 7.94–8.07, the fertilized eggs hatched in 19 hours and 10 minutes. The oil globule was completely absorbed at 48 hours, and the swimming bladder appeared at 72 hours. Embryonic development included 8 main stages, subdivided into 23 periods: fertilized egg, blastoderm, cleavage, blastula, gastrula, neurula, organogenesis, and hatching. Post-hatch development consisted of prelarval and larval stages. Newly hatched larvae had an average total length of (1 777.5±156.5) μm, with an average daily growth rate of 565 μm/d from 0 to 17 days post-hatching.

• Effect of trimethylamine-N-oxide dietary enrichment on the molting of the swimming crabs (Portunus trituberculatus) and their survival and osmoregulation under low salinity

  WU Cenyan, LIN Weichuan, SHI Ce, MU Changkao, WANG Chunlin, YE Yangfang

  2025,49(1):019609-019609, DOI: 10.11964/jfc.20230714082

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  To investigate the effects of trimethylamine-N-oxide (TMAO) enrichment on the survival and osmoregulation of Portunus trituberculatus under low salinity conditions, P. trituberculatus juveniles were fed diets containing different concentrations TMAO (0, 0.2%, 0.4% and 0.8%). Following a 15 day-TMAO enrichment period, the P. trituberculatus were subjected to low salinity (4) stress. The results showed that dietary TMAO supplementation increased the molting rate of P. trituberculatus under normal salinity (26). Specifically, the highest molting rate was observed in the 0.8% TMAO-supplemented group, reaching 53.9%±0.4% on day 15. All TMAO concentrations enhanced the survival rate of P. trituberculatus under low salinity stress. Notably, the 0.2% TMAO-enriched group exhibited the highest survival rate of 75% at 216 h of low salinity stress, which was significantly higher than the control group (P<0.05). Furthermore, the TMAO-enriched P. trituberculatus displayed higher serum osmotic pressure, gill Na⁺-K⁺ ATPase activity, mRNA gene expression of the α subunit of this enzyme, and TMAO content in various tissues compared to the control. This study suggests that TMAO enrichment may enhance the survival of P. trituberculatus under low salinity conditions by promoting molting and improving osmatic regulation through the use of inorganic ion and osmolytes. These findings provide a potential dietary supplement for the aquaculture of P. trituberculatus in low salinity environments.

• Comparison of growth, survival and evaluation of genetic parameters in the rapid-growth strain of the orange shell Crassostrea gigas

  DU Lijie, XU Chengxun, LI Qi

  2025,49(1):019610-019610, DOI: 10.11964/jfc.20230514002

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  The Pacific oyster, Crassostrea gigas, is a globally important aquaculture shellfish species. In recent years, it has faced challenges such as germplasm degradation and high mortality rates. Both China and international communities are actively working to cultivate new oyster varieties with superior growth performance and robust stress resistance. In this study, we constructed 11 half-sib families and 28 full-sib families using a nested design from rapid-growth strain of the orange shell C. gigas that had been mass-selected over three consecutive generations. Concurrently, wild individuals were used to establish control families to assess the growth and survival traits of the rapid-growth families of the orange shell C. gigas at different ages. The results indicated that during the larval stage, the growth and survival rates of the oyster families were higher than those of the control group, with average shell height and survival rates increasing by 12.40%–23.70% and 1.52%–13.98%, respectively. In the juvenile stage, compared with the control group, the shell height and survival rates of these families increased by 5.62%-10.74% and 2.34%-2.80%, respectively. However, further improvements in the survival rates of juvenile shellfish are needed. Significant differences were observed in growth and survival traits among different families (P<0.05), with families G14 and G23 showing greater advantages in growth and survival. Additionally, we evaluated the genetic parameters of shell height and shell length. The heritability of shell height and shell length ranged from (0.41±0.07) - (0.76±0.12) and (0.50±0.10) - (0.82±0.09), respectively, indicating medium and high heritability. The genetic and phenotypic correlations of shell height and shell length at different ages were positive, with correlation coefficients ranging from 0.95-0.99 and 0.28-0.75, respectively. This suggests that the growth traits of orange C. gigas have good breeding potential and can be selected indirectly. The fingdings of this study provided fundamental data for the development of the rapid-growth strain of the orange shell C. gigas.

• Ammonia nitrogen prediction model for recirculating aquaculture system based on different feeding strategies

  SUN Xueqian, LI Li, DONG Shuanglin, TIAN Xiangli, ZHANG Shengkun

  2025,49(1):019611-019611, DOI: 10.11964/jfc.20220613532

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  The prediction and warning of total ammonia nitrogen (TAN) in aquaculture are crucial. Current optimizations of TAN prediction models primarily rely on improved algorithms. However, various management strategies, such as feeding strategies, may be implemented during the aquaculture production process, potentially affecting the prediction performance of these models. This study aims to model and predict TAN concentrations in recirculating aquaculture system (RAS) and investigate the impact of different feeding strategies on the prediction performance of TAN models. We measured 7 water quality parameters in the tanks of Oplegnathus punctatus within an RAS. The data were pre-processed using principal component analysis (PCA) or Pearson correlation analysis, resulting in three datasets: the original dataset (OD), the Pearson dataset (PearsonD) and the PCA dataset (PCAD). These datasets were then integrated with random forest (RF), back propagation neural network (BP), gated circulation unit (GRU), and long short-term memory (LSTM) to forecast TAN concentrations under two distinct feeding strategies. The performance of the models was evaluated using root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE), and R-square value (R²-score). The RF modle exhibited the poorest prediction performance. The GRU and LSTM models demonstrated acceptable and stable prediction accuracy, while the accuracy of the BP model varied. Optimal prediction models differed under the two feeding strategies: under artificial feeding, Pearson correlation analysis combined with BP yielded higher accuracy, wheras under automatic feeding, Pearson correlation analysis combined with GRU performed better. Pearson correlation analysis combined with LSTM or GRU, and PCA combined with LSTM, showed superior performance throughout the experimental period. Compared to the automatic feeding strategy, under artificial feeding, the RMSE, MSE and MAE of the models built with Pearson correlation analysis and LSTM decreased by 0.007 2, 0.001 9 and 0.003 6 respectively, while the R²-score increased by 0.107 5. Similarly, the RMSE, MSE and MAE of the models built with Pearson correlation analysis and GRU decreased by 0.003 0, 0.000 8 and 0.003 0 respectively, and the R²-score increased by 0.082 6. Feeding strategy significantly influences the prediction accuracy of TAN models, and Pearson correlation analysis combined with GRU or LSTM could be employed to predict TAN in RAS effectively. This study provides a reference for the optimization of ammonia nitrogen prediction technology in RAS.

• Stock assessment of Setipinna taty in Shandong inshore waters based on length-based model and ensemble model

  HAN Qingpeng, WU Qiang, SHAN Xiujuan, JIN Xianshi, SU Chengcheng

  2025,49(1):019312-019312, DOI: 10.11964/jfc.20230113877

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  Assessing the status of fish stocks is fundamental to the scientific management of fishery resources. Setipinna taty, an economically and ecologically significant forage species, plays a crucial role within fish communities, and changes in its stock status can have critical ecological impacts. It is essential that the management of S. taty resources is based on robust scientific analysis of stock status. The data requirements of traditional stock assessment methods have hindered their use in assessing S. taty due to data scarcity. The rapid development of data-limited methods for estimating stock status has made it possible to achieve a credible assessment of S. taty resources despite the inadequacy of the data to support conventional analysis methods. In this study, the length-based spawning potential ratio model (LB-SPR), the length-based integrated mixed effects model (LIME), and Ensemble modeling based on a combination of these two models were used to evaluate the status of S. taty in Shandong inshore waters in 1999, 2000, 2006, 2017, and 2021. The spawning potential ratio (SPR) estimated by these models served as a biological reference point (BRP) for this study and as a proxy for maximum sustainable yield (MSY) in the absence of information on population size. Model results could potentially inform a sustainable fishing harvest strategy that targets a fishing mortality rate expected to result in 40% of unfished spawning output (known as "SPR_40%"), ensuring risk-averse management of populations with very low resilience. The SRP of SPR_30% is a threshold below which stocks are often considered overfished. Both LB-SPR and LIME model results showed that from 1999 to 2021, stock status reached its lowest level in 2000, then improved to its best state in 2017, before beginning to decline, and by 2021 had fallen to a similar level as that during 1999-2000. The SPR estimates from the LIME model were higher than those of LB-SPR for all years. Ensemble model SPR estimates were all lower than LIME results, but not all of them occurred between the LIME and LB-SPR results. The ensemble estimates of SPR from 1999 to 2021 showed an increasing trend (0.48–0.77) followed by a decrease to 0.47, all greater than the risk-averse value of 0.4. These values implied that the S. taty stock in Shandong inshore waters was in a healthy state throughout the study period. During the study period, favorable environmental conditions supported the growth and reproduction of S. taty in Shandong inshore, providing a certain guarantee for the health status of the S. taty resources. However, continually increasing exploitation intensity and spatial contraction and habitat deterioration of the core spawning and nursery grounds may adversely affect the stock status in the future. Currently, the S. taty stock in Shandong inshore has just reached full utilization, yet the fork length compositional structure remains above the population decline risk threshold (SPR_40%). Compression of this compositional structure nonetheless signals a need for precaution within the context of increasingly complex climatic change and increasing anthropogenic pressure. Considering the key position of S. taty in the Shandong fish community and its trophic characteristics should motivate fisheries researchers to evaluate the impacts of current commercial mesh net size of fishing gear and propose reasonable size constraints that can provide an optimal balance between ecological protection and economic benefit. The present study provides a credible scientific basis for the sustainable utilization of S. taty resources in Shandong inshore waters. It is the first public Chinese assessment report on the application of a multi-model combination to data-limited fishery stocks in China, and could help advance the progress of resource assessment for data-limited stocks throughout the country.

• Evaluation of seasonal variations on the growth features and removable carbon sinks of cultured mussels Mytilus coruscus in Gouqi Island

  WANG Yihang, PAN Yufeng, XIA Feiyu, XU Ying, DONG Yifei, YANG Yang, WANG Xiaoli, TIAN Xiaofei, TIAN Kuo, YANG Xiaolong, LI Hongliang, ZHANG Xiumei

  2025,49(1):019313-019313, DOI: 10.11964/jfc.20240114308

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  Abstract:

  Marine fishery carbon sinks are an important component of blue carbon. Fishery activities such as shellfish farming are considered among the most promising carbon sink activities. However, precise assessment of carbon sinks in shellfish farming still requires further investigation. To explore the potential of carbon sink in shellfish farming, this study focused on the raft-cultured mussels Mytilus coruscus near Gouqi Island. We examined the seasonal variations in their growth characteristics and the community features of the epiphytic animals, as well as their correlation with environmental factors. Based on the biomass carbon density (BCD) of the cultured mussels and epiphytic animals, we evaluated the removable carbon sink. The results revealed seasonal, age, and regional differences in the tissue moisture, fatness, and gonad index of the mussels. Tissue moisture exhibited the following patterns: spring > winter > autumn > summer, age 1 > age 2+, and the center area > the periphery area, showing opposite trends to both fatness and gonad index. Additionally, the gonad index followed the pattern of age 4 > age 3 > age 2 > age 1. There are significant seasonal differences in the carbon content of the tissues and the shells, as well as the wet weight ratio of the tissues. Redundancy analysis (RDA) showed a positive correlation between tissue moisture and ammonia nitrogen. Carbon content of the tissues, fatness, and gonad index were positively correlated with environmental factors such as chlorophyll a, temperature, and total nitrogen. A total of 153 species were identified among the epiphytic animals, belonging to the phyla Coelenterata, Mollusca, Annelida, Arthropoda, Echinodermata, Nemertina, and Chordata. The main classes included Polychaeta, Malacostraca, Bivalvia, Gastropoda, Anzhozoa, Thecostraca, and Ascidiacea. Seasonal differences were observed in the abundance and biomass of epiphytic animals, with the highest biomass detected in spring, primarily consisting of Anthopleura midori, Amphibalanus reticulatus, Modiolus comptus, Menippe rumphii, and Halosydna brevisetosa. RDA analysis indicated that the biomass of the Malacostraca animals was positively correlated with chlorophyll a, temperature, total nitrogen, total carbon, salinity, and nitrite, while the biomass of Ophiuroidea, Anzhozoa, and Thecostraca animals was positively correlated with ammonia nitrogen and nitrate content. The BCD of the mussels was highest at 129.98 g C/kg in autumn and lowest at 108.29 g C/kg in spring. The BCD of epiphytic animals was highest at 6.85 g C/kg in spring and lowest at 1.38 g C/kg in summer. By harvesting the mussels and epiphytic animals, the maximum BCD that can be removed from the water can reach 135.34 g C/kg. In 2021, farming M. coruscus in Gouqi could harvest approximately 3.02×10⁴ tons of carbon, generating an economic value of carbon sink about 10.49 million yuan. Our results provide an important theoretical basis and practical significance for maximizing the removable carbon sink capacity through farming M. coruscus, as well as for deepening the understanding and evaluation of the carbon sink effects of shellfish farming.

• Comparative study on phenotypic characteristics, health status and muscle nutritional quality of largemouth bass (Micropterus salmoides) under different depuration time and stocking density

  XU Qing, YUAN Julin, NI Meng, ZOU Songbao, LIU Mei, GU Zhimin

  2025,49(1):019614-019614, DOI: 10.11964/jfc.20230313953

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  Abstract:

  This study aimed to determine the optimal depuration strategy for largemouth bass (Micropterus salmoides) by examining the effects of varying treatment times and stocking density on phenotypic characteristics, health status, and muscle nutritional quality. M. salmoides with an initial body mass of (460.60±12.74) g were used as the research object. Three stocking densities (2.5, 7.5 and 12.5 kg/m³) were established, and two feeding modes were combined: short-term depuration (7 d, non-feeding) and long-term starvation (28 d, small-scale feeding). The results showed that, compared with the control (0 d), the hepatosomatic index (HSI), visceral index (VSI), and saturated fatty acid (SFA) content in muscle decreased significantly after depuration, while the condition factor (CF) and the proportion of essential amino acids (EAA/TAA) in muscle increased significantly. The content of essential amino acids (EAA), amino acid score (AAS), and essential amino acid index (EAAI) generally increased with the extension of net rearing time. Compared to short-term depuration (7 d), the body weight, CF, and total blood protein content (TP) of fish increased significantly after long-term depuration (28 d), while VSI and blood low-density lipoprotein cholesterol (LDL-C) content decreased significantly. Furthermore, comparisons among different density groups revealed that HSI, VSI, blood glucose (GLU), and LDL-C content, as well as muscle SFA content, decreased with increasing breeding density. In contrast, blood biochemical indexes, liver superoxide dismutase (SOD) content, and muscle crude protein, ash, and total essential amino acids (TAA) generally exhibited the highest values in the medium stocking density (MSD) group. Overall, long-term depuration can lead to greater consumption of visceral fat, improved fish body shape characteristics, and enhanced nutritional quality of fish muscle. Therefore, the optimal depuration strategy for M. salmoides is 28 d depuration with small amounts feeding at stocking density of 7.5 kg/m³. This study provides a theoretical reference for the application and popularization of ecological depuration culture model of M. salmoides.

• Comparison of nutritional quality between two fattening methods and lake-cultured Eriocheir sinensis

  XIAO Changlun, SUN Yunfei, LU Zhenzhen, CHENG Yongxu

  2025,49(1):019615-019615, DOI: 10.11964/jfc.20220913673

  Abstract(25) HTML(0) PDF(1.57 M)( 155) Collect

  Abstract:

  To assess the nutritional quality of pond-reared and lake-cultured Eriocheir sinensis, this study utilized compound feed (CF) and chilled fish (CTF) to fatten E. sinensis for one month and compared their edible rate, conventional nutrients, fatty acids, and free amino acids with lake-cultured E. sinensis (LC). The findings are as follows: (1) The gonadosomatic index (GSI) of fattened E. sinensis with chilled fish was significantly higher than those fattened with compound feed and lake-cultured E. sinensis, while the hepatosomatic index (HSI) was significantly lower compared to those with compound feed and lake-cultured E. sinensis (P<0.05). No significant differences in meat yield and edible rate were observed among the three groups of E. sinensis (P>0.05). (2) The total lipid content in hepatopancreas of E. sinensis fattened with compound feed and lake-cultured were significantly higher than those fattened with chilled fish, while the water and crude protein contents in hepatopancreas were significantly lower than those of E. sinensis fattened with chilled fish (P<0.05). The fattened E. sinensis with CTF had significantly lower water and total lipid contents in gonads than lake-cultured E. sinensis, while crude protein content was significantly higher than that of lake-cultured E. sinensis (P<0.05), and there was no significant difference in ovarian nutrients (P>0.05). Crude protein content in meat of female lake-cultured E. sinensis was significantly higher than those of E. sinensis fattened with CF and CTF (P<0.05), with no significant difference in other nutrients (P>0.05). (3) The content of C18:2n6 (LA), ∑PUFA and ∑n-6PUFA in the edible tissues of E. sinensis fattened with CF was significantly higher than those fattened with CTF and lake-cultured E. sinensis, and the contents of EPA and DHA in the hepatopancreas and ovary of E. sinensis fattened with CTF were significantly higher than those of E. sinensis fattened with CF and lake-cultured E. sinensis (P<0.05). (4) The content of glutamic acid (Glu) and aspartic acid (Asp) in lake-cultured E. sinensis were significantly higher than those of CF and CTF fattened E. sinensis, while serine (Ser), leucine (Leu), tyrosine (Tyr) and lysine (Lys) content was lower in those of CF and CTF fattened E. sinensis, and the contents of umami and sweet amino acids in the gonads of lake-cultured E. sinensis were significantly higher than those of the two fattened E. sinensis (P<0.05). In conclusion, CF can enhance gonadal development in E. sinensis, yielding the highest GSI. There are notable differences in conventional nutrients in the hepatopancreas and testis among the three types of E. sinensis. The fatty acid composition of the two types of fattened E. sinensis is superior to that of lake-cultured E. sinensis, while lake-cultured E. sinensis exhibit the highest umami taste and sweet amino acid content.

• Isolation and identification of Exiguobacterium profundum and its pathogenicity analysis on Crassostrea gigas

  JIANG Jun, SUN Jiejie, YANG Wenwen, GAO Lei, LENG Jinyuan, WANG Lingling, SONG Linsheng

  2025,49(1):019416-019416, DOI: 10.11964/jfc.20240514519

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  Abstract:

  In the present study, a potential pathogenic bacterium was isolated and identified from Pacific oysters (Crassostrea gigas) with abscess disease collected from a culture area in Zhuanghe, Dalian, Liaoning. Exiguobacterium profundum was identified in the lesions of the diseased C. gigas using 16S rDNA sequencing and bioinformatics techniques. Antimicrobial susceptibility and hemolysis experiments were conducted. The expression of inflammation-related genes and changes in bacterial community structure in the gill tissues following E. profundum infection were further analyzed using artificial infection experiments, high-throughput sequencing technology, and quantitative real-time PCR. The results showed that the strain formed creamy-yellow colonies with a diameter of 1.0-1.5 mm on marine agar 2216 E, exhibiting uniform and stable morphology. E. profundum demonstrated high sensitivity to cefoperazone, penicillin, and amoxicillin. It exhibited significant β-hemolytic activity at 28 °C. Artificial infection experiments revealed the presence of abscesses on the mantle and white spots and swelling on the gills, with significant increases in the mRNA expression levels of Cgtlr3, Cgap-1, Cgcaspase-3, Cgil-17-5 and Cgil-17-6 in the gills post-infection. High-throughput sequencing analysis showed an increase in the relative abundance of Proteobacteria and Campylobacterota, as well as an induction in the relative abundance of Vibrionaceae in the gill tissues following E. profundum infection. These findings suggest that E. profundum may contribute to the pathogenesis of C. gigas by promoting the mRNA expression of inflammation-related genes and inducing the abundance of Vibrio spp. in the gill tissue. This study identifies E. profundum as a potential pathogen of C. gigas with abscess disease, providing valuable data support for the prevention and control of shellfish diseases.