Abstract:

To investigate the genetic diversity， phylogenetic relationships， and genetic differences between the northern subspecies （BFL） and “YOULU No.3” strain of largemouth bass， this study analyzed the genetic diversity of both populations. A total of 20 individuals from the BFL and 20 from the “YOULU No. 3” strain were selected for whole-genome sequencing. Genetic diversity was assessed by comparing observed heterozygosity （H_o）， expected heterozygosity （H_e）， polymorphism information content （PIC）， and nucleotide diversity （P_i） between the two populations. Phylogenetic relationships and genetic structure were explored through a phylogenetic tree， relationship matrix， principal component analysis （PCA）， linkage disequilibrium decay curves， and Admixture analysis. Additionally， a selection scan based on population differentiation index （F_ST） and P_i was conducted to identify selected genes， followed by Gene Ontology （GO） and Kyoto Encyclopedia of Genes and Genomes （KEGG） enrichment analysis. The results showed that the H_o， H_e， and PIC values for the two populations were 0.329， 0.344， 0.276 for the BFL and 0.327， 0.342， 0.275 for “YOULU No.3，” with no significant differences （P>0.05）. However， the P_i value of the BFL was significantly higher than that of “YOULU No.3” （P<0.01）. Phylogenetic trees， relationship matrices， PCA， and admixture analysis revealed that the two populations belong to different subgroups. Linkage disequilibrium decay analysis indicated that the BFL exhibited faster decay than “YOULU No.3”. Selection scan results showed strong selection signals on chromosomes 5，6，7，14，22， and 23 in “YOULU No.3” GO and KEGG enrichment analysis suggested that genes related to feeding and immunity were under selection during the domestication and breeding of “YOULU No.3”. This study indicates that the BFL and “YOULU No.3” come from different subgroups， with the BFL exhibiting higher genetic diversity and “YOULU No.3” undergoing stronger selection pressures， mainly related to feeding and immunity. The findings provide support for the conservation and genetic improvement of largemouth bass resources.

Abstract:

To investigate the role of the vasa gene in gonadal development of the triangle sail mussel （Hyriopsis cumingii）， techniques including quantitative real-time PCR （qRT-PCR） and in situ hybridization were employed to analyze the structural characteristics and spatiotemporal expression patterns of the vasa gene in male and female tissues， as well as during early and mature developmental stages of testes and ovaries. The results revealed that the vasa gene cDNA consisted of 4 673 bp， encoding 808 amino acids， containing two functional domains （DEXDc and HELICc） and nine conserved motifs characteristic of the DEAD-box protein family. The vasa gene exhibited significantly higher expression in ovaries and testes compared to other tissues （P<0.05）. During early gonadal development， its expression showed an initial increase followed by a decline， reaching significant elevation at 6 months of age with marked differences compared to other age groups （P<0.05）. In mid-to-late gonadal development， vasa expression displayed a progressive upward trend， with significantly higher levels in females than in males （P<0.01）. In situ hybridization localized vasa expression to oocytes， spermatogonia， spermatocytes， sperm cells， follicle walls， as well as primordial germ cells and follicular cells in juvenile gonads. This study suggests that the vasa gene participates in gonadal development in H. cumingii， potentially regulating primordial germ cell proliferation and gamete meiosis， serving as a putative regulatory factor in gametogenesis， and playing crucial roles in maintaining testicular/ovarian and germ cell development. These findings provide theoretical insights for research on gonadal development， gametogenesis， and monosex breeding techniques in H. cumingii.

Abstract:

To investigate the transcriptional regulatory mechanism of the slc5a1 gene promoter in the large yellow croaker （Larimichthys crocea）. The study employed bioinformatics methods to perform a phylogenetic tree analysis of the slc5a1 amino acid sequences from large yellow croaker and other species. Using large yellow croaker genomic DNA as a template， the slc5a1 gene promoter region was obtained by PCR amplification. Bioinformatics software was then utilized to predict and analyze the molecular structural features of this sequence， including the core promoter， regulatory elements， and transcription factors. Finally， the transcriptional activity of different fragments of the promoter region was assessed using a dual-luciferase reporter gene system. Bioinformatics analysis results showed that the slc5a1 amino acid sequence is highly conserved in fish species. Prediction of the large yellow croaker slc5a1 gene promoter region identified three potential core promoters， as well as binding sites for several transcription factors， including Sp1， C/EBPα， GATA-1， and Oct-1. The results from the dual-luciferase reporter gene system revealed that the region from -2 073 to -1 723 bp of the large yellow croaker slc5a1 gene promoter contains positive regulatory elements， the region from -1 723 to -1 404 bp contains positive regulatory elements， the region from -1 404 to -743 bp contains negative regulatory elements， the region from -743 to -272 bp contains negative regulatory elements， and the region from -272 to +153 bp contains no regulatory elements. The study indicates that the upstream region from -2 073 to -1 404 bp of the large yellow croaker slc5a1 gene is the core promoter of this gene. The research results lay the foundation for further investigation into the transcriptional regulatory mechanism of the large yellow croaker slc5a1 gene.

Abstract:

To estimate the genetic parameters for growth and nutritional quality traits in Tegillarca granosa， this study used the “Yue Qing Wan No.1”strain as parents and constructed 30 full-sib families using a nested mating design. Variance components and genetic parameters were estimated using a mixed linear model. The results showed that the heritabilities for shell length， shell height， shell width， and glycogen content were 0.23±0.08， 0.31±0.09， 0.30±0.09， 0.34±0.09， respectively， all indicating moderate heritability. The heritabilities for wet weight and hemoglobin content were 0.15±0.06， 0.16±0.06， respectively， indicating a low heritability. In contrast， the heritability for total protein content was 0.44±0.11， indicating a high heritability. These findings suggest that selectively breeding for shell length， shell height， shell width， total protein， and glycogen content would yield higher genetic progress. High phenotypic （0.66-0.86） and genetic （0.77-0.99） correlations were observed among the four growth traits. However， both phenotypic and genetic correlations among the three nutritional quality traits （hemoglobin， total protein， glycogen） themselves， and between these nutritional traits and the growth traits， were low （r<0.2）. This indicates that indirect improvement of nutritional quality traits through selection for growth traits would be difficult. This study provides essential genetic baseline data for the selective breeding of Tegillarca granosa targeting high-quality traits.

Abstract:

Energy metabolism homeostasis regulation is crucial for the growth， development， and reproduction of organisms in response to environmental stress. To investigate whether AMPK is involved in the energy homeostasis regulation of the razor clam under long-term low-salinity stress， this study identified the AMPK subunit genes of the razor clam and explored their expression patterns under prolonged low-salinity stress. Results showed that the amino acid sequences of the AMPKα， β， and γ subunits in the razor clam exhibited high similarity to intertidal mollusks， with the highest homology observed with Mercenaria mercenaria， at 84%， 74%， and 77%， respectively. Under low salt 2 salinity stress， AMPKα and β subunits were found to participate in the regulation of energy metabolism in the gills， hepatopancreas， and water pipe of the razor clam， with significantly increased expression levels （P<0.05）. During the 35 day low salt aquaculture process， the expression of AMPKα and β genes in gill tissue showed a significant increase （P<0.01）. In hepatopancreas tissue， the expression of AMPKα， β， and γ genes during the low-salinity acclimation and early cultivation stages （0-14 days） was significantly higher than that of the normal salinity group （P<0.01）. In the late stage of low-salinity cultivation （21-35 days）， the AMP/ATP ratio in gill and hepatopancreas tissues gradually approached the level of the normal salinity group， indicating a stabilization of energy metabolism. Overall， these findings demonstrate the significant role of AMPK subunit genes in the razor clam adaptation to long-term low-salinity cultivation through energy metabolism regulation.

Abstract:

Cell cycle protein L1 （ccnl1a） is a nuclear protein. As a key regulatory factor of CDK， it regulates the activity of CDK through its periodic expression and jointly regulates alternative splicing with CDK12. To elucidate the physiological function of cell cycle protein L1 （ccnl1a） in the development of vertebrates， this study used CRISPR/cas9 technology to construct a zebrafish ccnl1a knockout model. Phenotypic analysis showed that the mutant exhibited significantly lower body weight， body length， and body height compared to the wild type （P<0.05）， confirming that ccnl1a is a key regulatory factor for growth traits. Whole transcriptome analysis further revealed that upregulated genes included members of the apoptotic pathway dthd1， negative regulators of proliferation pias2， and cell population regulators cgref1； downregulated genes covered metabolic-related factors （fatty acid synthase elovl2， cholesterol pathway genes ebp）， angiogenic factors mydgf， protein transport protein lman1， secretion pathway components spcs2， and sugar metabolism receptors gcgra. This study first revealed an in vivo model the association between ccnl1a deficiency and systemic growth disorders， and based on transcriptome analysis， constructed a cross-pathway regulatory model： that ccnl1a deficiency may coordinate the regulation of activation， proliferation inhibition， and metabolic/suppression functions， jointly leading to growth defects.

Abstract:

To systematically evaluate the culture performance of different early-maturing strains of Chinese mitten crab （Eriocheir sinensis） during the adult stage， culture experiments were conducted with four strains： Shenjiang No. 1 （SJ）， Guanghe No. 1 （GH）， unselected Liao strain （ULS） ，and Northern-breed strain（NBS）. Key indicators such as average body weight， puberty molting， organ coefficients， survival rate and yield were compared. The results revealed that： （1） The average body weight of SJ individuals （both female and male） in the mid-to-late adult rearing stage （July and September） was significantly higher than that of ULS （P<0.05）， with GH and NBS ranking between them. （2） The puberty molting rate and gonadosomatic index（GSI） of ULS （both female and male） were the highest at all sampling points. On August 10 and August 25， the puberty molting rate of ULS was significantly higher than that of SJ and GH （P<0.05）， while on October 28， their GSI was significantly higher than that of GH （P<0.05）. （3） The survival rate of ULS was significantly lower than that of SJ and NBS， and the male and overall yield of ULS was significantly lower than that of the other strains （P<0.05）. In conclusion， SJ outperformed the other strains in average body weight， the proportion of large-size adult crabs， and final yield. However， its puberty molting rate and gonadal development speed were slightly lower than those of ULS. Thus， the selection of suitable early-maturing varieties （strains） of E. sinensis for adult culture in different region should be based on specific production requirements.

Abstract:

This study aimed to systematically compare the nutritional composition and taste activity value in the muscle of Macrobrachium rosenbergii cultured in saline-alkaline water versus freshwater. Basic nutrients， minerals， fatty acids， and amino acids were analyzed to evaluate nutritional differences. Flavor characteristics were analyzed through taste activity value （TAV）. No significant differences were observed in moisture， crude protein， crude fat， or ash content between the two groups. However， the saline-alkali group exhibited significantly higher levels of Na， Mg， P， Fe， Cu and Zn（P<0.05）. The EPA and DHA contents in the saline-alkali group were （15.69 ± 0.70）% and （8.95 ± 0.49）%， respectively， significantly exceeding those in the freshwater group （14.12 ± 0.66）% and （5.25 ± 0.31）% （P<0.05）. The EAAI score of the saline-alkali group （84.89） was slightly higher than that of the freshwater group （83.83）. Taste analysis revealed that TAV values of Glu， Gly， Ala， Arg， AMP， and IMP in the saline-alkali group （1.83， 2.56， 2.15， 5.65， 1.64， 8.14） were higher than those in the freshwater group （1.38， 1.89， 2.03， 4.17， 1.04， 4.64）， whereas the TAV of His （2.76） was lower. Saline-alkali aquaculture enhances mineral accumulation， polyunsaturated fatty acid content， and umami-related compounds in M. rosenbergii， demonstrating superior nutritional and flavor qualities compared to freshwater systems. This study provides a scientific basis for optimizing saline-alkali land utilization in aquaculture.

Abstract:

This study aims to analyze the dynamic changes of intestinal microbiome in female Scylla paramamosain from the southeast coastal China during the overwintering period （ΔT≥10℃）， and to reveal the changes in gut bacterial structure during the natural overwintering process. Intestinal samples （n=18） were collected before （November， 20 ℃）， during （January， 8 ℃） and after （March， 18 ℃） overwintering. High-throughput sequencing of the V3-V4 region of the 16S rRNA gene was performed. The richness and diversity of the microbiota structure were systematically evaluated. The results showed that a total of 1 500 137 high-quality and effective sequences were detected in the three groups of samples， which belonged to 2 518 OTUs. The highest number of OTUs was observed during overwintering， and the intestinal microorganisms of S. paramamosain shared 164 OTU in the three periods. The dominant phylum was Firmicutes and the dominant genus was Candidatus Hepatoplasma before overwintering， and the dominant phylum， genus was Spirochaetota， Sediminispirochaeta during overwintering. After overwintering， the dominant phylum was Bacteroidota， and the dominant genus was Sediminispirochaeta. The Alpha diversity analysis of the intestinal microbial community at different stages showed that the abundance and species diversity in the overwintering were higher than before and after overwintering. Evenness analysis showed that the distribution of intestinal microbial species was the lowest uniformity in overwintering， and the evenness of intestinal microbial species was the most before overwintering. The flora before overwintering was obviously different from that in the middle and late stages of overwintering. LEfSe analysis showed that probiotics can be developed during overwintering， but they need to be verified. During the overwintering period， the overall metabolism of S. paramamosain is enhanced， including carbohydrate metabolism in the early stage， lipid and amino acid metabolism in the middle and late stages， and the functional expression of stress-related genes is up-regulated in the middle and late stages， which may lead to the increased resistance of S. paramamosain during the overwintering period. This is the first study to systematically reveal the composition， diversity， and functional changes of the gut microbiota in S. paramamosain during overwintering， which provides a theoretical basis for the development of overwintering management strategies for S. paramamosain based on gut microbiota.

Abstract:

To characterize the trophic structure of the Chenhang Reservoir ecosystem in the Yangtze River Estuary， this study utilized carbon and nitrogen stable isotope analysis to examine primary carbon sources， trophic levels， trophic structure indices， and niche characteristics of fish communities in 2023. The results demonstrated that the fish δ¹³C values in Chenhang Reservoir ranged from -27.19‰ to -20.46‰， with a mean value of -25.27‰±1.91‰， showing significant differences （P<0.05） from organic detritus （-14.53‰±0.50‰） but aligning closely with phytoplankton， zooplankton， and aquatic plants.Notably，Xenocypris davidi exhibited distinctly higher δ13C values （-20.46‰±0.59‰） compared to other species. The trophic levels of fish with different feeding habits were as follows： secondary carnivorous fish （3.8±0.09）>primary carnivorous fish （3.17±0.19）>herbivorous fish （2.84±0.25）>Planktivorous fish （2.57±0.10）>omnivorous fish （2.53±0.25）. Notably， herbivorous species including Megalobrama amblycephala（3.02） and Parabramis pekinensis （2.74） displayed higher trophic levels than filter-feeding Hypophthalmichthys molitrix （2.64） and Aristichthys nobilis （2.5）.The fish community exhibited intermediate trophic range （NR=5.21）， carbon source diversity （CR=7.24）， core niche space （SEAc=12.77）， and average trophic diversity （CD=1.54）. However， species aggregation density （MNND=1.21） and evenness （SDNND=0.78） were relatively high， while trophic redundancy remained low. These findings indicated that plankton served as the predominant carbon source for most fish consumers in Chenhang Reservoir， although X. davidi additionally incorporated substantial organic detritus. The elevated trophic positions of herbivorous fish likely reflected limited aquatic plant availability， resulting in a dietary transition toward more omnivorous feeding strategies. The findings of this study may serve as a scientific foundation for reservoir water quality management and ecological regulation strategies.

Abstract:

This paper employed an enrichment culture and isolation method to screen a bacterial strain with high ammonia nitrogen degradation capability from some cultivation ponds of Chinese mitten crab （Eriocheir sinensis）.Based on morphological， physiological & biochemical， and molecular biological characteristics， the strain was identified as the BC17 of Bacillus licheniformis. The analysis results of bacterial growth and ammonia nitrogen degradation efficiency under different environmental conditions revealed that the optimal carbon source for the strain was sodium citrate. The most effective parameters for ammonia nitrogen degradation were a carbon-to-nitrogen ratio of 15， temperature of 37-40 ℃， pH=7.0， and salinity of 0-5. Juvenile crabs with an initial body weight of （9.97±1.12）g were randomly divided into an experimental group and a control group. The aquaculture water in the experimental group was supplemented with a bacterial suspension at an initial concentration of 10⁶ CFU/mL during the experimental period of 31 days. The results indicated that the ammonia nitrogen concentration in the water of the experimental group was significantly lower than that of the control group （P<0.05）. The survival rate， growth rates of carapace length and width in the experiment group were significantly higher than those in the control group （P<0.05）， meanwhile， the weight gain rate after molting was a light higher in the experiment group compared to the control group （P>0.05）. Analysis of the intestinal microbiota of the crabs revealed reduced abundance of pathogenic bacteria such as Malaciobacter and Shewanella in the experimental group.This study demonstrates that the strain BC17 of Bacillus licheniformis not only effectively removes ammonia nitrogen and nitrite nitrogen in aquaculture waters and improves water quality， but also enhances the survival and growth performance， and suppresses pathogenic bacteria in the intestine of the Chinese mitten crab. Generally， these findings highlighted the potential application value of the strain BC17 of Bacillus licheniformis in sustainable aquaculture industry of Chinese mitten crab.

Abstract:

To investigate the alterations in the physiological characteristics of Vibrio parahaemolyticus after cold shock， the standard strain ATCC17802 of V. parahaemolyticus was employed as a typical representative to systematically explore the patterns of physiological phenotypic changes under moderate low temperatures of -20， 4， 10， and 15 ℃ for 3， 6， 12， and 24 h， respectively. Through the analysis of sublethal rate， hemolytic activity， swimming motility and biofilm formation ability， combined with the observation of the bacterial morphology via scanning electron microscopy， the impacts of cold shock on V. parahaemolyticus were comprehensively analyzed. The results revealed that the effects of cold shock on V. parahaemolyticus exhibited significant temperature-dependent characteristics： Cold shock above freezing point （4 ℃， 10 ℃， and 15 ℃） promoted biofilm formation through sustained secretion of extracellular proteins， thereby enhancing the environmental adaptability and pathogenic potential of the strain. Conversely， cold shock at -20 ℃ disrupted the cellular structure via ice crystal formation， leading to significantly suppressed bacterial motility， hemolytic activity and biofilm formation.This study provides phenotypic data and a theoretical foundation for the precise risk assessment of V. parahaemolyticus in cold-chain aquatic products and the exploration of cold shock pathways.

Abstract:

In order to study the vibrio anguillarum minus toadstool inactivated vaccine immune effect， this study attenuated strains of V. anguillarum Δvah1-vah4-rtxA for high temperature inactivated bacteria fermentation preparation into inactivated vaccines， 2% according to the proportion of added to the feed， oral immune Lateolabrax maculatus 21 d. Blood was collected from the caudal vertebral vein at 0 d， 7 d， 14 d and 21 d after immunization， and the serum levels of immunoglobulin M （IgM） and lysozyme （LZM） were measured. After 21 days of immunization， the fish were challenged with wild type V. anguillarum via intraperitoneal injection.The results showed that compared with the control group， IgM content in the serum of the immunized group of L. maculatus increased significantly and reached the highest value by the 21st day. Serum LZM content increased to reach the highest value by the 14th d， and thereafter， decreased slightly. Transcriptome analysis of the head kidney of L. maculatus for 21 d of immunization showed 252 significantly up-regulated genes and 200 significantly down-regulated genes compared to the control group， and KEGG analysis showed that these differential genes were significantly enriched for hematopoietic cell spectrum， natural killer cell-mediated cytotoxicity， phagolysosomes， the NF -κB signaling pathway， the production of IgA by intestinal immune network， and the Fc epsilon RI and other pathways. The relative immunoprotection rates at 7 d and 14 d were 62.5% and 25.0%， respectively. Pathological observations of the immunized group showed that the extent of vacuolization of the intestinal mucosa and structural damage to the gill tissues were relatively mild.The above results indicated that the attenuated strain of V. anguillarum Δvah1-vah4-rtxA preparation into inactivated vaccine， to improve the flower L. maculatus against V. anguillarum infection have better effect.

Abstract:

To address the current challenges of low efficiency in single detection and difficulty in identifying co-infections， this study establishes a duplex fluorescence real-time PCR method for simultaneous and rapid detection of Cyprinid herpesvirus type Ⅱ （Cyprinid herpesvirus 2， CyHV-2） and type Ⅲ （Cyprinid herpesvirus 3， CyHV-3）. This method seeks to address the current challenges associated with low efficiency in single-virus detection and the difficulty in distinguishing mixed infections. Utilizing the conserved regions of the ORF71 gene of CyHV-2 and the ORF140 gene of CyHV-3， three pairs of specific primers were designed and evaluated. Through the optimization of primer design， reaction systems， and reaction conditions， the specificity， sensitivity， and repeatability of the method were validated， culminating in the establishment of a duplex fluorescence qPCR method for the concurrent detection of CyHV-2 and CyHV-3. The study successfully established a duplex fluorescence qPCR detection method. The optimal primer sets were determined to be CyHV-2-F1&R1 （T_m= 82.78 ℃） and CyHV-3-F1&R1 （T_m= 89.22 ℃）， with a clear separation of the two peaks observed in the melting curve. This study introduces a novel duplex fluorescence quantitative PCR （qPCR） method for the concurrent quantitative detection of CyHV-2 and CyHV-3. The method demonstrated a sensitivity of 14.8 copies/μL for CyHV-2 and 21.9 copies/μL for CyHV-3， with no cross-reactivity observed with grass carp reovirus type Ⅰ， Ⅱ， and Ⅲ （GCRV-Ⅰ， GCRV-Ⅱ， GCRV-Ⅲ） or Spring viraemia of carp virus （SVCV）. The coefficients of variation for the cycle threshold （Ct） values and melting temperature （T_m） values were less than 4.0% and 0.2%， respectively. Clinical validation indicated a positive detection rate of 22.5% for CyHV-2 and 25.0% for CyHV-3， which is consistent with the results obtained by conventional PCR methods according to national and industry standards. This indicates that the dual fluorescent quantitative PCR method established in this study exhibits high sensitivity， specificity， and repeatability. In conclusion， this study is to establish a duplex fluorescence qPCR method for the simultaneous quantitative detection of CyHV-2 and CyHV-3. The method offers significant advantages， including rapid processing （completion within 2 hours）， precise dual-target discrimination， high sensitivity （detection limit <30 copies/μL）， and excellent repeatability. This method can be used for the rapid diagnosis and disease monitoring of CyHV-2 and CyHV-3 in aquaculture， serving as a reliable tool for the rapid differential diagnosis， prevention， and control of cyprinid herpesviruses， as well as a valuable reference for developing multiplex detection assays for other aquatic viruses.

Abstract:

To address the issues of deteriorated water exchange capacity and localized seston depletion in the suspended raft mussel farming area of Gouqi Island caused by suboptimal layout design， which severely impacts mussel growth， this study employed the three-dimensional hydrodynamic model FVCOM coupled with a tracer module and a particle-tracking module to systematically evaluate optimization schemes for their effects on water exchange capacity， exogenous seston supply， and mussel condition index. The results revealed that under the current farming layout， periodic seston depletion occurs during neap tides in nearshore areas and the central farming zone， with the maximum water exchange time exceeding 30 hours. Single-factor optimizations， including removal of nearshore farming units， addition of trumpet-shaped channels， and optimization of raft orientation， reduced the area of low-seston zones during neap tides by approximately 30.3%， 48.4%， and 11.3% respectively while decreasing the farming area by 7.1%， 9.6%， and 0 compared to the current layout， significantly mitigating localized seston shortages. The comprehensive optimization scheme integrating all three single-factor measures reduced the total farming area by 13.7% compared to the current layout while achieving a 70% reduction in low-seston zones during neap tides and shortening the maximum water exchange time to less than 20 hours. This significantly enhanced the overall seston concentration and daily growth rate of mussels in the farming area. With increased average seston intake per mussel， the condition index across the entire farming area improved by 6.0%. The study demonstrates that the comprehensive optimization scheme effectively improves water exchange and seston replenishment in the farming area while reducing spatial disparities in mussel growth among different zones. This research provides scientific reference for the management of suspended raft mussel farming areas.

Abstract:

To improve the spatiotemporal granularity of fishing-ground prediction for Dosidicusgigasin the southeastern Pacific， we evaluated how multiple time scales and environmental-factor combinations influence the distribution of the center fishing ground. Using fishery and environmental datasets from 2012 to 2021， we considered five temporal windows （3 d， 6 d， 10 d， 15 d， 30 d） and seven input combinations derived from sea surface temperature （SST）， sea surface height （SSH）， sea surface salinity （SSS）， and photosynthetically active radiation （Par）. The application effect index of fishing ground （AEI_FG） was introduced to define the center fishing ground as the prediction target. Because PAR degraded performance at the 30 d scale， we applied a weight-optimization scheme to mitigate its adverse effect. We compared three models： U-Net， generalized additive model （GAM）， and artificial neural network （ANN）. Results show that U-Net consistently achieved the best performance across schemes and accurately captured the spatial structure of center fishing grounds. Prediction accuracy depended strongly on the environmental-factor configuration， with the SST and SSS combination performing best overall. These findings demonstrate that deep learning can effectively integrate multi-source oceanographic information to enhance prediction accuracy for fishing grounds， providing methodological support for multi-timescale forecasting and intelligent fishery information services.

Abstract:

The Antarctic krill （Euphausia superba）， a keystone species in the Southern Ocean， exhibits energy storage strategies that directly influence both its reproductive success and regional biogeochemical cycling. To investigate the characteristics of lipid accumulation and its relationship with feeding habits in this species， this present study utilized krill specimens collected from Fishing Area 48 in the Southern Ocean between November 2023 and August 2024. Lipid extraction techniques and fatty acid biomarker analysis were employed to determine the lipid content and fatty acid composition of soma tissue. Principal component analysis and linear mixed-effects model were also applied to examine dietary shifts across different maturation stages and their impact on lipid accumulation. The results revealed significant seasonal variation in soma lipid content， with the highest levels observed in autumn， followed by summer and winter. Ovigerous females exhibited significantly lower lipid content [（185.60±37.72） mg/g] compared to non-ovigerous adults [（230.55±70.96） mg/g]. Non-ovigerous adults had higher levels of saturated fatty acids， whereas ovigerous females showed a marked increase in polyunsaturated fatty acids. Lipid content was positively correlated with diatom-associated fatty acids [C16：1n7 and C20：5n3 （EPA）]， but negatively correlated with C18：1n9c， an indicator of trophic plasticity.This study demonstrates that lipid accumulation in Antarctic krill follows distinct seasonal patterns and is closely linked to dietary composition. These findings provide valuable scientific insights into the ecological adaptation mechanisms of Antarctic krill and contribute to the development of effective resource conservation and management strategies.

Abstract:

The shortbill spearfish （Tetrapturus angustirostris） is a large pelagic fish species inhabiting tropical and temperate waters， primarily distributed in the Pacific and Indian Oceans. To clarify its biological traits and bycatch status in longline fisheries， this study conducted an integrated analysis of its bycatch patterns， including bycatch per unit effort （BPUE） and on-deck mortality， and population structure（such as fork length， sex， and sexual maturity） using observer data from the Chinese Pacific tuna longline fishery （2010-2021）. A Tweedie Generalized Additive Model （Tweedie-GAM） was employed to analyze the effects of spatiotemporal factors， environmental variables， and operational parameters on the BPUE of the shortbill spearfish. The results indicated an annual average BPUE was 0.21ind./1 000 hooks； the on-deck mortality was notably high at 56.43%；the sex ratio was approximately 1∶1 （0.97∶1）；the dominant fork length for both male and females was 150-170 cm； males exhibited significantly greater mean fork length than females（P<0.01）. The cumulative deviance explained by the Tweedie-GAM was 39.07%， with sea surface temperature （SST） exhibiting the highest individual deviance explained （27.65%）， followed by latitude （4.94%）， salinity （1.90%）， year （1.20%）， and hooks per basket （1.35%）. Contributions from all other variables were below 1%. Bycatch hotspots were concentrated in the area 100°W-130°W， 10°S-20°S， with two potential hotspot regions identified at 170°E-180°W near 20°S and 170°E-170°W， 15°N-25°N. This study elucidated population structure characteristics and bycatch dynamics of the Pacific shortbill spearfish， providing critical references for monitoring resource fluctuations and formulating science-based conservation measures.

Abstract:

As a vital component of pelagic fisheries， the fishing efficiency of tuna purse seine operations is heavily reliant on a multi-platform， cooperative fish school detection system. This system integrates a variety of technological approaches， including underwater acoustic detection （e.g.， sonar）， sea surface observation （e.g.， radar）， and aerial detection （e.g.， helicopters）， forming a three-dimensional detection network that covers the vertical water column， sea surface， and airspace. While these technologies have significantly enhanced fishing efficiency， several challenges remain. These include the subjective interpretation of radar and acoustic signals， limited adoption of high-efficiency equipment such as helicopters， and the need for upgrades in key technologies. Therefore， this paper reviews the evolution of three key fish detection technologies：seabird radar， sonar， and echo-sounding buoys，across different target species. It details their current technical specifications and scientific applications， and examines the use of Unmanned Aerial Vehicles（UAVs）in tuna purseseine fisheries. Looking forward， we project a trend of deep integration between advanced hardware and artificial intelligence in next-generation detection systems. Guided by the principles of data-driven operation， intelligent synergy， and precision efficiency， we explore a future development path toward an integrated "sense-discriminate-decide" paradigm.

Abstract:

Sea turtles are a key group among globally endangered and threatened species （ETPs）， holding significant ecological importance and conservation value.To investigate the species composition， influencing factors of bycatch abundance， and interannual variation of sea turtle bycatch in the tuna purse seine fishery of the Western and Central Pacific Ocean （WCPO）， this study utilized data from the Western and Central Pacific Fisheries Commission （WCPFC） Regional Observer Programme （ROP） from 2013 to 2019. Generalized Additive Models （GAMs） were applied to standardize the bycatch per unit effort （BPUE） for major sea turtle species. The results identified four primary bycaught species：green turtle （Chelonia mydas）， olive ridley turtle （Lepidochelys olivacea）， loggerhead turtle （Caretta caretta）， and hawksbill turtle （Eretmochelys imbricata）， which together accounted for over 90% of total bycatch. The GAM results indicated that the contributions of environmental and spatiotemporal variables varied among species. Sea surface temperature （SST） was a key driver of BPUE for both olive ridley and green turtles， while longitude （LON） was a significant variable （P<0.05） in all models. Standardized BPUE values were higher than nominal BPUE， though their trends were generally similar across most years. From 2015 to 2019， BPUE declined continuously for olive ridley， hawksbill， and loggerhead turtles， whereas it increased for green turtles. This study enhances understanding of the mechanisms driving sea turtle bycatch in purse seine fisheries and provides a scientific basis for future risk assessments and the development of targeted mitigation strategies.

Abstract:

To promote the sustainable utilization of fishery resources and support the healthy development of fisheries in the Bohai Sea， this study examines the historical evolution of its fisheries， evaluates the effectiveness and challenges of current management measures， and proposes optimization strategies through literature review and questionnaire surveys. The findings indicate that over the past four decades， changes in fishing capacity， catch volume， and fleet structure have generally aligned with policy objectives， and management measures have been implemented effectively， albeit with observable time lags in outcomes. While conservation efforts have reached an unprecedented level， institutional limitations persist. It is recommended to explore property rights-based management approaches. Additionally， the catch quota system represents a future direction for fisheries management， though its implementation faces challenges such as inadequate scientific support， lack of regional coordination mechanisms， and multi-species fisheries.