Monitoring the anadromous fish Coilia nasus using conventional methods is hindered by low detection rates and restricted access during seasonal fishing moratoriums. Here, we developed a species-specific environmental DNA (eDNA) assay and integrated it with a Maximum Entropy (MaxEnt) model to investigate the spatiotemporal distribution and habitat suitability of C. nasus in the central-northern coastal waters of Zhejiang, China. A total of 39 high-quality occurrence records compiled from open databases, eDNA detections, and fishery surveys were used for model calibration. Our results revealed clear seasonal patterns: eDNA peaks in Hangzhou Bay during summer, indicating migratory activity, while autumn increases along the coast reflected post-spawning aggregation. The MaxEnt model (mean test AUC = 0.864) identified minimum salinity, minimum phosphate, and mean temperature as the key environmental drivers of habitat suitability. Only 5.07% of the East China Sea was predicted as highly suitable habitat, concentrated in estuarine zones including the Yangtze River Estuary and Hangzhou Bay. Notably, compared with a model based solely on traditional survey data, the integrated eDNA‑MaxEnt framework predicted a greater extent of highly suitable habitat (5.07% vs. 4.09%). This finding suggests that eDNA data improved the representation of potentially suitable areas that might otherwise be overlooked by conventional surveys. Our integrated framework provides a promising tool that can complement traditional monitoring approaches, with applications in spatial conservation planning and sustainable fisheries management of C. nasus and other data-limited anadromous species.

Cephalopods are commercially valuable invertebrates with short lifespans and rapid responsiveness to climate change, making them sensitive indicators of ecosystem dynamics. In recent decades, they have become the primary target species in the East China Sea (ECS) fishery following declines in demersal fish catches. Investigating the relationship between cephalopod populations and environmental factors enables researchers to characterize the ecological conditions conducive to their proliferation. The study employed six machine learning models to predict cephalopod distributions in the coastal waters of Zhejiang. Sea water temperature (SST) and chlorophyll-a concentration (Chl-a) were identified as key seasonal distribution drivers. Family-level patterns largely reflected the dominant species, yet inter-family differences revealed distinct environmental niches: Loliginidae favored warmer, nutrient-rich waters, whereas Sepiolidae exhibited different seasonal patterns in their preferences for SST and Chl-a. Notwithstanding these general consistencies, both cephalopods exhibited distinct spatiotemporal distribution patterns under different climate change scenarios. Under RCP2.6, Loliginidae were concentrated in the coastal waters of southern Zhejiang in spring and displayed a broader distribution in autumn. In contrast, under RCP8.5, their distribution range expanded notably with a northward migration in autumn. Sepiolidae showed a more constrained spatial distribution pattern, with shifts in their concentration areas across different climate scenarios and seasonal periods. Our findings systematically establish links between cephalopod spatiotemporal distribution patterns and dynamic environmental conditions, and highlight taxon-specific responses to climate change, thereby providing a scientific reference for the formulation of future fisheries management strategies under variable climate scenarios.

Fish assemblages are important participants in regulating biogeochemical cycles and maintaining the health of island ecosystems. However, studies that analyze the diversity of fish assemblages in China’s island waters are scarce. In this study, we evaluated the taxonomic, functional, and phylogenetic diversity of fish assemblages around eight islands using 11 diversity indices, and explored the effect of human activity and natural factors on fish assemblage diversity via structural equation modeling (SEM). Results showed that three types of diversity exhibited significant differences among islands, the northern islands had highest values, followed by the southern, and the central was lowest. The environmental factors affecting the three types of diversity were varied, and the main factors regulating fish assemblages in spring and autumn were also different. Based on the SEM analysis, marine environmental factors exhibited a positive relationship with fish assemblage diversity (0.675), whereas socioeconomic factors demonstrated a negative relationship (-0.173). Furthermore, climate factors were associated with a reduction in fish assemblage diversity via indirect mechanisms (-0.456).SEM revealed that marine environment factors impacted fish assemblage diversity positively and directly, with a high path coefficient of 0.675. Socioeconomic factors exerted direct negative effects on fish assemblage (-0.173), while the influence of climate factors was indirect and negative (-0.456). These findings provided a comprehensive picture of fish assemblage diversity around Zhejiang islands and could facilitate the conservation and restoration of fish assemblages.

The fish community structure of the Zhoushan Fishing Ground is undergoing change due to overfishing, climate variability, and other anthropogenic stressors. To investigate community-level environmental responses and interspecific associations in this region, we used 11 consecutive years (2014-2024) of spring bottom trawl survey data from the Zhoushan Fishing Ground and integrated environmental covariates to build a two-part hurdle model within the Hierarchical Modelling of Species Communities (HMSC) framework. The results showed that the spatial random effect had the highest contribution (41%), followed by the interannual trend (18%), indicating that community occurrence patterns are primarily shaped by the superposition of stable spatial structuring and long-term change. Depth was significant for more species, whereas salinity was significant for the fewest. Residual correlations further revealed that the focal fish species could be partitioned into two assemblages with one linking species. Meanwhile, within the two-part hurdle model, the direction and significance of responses to the same covariate were not always consistent, supporting that species occurrence probability and positive biomass are governed by different ecological processes. Overall, this study provides a transferable quantitative framework for community assessment in coastal fishing grounds and offers a more operational chain of evidence for ecosystem-based fisheries management.

As a flagship species in marine, the conservation of Acipenser sinensis habitat is of great significance for biodiversity maintenance. Based on 339 records of A. sinensis bycatch in the ocean and related environmental data from 2022 to 2023, we investigated its distribution characteristics and habitat selection using the MaxEnt model. The results showed that A. sinensis was primarily distributed in the waters of Hangzhou Bay and the Xiangshan area, with a relatively broad range in spring and winter, while the distribution was more concentrated in summer and autumn. The MaxEnt model revealed that key environmental factors influencing the potential habitat of A. sinensis were bottom water temperature, silicate concentration, and pH. When the temperature of bottom water ranged between 19-23 ℃, the silicate concentration exceeded 15 mmol·m-3, and pH was between 8.2 and 8.5, the probability of A. sinensis presence was higher. Within the study area, the highly suitable zone covered an area of 258.71 km2 (6.9% of the total), while the suboptimally suitable zone spanned 703.46 km2 (18.7%). The main highly suitable zones were located in the waters of Hangzhou Bay, the Xiangshan Port-Jiushan Archipelago-Sanmen Bay-Jiaojiang area, while the suboptimally suitable zones were primarily found in the waters near Zhoushan-Ningbo-Taizhou to the east and south, as well as the coastal waters of Jiangsu.

Identifying key habitats within marine protected areas is essential for biodiversity conservation and ecosystem-based fisheries management. To characterize the spatial organization and environmental background of spring nekton key habitats in the Hairtail National Aquatic Germplasm Reserve of the East China Sea, this study integrated bottom-trawl survey CPUE data from April 2015-2024 with multi-source marine environmental data, including sea surface temperature (SST), chlorophyll-a concentration (Chl-a), and current speed. Key habitat stations were defined as the upper 25% of annual station-level CPUE values, and their spatial configuration was quantified using average nearest-neighbor distance (ANN) and minimum spanning tree length (MST). Potentially suitable habitat maps were further generated for representative years using environmental windows derived from key habitat stations. Results showed that key habitats in 2015 and 2022 had shorter inter-station distances and stronger spatial connectivity, representing continuous configurations, whereas those in 2019 and 2023 were more dispersed and had longer connection paths, representing fragmented configurations. Comparisons among representative years indicated that key habitat differences were expressed not only by the locations of high-CPUE stations, but also by the spatial organization of these high-value habitats. In continuous years, key habitats were more closely associated with spatially coherent suitable temperature bands, relatively high-productivity areas, and coordinated hydrodynamic conditions. In fragmented years, the spatial overlap among suitable environmental conditions weakened, and potentially suitable habitats were divided into small, isolated patches. These findings suggest that marine protected area management should consider both resource intensity and habitat continuity. The proposed framework provides spatial information for identifying priority areas, optimizing monitoring stations, and supporting ecosystem-based fisheries management.

The marine ecological environment of Hangzhou Bay and its adjacent waters ( 30°-31° N, 121.5-123.5° E ) shaped by various factors, serves as a spawning and feeding ground for diverse species of fish, shrimp and crabs, including a traditional gillnet fishing area for the gazami crab, Portunus trituberculatus. The study investigates spatiotemporal distribution and the mechanisms underlying the formation of these fishing grounds of P. trituberculatus using single bottom trawl survey data from 31 stations in Hangzhou Bay and its adjacent waters across four seasons in 2014, gillnet survey data during the period 25-29 July 2019 to 2021 and gillnet vessel fishing logs from September 2020 to January 2021. Seasonal variations and spatiotemporal distributions of P. trituberculatus abundance and body mass were analysed. A generalised additive model was applied to assess the influence of external factors identifying key drivers of fishing ground formation. Gillnet monitoring and fishing log data were used to explore inter-annual trends in population characteristics and catch per unit effort (CPUE). The findings revealed pronounced seasonal patterns in P. trituberculatus abundance and distribution, with notable seasonal differences in spatial and temporal dynamics. The primary external factors affecting abundance were season and bottom salinity, followed by latitude and surface chlorophyll a content. Bottom salinity emerged as the critical environmental factor driving the formation of the gillnet fishing grounds. Significant inter-annual differences were observed in P. trituberculatus carapace length (P < 0.05), although no significant differences were found between sexes within the same year. Monthly variation in CPUE 0.49-1.38 kg/net and carapace length 75.6-82.1 mm were also significant (P < 0.05). This study elucidates the spatiotemporal distribution patterns and environmental drivers shaping P. trituberculatus fishing grounds in Hangzhou Bay and its adjacent waters, providing insights for sustainable management and conservation of these fishery resources.

The small yellow croaker (Larimichthys polyactis), a migratory estuarine-demersal fish critical to East Asian fisheries, has faced severe population declines because of anthropogenic pressures (e.g., overfishing and anthropogenic habitat modification) and shifting environmental conditions. This study investigates its spatio-temporal habitat dynamics in Hangzhou Bay (2017–2023) using fisheries surveys and species distribution models (SDMs), with insights applicable to Pacific Coast migratory fish conservation. We evaluated the performance of eleven modeling algorithms to identify the most accurate model for predicting small yellow croaker distributions. Our results showed that the random forest algorithm outperformed other models, with a high sensitivity (95.238) and specificity (99.49), demonstrating its ability to capture complex non-linear relationships between environmental factors and species distribution. Depth emerged as the most influential factor, accounting for 30% of the importance in the model, with small yellow croakers preferring deeper waters around 60 m. Salinity was the second most important factor, with higher occurrence probabilities in areas where salinity exceeded 25 PSU. Other environmental factors, such as temperature and dissolved oxygen, had relatively smaller impacts on distribution. Spatially, small yellow croakers were predominantly distributed in offshore regions east of 122.5° E, where deeper waters and higher salinity levels provided suitable habitat conditions. This study underscores the need for targeted management measures, such as habitat restoration, to ensure the sustainable management of small-bodied yellow croaker populations.

The Larimichthys crocea represents a critically important economic marine species in China’s East Yellow Sea. However, its populations have experienced significant decline due to overexploitation. Despite implemented conservation measures—including stock enhancement, spawning ground protection, and seasonal fishing moratoria—the recovery of yellow croaker resources remains markedly slow. To address this, our study employed the Maximum Entropy (MaxEnt) model to evaluate and characterize the habitat selection patterns of Larimichthys crocea, thereby providing a theoretical foundation for scientifically informed stock enhancement and resource recovery strategies. Species occurrence data were compiled from field surveys conducted during April and November (2019–2023), supplemented with records from the GBIF database and peer-reviewed literature. Concurrent environmental variables, including primary productivity, current velocity, depth, temperature, salinity, silicate, nitrate, phosphate, and pH, were obtained from the Copernicus and NOAA databases. After rigorous screening, 136 distribution points (April) and 369 points (November) were retained for analysis. The model performance was robust, with an AUC (Area Under the Curve) value of 0.935 for April (2019–2023) and 0.905 for November (2019–2023), indicating excellent predictive accuracy (AUC > 0.9). April (2019–2023): Nitrate, salinity, phosphate, and silicate were identified as the primary environmental factors influencing habitat suitability. November (2019–2023): Silicate, salinity, nitrate, and primary productivity emerged as the dominant drivers. Spatially, Larimichthys crocea exhibited high-density distributions in offshore regions of Zhejiang and Jiangsu, particularly near the Yangtze River estuary. Populations were also associated with island-reef systems, forming continuous distributions along Zhejiang’s offshore waters. In Jiangsu, aggregations were concentrated between Nantong and Yancheng. This study delineates habitat suitability zones for Larimichthys crocea, offering a scientific basis for optimizing stock enhancement programs, designing targeted conservation measures, and establishing marine protected areas. Our findings enable policymakers to develop sustainable fisheries management strategies, ensuring the long-term viability of this ecologically and economically vital species.

Global marine fisheries production remains at a high level of approximately 80 million tonnes, partly due to the significant increase in cephalopod catches, which exhibit rapid adaptation to changing marine environments. Since the implementation of stock enhancement in 2008, Cuttlefish Sepiella japonica populations in coastal China have rebounded, and the establishment of closed areas and spawning ground reserves has effectively ensured the spawning and reproduction of cuttlefish. However, how to effectively protect the cuttlefish throughout its life cycle is still an unresolved issue, especially considering its migratory nature. To determine the suitability and connectivity of cuttlefish habitats, a Habitat Suitability Index (HSI) model was constructed using spring and fall bottom trawl survey data of 120 stations collected in the coastal Zhejiang Province from 2017 to 2021. Resistance surfaces in the ocean were generated using the habitat suitability output from the model, and the least-cost paths between key habitat nodes along the resistance surfaces were simulated and calculated, thus identifying potential ecological corridors of cuttlefish. The suitable habitats for cuttlefish are found to vary significantly between seasons, with different environmental drivers of migratory behaviors. In the spring, the distributions of suitable habitats are more scattered and patchier, with a higher percentage of key habitat nodes, longer paths, and a wider range of potential ecological corridors. Conversely, in the fall, the distributions of suitable habitats exhibit a reversal of characteristics. We had further confirmation that small MPAs are not effective in protecting the overall dynamics of cuttlefish populations. Consequently, it is not feasible to carry out stock enhancement without a comprehensive plan, so it is necessary to optimize the stocking strategies in the spawning ground reserve according to the actual situation in a larger scale. These findings improve our understanding of the suitability and connectivity of cuttlefish habitats, highlighting the need for population conservation at larger scales and based on species' critical life histories. With the increasing of anthropogenic interventions via large-scale stock enhancement globally, these knowledges have valuable inspirations for guiding artificial releasing projects.

Cephalopods are predominantly short-lived marine organisms, and their habitats are more susceptible to the effects of climate change. Modelling and predicting the distribution of potential habitats of cephalopods and their changing habitat spatial patterns under climate change scenarios can provide an essential scientific foundation for cephalopod habitat conservation and fisheries ecosystem management in the context of climate change. The trawl survey data collected along Zhejiang offshore in the spring and autumn of 2017-2023, in conjunction with marine environmental data including sea surface temperature (SST), sea surface salinity (SSS), dissolved oxygen concentration (DO) and chlorophyll-a concentration (CHLA), collected by temperature-salt-depth instrument, were employed to simulate and predict the potential habitat distribution of Uroteuthis duvauceli, Abralia multihamata, and Sepiella maindroni in the four RCP climate scenarios in 2100 by random forest as a species distribution model. The results demonstrated that the Random Forest predictions were accurate and reliable, with an AUC exceeding 0.8 for each group and a standard deviation below 0.05. The main environmental factors affecting the habitat distribution of three cephalopod species are SST and SSS, with an average contribution rate of 0.28 in spring and 0.33 in autumn. The average contribution rate of SSS in spring is 0.32, and in autumn it is 0.29. The response curves demonstrated that the three cephalopod species exhibited varying degrees of response to changes in SST and SSS. During the spring period, the optimal habitat for cephalopods was characterised by SST ranging from 18 °C to 20 °C, and SSS exceeding 28 ‰. In contrast, in autumn, S. maindroni exhibited a preference for warmer water compared to U. duvauceli and A. multihamata. The potential habitat suitability zones of cephalopods under high gas emission scenarios were found to mainly extend to the southern and northern coast of Zhejiang. Among them, the area of the high adapted zone of S. maindroni increased by 352 % in the RCP4.5 scenario, the area of the high adapted zone of U. duvauceli increased by 69 % in the RCP4.5 scenario, and the area of the high adapted zone of A. multihamata increased by 69 % in the RCP8.5 scenario. The centroid changes of the three species of cephalopods were not found to be significant in the high suitability zones of the three cephalopod species in different climatic scenarios. The present study proposes that climate change will result in alterations to the potential habitat of cephalopods offshore Zhejiang, which is a significant consideration for the future conservation and management of cephalopod fisheries.

In order to investigate the relationship between the growth characteristics of Rhopilema esculenta and surface water temperature during the rapid growth period in Hangzhou Bay, the authors conducted a survey of Rhopilema esculenta biology and environmental factors in Hangzhou Bay in June—July 2022. The results showed that: (1) The umbrella diameter of Rhopilema esculenta ranged from 45 to 650 mm, the average umbrella diameter was 327.55 mm; the body mass of Rhopilema esculenta ranged from 9 to 18 260 g, the average body mass was 2 748.21 g. (2) The relationship between umbrella diameter and body mass was given by W=1.578 5×10-5 UB3.120 8 (R2=0.975 4，n=1 601).(3) With the increase of date, the average umbrella diameter of Rhopilema esculenta increased from 104.33 mm to 361.20 mm and the average surface water temperature increased significantly from 21.69 ℃ to 27.94 ℃. (4) The average umbrella diameter and average surface temperature during the investigation period were fitted, and the relationship between them was as follows UB=6.07ST2-259.62ST+2 880.32 (R2=0.998 5). (5) After the opening of the fishery, the umbrella diameter of Rhopilema esculenta ranged from 115 to 650 mm with an average umbrella diameter of 391.96 mm; the body mass ranged from 40 to 18 260 g with an average body mass of 3857.60 g. The umbrella diameter and body mass of Rhopilema esculenta gradually increased with the date. This article studied the growth characteristics of Rhopilema esculenta and its relationship with surface water temperature during the rapid growth period in Hangzhou Bay, which can provide a reference basis for scientific mangement of Rhopilema esculenta fishing production during the summer fishing moratorium in Hangzhou Bay in the future.

Bamboo is regarded as a renewable material in modern architecture and interior decoration, however, the susceptibility to mold deterioration and moisture-induced deformation limits its industrial applications. To address these challenges, this study proposed a feasible and eco-friendly method for thermally modifying bamboo via superheated steam without the addition of any chemicals. This modification process emphasized the application of heat-moisture coupling to alter the chemical composition and cellular structures of bamboo. Compared to the natural bamboo (NB), superheated steam treated bamboo (SHT-B) exhibited a 3.45 % increase in porosity, along with the separation and buckling of wall layers within parenchyma cells, and the thermal degradation of starch granules. The heat-moisture coupling facilitated the degradation of hemicelluloses in bamboo, leading to a higher relative content of lignin, increased crystallinity, thicker crystallite thickness, and a reduced proportion of intramolecular hydrogen bonds. Consequently, SHT-B demonstrated reductions in equilibrium moisture content (EMC), thickness swelling rate, and volume swelling rate by 8.80 %, 66.39 %, and 70.69 %, respectively, indicating enhanced dimensional stability. Additionally, SHT-B displayed a deepening of surface color and an increased mass loss rate, accompanied by a slight reduction in density and modulus of rupture (MOR). Moreover, SHT-B exhibited exceptional mold resistance to Aspergillus niger and Botryodiplodia theobromae over 30 days. Overall, superheated steam treatment is anticipated to emerge as a feasible and clean method for the enhancement of bamboo's functional performances, with broad application prospects in the future.

Larimichthys polyactis, a key species in East Asian coastal ecosystems, shows distinct seasonal changes in density distribution, shaped by environmental factors and migratory behaviors of two dominant populations (East China Sea and South Yellow Sea). This study explored its 2023 density dynamics in Zhejiang coastal waters using quarterly surveys across 83 stations, combined with generalized additive models (GAM) and random forest (RF) models. Results showed that RF outperformed GAM overall, with bottom dissolved oxygen (SBO), salinity, and depth as the most influential environmental drivers. Density peaked in summer (77.88 thousand ind./km2) in central and northern offshore areas, dominated by the South Yellow Sea population migrating into the region. Autumn densities (3.76 thousand ind./km2) declined sharply as populations moved to overwintering grounds, while spring (0.41 thousand ind./km2) and winter (0.26 thousand ind./km2) densities were lowest. These findings highlight the role of seasonal environmental filters and population-specific migrations in shaping distribution patterns. RF models provide robust tools for predicting habitats, supporting seasonally tailored conservation strategies to protect critical spawning, foraging, and overwintering areas, which are vital for the sustainable management of this ecologically and economically important species.

This study investigated how microwave treatment effects vary with wood thickness, revealing differences in energy transfer across different wood thicknesses. We hypothesized that microwave treatment would induce depth-dependent structural modifications in Cunninghamia lanceolata, with thicker specimens exhibiting reduced degradation due to energy attenuation. Through in situ temperature monitoring, we observed a 62.3% decrease in core temperature from 35 mm (181.5 degrees C) to 80 mm (109.1 degrees C) samples, which was directly related to microwave energy attenuation. Thinner samples (<= 50 mm) maintained sufficient energy penetration to induce significant physicochemical changes: 11.05% decrease in O/C ratio (XPS), 44.87% increase in hardness (nanoindentation), and steam-generated cracks. In contrast, the center of thick samples (80 mm) showed limited changes (<0.1% decrease in O/C ratio) due to lower temperatures caused by microwave attenuation. XRD analysis showed that microwave-induced improvements in cellulose crystallinity and lignin composition structure decreased with depth. This research has opened up a new path for thickness-responsive microwave processing for the wood processing industry: by adding thickness sensing, the energy efficiency synergistic optimization of resin homogeneous modification and impregnation of wood of different thicknesses can be achieved, overcoming the uneven modification defects of traditional processes and achieving precise matching of precise energy delivery and product performance.

Brown croaker (Miichthys miiuy) is an economically, ecologically, and culturally important species in the East China Sea (ECS); however, populations of M. miiuy have declined in recent years due to climate change and high fishing intensity. Our limited understanding of wild M. miiuy’s migratory life history hampers effective population conservation. To meet this need, and to elucidate the migratory life history of wild M. miiuy, we quantified the elemental composition of otolith samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This approach, combined with analysis of otolith microstructure, was used to evaluate the feasibility of using the Mg:Ca of otoliths chemical clock for M. miiuy. Using cluster analysis alongside bivariate time series analysis, we identified natal sources and reconstructed migratory histories. The results showed that consistent, periodic fluctuation of Mg:Ca ratios in otolith profiles can be used as a chemical index to indicate the age and life history stage of M. miiuy. Natal sources of M. miiuy originated from three distinct water environments: estuary (14.2%), coastal mixed waters (57.3%), and coastal reef waters (28.5%). A diverse migratory life history of M. miiuy was observed based on Sr:Ba thresholds, and ultimately, we identified four migratory life histories of the species, including an estuary–coastal migratory type, a coastal resident type, a coastal–offshore migratory type and an estuary–coastal–offshore migratory type. This study provides a scientific basis for the protection of key habitats and seasonal management of M. miiuy in the ECS.

The critically endangered Chinese sturgeon (Acipenser sinensis) has suffered catastrophic population declines due to habitat fragmentation and overexploitation, with complete cessation of natural spawning observed since 2017. While accurate distribution data are crucial for conservation, conventional monitoring approaches remain limited in marine ecosystems. To address this critical knowledge gap, we developed and applied an integrative framework combining environmental DNA (eDNA) with species distribution modeling (SDM) to detect the distribution of Chinese sturgeon in the East China Sea. We developed Chinese sturgeon-specific real-time PCR assays to analyze 244 water samples from 73 stations in the East China Sea. Our results showed a 20.5 % occurrence rate of sturgeon, with notable spatial aggregation in the Zhoushan Archipelago and Hangzhou Bay. Vertical distribution analysis revealed that 53.3 % of the positive detections occurred in benthic water. While a Mantel test correlated Chinese sturgeon presence with turbidity, salinity, and chlorophyll-a, the MaxEnt model, which incorporated nine variables for prediction, identified mean temperature, maximum pH, and total suspended matter as the primary factors determining habitat suitability. The resulting habitat suitability map indicated that the coastal waters of Zhejiang represent the optimal habitat. Habitat suitability projections under three Shared Socioeconomic Pathways (SSPs) predict a reduction in habitat suitability. Our study (1) is the first to integrate eDNA and SDM for Chinese sturgeon in marine habitats, addressing a critical knowledge gap in the sturgeon life cycle, and (2) provides a transferable framework for conservation prioritization of endangered migratory fishes under climate change. Our study provides a transferable framework for conservation prioritization of endangered migratory fishes under climate change, and the identified turbid coastal zones emerge as critical conservation targets requiring immediate protection measures.

Group discrimination is a critical prerequisite for studying fish population dynamics, implementing effective fisheries management, and evaluating the outcomes of stock enhancement programs. However, research on group differentiation of Oplegnathus fasciatus (Kroyer, 1845), an economically important species in the East China Sea, remains limited across different geographical regions. We conducted a comparative analysis of trace element concentrations, including iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), cadmium (Cd), and mercury (Hg), as well as metalloid arsenic (As), in the muscle tissues of three distinct groups of O. fasciatus: the farmed group, the Yangtze River Estuary group, and the Zhongjieshan group. Trace elements were detected using inductively coupled plasma mass spectrometry. Group classification methods such as cluster analysis, stepwise discriminant analysis, and random forest were used to differentiate the groups based on these eight trace elements. Consequently, significant differences were observed in the concentrations of Fe, Cu, Zn, Cr, As, and Hg among the groups (p< 0.05), while differences in Mn and Cr were not statistically significant (p > 0.05). Discriminant analysis showed that cluster analysis effectively differentiated the farmed group from the Zhongjieshan group. Stepwise discriminant analysis achieved an overall accuracy of 85.1%, while the random forest model demonstrated an accuracy of 92.86%. These findings suggest that trace element concentrations could be applied to effectively distinguish among groups of O. fasciatus, with the random forest model outperforming traditional statistical methods to some extent. Our results are relevant to the activities of stock release and fisheries management.

Beta diversity is an important way to analyze community assembly mechanisms in different habitats or along environmental gradients. However, research on marine fish assemblages around islands has lagged, especially for functional beta diversity. In this study, we evaluated taxonomic and functional beta diversity change of island fish assemblages along the coast in two seasons and revealed its relationship with environmental factors and geographical distance. Taxonomic and functional beta diversity were both dominated by turnover (over 80% and 60%), while the contribution of nestedness on functional beta diversity was significantly increased. Environmental factors such as temperature and dissolved oxygen were important drivers of beta diversity rather than geographical distance. Fish assemblages around islands that are far away from mainlands or affected greatly by anthropogenic activities usually have higher beta diversity. These results indicated that environmental filtration is the primary factor driving the mechanism of fish community assembly. Our study revealed the importance of the integrated application of two facets of biodiversity to investigate beta diversity. The findings can provide theoretical support for the protection of marine fish and the planning of marine protected areas in the future.

The East China Sea (ECS) off the Coast of Zhoushan Archipelago, Zhejiang (ECS-CZA) is home to abundant fishery resources and an important spawning, feeding, and nursing ground for a variety of fish species. Due to long-term overfishing, the ichthyoplankton structure has been dramatically altered. Understanding the species composition and distribution of fish eggs and larvae is one of the most essential tasks to accurately regulate fishery resources and formulate effective management policies; however, little is known about the ichthyoplankton in this region. In this study, an integrated strategy of morphology identification (MI) and mitochondrial COI DNA barcoding were used to identify species of fish eggs and larvae collected from the ECS-CZA. MI revealed 15 fish egg species belonging to 12 families and 12 fish larva species belonging to 12 families; in contrast, DNA barcoding altogether identified 30 species, including 18 fish egg species and 13 fish larva species. One species was shared between the egg and larva samples. Our study offers useful tools and critical scientific information for understanding the recruitment, distribution, and conservation management of various fish species in this marine environment.