Collichthys lucidus is a small fish found in offshore waters that is economically important for China. It is imperative to understand its distribution characteristics and driving factors. Based on survey data of trawl fishery resources offshore of Zhejiang province, China, in spring (April) and autumn (November) from 2018 to 2022, the spatial and temporal distributions of C. lucidus in this area were analyzed. The random forest (RF) model was used to determine the important marine factors affecting the distribution of C. lucidus. The relationship between the distributions of the important variables was analyzed. The results showed that C. lucidus was mainly distributed in coastal waters. The tail density of the species exhibited obvious seasonal variation and was significantly greater in autumn than in spring. The most important factor affecting the distribution of this species in spring and autumn was water depth. The bottom temperature, bottom salinity and dissolved oxygen concentration were also important influencing factors. The importance of these factors differed among the different seasons, while the chlorophyll a concentration and pH had no significant effect on the species distribution. This study revealed the distribution pattern of C. lucidus in offshore waters of Zhejiang Province and the influence of important marine factors on its distribution. This study can enrich the survey data on C. lucidus and provide basic data for its scientific management and protection.

This study systematically evaluated the dynamic habitat suitability of Portunus trituberculatus in the East China Sea and the Yellow Sea region (referred to herein as the East Yellow Sea region for brevity) under climate change impacts by integrating a species distribution model (Biomod2) with multi-source environmental data. Through the construction and evaluation of an ensemble model combining 10 algorithms, using the Area Under the Curve (AUC) and True Skill Statistic (TSS) for validation, we identified seabed temperature, seabed salinity, and chlorophyll as key environmental factors. Results showed that current high-suitability areas are concentrated in coastal Jiangsu, the Yangtze River estuary, and Zhoushan Archipelago waters, which overlap significantly with fishing hotspots. Under future climate scenarios, the species’ suitable habitat distribution is projected to shift significantly poleward: In the SSP5-8.5 scenario 2100, low/medium suitability areas increased by 38.2% and 88.2% respectively, while high-suitability areas decreased by 36.5%, with core spawning grounds (e.g., Zhoushan Archipelago waters) showing reduced suitability indices. The Bohai Sea’s summer water temperature unsuitability for Portunus trituberculatus migration creates an “ecological bottleneck” for northward expansion. The study proposes strengthening habitat management in Jiangsu coastal areas and integrating dynamic habitat prediction into fisheries policies to address climate-induced resource redistribution and ecosystem service changes. Our findings underscore the urgency of incorporating climate-driven habitat shifts into adaptive marine spatial planning and fisheries management frameworks.

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.

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.

Understanding the seasonal dynamics of the fisheries and crustacean communities are of crucial ecological significance. To investigate the structural characteristics of these communities and their seasonal dynamics in the offshore of the Zhoushan Archipelago Seas, China, this study conducted a four seasons’ trawl survey to collect fisheries data in spring, summer, autumn, and winter of 2022. A normalized abundance size spectrum approach was applied to investigate the seasonal variation in regressed parameters (slope and intercept) for fish-only and fish-plus-crustacean communities. Our study found that average values of the slope of the size spectrum for fish and fish-plus-crustacean were −1.36 and −1.53, respectively; the overall adding effect with crustaceans in all seasons was more negative (a steeper slope). The results also showed that the adding effect of crustaceans in the fisheries communities were season-specific and region-specific. Temporally, adding crustaceans into fisheries communities contributed to more/less negative slopes in temperate/warm seasons, respectively. Regionally, the inclusion of crustaceans induced a reverse distribution pattern (nearshore–offshore) for fish abundance, as well as the re-scaled intercept, which could indicate the abundance in all seasons except in summer. It was assumed that although fish dominated the overall community structure, crustaceans contributed a compensatory effect by regulating the size distribution across trophic levels. This study provides valuable insights for the dynamic assessment and scientific management of fisheries and crustacean resources in the whole ecosystem.