The choice of spatial and temporal scales affects the performance of fisheries models and is particularly important in exploring the relationship between resource abundance and the marine environment. Traditional fishery models are constructed at a particular scale, and the results of the study hold only at that scale. Sthenoteuthis oualaniensis is one of the main target species of large-scale light falling-net fishing in the Nansha Islands in the South China Sea. We used the S. oualaniensis fishery in the Nansha Islands as an example to compare the performance of fisheries models for 12 spatial and temporal settings and to explore the relationship between the abundance of S. oualaniensis and the marine environment in the Nansha Islands under the optimal spatial and temporal settings. The results show that the spatial and temporal scale chosen in the construction of the fishery model is not as fine as possible in generalized additive models (GAMs) for abundance index-catch per unit effort (AI-CPUE)-based scenarios, and 0.5° with the season was the best spatial and temporal setting; meanwhile, in GAMs for AI-effort-based scenarios, 0.1° with the month was the best spatial and temporal setting. The distribution of S. oualaniensis resources in the Nansha Islands was characterized by significant seasonal variation, and the monthly center of gravity had a significant negative correlation with the Niño 3.4 index and the PDO index, with correlation coefficients of 100 and 1000, respectively. It is hypothesized that Pacific Decadal Oscillation and ENSO events affect the marine environment in the South China Sea by influencing the strength of the Kuroshio force and the degree of Kuroshio curvature, which in turn affects the distribution of S. oualaniensis in the Nansha Islands. The results help us to understand the influence of spatial and temporal scales on fisheries models and the environmental factors affecting the distribution of S. oualaniensis resources in the Nansha Islands. Thus, they provide a scientific basis for the sustainable development of S. oualaniensis fisheries in this region.

Mischief Reef is located in the eastern Nansha Islands of the South China Sea. With increasingly intense anthropogenic disturbance, Pinctada fucata, a previously unrecorded species in the reef, has occurred in the region. In this study, we identified and described the occurrence of P. fucata in Mischief Reef based on morphology and molecular markers. Furthermore, we performed a population genetics analysis of seven P. fucata populations of the South China Sea. All P. fucata populations showed significant high-level genetic diversity, but the differentiation among P. fucata populations was small. There was an F_ST value close to zero (−0.0083) between the Lingshui and Mischief Reef populations. Our results hint that Lingshui may be one of the potential sources of P. fucata to Mischief. In addition, we discussed the possible cause of the mass occurrence of P. fucata. The present study serves as a warning that anthropogenic disturbances have disrupted the local ecosystem in Mischief Reef.

Fishery resource and environmental data from four surveys conducted in the Hainan Island offshore area from March 2021 to June 2022 were used to investigate the spatiotemporal distribution of round scad (Decapterus maruadsi). A generalized additive model was applied to explore the relationships among abundance and distribution, also biotic and abiotic factors (i.e., temperature, salinity, chlorophyll-a concentration, water depth, phytoplankton abundance, zooplankton abundance, and jack mackerel (Trachurus japonicas) abundance). Round scad abundance (average 67.17 kg/km²) showed distinct spatial and seasonal differences around Hainan Island, with highest abundance in summer (171.72 kg/km²) and lowest abundance in spring (3.06 kg/km²). The optimal model revealed that jack mackerel abundance, sea bottom temperature, sea surface temperature, and latitude very significantly (p < 0.01) affected round scad distribution. Jack mackerel abundance (mainly in the range 0–50 kg/km²) was positively correlated with round scad distribution. The distribution showed a dome-shaped relationship with bottom water temperature in the range 18–30 °C, with maximum abundance at 24 °C. The distribution was negatively correlated with surface water temperature in the range 22–30 °C. Sea surface chlorophyll-a concentration and longitude were significantly correlated (p < 0.05) with round scad distribution. The results provide theoretical support to further investigate the formation mechanism of round scad fishing grounds and to enrich knowledge of pelagic fish abundance in the continental-shelf waters of the northern South China Sea.

In recent years, with the formal implementation of the Regional Comprehensive Economic Partnership (RCEP) and the rise of the blue economy, the trade cooperation between China and ASEAN in aquatic products has been further deepened and expanded. This paper utilizes United Nations Commodity Trade (UN Comtrade) data from 2001 to 2023 and combines the perspective of the blue economy to systematically analyze the characteristics of bilateral trade volume, growth rate, market distribution, and trade types of aquatic products between China and ASEAN. By applying the modified Constant Market Share (CMS) model, the paper conducts a factor decomposition and effect analysis of the growth factors in China’s aquatic exports to ASEAN. The analysis indicates that the competitiveness effect has the highest contribution rate, and competitiveness has been the primary driver of growth in China’s aquatic product export trade to ASEAN, followed by the growth effect increasing year by year, which shows the impact of the scale of demand, while the product effect is relatively low. In particular, product structure urgently needs improvement to meet the requirements of the blue economy. In ASEAN’s aquatic product exports to China, demand scale serves as the main driving force, with the product variety adapting to the Chinese market as a secondary contributor. However, under the blue economy framework, product sustainability and environmental friendliness have emerged as new considerations, while the contribution of competitiveness remains relatively low, suggesting a need for further enhancement to align with green trade standards.

With the rapid modernization of methods for monitoring fishing vessels, different ways of obtaining data on large-size light falling-net vessels have developed. In particular, the vessel monitoring system (VMS) may be used to track fishing activities in the South China Sea (SCS). In this study, we used VMS data to show the characterize and differences in the information transmitted when monitoring large-size falling-net fishing vessels, as well as their advantages and disadvantages. We investigated the spatial distribution of large-size light falling-net fisheries in the SCS using Beidou VMS data from 2017 to 2020. We also compared trajectories of fishing vessels from various provinces. According to these data, vessels operate in the Nansha Islands and the waters of the Pearl River Estuary, Beibu Gulf, Zhongsha, and Xisha Islands, and there is a clear seasonal pattern of fishing in the SCS. There are the differences of vessels in terms of distribution areas and ports of entry and exit. Additionally, we found the operation area of the large-size falling-net fishing vessels divided into four main fishing zones. The analysis compares the number of days of operation in the different fishing areas as well as seasonal variations. Our study shows that the operating area of large-size light falling-net vessels has extended southwards and that the number of days for which fishing vessels operate has increased compared with the last decade. Using the Beidou VMS to study the large-size light falling-net vessels in the SCS can provide more detailed scientific reference data for the SCS fisheries.

Members of the genus Nemipterus are economically important fish species distributed in the tropical and subtropical Indo-West Pacific region. The majority of species in this genus inhabit waters with sandy–muddy substrates on the continental shelf, although different species are found at slightly varying water depths. In this study, we sequenced seven species within the genus Nemipterus after identifying the specimens using complementary morphological analysis and DNA barcoding. Each species yielded over 40,000,000 clean reads, totaling over 300,000,000 clean reads across the seven species. A total of 276,389 unigenes were obtained after de novo assembly and a total of 168,010 (60.79%) unigenes were annotated in the protein database. The comprehensive functional annotation based on the KOG, GO, and KEGG databases revealed that these unigenes are mainly associated with numerous physiological, metabolic, and molecular processes, and that the seven species exhibit similarity in these aspects. By constructing a phylogenetic tree and conducting divergence time analysis, we found that N. bathybius and N. virgatus diverged most recently, approximately during the Neogene Period (14.9 Mya). Compared with other species, N. bathybius and N. virgatus are distributed in deeper water layers. Therefore, we conducted selection pressure analysis using these two species as the foreground branches and identified several environmental-responsive genes. The results indicate that genes such as aqp1, arrdc3, ISP2, Hip, ndufa1, ndufa3, pcyt1a, ctsk, col6a2, casp2 exhibit faster evolutionary rates during long-term adaptation to deep-water environments. Specifically, these genes are considered to be associated with adaptation to aquatic osmoregulation, temperature fluctuations, and skeletal development. This comprehensive analysis provides valuable insights into the evolutionary biology and environmental adaptability of threadfin breams, contributing to the conservation and sustainable management of these species.