The Taiwan Bank (TB) is located in the southern Taiwan Strait, where the marine environments are affected by South China Sea Warm Current and Kuroshio Branch Current in summer. The bottom water flows upward along the edge of the continental shelf, forming an upwelling region that is an essential high-productivity fishing ground. Using trophic dynamic theory, fishery resources can be converted into primary production required (PPR) by primary production, which indicates the environmental tolerance of marine ecosystems. This study calculated the PPR of benthic and pelagic species, sea surface temperature (SST), upwelling size, and net primary production (NPP) to analyze fishery resource structure and the spatial distribution of PPR in upwelling, non-upwelling, and thermal front (frontal) areas of the TB in summer. Pelagic species, predominated by those in the Scombridae, Carangidae families and Trachurus japonicus, accounted for 77% of PPR (67% of the total catch). The benthic species were dominated by Mene maculata and members of the Loliginidae family. The upwelling intensity was the strongest in June and weakest in August. Generalized additive models revealed that the benthic species PPR in frontal habitats had the highest deviance explained (28.5%). Moreover, frontal habitats were influenced by NPP, which was also the main factor affecting the PPR of benthic species in all three habitats. Pelagic species were affected by high NPP, as well as low SST and negative values of the multivariate El Niño–Southern Oscillation (ENSO) index in upwelling habitats (16.9%) and non-upwelling habitats (11.5%). The composition of pelagic species varied by habitat; this variation can be ascribed to impacts from the ENSO. No significant differences were noted in benthic species composition. Overall, pelagic species resources are susceptible to climate change, whereas benthic species are mostly insensitive to climatic factors and are more affected by NPP.

Basin-scale sampling for high frequency oceanic primary production (PP) is available from satellites and must achieve a strong match-up with in situ observations. This study evaluated a regionally high-resolution satellite-derived PP using a vertically generalized production model (VGPM) with in situ PP. The aim was to compare the root mean square difference (RMSD) and relative percent bias (Bias) in different water masses around Taiwan. Determined using light–dark bottle methods, the spatial distribution of VGPM derived from different Chl-a data of MODIS Aqua (PP_A), MODIS Terra (PP_T), and averaged MODIS Aqua and Terra (PP_A&T) exhibited similar seasonal patterns with in situ PP. The three types of satellite-derived PPs were linearly correlated with in situ PPs, the coefficients of which were higher throughout the year in PP_A&T (r² = 0.61) than in PP_A (r² = 0.42) and PP_T (r² = 0.38), respectively. The seasonal RMSR and bias for the satellite-derived PPs were in the range of 0.03 to 0.09 and −0.14 to −0.39, respectively, which suggests the PP_A&T produces slightly more accurate PP measurements than PP_A and PP_T. On the basis of environmental conditions, the subareas were further divided into China Coast water, Taiwan Strait water, Northeastern upwelling water, and Kuroshio water. The VPGM PP in the four subareas displayed similar features to Chl-a variations, with the highest PP in the China Coast water and lowest PP in the Kuroshio water. The RMSD was higher in the Kuroshio water with an almost negative bias. The PP_A exhibited significant correlations with in situ PP in the subareas; however, the sampling locations were insufficient to yield significant results in the China Coast water.

This study investigates the historical changes in resource development of offshore and coastal fisheries around Taiwan from 1970 to 2021 using the mean trophic level (MTL) and Fishing-in-Balance (FiB) indices. Utilizing data from the Fisheries Statistical Yearbook, three scenarios were employed to assess the effects of highly migratory, oceanic migratory, and seasonal migratory fish species on the MTL and FiB indices. The analysis revealed a continuous increase in MTL for offshore and coastal fisheries, suggesting shifts in the trophic structure and potential over-exploitation of higher trophic level species. The FiB index for offshore fisheries exhibited a declining pattern after 1990, reflecting the depletion of indigenous fish stocks, while the FiB for coastal fisheries showed an increasing trend from 1970 until the 2000s, followed by a decrease, highlighting unsustainable fishing practices. Moreover, the study identified Scomber australasicus, targeted by Taiwanese Purse Seine, as an influential species affecting the resource dynamics of offshore fisheries. The trawling fisheries would also be a crucial issue affecting the indigenous resource dynamics of offshore fisheries in Taiwan. This study identified a fishing-down mechanism within indigenous fishery dynamics. The potential over-exploitation of fish stocks could result in long-term unsustainable practices if left unaddressed. This study advocates for enhanced fisheries management through stricter regulations on fishing gear, continuous monitoring, and adaptive management strategies. These measures are essential for achieving sustainable development goals and conserving marine biodiversity in Taiwan’s waters. By addressing these critical issues, Taiwan can better manage its fisheries resources and promote ecological balance.

Context: Climate change reportedly affects global fisheries, including the highly valuable swimming crabs, an important benthic species in Asian waters. Aims: The aim of this study was to determine the effects of El Niño–Southern Oscillation (ENSO) events on catch rates and habitat suitability of Portunus pelagicus, Portunus sanguinolentus and Charybdis feriatus in the Taiwan Strait. Methods: We combined marine remote sensing data with Taiwanese trap vessel data to develop a weighted habitat suitability index modelling and analyse the recruitment dynamics of swimming crabs in different ENSO events. Key results: Our results suggest that Increasing salinity (>33.5 PSU) and sea temperature (>18.6°C) during La Niña events had a positive effect on stock recruitment and habitat suitability index of P. pelagicus and C. feriatus. By contrast, P. sanguinolentus were not affected by ENSO events. The low catch rates for P. sanguinolentus in normal years and for C. feriatus and P. pelagicus in normal and El Niño years were highly consistent with the significant shrinkage of the habitat suitability index. Conclusions: Monitoring climate change and environmental factors is essential for understanding their effects on marine ecosystems. Implications: This research can help implement sustainable crab fisheries.

Taiwan Bank (TB) is located in the southern Taiwan Strait (TS). The uplifted continental slope and bottom currents in this area result in the formation of upwelling areas, which serve as crucial fishing grounds. Climate-induced fluctuations in fish populations occur in the TS. However, how predation and competition affect the interspecies relationships in the TB ecosystem warrants clarification. In this study, we collected high-grid-resolution data on fishery activity (2013–2019) and constructed ecosystem models using Ecopath with Ecosim (EwE). Three mass-balanced models for determining the influence of El Niño–Southern Oscillation (ENSO) events on the TB ecosystem were constructed using EwE. A range of groups, including representative pelagic, benthic, and reef species, were collected for analyzing the relationship between migratory and sedentary species in terms of ecosystem structure variation due to climate change. The results demonstrated that the total system throughput (TST) was 10,556–11,122 t km⁻² year⁻¹, with an average transfer efficiency of 12.26%. According to the keystoneness index, calculated through mixed trophic impact analysis, Polydactylus sextarius and Scomber japonicus were the key species with top–down control and relatively high impact on the ecosystem in normal years. The keystone species also shifted to the predator fish Thunnus albacares and Katsuwonus pelamis during El Niño and La Niña events, respectively. Moreover, total biomass, TST, consumption, and respiration were noted to increase during ENSO events. However, during La Niña events, the diversity and connectance indexes were relatively low but pelagic species’ biomass was relatively high, whereas the biomass of most benthic and reef species was relatively high during El Niño events.

Offshore wind farm (OWF) development raises concerns regarding potential conflicts with local fisheries and marine ecosystems. This study investigated the spatiotemporal dynamics of gillnet and trawl fisheries in the coastal waters off Changhua, Taiwan, across various development phases. (2016–2024). Spatial analysis revealed distinct operational patterns: gillnet fleets operated within and adjacent to wind farms, while trawl activities were concentrated in northern offshore waters, largely avoiding the development zone. The gillnet fishery demonstrated a significant increase in Income Per Unit Effort (IPUE), suggesting that local fishers successfully employed adaptive strategies. The IPUE of the trawl fishery indicated a slightly lower value during this period. These findings indicate that current OWF development has historically coexisted with gillnet fisheries without causing economic loss. The catch composition of gillnet fisheries remained stable, dominated by Silver croaker and Pharaoh cuttlefish. The species diversity indices of both fisheries showed a stable to increasing trend driven by seasonal variability rather than construction impacts. The habitat-driven shift in community structure was observed within the wind farm zone (gillnet fisheries), where the dominance of benthic species (e.g., Flatfish) transitioned toward reef-associated taxa (e.g., Spotted catfish, Black Sea bream). This indicates that the turbine foundations may function as artificial reefs, supporting a more complex assemblage. Nevertheless, the observed habitat alterations highlight the necessity for long-term monitoring to ensure the sustainable symbiosis of renewable energy expansion and marine resource conservation.