The spatial distribution patterns of fish larvae and the relationships with hydrographic conditions in the waters surrounding Taiwan were studied in August 2004 when the south-westerly monsoon prevailed. A total of 6566 fish larvae were identified, belonging to 80 families, 129 genera and 230 species. Cluster analysis revealed two station groups, one associated with the South China Sea Surface Current (SCSSC) and the other with the Kuroshio Current (KC). The SCSSC group was characterized by mostly coastal and neritic species, and the KC group was predominated by oceanic species. Larger fish larvae were generally more abundant in the neritic waters west of Taiwan where the SCSSC prevails than in the waters east of Taiwan where the KC prevails. The combination of chlorophyll a, zooplankton and nitrite best explained the relationship of larval fish distribution and environmental variables, implying that the distribution of fish larvae in summer was closely linked to the food source. The changing of monsoons potentially affects the succession of water masses and the transport and assemblage of fish larvae in this study area.

This study, based on samples taken in seven cruises from February 2003 to November 2004, linked larval fish assemblages with mesoscale oceanographic features dominated by the monsoon‐driven current system in the Taiwan Strait. A total of 7753 specimens of larval fish were identified from our samples, belonging to 467 taxa in 112 families and 230 genera. Engraulidae, Myctophidae, Scombridae, Carangidae, and Gobiidae were the five most abundant families. Three larval fish assemblages were distinguished by association respectively with the China Coastal Current, Kuroshio Branch Current, and South China Sea Surface Current, and accordingly designated as the cold‐period northern Taiwan Strait (CNTS), southern Taiwan Strait (STS), and warm‐period northern Taiwan Strait (WNTS) assemblages. The composition of larval fish differed significantly between assemblages, with the CNTS being the most dissimilar assemblage, probably due to the presence of neritic/oceanic taxa in the STS and WNTS and primarily neritic‐associated taxa in the CNTS. The alternate intrusions of currents in the Taiwan Strait driven by seasonal monsoons play a pivotal role in the dispersal and community structure of larval fish. In addition, winter front turbulence and local topographic upwelling contributed to the increase in biological production; consequently resulting in high chlorophyll a concentrations and zooplankton biomass to provide abundant food for the survival of larval fish. The high correlation between the environmental variables and the larval fish assemblages offers the possibility to use the assemblages as indicators of the surface circulation in the Taiwan Strait and thereby improve our understanding of the ecosystems.

This study analyzed the spatiotemporal occurrences of mesopelagic fish larvae in relation to environmental forcing in the Gaoping coastal waters off southwestern Taiwan during August 22–23, 2014 (summer), December 5–6, 2014 (winter), and April 28–29, 2015 (spring). Forty taxa or morphotypes of mesopelagic fish larvae were identified. Skinnycheek Lanternfish Benthosema pterotum (19.1%), Bristlemouth Cyclothone alba (11.6%), Spinycheek Lanternfish B. fibulatum (10.8%), Benthosema spp. (9.4%), and Neoscopelus spp. (9.2%) were the five predominant taxa. Maximum abundance of these taxa generally occurred during the cold period (winter and spring). Although the temporal difference in the abundance of mesopelagic fish larvae was not significant, the assemblage of mesopelagic fish larvae was more diverse in winter than in other seasons. Cluster and distance‐based linear model analysis suggested a distinctly structured assemblage of mesopelagic fish larvae. The intrusion of the Kuroshio Branch Current played an important role in the transport of mesopelagic fish larvae. The distribution of mesopelagic fish larvae was closely related to the hydrographic features, with surface temperature and mixed‐layer depth being the major factors affecting the occurrence of mesopelagic fish larvae. Also, the vertical mixing of the water column in winter induced the vertical distribution of natural food favorable for mesopelagic fish larvae.

The aim of this study was to investigate the species composition and distribution of fish larvae in relation to hydrographic conditions in the waters surrounding Taiwan Island (TI) in February 2003. In total, 242 kinds of fish larvae belonging to 127 genera and 75 families were recognized. Among these, 109 taxa were identified to the family or genus level, others to the species level. The 12 predominant types, which constituted 71% of the total fish larvae, were Engraulis japonica, Scomber sp., Diaphus spp., Benthosema pterotum, Carangoides ferdau, Embolichthys mitsukurii, Maurolicus sp., unidentified Myctophidae, Gonostoma gracile, Trichiurus lepturus, unidentified Gobiidae, and Myctophum asperum. The distribution of fish larvae showed a clear association with water masses around TI, with higher abundances and lower species richness northwest of TI where the China Coastal Current prevails, and lower abundances and higher species diversity east of TI where the Kuroshio Current dominates. Cluster analysis distinguished three station groups and four species groups, and the distribution patterns of fish larvae also corresponded to hydrographic conditions. The total abundances of fish larvae and eight of the 12 predominant taxa showed significant and positive correlations with zooplankton abundance, which suggests that food source might be a key factor determining the abundance and distribution of fish larvae during the winter.