Early Growth Pattern of Japanese Anchovy Engraulis japonicus in the Coastal Yellow Sea and Its Influencing Factors

Abstract

The growth rate during the early life stages is a key factor influencing fish recruitment variability. Extrinsic environmental factors such as temperature are generally having significant effects on early growth of larvae, while the intrinsic effects (e.g., ontogenetic or individual-specific differences) are often underestimated. In this study, the early growth pattern of Japanese anchovy (Engraulis japonicus) in the coastal Yellow Sea was estimated using otolith daily growth increments and the effects of both extrinsic and intrinsic factors on the early growth of anchovy were investigated using increasingly complex mixed-effects models. Mean growth rate during first otolith increment deposition to capture, estimated from otolith daily increment trajectories, was 0.43 ± 0.11 mm day⁻¹, and the proportion of anchovy larvae that hatched during neap tidal periods was relatively high. Early growth rate of anchovy was positively correlated with intrinsic factors (age, width of the first daily increment) and extrinsic factors (seawater temperature at hatching and during growth). The results of mixed-effects model also detected the faster growth occurred during the spring tide and that later hatching larvae were characterised by a higher growth rate. In addition, anchovy larvae exhibited a marked aggregation in the nearshore area and showed negative distribution characteristics in the upwelling areas. These results provide new evidence on the early growth pattern with intrinsic factors and spring tide; it is crucial for understanding the early growth and recruitment variability of anchovy in the context of climate change and may contribute to sustainable management policies for this valuable resource.