Early life history of the small yellow croaker (Larimichthys polyactis) in sandy ridges of the South Yellow Sea

The early life history of the small yellow croaker Larimichthys polyactis was studied using the otolith microchemistry of juvenile fish and a recruitment survey in the sandy ridges of the South Yellow Sea. The otolith Sr/Ca ratio regime shifted markedly at the age of 5-7 days (early April) and 37-41 days (around early May). Subsequently, the Sr/Ca ratio was almost constant until late June, indicating an aggregation of L. polyactis juveniles in the relatively stable habitat of the sandy ridges, which was supported by a recruitment survey that showed a rapid increase in the number of juveniles in the same area between early May and the end of June. Variations in the Sr/Ca ratio between early April and early May might reflect a habitat adaptive strategy of L. polyactis in the pelagic stage to hydrodynamic processes of the sandy ridges. Based on the aforementioned habitat shifts and recruitment phenology, it was hypothesised that L. polyactis juveniles disperse between early April and early May, inhabit sandy ridges to feed, and migrate offshore in late June.