Identifying Individuals of Neosalanx taihuensis Born in Different Spawning Seasons Using Otolith Microstructure

Otolith microstructure was used to distinguish Neosalanx taihuensis born in spring and autumn. Increment width during the early life stage was significant narrower for the spring-born than the autumn-born juveniles, and the frequency distributions of the width of the first 5 increments were distinctive and diagnostic. Otolith growth trajectories and frequency distribution of the first 5 increments of the spring-spawning adults displayed similar patterns to spring-born juveniles, indicating that the spring-spawning adults were recruited from spring-born fish. Otolith growth trajectories of the autumn-spawning adults were intermediate to those of the spring- and autumn-born juveniles, and the frequency distribution of width of the first 5 increments showed two modes (one similar to the spring-born juveniles and the other similar to the autumn-born juveniles), suggesting that the autumn-spawning adults were recruited from both the spring- and autumn-born juveniles. Previous study showed that population of N. taihuensis is highly dominant by the spring-spawning fish compared to the autumn-spawning. Thus, the putative life history of N. taihuensis can be summarized as: 1) a small part of the spring-born fish mature and spawn in autumn of the year of their birth; 2) the majority of the spring-born cohort matures and spawns in spring of the next year; and 3) offspring of the autumn-born fish mature and spawn in autumn of the following year.