MEPS 562:135-146 (2016)  -  DOI: https://doi.org/10.3354/meps11942

ABSTRACT: Seasonal (inter-cohort) variability in the development of Japanese anchovy Engraulis japonicus during the transition from larval to juvenile stages was examined based on changes in head size, degree of guanine deposition and ossification. Seasonal variability was observed in the relationships between head length and standard length (SL) at 20, 25, and 30 mm SL, which were all positively related to sea temperature. In addition, SL immediately before and immediately after the start of guanine deposition was negatively related to temperature. Moreover, the development of the caudal fin supports was faster in the order August (warmest month), June (intermediate), and January (coldest); the full complement of pectoral fin rays (≥14 rays) was observed at 26.5 mm SL in August and 32.7 mm SL in June, but was not observed in January. Thus, morphology at length differed among seasons. Furthermore, there was parallel development of external (head length and pectoral fin rays) and internal (degree of guanine deposition and caudal fin supports) characteristics. The energy requirement for development of some characteristics did not result in delayed development of other characteristics. Overall, larvae at the same somatic size would have a higher potential for predator avoidance and prey capture under higher temperatures, although additional factors will influence potential survival.

KEY WORDS: Development · Head length · Guanine deposition · Ossification · Japanese anchovy · Sea temperature