Effects of temperature, food availability, and body size on daily growth rate of Japanese anchovy Engraulis japonicus larvae in Hiuchi-nada

Abstract

With data sampled from 2003 to 2006, this study presents the effects of temperature, food availability (C), and body size on the somatic growth rate \( \hat{g} \) (mm day−1) and on the size-specific growth rates \( \hat{G} \) (day−1) of larval Japanese anchovy Engraulis japonicus caught in Hiuchi-nada, Seto Inland Sea, Japan, a semi-enclosed narrow sea. C was calculated using an individual-based model, which is an encounter model between copepods and anchovy where the anchovy resulted in a successful capture of the copepod. \( \hat{g} \) decreased with increasing anchovy length, but increased with increasing C. No significant relationship was found between \( \hat{g} \) and temperature. \( \hat{G} \) decreased with increasing temperature, but anchovy weight, on the other hand, increased with increasing C. In the literature, the mechanism of growth determination for larvae of pelagic fish species is considered to be primarily determined by sea temperature and secondarily by food availability. However, \( \hat{g} \) and \( \hat{G} \) were found to be dependent on C rather than temperature. \( \hat{G} \) was dependent on anchovy weight rather than C and temperature. For forecasting the number of days required for development from an arbitrary pre-recruitment size to the recruitment size, we address not only temperature but also food availability and the size effect when considering the mechanism of growth determination for larvae.