High-temperature and starvation tolerances of juvenile Japanese Spanish mackerel Scomberomorus niphonius

Japanese Spanish mackerel Scomberomorus niphonius is a target species for stocking, but its biological characteristics at the juvenile stage are not well understood. Here, we investigated the high-temperature and starvation tolerances of hatchery-reared juveniles in captivity. We used juveniles of approximately 40 mm standard length, the size of juveniles released into the field. The upper incipient lethal temperature (50% lethal water temperature) was estimated to be 31.8 °C, higher than the maximum sea surface temperature in the field (approximately 29 °C). The critical thermal maximum was 34.8 °C, whereas it was 36.1 °C when juveniles were preliminarily acclimated to 31 °C for 24 h. Juveniles died from 3 to 11 days under nonfeeding conditions at 20 °C, but from 2 to 7 days at 27 °C. This information is expected to contribute to the development of the production of juvenile Japanese Spanish mackerel.This study was partly supported by JSPS KAKENHI Grant Number 19K06207