Age, growth and feeding habit of Watases lanternfish Diaphus watasei (Pisces: Myctophidae) in the East China Sea

Life history characteristics of Watases lanternfish Diaphus watasei from a deep sea fishing ground of the East China Sea were studied. Overall, 452 adult individuals with standard length ranging from 91 to 147 mm were collected in the continental slope during 3 years. The growth pattern and hatching date were inferred from otolith microstructure analysis, and the stomach contents were examined to clarify feeding ecology. Three distinct zones of the otolith microstructure were depicted, the numbers of increments in the central and middle zones of the D. watasei otolith are in the lowest level in myctophid species studied. The maximum number of growth increments indicated a short lifespan of 2 years. The spawning time almost lasted throughout the year, and then two cohorts were separated according to the estimated hatching time. The length–weight relationship revealed a negative allometric pattern and significant difference between the two cohorts, and a significant seasonal difference was also detected in somatic growth pattern. A piscivorous habit dominated by Maurolicus muelleri was revealed across sampling seasons and standard length groups. Overall, D. watasei show distinct life history characteristics compared to coinhabiting myctophids, and such characteristics could reduce interspecific competition.