Growth patterns and sex ratios of Conger japonicus and C. erebennus in Tokyo Bay

Abstract

Ages of the eels Conger japonicus (n?189) and C. erebennus (n?448) in Tokyo Bay were determined by otolith sectioning. The estimated age range of C. japonicus specimens was 1? to 6? yr (modal range 2? to 4? yr), and of C. erebennus 0? to 11? yr (modal range 5? to 8? yr). Many C. erebennus taken measured over 1000 mm in total length and were more than 6? yr. C. erebennus is therefore characterized as a large-sized eel in comparison with C. myriaster, for which size, age estimations and growth patterns are well documented. Males of C. japonicus and C. erebennus accounted for 2-6% of the specimens sampled in this study, suggesting that the population in Tokyo Bay is composed predominantly of females.