Age, growth and reproduction of the banded houndshark Triakis scyllium around the tip of the Izu Peninsula, Japan

Abstract

We examined the biological characteristics, such as age, growth and reproduction, of the banded houndshark Triakis scyllium, which was caught around the tip of the Izu Peninsula between 1991 and 2012. Age and growth were estimated by counting growth bands in the vertebral sections from 52 males and 58 females. The number of growth bands observed for males and females was 3-15 and 2-18, respectively. One growth band formed from December to May. A growth curve was fitted to the observed length using the following modified von Bertalanffy growth equations with fixed length at birth: Lt=1329- 1079exp(-0.178 t ) for males, Lt=1436-1186exp (-0.165 t ) for females. The growth curve was significantly different between sexes. Longevity was estimated to be 18.4 years for males and 20.6 years for females. Size and age at 50% maturity were estimated to be 914 mm total length (TL) and 5.7 years old for males, and 1083 mm TL and 8.6 years old for females. The number of embryos per litter was 8-29, and the sex ratio of embryos was 1:1.