抄録
The present study estimated the age and growth of the silky shark Carcharhinus falciformis in the Pacific Ocean. Samples and biological data were collected from Japanese tuna longline and purse seine fisheries from 1992 to 1999. Vertebra centra were picked from 145 males and 153 females for age determination. The number of annual rings observed for males and females was 0-8 and 0-13, respectively. Combined sex von Bertalanffy growth equations were obtained as follows: Lt=216.4(1-e-0.148(t+1.76)) where Lt is precaudal length in cm at age t. A mature size for males was considered to be approximately 135-140 cm (precaudal length), with an estimated age of 5-6 years, whereas corresponding values for females were 145-150 cm and 6-7 years, respectively. Birth size ranged from 48 to 60 cm. There was no remarkable difference in growth, birth size and age at maturity between the Pacific and Atlantic Oceans. The life history parameters of the silky shark are approximately the same in both oceans.
