Age, Growth and Reproduction of the Oceanic Whitetip Shark from the Pacific Ocean
1998 年 64 巻 1 号 p. 14-20
詳細
1998 年 64 巻 1 号 p. 14-20
We studied age, growth, and maturity of the oceanic whitetip shark Carcharhinus longimanus in the North Pacific, and the reproduction in the North and South Pacific, captured with tuna longline from Nov. 1967 to Oct. 1995. Vertebral rings were examined from 111 males (precaudal length: 54-172cm) and 114 females (precaudal length: 50-195cm). Minimum and maximum numbers of translucent rings were 0 and 11. Marginal increment analysis suggested annualus deposition occurs during spring. A growth difference between sexes was not found. A von Bertalanfly growth equation combining both sexes was as follows;
Lt=244.58×{1-e-0.103×(t+2.698)}
Lt was expressed as precaudal length in cm at age t.
The reproductive condition was examined from 136 males and 85 females. Maturation was determined to be when precaudal length was between 125 and 135cm for both sexes (4-5 years). The parturition period is extended over a long duration. The birth size was 45-55cm and litter size varied from 1-14 with a mean of approximately six in the North Pacific.
