Growth and maturation of red tilefish Branchiostegus japonicus in waters off Yamaguchi Prefecture, southwestern Sea of Japan
2020
Kawano, M. | Amano, C.
Growth and maturation of red tilefish Branchiostegus japonicus caught in waters off Yamaguchi Prefecture, southwestern Sea of Japan were studied. The age was determined by reading yearly rings of the otolith. The length-at-age data were fitted to the von Bertalanffy's equations by non-linear least squares method. The equations were estimated as follows: Lt= 376.8 (1 - exp (-0.337 (t+ 0.498))) for females and Lt = 518.8 (1 - exp (-0.212 (t+ 0.654))) for males, where Lt is the total length (mm) at t year-old. The growths of the both sexes during younger ages were slightly greater than those of previous studies conducted in the East China Sea and western Wakasa Bay. Relationships between the total length (l, mm) and maturity rate (Ml) at l mm were estimated by non-linear least squares method as follows: Ml = l / exp (exp (11.32 - 0.0373l)) for females and Ml = l / exp (exp (14.478 - 0.0428l)) for males. The biological minimum sizes in total length were 244 mm for female and 285 mm for male and total lengths at 50 % maturity rate were estimated to be 313 mm for female and 347 mm for male. Both the minimum biological sizes and total lengths at 50 % maturity were larger than those of previous studies conducted in the East China Sea. The faster growth and slower maturation at younger ages in this area may be caused by the lower fishing pressure than that in the East China Sea.
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