Growth and age-length key of the tiger puffer Takifugu rubripes in the East China Sea, Sea of Japan, and Seto Inland Sea, Japan

The age and growth of wild and hatchery-reared tiger puffer Takifugu rubripes caught in the East China Sea, Sea of Japan, and Seto Inland Sea, Japan were studied by observing the age-ring of the vertebra centrum of 1,071 individuals. The total length of the collected T. rubripes ranged from 261 to 592 mm in males and from 268 to 632 mm in females. Monthly changes of the occurrence ratio of the marginal transparency at the vertebra centrum showed that the ring was formed once a year from May to June. The ages of T. rubripes captured in these waters were from 0 to 9 years old. Females grew faster than males in the population above 3 years old, and the wild population grew faster than the hatchery-reared one. The relationships between age and total length in the population above 1 year old showed wide variations of total length in the same year class. As these results suggest that the age composition of T. rubripes cannot be accurately estimated based on length-frequency analysis only without age determination, we suggest using the age-length key for converting the length frequencies of T. rubripes into age frequencies.