Abstract:[Objectives] The growth of the gladius is irreversible throughout the entire life cycle, which can completely record the life information of cephalopod. It is a good material for the study of the age and growth of cephalopod. This study used the gladius to analyze the individual growth of Berryteuthis magister shevtsovi, and provided a research basis for the subsequent exploration of its migration route, stock assessment, and rational development and utilization [Methods] In December 2018, 261 samples of B. m. shevtsovi were collected in the Sea of Japan by the Chinese Jigging fishing fleets. Linear regression or power function regression was used to evaluate the relationships between gladius length, proostracum length and individual growth, and frequency analysis was used to study the relationship between greatest width of conus, greatest width of vanes and sex maturity. We also analyzed the growth characteristics between proostracum, vanes and conus, by the analysis of covariance to test whether there were significant differences in various parameters between males and females. [Results] The results showed that gladius length and proostracum length both had a linear relationship with mantle length (ML) (R2 > 0.76), and a power function relationship was best for the growth with body weight (BW) (R2 > 0.77) (Fig. 4, 5). Greatest width of conus and greatest width of vanes both showed a significant increase after sex maturity reaching stage III (Fig. 6, 7). For individuals at stage III, greatest width of conus was not less than 5 mm, and greatest width of vanes was not less than 6 mm. The coefficient of the linear relationship between the standardized vanes length and the standardized length of greatest width of proostracum was slightly less than “1”. The coefficient of the linear relationship between the standardized proostracum length and standardized conus length was much less than “1”. Moreover, the ratio of vanes length to the length of greatest width of proostracum and the ratio of conus length to proostracum length were all similar, about 0.77 and 0.27, respectively. This showed that the growth rate of proostracum and vanes of B. m. shevtsovi was basically the same, which was much faster than that of the conus. [Conclusion] The study show that it is feasible to use the gladius to analyze the individual growth of B. m. shevtsovi, especially when the body ia damaged, and the width of gladius grows mainly after the individual has matured.
