Fig. 3

The annual penetration cycles from juveniles to adults based on the eight-year capture data during 2006–2013. a Usually in August of every year, a notable amount of neonates begins to hatch, and reaches the highest proportion of the population from September to December. In the next spring, juveniles gradually reach the size of the adults and join the breeding group. After the breeding season, most adults die out and the cycle repeats. b The distribution of snout-vent length in each month demonstrates the annual cycle and the rapid growth from small-sized neonates and juveniles to large-sized adults