Population structure and reproductive dynamics of the ridged swimming crab Charybdis natator in the southern Taiwan Strait of China: significant changes within 25 years

The ridged swimming crab Charybdis natator (Portunidae) is a commercially important crustacean species in China. purpose of this study to compare its population structure and reproductive pattern within the same fishing area (the southern Taiwan Strait) from two datasets over 25 years; one 1994−1996 early years C. fishery) other 2019. overall sex ratio (male:female) changed male bias (1:0.76, p < 0.01) female (1:1.38, Male body sizes (carapace width, CW) were significantly larger than those females both ( 0.05). average CW weight (BW) males 2019 smaller lighter 1994−1996. maximum size proportion large-sized individuals (CW > 10 cm) decreased dramatically years. One spawning peak season was identified each dataset, i.e., March−August February−April 2019, revealing 1-month shift. minimum for maturation (carrying eggs) 6.9 cm 6.1 an 11.6% reduction For first time, at 50% maturation, relationship between absolute fecundity CW, egg diameters obtained which can be applied future comparisons. Recent studies have revealed consistent February–April several crabs Strait. These findings should considered fishery management. Furthermore, fishery- environment-associated factors influencing dynamics merit further investigation.