Growth and reproduction of the red frog crab, <Emphasis Type="Italic">Ranina ranina</Emphasis> (Linnaeus, 1758), in the Andaman Sea off Thailand

ABSTRACT:   Studies were conducted on growth and reproduction of the red frog crab, Ranina ranina (Linnaeus, 1758), in the Andaman Sea off Thailand from 1998 to 1999. Samples were collected from Ko Similan, Ko Surin and Thai-Myanmar boundary waters by gill net. Results showed that the relationship between carapace length (CL) and body weight (BW) for males (CL, 5.84–14.10 cm) was BW = 0.2598 CL^3.0931, and for females (CL, 5.35–10.97 cm) was BW = 0.4280 CL^2.8656. Growth in each gender showed allometric growth. The average CL of males was significantly larger than that of females. Average male and female crab sizes in 1999 were smaller than in 1998. The spawning season was found to be from November to February; maturing male crabs were abundant from September to December. Average sizes of CL at first maturity for males and females were 7.44 and 7.22 cm, respectively. Fecundity ranges of ovigerous female crabs were 74 600–167 900 eggs with an average egg diameter of 0.62 mm. The monthly sex ratios (male : female) varied between 1:0.56 and 1:2.77.