Color and Morphometric Markers for Gender Recognition of Blue Swimming Crab (Portunus pelagicus) Seeds

Abstract

This research aims to reveal whether differences in seed color can be used as a benchmark in determining the sex of blue swimmer crab (BSC) seeds. To reveal the morphological differences between the seed color and gender, firstly the crab seeds were grouped based on color, namely dark, dark-spotted, and light. The morphological characteristics were measured at the age of 10 days (C10) and sexual confirmation at 31 days (C31) of crabs. Measurements were carried out using a surgical microscope. Fisher's F asymptotic approximation shows that seed color has different morphometric characters (P < 0.05). The results of the Fisher distance test explained that there was no significant difference between dark spotted and light (P?> 0.05), but both were different from dark (P < 0.05). Based on the canonical discriminant function, six discriminator characters are obtained namely the CL/CW, MEL/CW, MAL/CW, MEW/CW, PL/CW and TW/CW ratios. The classification of dark members can be seen with a percentage of accuracy (% correct) of 76.67%, dark-spotted (70.00% accuracy), and light pattern of 60.00%. After cross-validation, it can be seen that the percentage of classification accuracy is 62.22%. Observations for secondary sexual traits (pleopods and gonophores) showed that the dark spotted and light crab seeds were predominantly female (60–63% each) while the dark crab seeds were dominantly male (63%). The findings contribute greatly to the accuracy of gender identification of BSC during the early stages and provide an understanding of selecting crabs of a certain gender for cultivation.