Relations biométriques chez l'araignée de mer Maja squinado : longueur de référence, distinction juvénile-adulte, taille-poids.

For the analysis of spider crab populations it is necessary to split the size composition by sex and between age groups, and to convert length to weight. In some cases different length measurements need to be correlated in order to compare the results from different authors. Morphometricaly it is easy to use the abdominal flap to distinguish between male and female, and between immature and adult females, but for immature and adult males it is necessary to use Somertons method to analyse the relation between carapace length and claw width. The relation between carapace length and weight is normally established at moult stage 4, and it obtained separately for males, females, immature and adults spider crabs. When measuring carapace length the present length reference is from the rear of the carapace to the front edge between the rostral spines, whereas in the past the rostral spines were included. The relation between these two measurements can be used to standardise the carapace length measurement. The results suggest that in the male the relative size of the rostrum is a secondary sexual character.