photoperiodic induction on the growth-rate and gonads maturation in the crayfish procambarus-clarkii during ontogeny

Abstract

Five groups of 20 juvenile instars of crayfish each, were submitted to five experimental photoperiodic cycles of different photophase and scotophase characteristics during 13 weeks. The animals' total length and weight were measured weekly, When the size and maturation of the first animals were adequate, all the animals were sacrificed, and the histological study of gonads was performed, The results indicate that animals submitted to a light-dark (LD) cycle 12:12 with light interruptions in the scotophase, showed the greatest gonadal induction. However the greatest growth induction appeared in animals submitted to control condition (LD 12: 12). These results could indicate for both functions two different models of photoperiodic induction.