Gonadal Maturation and Maturity Staging of the Pacific Sand Lance Ammodytes personatus (Ammodytidae)

Detailed attributes on oogenesis, spermatogenesis, ovarian, and testicular maturity phases of the Pacific sand lance Ammodytes personatus are described here for the first time. Histology was subsequently used to define detailed morphological criteria related to five distinct histological and macroscopic maturity phases. This study revealed that Pacific sand lance do not exhibit sexual dimorphism in length and weight, however, statistically significant differences were noted for immature and mature fish. Maturation in Pacific sand lance occurred in females at a minimum FL of 97 mm and weight of 3.0 g. Maturation in males occurred at a minimum FL of 92 mm and weight of 2.5 g. First spawning was observed in females > 107 mm and > 3.5 g and in males > 104 mm and > 3.8 g. Bimodal size distributions were observed in mature ovaries, providing strong evidence for group-synchrony ovary organization, determinate fecundity, and the ability to estimate total fecundity prior to the onset of spawning. These results provide a useful reference for size-at-maturity and present a rigorous methodological approach to rapid and accurate assessment of reproductive maturation stages in this species. Moreover, the high-resolution maturity data provided in these analyses may be applied to inform stock-recruitment relationships and to estimate effects of parental stock composition on reproductive potential. The histological description of gonadal morphology may species be relevant to the reproductive biology of other members of family Ammodytidae, a closely related group of fishes.

Automated summary

This study provides a detailed description of reproductive characteristics of Pacific sand lance for the first time. The results show that there is no sexual dimorphism in length and weight, but statistically significant differences exist between immature and mature fish. The size distributions in mature ovaries suggest group-synchrony ovary organization and determinate fecundity.