Marchelidon, J. and Le Belle, N. and Hardy, A. and Vidal, B. and Sbaihi, M. and Burzawa-Gerard, E. and Schmitz, M. and Dufour, S. (1999) Study of variations of anatomical and endocrine parameters in sedentary and downstream migrating female European eels (Anguilla anguilla): application to the characterization of the silver stage. Bulletin francais de la peche et de la pisciculture. Paris [Bull. Fr. Peche Piscic.]., pp. 349-368
| Species | Development state | Trait | Primary Data | Secondary Data |
| Anguilla anguilla | Female | Resting period | > 1.4% for the silver stage | 1.4 months |
| Anguilla anguilla | Male | Resting period | About 0.1 for the silver stage | 0.1 months |