Lenhardt, M. (1992) Seasonal changes in some blood chemistry parameters and in relative liver and gonad weights of pike (Esox lucius L.) from the River Danube. Journal of Fish Biology [J. FISH BIOL.], pp. 709-718
| Species | Development state | Trait | Primary Data | Secondary Data |
| Esox lucius | Female | Onset of oogenesis | August-September | ['August', 'September'] |
| Esox lucius | Female | Intensifying oogenesis activity | Winter [Important in increase in November, and continue to increase until spawning] | ['January', 'February', 'March', 'November'] |
| Esox lucius | Female | Maximum GSI value | About 22% | 22.0 percent |
| Esox lucius | Female | Resting period | 3 Months (June to end of August) | 3.0 months |
| Esox lucius | Female | Resting period | Almost 0% (June, July, August) | 4.0 months |
| Esox lucius | Male | Onset of spermatogenesis | End of August | ['August'] |
| Esox lucius | Male | Main spermatogenesis activity | September-October | ['September', 'October'] |
| Esox lucius | Male | Maximum GSI value | 2-3 [End of October] | 2.5 percent |
| Esox lucius | Male | Resting period | < 0.1 [June, July, mid-August] | 4.0 months |
| Esox lucius | Spawning conditions | Spawning season | Mid-February until Mid-April | ['February', 'March', 'April'] |