Diana, J.S. and Mackay, W.C. (1979) Timing and magnitude of energy deposition and loss in the body, liver and gonads of northern pike (Esox lucius). J. Fish. Res. Bd Can., pp. 481-487
| Species | Development state | Trait | Primary Data | Secondary Data |
| Esox lucius | Female | Onset of oogenesis | Gonad growth began in August; testicular growth was completed by september | ['August'] |
| Esox lucius | Male | Onset of spermatogenesis | Gonad growth began in August; ovarian growth occurred mainly during winter | ['January', 'February', 'March', 'August'] |