Brown, W.P. and Selgeby, J.H. and Collins, H.L. (1998) Reproduction and early life history of ruffe (Gymnocephalus cernuus) in the St. Louis River, a Lake Superior tributary. Journal of Great Lakes Research [J. Great Lakes Res.], pp. 217-227
| Species | Development state | Trait | Primary Data | Secondary Data |
| Gymnocephalus cernua | Egg | Incubation time | 5-6 [At 16°C] | 5.5 days |
| Gymnocephalus cernua | Egg | Temperature for incubation | 16°C | 16.0 °C |
| Gymnocephalus cernua | Egg | Degree-days for incubation | About 90 [5-6 days at 16°C] | 5.5 °C * day |
| Gymnocephalus cernua | Larvae | Larvae behaviour | Larval ruffe hatch and become pelagic within 1 to 2 weeks after egg deposition and could possibly be netrained in ballast water duting the pelagic period | Pelagic |
| Gymnocephalus cernua | Larvae | Temperature during larval development | Larvae were captured at Allouez Bay from 30 May to 10 July, with peak catch the week of 13 June, corresponds to a temperature of 12-17°C on the graph. Larvae were captured at whaleback from 23 May to 3 June with a peak catch the week of 30 May, which corresponds to 12-16°c on the graph | 14.5 °C |
| Gymnocephalus cernua | Larvae | Onset of exogeneous feeding | 120-130: Active feeding and swim-up occurring 13 days after fertilization (hatching 5-6 days after fertilization) at 16°C | 125.0 °C * day |
| Gymnocephalus cernua | Female | Maximum GSI value | 9-11 [May] | 10.0 percent |
| Gymnocephalus cernua | Spawning conditions | Spawning season | May-July | ['May', 'July'] |
| Gymnocephalus cernua | Spawning conditions | Spawning period duration | 8 | 8.0 weeks |
| Gymnocephalus cernua | Spawning conditions | Spawning temperature | 5-18 [mainly between 12-14] | 11.5 °C |
| Gymnocephalus cernua | Spawning conditions | Parity | The prolonged spawning period is possibly due to different rates of development of the ovaries among females of different ages | No category |