Neja, 1988



Citation


Neja, Z. (1988) On some problems of reproduction of ruff, Gymnocephalus cernuus (L., 1758) in the Lake Dabie. Acta Icthyologica Piscatoria, pp. 33-50

Associated characteristics


Species Development state Trait Primary Data Secondary Data
Gymnocephalus cernuus Spawning conditions Spawning period duration Started spawning in early May, the spawning lasting no longer than until early June No data
Gymnocephalus cernuus Female Maximum GSI value Gonad in stage VI, meaN: 13.81, range 9.52-24.29 [In other study, the coefficient in females migrating to spawn to average 15.6 (9.0-22.0)] 16.905 percent
Gymnocephalus cernuus Male Onset of spermatogenesis In September, male gonads were more advanced in development (23.5% and 76.5% at stage 2 and 3, respectively). No stage 4 gonads were found at that time ['September']
Gymnocephalus cernuus Female Relative fecundity Mean 1066.3, range 585-1540 eggs/g 1062.5 thousand eggs/kg
Gymnocephalus cernuus Male Maximum GSI value Male in VI stage, were on average 7.11, range 5.26-12.18 8.72 percent
Gymnocephalus cernuus Female Onset of oogenesis In September, most females (64.1%) had ovaries at stage 2. No stage 4 gonads were found at that time ['September']
Gymnocephalus cernuus Egg Oocyte diameter The maximum diameter reaching 0.98 (in ova). Other described as 1.03 (range0.90-1.21) 1.055 mm
Gymnocephalus cernuus Female Absolute fecundity 13.338-82.233 47.7855 thousand eggs
Gymnocephalus cernuus Spawning conditions Spawning season In Polish waters typically from mid-April through end of May ['April', 'May']
Gymnocephalus cernuus Female Weight at sexual maturity 20-30 g ! [Different class studied strating at 11.0-20.9 g !] 25.0 kg
Gymnocephalus cernuus Female Length at sexual maturity Described as 11-12, but also at 6.5-7.0 [sex not specified] 11.5 cm
Gymnocephalus cernuus Female Age at sexual maturity All the individuals caught before spawning and belonging to age group 2 and older groups had their gonads at stage 4 or 5, that is they were ready to the nearest spawning. One may infer that some individuals spawn as early as at age 1+. In Poland, it marres at the end of its second year of life. In the river Nadym drainage, it matures at age 2 (usually hower, 3+ or 4+) 2.0 year
Gymnocephalus cernuus Spawning conditions Spawning release Spawing is prolonged and portional, the eggs being laid in two or three portions No category