| Popis: |
Data are reported on the growth and maturation cycle of the gonads of two cyprinids inhabiting Lake Bracciano (Central Italy) — the rudd, Scardinius erythrophthalmus (L.) and the red‐eye roach, Kutilus erythrophthalmus Zer. Observations were made on the length, weight and stage of gonad maturation and of the annuli visible on the scales of 259 fish collected every two months for more than a year. The rudd grows from May to November, when the lake temperature is higher than 13°C; the red‐eye roach grows from March to November, when the temperature is over 10°. Both populations display good growth compared with that observed in other conspecific populations. The females of the rudd and the red‐eye roach grow faster than the males. The rudd spawns in the second half of June. The males are sexually mature in their first year of life and the females in the second year. The red‐eye roach spawns in the second half of May: both sexes reach sexual maturity during their first year of life. The disagreement... |
