Witkowski et al, 1989


Witkowski, A. and Blachuta, J. and Kokurewicz, B. and Kowalewski, M. (1989) Changes of gonado-somatic index (GSI) and egg diameter in the grayling Thymallus thymallus (L.) in annual cycle. Acta Ichthyologica et Piscatoria [ACTA ICHTHYOL. PISC.], pp. 21-28

Associated characteristics

Species Development state Trait Primary Data Secondary Data
Abramis brama Female Resting period About one month No data
Rutilus rutilus Female Resting period 1.5-2 months, but could be shorted in heated reservoirs 1.75 months
Coregonus albula Female Resting period About 2 months 2.0 months
Thymallus thymallus Egg Oocyte diameter Mean 2.67, up to 2.9 [Egg immediately before spawning] 2.67 mm
Thymallus thymallus Female Onset of oogenesis July and then increase regularly ['July']
Thymallus thymallus Female Intensifying oogenesis activity The most intense growth takes place as late as autumn and winter (September-March) ['January', 'February', 'March', 'September', 'October', 'November', 'December']
Thymallus thymallus Female Maximum GSI value Mean of 15.7 but up to 18% [The highest GSI values are observed in March and at the beginning of April] 15.7 percent
Thymallus thymallus Female Resting period About two months: May and June 3.0 months
Thymallus thymallus Female Resting period 0.8 [May and June] 3.0 months
Thymallus thymallus Male Onset of spermatogenesis Mid-July, slight increase ['July']
Thymallus thymallus Male Main spermatogenesis activity August then remained almost constant during the winter ['January', 'February', 'March', 'August']
Thymallus thymallus Male Maximum GSI value Mean 1.63, up to 2 [September] 1.63 percent
Thymallus thymallus Male Resting period 0.3% [Three months after spawning May -July] 3.0 months