Pina et al, 2003


Pina, T. and Esteves, E. and Andrade, J.P. (2003) Gross and histological observations of ovarian development in twaite shad, Alosa fallax fallax, from the Rivers Mira and Guadiana (Portugal). Scientia Marina (Barcelona) [Sci. Mar. (Barc.)]., pp. 313-322

Associated characteristics

Species Development state Trait Primary Data Secondary Data
Alosa fallax Egg Oocyte diameter In ripe ovaries, ooctye diameter reaches 1.052 mm. Nevertheless, larger oocytes (1.415 mm) can be observed in partially spent and spent ovaries, which were not shed and will be resorbed 1.05 mm
Alosa fallax Female Oocyte development The development of oocytes in twaite shad is asynchronous because these fish are capable of bringing oocytes from an immature conditions through vitellogenesis during the spawning season. Eggs are recruited from a heterogeneous population of developing oocytes and are subsequently ovulated in several batches during each spawning season. Asynchronous
Alosa fallax Spawning conditions Spawning migration period This species still migrates into the River Mira and the River Guadiana, Portugal to spawn. In theses rivers, spawning migration is triggered by favourable environmental conditions, such as the increase in water temperature, and starts between March and April, when adult twaite shad congregate in the sea near the mouth of the river ['March', 'April']
Alosa fallax Spawning conditions Spawning season The spawning season can last until June ['June']
Alosa fallax Spawning conditions Spawning release Evidence that twaite shad are serial spawners releasing discrete batches of eggs over an extended spawning season includes macroscopic and histologic indications of recent spawning concurrent with mature vitellogenic oocytes Multiple