Out-of-season spawning

Species Fecundity Out-of-season spawning Sexual differentiation Spawning... 

The maturational processes need time to adjust to the new cycle and the bigger the change the more time required to adjust. Ideally, cycles would be adjusted two years before spawning is required to give the fish a full 12-month phase shifted cycle before the second phase shifted cycle under which out-of-season spawning will be expected. 

The natural spawning periodicity of A. japonicus remains poorly understood. However, it seems to spawn between March and August, with variations among locations (Ito and Kitamura, 1998 Xiyin et al., 2004). FuUy mature broodstock will spawn naturally in the tanks between 1900 h and 2000 h. Moreover, some laboratories in China are keeping individuals out-of-phase temperature-wise to stimulate spawning outside the normal season (Xilin, 2004). I. fuscus spawns mainly in the fall in Mexico and every month closer to the equator (Mercier et al., 2004). Gametes are released between sunset and 2100 h, a few days after the new moon (Mercier et al., 2007). 

Vitellogenesis is a process hormonally controlled and that can be affected by the exposition to xenoestrogens. In most fish species, ooc de maturation process occurs seasonally, in which one spawn occurs in each annual reproductive ( cle. In this way, factors that affect vitellogenesis can cause a drastic reduction in the reproductive success of the individual and, consequently, affect an entire species population. According to a review carried out by Nicolas (1999), deleterious effects in fishes vitellogenesis were reported for PAHs both for wild populations and laboratorial experiments. Amongst the effects cited, it is... 

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