| Abstract: | 10 In the rainbow trout and the tench, at the time of spermatogonia divisions a rise in the plasma gonadotropin levels was observed. Just before or during the spawning period, E217 beta and plasma gonadotropin reach their maximum levels. 20 When the effects of raising the natural cycle temperature of the tench were studied (deltat + 3 degrees C and + 6 degrees C), in conditions where nycthemeral and seasonal rythmicity were maintained, a significant increase in fertility was observed with the increase in temperature (the first spawning period was earlier and there was a rise in the number of spawnings). This effect of temperature seems to act at the level of the hypothalamo-pituitary system. |
