Manipulation of hours of light and temperature on induced spawning of the lambari-do-rabo-amarelo, Astyanax altiparanae in winter

Abstract

In fish, the reproductive seasonality is associated not only to the action of endogenous rhythms, but also physiological changes conditioned to environmental factors. Thus, it is postulated that the manipulation of these factors such as photoperiod and temperature could result in the shortening or extension of the reproductive cycle, with the possibility of obtaining spawning during different periods of which occur in nature. The aim is to evaluate the handling of hours of light and temperature on induced spawning (carp pituitary extract) of the lambari-do-rabo-amarelo during the winter under laboratory conditions. Thus, the experiments will be divided into two phases: (1) in winter, the fish in the control group (T0, 125 couples) will be kept in local environmental conditions, while another group of fish (T1, 125 couples) will be subjected to a gradual increase of hours of light and water temperature simulating spring conditions. (2) In the spring the second phase will take place, and 125 couples will be subject to local conditions of hours of light and water temperature. During the two phases, each 14 days, eight (8) pairs of each treatment will be induced with carp pituitary extract, proceeding to semi-natural spawning. The number of ovulated females, the number of eggs released per female, the egg diameter, the percent egg hatch, the number of larvae, the frequency percentage of oocytes at each stage of development and the gonadsomatic index will be evaluated. The data of the experimental group at each sample will be compared to those of the control group of the first phase, and also to those obtained during the second phase. For this, being met assumptions of normality (Shapiro-Wilk), it will be applied a t-test for paired samples (± <.05). (AU)