Effects
of an artificial photothermal cycle on the reproduction of the shortfin
silverside, Chirostoma humboldtianum, Valenciennes, 1835 (Pisces:
Atherinopsidae)
G.A.
Blancas-Arroyo, G. Figueroa-Lucero, I. de los A. Barriga-Sosa, J.L.
Arredondo-Figueroa-2004
Aquaculture, 241(1-4): 575-585
Abstract:
We
report, for the first time, the controlled reproduction of the shortfin
silverside fish (Chirostoma humboldtianum, Valenciennes, 1835) and
determine the effects of the artificial photothermal cycle (APC) on male and
female reproduction. Two trials were carried out utilizing an 81-day APC,
which consisted of gradual increases and decreases of temperature and
photoperiod. The initial conditions of 13 °C temperature and a photoperiod
of 9L/15D were followed by increases of 1 °C and 30 min until 14L/10D at 23
°C was reached. Thereafter, the cycle was completed when the initial
conditions were reached by decreasing at the same rate. The trials were
carried out in two 4000-L circular tanks; one treated and one control. In
the first trial the time and percent motility of the sperm, number and
viability of sperm and semen consistency were evaluated, the control tank
was maintained at the conditions of the Experimental Production Plant (EPP)
at 17.4 °C and 11L/13D. In the second trial the broodstock were subject to
a second APC, and thereafter, this tank as well as the control tank were
maintained under the climatic conditions of EPP during other 48 days. In
both tanks, the number of spawns, number of eggs and the survival rates of
eggs and larvae were evaluated. In the first trial, the results indicated
that male brooders responded adequately to the photothermal stimulation of
19 °C and 12L/12D, females did not respond to this first stimulation. In
the second trial, females responded at 19 °C and 12L/12D presenting
multiple spawns. At the end of this experiment 48 spawns and more than
26,000 fertilized eggs were obtained, with more than 80% of survival.
(Planta
Experimental de Producción Acuícola, Departamento de Hidrobiología, CBS,
UAM Iztapalapa. Av. San Rafael Atlixco 186, Colonia Vicentina, Apartado
Postal 55-535. Iztapalapa 09340, México, D.F., México, e-mail of J.L.
Arredondo-Figueroa: afjl@xanum.uam.mx)