February 15-18, 2009 Washington State Convention Center Seattle ...

TWICE-ANNUALLY SPAWNING RAINBOW TROUT FEMALES IN A CULTURED
POPULATION FROM SOUTHERN CHILE
Francisco Estay*, Nelson Colihueque and Cristián Araneda
Piscícola Huililco Ltda.
Pucón, IX Región, Chile
fjestay@ctrnet.cl
Rainbow trout is characterized for being an annual spawner species, however it has been described that eventually it can experience
a twice annually spawning, determined by a double anually reproductive cycle (DARC), without photoperiodic manipulation.
This study was developed in the rainbow trout breeding center “Ojos del Caburgua” owned by Piscícola Huililco Ltda.,
located in Pucón, Chile.
About 1000 females three years aged of an autumn strain (Whyteville) were used during its first maturation time during the
2005 season. 934 spawns were registered during the autumn, and 321 specimens of the same group (36.2%), had an additional
spawn, during the next spring (Fig. 1). The reproductive performance of the normal and the additional cycle, was comparatively
evaluated (Table 1).
The average weight of the spawning females, the total
fecundity and the relative fecundity, exhibited significant
differences in favor of the additional cycle. Nevertheless,
the eggs’s diameter, the fertility rate and the
eyed eggs survival rate, were significantly higher in
the normal cycle, although, the eggs and fry obtained
from additional cycle, exhibited an acceptable performance,
compatible with the productive use of eggs.
On the other hand, the average eyed eggs per female,
were significantly higher in the additional cycle.
The additional reproductive cycle length, (LCRa) that
is to say, the period time from autumn spawning date
to spring spawning date, showed a statistically significant
increase, while the spring spawning season progressed.
The first spring spawner females registered
a LCRa average of 149 days (14/10/05) and the last
in spawning showed a LCRa average of 217 days
(03/02/06). Eggs diameter also registered a statistically
significant increases while the spring spawning
season progressed.
Macroscopic and histological aspect of ovary development
stages of mono and double-cyclers are also
showed and comparatively analyzed. Our aim is to
continue the research of the DARC character for improving
both the biological knowledge that supports
this character, and it industrial potential application.
Table 1. Comparative reproductive performance between normal and
additional spawn
Normal autumn Additional spring
spawn
spawn
Average ± S D Average ± S D
(n = 965)
(n = 321)
Female weight (g) 1,153 ± 217 a
1,512 ±176 b
Fertilization rate (%) 94.5 ± 7.5 a
77.8 ± 24.9 b
Total fecundity 2,691 ± 600 a
3,680 ± 509 b
Relative fecundity 2,271 ± 420 a
2,461 ± 354 b
Eggs diameter (mm) 4.89 ± 0.16 a
4.58 ± 0.23 b
Eyed eggs per female 2,341 ± 616 a
2,608 ± 678 b
Eyed eggs survival rate (%) 84.73 ±11.80 a
Different letters means statistical significative differences (P < 0.05)
68.84 ± 15.95 b