Aquaculture, 114 (1993) 33-40 Elsevier Science Publishers B.V., Arnsterdam 
Physiological factors affecting triploid production in rainbow trout, Oncorhynchus mykiss* 

N.F. Diaz1, P. Iturra2 , A. Veloso1, F. Estay1 and N. Colihueque1

1.- Facultad de Ciencias, Casilla 653, and 
2.- Facultad de Medicina, Universidad de Chile, Santiago, Chile
(Accepted 25 February 1993)


The influence of three physiological factors related to triploid production was examined for rainbow trout. Individual spawnings of 46 females were used to perform triploid production experiments from 1989 to 1991, with various water temperaturas (6-13.8ºC) at stripping and egg incubation. The percentage of triploids was similar for a heat shock of 26.5ºC for 15 min applied 15 or 25 min after fertilization (73.4 ± 5.6% vs 78.6 ± 4.5%). A tendency to a higher percentage of triploids (85.9 ± 5.7%) was observed for water temperaturas of 6-8.0ºC at stripping and incubation, compared to at higher water temperaturas of 12.1-14ºC (63.0 ± 8.4%). Analysis of variance indicated an effect of four categories of water temperatura (6-8, 8.1-10, 10.1-12, 12.1-14ºC) on triploid product at P= 0.14. Regression analysis confirmed these as significant (r= -0.36; P< 0.02). A significan increase in percentage of triploids was observed when eggs remained 2, 6 and 10 days in the body cavity. The mean % triploidy was 46.1, 54.7 and 76.8, respectively. Similar results were observed for survival of the eggs.
*Supported by FONDECYT 1043/90 Grant.