Effects of timing of stripping and female on the viability of gynogenetic and non-gynogenetic diploid pink salmon (Oncorhynchus gorbuscha)

Abstract

Timing of stripping post-ovulation and female parent have been demonstrated to affect the viability of eggs and embryos of many species of fish. Viability of gynogenetic embryos is also influenced by the female, but the effect of timing of stripping on gynogenetic survival has not been investigated. This study examined the effects of timing of stripping and female on viability of gynogenetic and non-gynogenetic diploid progeny of pink salmon. Progeny were produced using eggs successively stripped from eight female pink salmon at 1, 7, 10, and 13 days post-ovulation. Neither type of progeny's survival was significantly affected by timing of stripping. Survival of the non-gynogenetic progeny was consistently high and not significantly affected by female or the timing X female interaction. Non-gynogenetic survival rates for the interval during which most mortalities occurred, between initial pick-off at 18 h post-fertilization and eyeing, ranged from 87.4–96.8% when averaged by female. Survival rates of gynogenetic progeny for the same interval were lower and more variable, ranging from 34.0–75.2%, and were significantly affected by female and timing X female (P < 0.05 and P < 0.01, respectively).

By itself, timing of stripping does not influence the viability of pink salmon embryos. However, because of significant female and timing X female effects on survival, any attempt to improve gynogenetic production must consider the effect of the female and control timing of stripping.