Characteristics of landlocked fall chinook salmon producing either viable or completely non-viable eggs

Abstract

Landlocked fall Chinook salmon Oncorhynchus tshawytcha from Lake Oahe, South Dakota, USA, frequently produce spawns where the eggs become visibly dead within four hours after fertilization. This study compared the characteristics of spawning females that produced dead eggs to those that produced spawns with at least some egg survival. No significant differences occurred between the groups of females in total length, post-spawn weight, the number of days held prior to perceived ovulation (ripeness), or egg size. However, females that produced spawns with no egg survival were held at for approximately one day longer after perceived ovulation compared to females producing spawns with at least some egg survival. In addition, total fecundity was significantly lower in the spawns which produced only dead eggs. Hatchery personnel can use this information to decide if spawns should be retained for further processing.