Potential Indicators of Egg Viability in Landlocked Fall Chinook Salmon Spawn with or without the Presence of Overripe Eggs

Abstract

Selected reproductive characteristics obtained during the spawning of landlocked fall chinook salmon Oncorhynchus tshawytscha from Lake Oahe, South Dakota, were evaluated for their use as predictors of embryo survival to the eyed egg stage. Spawn was categorized according to the presence or absence of observable overripe eggs. No significant differences in female length, female weight, the number of eggs per female, egg size, the amount of ovarian fluid released during spawning, and ovarian fluid specific gravity, pH, and conductivity were observed between spawn containing overripe eggs and spawn without overripe eggs. Conductivity was significantly positively correlated to embryo survival only in spawn without overripe eggs, while the total number of eggs per female was only positively correlated to embryo survival in spawn with overripe eggs. Spawning female weight, the number of eggs per female, and egg size were significantly different in spawn containing overripe eggs where no embryo survival was observed compared with spawn containing overripe eggs with at least some embryo survival to the eyed egg stage. Although no definitive predictors of subsequent embryo survival were detected, spawning personnel are probably justified in discarding landlocked fall chinook salmon spawn if more than 10% of the eggs are overripe and the female releasing the eggs is smaller than normal with relatively fewer, smaller eggs.

Impact of maturity on the physicochemical and biochemical properties of chinook salmon roe

“…Our pH results for chinook salmon roe are lower than the 7.94 ± 0.04 reported for chinook salmon (Barnes, Sayler, & Cordes, 2003). This might be related to the sample preparation.…”

“…This might be related to the sample preparation. Direct pH measurements on homogenised roes, as in the present study (Table 1) and other reports (Gagné & Adambounou, 1994;Katsiadaki, Taylor, & Smith, 1999) resulted in a lower pH range compared with other studies (Barnes et al, 2003;Fauvel et al, 1993;Lahnsteiner, Weismann, & Patzner, 1999) which measured the pH of the ovarian fluids after separation of solids by filtration. Thus Katsiadaki et al (1999) reported a pH range between 5.68 and 6.96 for cod (Gadus morhua) roe while Fauvel et al (1993) found the pH of ovarian fluids from turbot (Scophthalmus maximus) ranged from 7.0 to 8.2, and Lahnsteiner et al (1999) reported that trout (Salmo trutta lacustris) roe pH ranged between 8 and 9.…”

“…For Fauvel et al (1993), Lahnsteiner et al (1999), and Barnes et al (2003) egg quality means the viability and fecundity of the eggs which probably increases with the increase in pH within a certain range depending on the fish species, whereas in the present work and in the study of Katsiadaki et al (1999) fish egg quality refers to the potential eating and keeping quality of the eggs as food. The impact of pH on a food material is quite complex.…”

Landlocked Fall Chinook Salmon Ovarian Fluid Turbidity and Egg Survival

“…Oncorhynchus tshawytscha from Lake Oahe, South Dakota, typically exhibit poor survival during hatchery incubation, and survival varies dramatically from female to female (Barnes et al 2000a(Barnes et al , 2003. Because of the highly variable egg survival and the relatively high cost associated with incubating potentially nonviable eggs during hatchery rearing, the ability to eliminate poor-quality spawns immediately after removal from the female would lead to improvements in spawning efficiencies and cost reductions.…”

“…Additionally, objective quantitative egg assessments have also been used with mixed results (Satia et al 1974;Fauvel et al 1993;Lahnsteiner et al 1999Lahnsteiner et al , 2001Barnes et al 2000bBarnes et al , 2003.…”