Lack of Temporal Variation in Egg Size in Landlocked Fall Chinook Salmon from Lake Oahe, South Dakota

Abstract

This study examined 23 years of egg size data from a population entirely made up of hatchery-maintained fall Chinook Salmon Oncorhynchus tshawytschain Lake Oahe, South Dakota. Egg size data, obtained by water-displacement during hatchery egg inventories, ranged from 4.2 to 6.6 eggs/mL over the 23 years. However, linear regression of data from either pooled lots of eggs (y = 0.0035x -1.8116; P = 0.727) or individual spawns (y = 0.0003x + 5.3037; P = 0.907) indicated no significant change in mean egg size over time. The lack of change in egg size of Lake Oahe fall Chinook Salmon over the 23 years of this study indicates there was no hatcheryinduced evolutionary impacts on egg size.

Rearing Velocity Impacts on Landlocked Fall Chinook Salmon (<i>Oncorhynchus tshawytscha</i>) Growth, Condition, and Survival

“…No previous studies have been conducted examining the effects of exercise on growth of landlocked Chinook salmon in general or landlocked fall Chinook salmon from Lake Oahe, South Dakota. This strain of fish is relatively unique and has been genetically isolated from all other strains of Chinook salmon since 1989 [12] [13]. Because this salmon population is maintained solely by stocking, and progeny may be limited during certain years [13], using exercise to improve hatchery rearing performance and post-stocking survival is important.…”