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 hatchery-induced evolutionary impacts on egg size.

Received July 26, 2013; accepted September 6, 2013

ACKNOWLEDGMENTS

We thank Robert Hanten, Patrick Nero, Eric Krebs, Kristen Becket, and the spawning crews at Whitlock Bay Spawning Station for their assistance with this study.