Date of this Version
The Prairie Naturalist 48: 79–86. December 2016
Lake Oahe, South Dakota, USA, landlocked fall Chinook salmon (Oncorhynchus tshawytscha) reproductive characteristics were examined over a 27 year period, from 1988 to 2015. Mean total lengths of spawning females ranged from 665 mm (1995) to 812 mm (2015) with considerable year-to-year variation. Post-spawn female weights varied, ranging from 2.02 kg (2000) to 5.55 kg (2015), with an overall mean of 3.04 kg. Fecundity peaked at 4,555 eggs per female in 2003, which was just 3 years after a low of 2,011 eggs per female in 2000. Relative fecundity based on female weight was greatest at 1,211 eggs/kg in 2006 and lowest at 631 eggs/kg in 2015, while relative fecundity based on female length peaked in 2003 at 5.64 eggs/mm with the lowest value of 2.93 eggs/mm in 2000. Mean egg size for all years combined was 5.33 eggs/mL of water displaced, but was extremely variable, with the smallest eggs in 1998 and largest in 2015. Survival to the eyed-egg stage of development ranged from 0 to 100% for individual spawns, with an overall mean of 31.2%. Total fecundity was significantly correlated with both length and weight, and linear relationships between fecundity and female length, fecundity and egg size, and female length and egg size were observed. Egg survival was not significantly correlated to female length, weight, fecundity, or egg size. The information from this study will increase the efficiencies of salmon spawning operations, particularly with regard to the duration and intensity of egg collection efforts, as well as provide the foundation to evaluate possible management changes to improve Lake Oahe Chinook salmon reproductive success.
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