Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor

Dr. Yolanda Morbey

Abstract

I investigated the influence of growth history on the expression of female reproductive tactics in kokanee salmon (Oncorhynchus nerka) from Meadow Creek Spawning Channel, British Columbia, Canada. Female kokanee either arrive at the spawning area with red nuptial coloration, or less commonly, sexually immature with silver coloration. Silver- and red-arriving females may reflect different reproductive strategies in the population. I used otolith increment measurements to determine fish growth. In contrast to earlier studies, silver- and red-arriving females in 2013 did not differ in age at maturity (mostly were age 3+) or size at maturity (length from eye to tail, silver: 243.50 ± SE = 0.26 mm, red: 247.06 ± SE = 0.19 mm). In terms of females maturing at age 3+, silver- and red-arriving fish did not show a difference in any size-at-age or growth increment-at-age. This study indicates that growth is unlikely to influence the reproductive tactic adopted by spawning female kokanee salmon. Further research should focus on energy allocation differences during the pre-reproductive stages, and the heritability of the silver- and red-arriving tactics in female kokanee.


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