Egg Quality, Reproductive Success, and Behavioral Plasticity of Spawning Female Lake Sturgeon (Acipenser fulvescens)

Understanding factors affecting spatial and temporal variation in spawning activities and variance in individual reproductive success (RS) are vital for predicting potential population levels of recruitment. Environmental conditions and life-history traits such as age, size, and operational sex ratio (OSR) are well-documented influences on spawning behavior and RS. However, the effect of individual variation in female reproductive timing on egg quality and RS is unclear. In 2012 and 2013, we captured spawning adult lake sturgeon (N=519; Acipenser fulvescens) at one of seven locations in the Black River, Michigan. We recorded body length, sex, and individually marked fish using PIT and Floy tags. Location, group size, OSR, discharge and temperature were recorded daily. Blood was taken daily from females in 2013. RS was estimated by genotyping offspring captured during larval surveys. Timing of spawning was influenced by temperature, discharge, group size, and average body length of males. Egg quality varied between females based on timing of spawning. Female RS varied due to temperature, discharge, group size, and OSR. Results indicate that plasticity in female spawning time may affect egg quality, but female RS is largely influenced by environmental conditions and access to mates which are increasingly variable in riverine systems.