SummaryThis research assessed the endocrine and physiological effects of Ovaprim TM and synthetic homologous sturgeon gonadotrophic releasing hormone (GnRH) on spawning male and female adult lake sturgeon, Acipenser fulvescens (Rafinesque, 1817). Wild-caught adults were administered Ovaprim, GnRH, or Ringers solution (control), and serial blood samples were collected for up to 27 days following capture and hormone administration. Circulating cortisol levels appeared to increase following administration of both hormonal treatments. However, circulating cortisol was higher and plasma pH lower at capture than at any other time for all treatments, indicating that capture and transport stress were the largest disrupting factors, more so than the effects of induced spawning. Plasma concentrations of estradiol and testosterone in both sexes were similar to previously reported values. In all treatments the circulating estradiol and testosterone never significantly exceeded the values at capture prior to endocrine manipulation of the reproductive axis. Similarly, testosterone in males and estradiol in females in the muscle tissue were consistently at the same or lower concentrations than at capture. The apparent survival of all of the study animals following return to their native river indicated that the stress effects from capture and induced spawning were not severe. In concert, our results suggest that hormonal injections can be used to aid in gamete collection from wild A. fulvescens, without negative effects on longterm broodstock survival. Hatching success, larval survival to the juvenile stage, egg diameter, and concentrations of protein, triglyceride, and glucose in the egg, sperm, and ovarian fluid (but not seminal plasma), were the same or greater in GnRH-treated fish than gametes from the Ovaprim-treated group, suggesting that utilization of GnRH may be preferable to other common methods of spawning induction.