Human chorionic gonadotropin (HCG) is often used to induce spawning of fish. However, the U.S. Food and Drug Administration (FDA) has not approved HCG for use in fish because they claim additional efficacy data are required. Efficacy of HCG for spawning walleye (Stizostedion vitreum), was evaluated at 3 hatcheries for 3 years. During the 1993-1995 spawning seasons, 17.5% (54 of 308) of female walleyes spawned after a single injection of HCG. Of 253 females receiving a second injection, 92.1 % spawned for an overall spawning success of 93.2%. For females, a HCG dose as low as 330 IU/kg in each injection was as satisfactory as higher doses. Fish from ponds had a significantly lower spawning rate (8.7%) than wild fish (30.6%) after a single injection of HCG, but there was no significant difference in spawning success for these groups after 2 injections. Eggs spawned/kg body weight averaged 51,065 + 1,379 during 1994 and 1995, and hatching rates, based on total eggs spawned, averaged 49.0% ±2.1% during these years. All of the control and HCG-injected male walleyes produced milt. This study demonstrated HCG was effective for inducing spawning; 2 injections were often beneficial for spawning female walleyes.
