Comparative Biochemistry and Physiology, Part A (in press)

Courtship behaviors are androgen-dependent in many vertebrates and castration often decreases courtship.  We examined the effectiveness of castration in reducing courtship behaviors and 11-ketotestosterone (KT) and testosterone (T) in restoring them in male white perch.  Castrates were given implants containing KT, T or no hormone.  Sham-operated males received implants without hormone.  Three weeks later, males were exposed to an ovulated female for 1 h and two courtship behaviors were quantified. Attending behavior involves close and continuous following of a female with occasional contact.  Circling involves rapid transits around the female in a circular pattern or back and forth in front of her.  In plasma samples taken immediately after observations, KT and T were below detectable levels in castrated males but at high physiological levels in males implanted with KT or T.  Castrated males given KT attended females more often than castrated males given T implants or implants containing no hormone, but not more often than sham-operated males.  Circling was eliminated by castration but restored by implantation with T or 11-KT to values exhibited by sham-operated males. This is one of the few demonstrations that KT can regulate courtship behavior in a non-territorial and economically important fish species.