Effects of short term management stress on the ability of GnRHa to induce gonadotropin secretion in male white sturgeon, Acipenser transmontanus

Successful breeding of captive white sturgeon ( Acipenser transmontanus) is dependent on the administration of exogenous gonadotropin releasing hormone agonists (GnRHa) to induce spermiation in males and ovulation in females. Since in other species stress can diminish the effectiveness of GnRHa to induce gonadotropin (GtH) secretion, it is possible that stress, related to hatchery management practices used during GnRHa treatment, might interfere with the action of exogenous GnRHa to induce the secretion of GtH. In this study, mature male sturgeon were studied to determine if stress associated with GnRHa treatment can reduce the effectiveness of GnRHa in inducing GtH release. In conjunction with GnRHa administration, the fish were exposed to one of two Stressors: low stress consisting of briefly removing fish from the tanks, and high stress treatment consisting of a sequence of removal from the tank followed by repeated brief air emersions, crowding and handling. All are typical hatchery practices. Both stress treatments resulted in significant elevations of plasma cortisol. Although the animals experienced stress, as indicated by the cortisol response, there was no difference between the two stress responses on the ability of GnRHa to induce the secretion of the two sturgeon gonadotropins (stGTH I and stGTH II). It is concluded that the short term management practices routinely used during the administration of GnRHa do not interfere with the action of GnRHa in male sturgeon