THE EFFECT OF THE ABSENCE OR PRESENCE OF CHANNEL CATFISH MALES ON INDUCED OVULATION OF CHANNEL CATFISH FEMALES FOR ARTIFICIAL FERTILIZATIONWITH BLUE CATFISH SPERM

Female channel catfish Ictalurus punctatus were induced to spawn with carp pituitary extract either singly paired with channel catfish males in aquaria (males present) or stocked with multiple females in aquari a or tanks (males absent). There was no difference between ovulation r ates of females induced to spawn in the presence or absence of channel catfish males (P = 0.57). Females hand-stripped with males absent pro duced more eggs per kilogram of body weight (4,585) than females with males present (2,942; P = 0.07). When females in the males-present tre atment deposited eggs in the aquaria, which allowed observation of the readiness of females, the number of eggs available for stripping was reduced. There was no difference in fertilization rate between treatme nts when using sperm from blue catfish I. furcatus (P = 0.35). Females that ovulated with males absent produced a similar (P = 0.12) number of viable eggs per kilogram of female body weight as females that ovul ated with males present (3,809 and 2,291, respectively). It may be com mercially feasible to artificially produce hybrids of channel and blue catfish by using the methods demonstrated in this experiment. This st udy has shown that pairing channel catfish females with males is unnec essary to induce ovulation in females and that more eggs are available to the culturist for hybrid production when males are absent.