Comparison of manual stripping and pen spawning for production of channel catfish x blue catfish hybrids and aquarium spawning of channel catfish

We compare manual stripping to pen spawning for production of hybrids of fe male channel catfish Ictalurus punctatus X male blue catfish I. furcatus, a s well as to aquarium spawning of channel catfish. The ovulation rate for m anually stripped females (91%) was not significantly different from that of females spawned in aquaria with channel catfish males (67%; P > 0.05); how ever, ovulation rate of manually stripped females during week 10 (80%) was superior to that of females spawned in pens (15%; P < 0.05) with blue catfi sh males. Female channel catfish spawned in aquaria with male channel catfi sh produced more (P < 0.05) eggs per kilogram body weight (6,607) than manu ally stripped females (4,587). Pen spawning of female channel catfish and m ale blue catfish also produced significantly more (P < 0.05) eggs per kilog ram (7,950) than hand-stripping females (3,448) during week 10. Hatching ra te (21%) and fry per kilogram (1,065) of female body weight were higher (P < 0.05) for channel catfish spawned with channel catfish in aquaria than fo r channel catfish manually stripped and fertilized with blue catfish sperm (8% and 325 fry/kg). This difference in means was a result of spawning tech nique because we have previously demonstrated that blue catfish and channel catfish sperm fertilize channel catfish eggs at equivalent rates. Hatching rate (66%) was also higher (P < 0.05) for pen-spawned hybrid embryos than for hybrid embryos produced by manual stripping and artificial fertilizatio n (21%). However, fry per kilogram of female body weight was not different (P > 0.05) for manual stripping and pen spawning (851 and 821, respectively ). The results from both experiments indicate that the quantity and quality of eggs and embryos obtained by manual stripping and artificial fertilizat ion are inferior to eggs and embryos produced naturally but with hormone in jections. Artificial fertilization procedures need to be improved. Hybrid f ry produced per kilogram of female body weight for manual stripping and pen spawning were almost identical because of the low hatch rate for manually stripped eggs and the low spawning rate for pen spawning. Therefore, neithe r technique is better for commercial production of channel catfish X blue c atfish embryos; improved hatching rates for manual stripping or higher ovul ation rates for pen spawning would enhance production.