No increase in developmental deformities or fluctuating asymmetry in rainbow trout (Oncorhynchus mykiss) produced with cryopreserved sperm

Although cryopreservation is a widely accepted tool in animal breeding and human reproduction, questions have arisen regarding the health and viability of fish sired by cryopreserved sperm. We examined rainbow trout families produced using fresh and cryopreserved milt to determine if sperm cryopreservation negatively influenced early development. Fresh and cryopreserved milt from 3 males were used to fertilize eggs from 6 females in a 3 × 6 factorial design. Survival to eye, survival to fry, proportion of fry deformities and developmental stability were compared for fresh vs. cryopreserved milt. Results revealed a significant reduction in survival to eye (P < 0.001) and survival to fry (P < 0.001) for families sired using cryopreserved milt. Survival during the interval from eye to fry did not differ among the groups (P = 0.127), indicating that survival differences occurred prior to the eye stage. These results could be explained by reduced fertilization success of cryopreserved sperm. We examined developmental differences by analyzing the proportion of haploid embryos at the eyed stage, the proportion of fry deformities at hatch and fluctuating asymmetry (FA) of pectoral fin rays. Results revealed no significant difference between the groups. Our observations that surviving fry produced using cryopreserved sperm showed no differences in early development suggest that sperm cryopreservation is a viable option for use in breeding programs and in conservation and recovery of imperiled salmonid populations.