Cryopreservation and Methanol Effects on Burbot Sperm Motility and Egg Fertilization

Abstract

Cryopreservation of semen from North American burbot Lota lota maculosa was investigated and optimal methanol concentrations were determined for a conservation breeding program. Methods were modified from those reported for Eurasian burbot L. lota lota. The permeable cryoprotectant (methanol) concentration in the semen extender was varied to provide final methanol concentrations of 5, 10, and 20%. Semen motility was evaluated at 80 and 363 d postfreeze (dpf). Fertilization was determined at 340 and 367 dpf. Methanol concentration in the extender significantly (P < 0.05) affected sperm motility and egg fertilization percentages. Motility and fertilization were lowest when 5% methanol was used. Motility of semen at 80 dpf was not significantly different between 10% and 20% methanol, but semen at 363 dpf had significantly higher motility when stored in 20% methanol than in 10% methanol. Egg fertilization was highest when semen was stored in extenders containing 10% or 20% methanol. Results suggest that good motility and fertilization can be achieved by cryopreserving burbot semen with 10% or 20% methanol in the extender instead of 5% methanol. This study demonstrates the potential to utilize cryopreserved burbot semen in the development of germplasm repositories for imperiled fish stocks.