Cryopreservation of sperm of red snapper ( Lutjanus campechanus)

Abstract

Interest in the culture of snappers (family Lutjanidae) has developed throughout the world because of declines in wild stocks combined with a consistent high demand and market value. Some snappers, such as the red snapper Lutjanus campechanus have proven to be difficult to spawn and culture in captivity. As part of a larger study to improve propagation techniques for red snapper, procedures were developed for the collection, handling, and commercial-scale cryopreservation of sperm. Utilization of cryopreserved sperm in spawning of red snapper allows efforts to be focused on maintaining female broodstock, monitoring ovarian development, and increasing efficiency during the strip-spawning process. Red snapper were collected during the 2000 and 2001 spawning seasons (May to August) off coastal Louisiana by hook and line. Testes were surgically removed and sliced to release sperm. Sperm were collected in 50-ml centrifuge tubes and diluted 1:3 (v:v) with calcium-free Hanks' balanced salt solution. Dimethyl acetamide, dimethyl sulfoxide, methanol, and glycerol were evaluated as cryoprotectants. Dimethyl sulfoxide produced the smallest reduction in motility of sperm cells in acute toxicity trials and produced the highest motilities after thawing (71±16%) in initial cryopreservation trials. During the 2-year study, sperm samples from 20 red snapper were frozen using commercial-scale cryopreservation methods developed for dairy bulls. Although sperm motility after thawing was typically greater than 80%, comparison with fresh samples revealed a significant difference in motility ( P=0.048). Refrigerated and cryopreserved sperm samples with motilities above 80% were used in fertilization trials. Fertilization rates were variable among females (11–85%), although results with refrigerated (non-frozen) and cryopreserved sperm were highly correlated ( r=0.85). These results demonstrate that refrigerated and cryopreserved sperm were each effective for the artificial fertilization of red snapper eggs.