Field collection, handling, and refrigerated storage of sperm of red snapper and gray snapper

摘要

Red snapper Lutjanus campechanus and gray snapper L. griseus support valuable sport and commercial fisheries. Because of their high market value and limited commercial harvests, these species are prime candidates for aquaculture and stock enhancement. Development of culture techniques for snapper species has been attempted over the past 30 years, but use of gonadotropic hormones with mature, wild-caught red snapper remains the most reliable method for inducing ovulation and producing eggs that can be fertilized. In this study, procedures for sperm collection, handling, and refrigerated storage were developed to improve strip-spawning techniques for these snapper species. Use of refrigerated sperm allows efforts to be focused on maintaining female broodstock, monitoring of ovarian development, and increasing efficiency during the strip-spawning process. Sperm were collected from male red snapper (n = 199) and gray snapper (n = 83) captured in the recreational fishery during the summers of 2000 and 2001. Sperm were diluted 1:4 with calcium-free Hanks' balanced salt solution (HBSS), placed in 4-L plastic bags, and transported to the laboratory on ice. Osmotic pressure (mean +/- SE) of seminal plasma was 428 15 milliosmoles (mOsm) per kilogram for red snapper (n = 19) and 411 +/- 5 mOsm/kg for gray snapper (n = 13). Blood plasma osmolality was 440 +/- 7 mOsm/kg for red snapper and 421 +/- 7 mOsm/kg for gray snapper. Activation studies of red and gray snapper sperm indicated that sperm motility was suppressed by decreasing the osmotic pressure of artificial seawater to a level less than 400 mOsm/kg. Refrigerated storage experiments demonstrated that sperm samples suspended in 200-mOsm/kg HBSS retained motility for 10 d when refrigerated at 4 degrees C. These results show that red snapper and gray snapper sperm can be stored for short-term repeated use in a hatchery.