Swimming Characteristics and Fertilizing Capacity of Meiogynogenetic Summer Flounder, Paralichthys dentatus, Spermatozoa

Summer flounder exhibit sexually dimorphic growth rates, with females growing considerably faster and larger than males. In an effort to produce monosex (all female) populations, meiogynogenetic fish were produced and raised at male-determining temperatures. Upon attaining sexual maturity, spermatozoa characteristics from normal and meiogynogenetic (meiogyn) summer flounder were compared using computer-assisted sperm analysis. Sperm concentration was lower for meiogyn fish, but not when normalized for body weight, and swimming characteristics of each group were similar. In a fertilization trial using pooled eggs from two females, sperm from normal and meiogyn males had equal fertilization success, but fewer embryos produced from meiogyn sperm survived through development. Twenty-four hour survival of hatched larvae was equal from both groups (>96%). Sperm from meiogyn males was used to fertilize eggs from seven domesticated female broodstock during commercial production. Mean fertilization and hatch were 56.0 +/- 6.8% and 32.7 +/- 8.9%, respectively, resulting in the production of 304,450 larvae.