Sperm Characteristics of Precocious 1-year-old Male Striped Bass Morone saxatilis

Abstract.— Captive-reared, 10-mo-old, male striped bass Morone saxatilis were sampled monthly for testicular development between February and June 1994. One of the five males sampled in February showed precocious testicular development and had a gonado-somatic index (GSI) of 1.26%. while the other four fish had immature testes with a mean GSI ± s^x, of 0.17 ± 0.03%. Spermiating individuals were present from April to June. In April the average body weight (BW) of spermiating males was 65 ± 4 g and their GSI reached a mean value of 4.75 ± 0.52%. In June, milt collected from ten precocious males contained motile spermatozoa with a mean of 31 ± 7% of the sperm showing forward movement. Mean milt volume and sperm concentration were 1.67 ± 0.41 mL/kg BW and 92.3 ± 1.8 ± 10⁹ spermatozoa/mL. respectively. These data show that male striped bass reared in captivity can reach sexual maturity during their first year. This is one year earlier than previously reported for striped bass in mid-Atlantic regions.