Reproduction of White Perch: The Annual Gametogenic Cycle

Abstract Circulating levels of the sex steroid hormones testosterone (T) and 11-ketotestosterone in males, and 17β-estradiol (E2) and T in females, were measured at monthly intervals in white perch Morone americana for 1 year. The egg yolk precursor vitellogenin was also measured in female blood plasma. The gonadal status of individual fish was assessed through histological examination and measurement of gonadosomatic index (GSI), size-frequency distribution of oocytes, sperm index, spermatocrit, and spermiation response. A biphasic pattern of maturation was seen in both sexes. At the onset of vitellogenesis in females, blood plasma levels of E2 and T increased moderately in November and then increased again to maximal levels during the spawning season in April and early May. All stages of oocyte development were observed in mature females, indicating that the white perch is a multiple-clutch, group-synchronous spawner. In males, androgen levels and GSI increased early in the reproductive cycle during spe...