PLASMA PROFILES OF THE SEX STEROIDS AND GONADOTROPINS IN MATURING FEMALE SPRING CHINOOK SALMON (ONCORHYNCHUS-TSHAWYTSCHA)

Plasma testosterone concentrations were low through the spring acid early summer, concentrations began rising in late July and reached maximum levels by ovulation in September. Plasma concentrations of 11-ketotestosterone were low throughout sexual maturation until ovulation when a significant increase occurred. Plasma androstendione and 17 beta-estradiol concentrations were high throughout sexual maturation, and decreased significantly at ovulation. Plasma 17 alpha,20 beta -dihydroxy-4-pregnen-3-one concentrations were low throughout maturation, and increased significantly at ovulation. Plasma gonadotropin I concentrations paralleled those of estradiol and exceeded gonadotropin II levels prior to ovulation. Plasma concentrations of gonadotropin II were low throughout the spring and summer, increasing dramatically at ovulation.