Changes in plasma androgen levels associated with changes in male reproductive behavior in a brood cycling marine fish.

Like many paternal-caring fishes, male garibaldi (Hypsypops rubicundus) exhibit changes in reproductive behavior during the course of a brood cycle. The purpose of this study was to compare plasma levels of testosterone and 11-ketotestosterone among males in different phases of the brood cycle. These phases are characterized by differences in male courtship, nest maintenance, and egg fanning behavior. Blood samples were taken from wild-caught males, and plasma androgen levels were measured using radioimmunoassay techniques. Androgen levels among males in different phases of the brood cycle were concordant with differences in courtship behavior and also showed a general, positive correspondence with nest maintenance behavior. Levels were nearly inversely related to egg fanning rates. These relationships were independent of seasonal or population level environmental effects. These data suggest a strong three-way relationship among androgen levels, reproductive behavior, and stimuli associated with the progressing brood cycle.