title: Seasonal testosterone pattern in Hawaiian monk seals (Monachus schauinslandi).
abstract: Blood samples from four captive male Hawaiian monk seals were collected at intervals of one month for one year for testosterone assay. Plasma testosterone concentrations, measured by radioimmunoassay, revealed a clear seasonal pattern. The lowest mean testosterone concentration (0.09 +/- 0.04 ng ml-1) occurred in January, and the highest (1.78 +/- 0.40 ng ml-1) in June. The seasonal occurrence of births and of injuries related to mating in wild populations of Hawaiian monk seals showed a distinct association with the period of high testosterone. This study supports other data that indicate that the Hawaiian monk seal is a seasonal breeder and is reproductively active for longer than monachine seals that live in higher latitudes.
authors.affiliation: Hawaii Institute of Marine Biology, University of Hawaii, Honolulu 96822.
authors.forename: S
authors.initials: S
authors.lastname: Atkinson
authors.forename: W G
authors.initials: WG
authors.lastname: Gilmartin
mesh_terms: D000818:Animals; D008297:Male; D011863:Radioimmunoassay; D012098:Reproduction / Q000502:physiology; D046048:Seals, Earless / Q000097:blood*; D012621:Seasons; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone