title: Effects of growth hormone and cortisol on the downstream migratory behavior in masu salmon, Oncorhynchus masou.
abstract: The effects of ovine growth hormone (oGH) and cortisol on downstream migratory behavior in yearling (1(+)) smolts and underyearling (0(+)) parr of masu salmon, Oncorhynchus masou, were examined during the downstream migratory period in spring using artificial raceways. In May, each of 22 1(+) smolts and 0(+) parr were implanted with cholesterol pellets containing 250 microg of oGH and/or 2 mg of cortisol. Their downstream migratory behavior was subsequently observed in artificial raceways, along with control groups 4-23 days after implantation. In 1(+) smolts, the frequency of downstream migratory behavior was 23%, 18%, 72%, and 82% in the control, oGH, cortisol, and oGH+cortisol-treated groups, respectively. The frequency was significantly higher in the cortisol and oGH+cortisol-treated groups than in the control and oGH-treated groups. In 0(+) parr, the frequency of downstream migratory behavior in the cortisol (82%) and cortisol+oGH-treated (90%) groups was significantly higher than in the control (18%) and oGH-treated (0%) groups. These results indicate that cortisol is an important endocrine factor inducing downstream migratory behavior in both 1(+) smolt and 0(+) parr of masu salmon.
authors.affiliation: Department of Biology, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan. munakata@staff.miyakyo-u.ac.jp
authors.forename: Arimune
authors.initials: A
authors.lastname: Munakata
authors.forename: Masafumi
authors.initials: M
authors.lastname: Amano
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Ikuta
authors.forename: Shoji
authors.initials: S
authors.lastname: Kitamura
authors.forename: Katsumi
authors.initials: K
authors.lastname: Aida
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D004343:Drug Implants; D005260:Female; D005618:Fresh Water; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood*; D006854:Hydrocortisone / Q000008:administration & dosage / Q000097:blood*; D008297:Male; D017683:Oncorhynchus / Q000097:blood* / Q000254:growth & development; D012621:Seasons; D012623:Seawater
chemical_list: D004343:Drug Implants; D013006:Growth Hormone; D006854:Hydrocortisone