title: Circulating insulin-like growth factor I in juvenile chum salmon: relationship with growth rate and changes during downstream and coastal migration in northeastern Hokkaido, Japan.
abstract: Chum salmon (Oncorhynchus keta) migrate to the ocean in their first spring, and growth during early marine life is critical for survival. We examined the validity of circulating IGF-I and muscle RNA/DNA ratio as indices of growth rate using individually tagged juvenile chum salmon fed or fasted for 10 days. Serum IGF-I level was highly, positively correlated with individual growth rate. Muscle RNA/DNA ratio also showed a positive correlation, but its relation was not as high as that of IGF-I. We next measured these physiological parameters in chum salmon juveniles caught at river, estuary, port and nearshore of the northeastern Hokkaido, Japan, from May to June in 2013 and 2014, respectively. In both years, there was a trend that serum IGF-I levels were high in nearshore fish and low in river/estuarine fish in June. In contrast, muscle RNA/DNA ratio showed no clear temporal and spatial patterns. The present study shows that circulating IGF-I can be used as a growth index in juvenile chum salmon. Monitoring growth status using serum IGF-I suggests that growth of juvenile chum salmon in the survey area was activated when they left the coast.
authors.affiliation: Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido, 041-8611, Japan.
authors.forename: Nobuto
authors.initials: N
authors.lastname: Kaneko
authors.forename: Natsumi
authors.initials: N
authors.lastname: Taniyama
authors.forename: Yu
authors.initials: Y
authors.lastname: Inatani
authors.forename: Yuta
authors.initials: Y
authors.lastname: Nagano
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Torao
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Miyakoshi
authors.forename: Munetaka
authors.initials: M
authors.lastname: Shimizu
mesh_terms: D025041:Animal Migration; D000818:Animals; D004247:DNA / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007564:Japan; D009132:Muscles / Q000378:metabolism*; D017685:Oncorhynchus keta / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D012313:RNA / Q000378:metabolism*; D012623:Seawater
chemical_list: D012313:RNA; D007334:Insulin-Like Growth Factor I; D004247:DNA