A comparison of the nutritional and energetic status of kelts from the Snake River
and coastal Situk River, AK using blood plasma metrics.
Zachary L. Penney1 , Christine Moffitt2, Brian Marston3, Chester Woods3, Bryan Jones1, and
Jessica Buelow1
(1) Zachary Penney (presenter), University of Idaho, Department of Fish and Wildlife
Resources, 208-885-7139, penn4282@vandals.uidaho.edu
(2) US Geologic Survey, Idaho Cooperative Fish and Wildlife Research Unit,
University of Idaho
(3) Alaska Department of Fish and Game
Steelhead trout iteroparity (repeat spawning) is highly variable, ranging from less than 1%
in inland populations to as high as 70% in coastal populations. In general, it has been
observed via scale analysis that coastal steelhead exhibit higher rates of iteroparity than
inland populations. The physiological capacity for iteroparity between inland and coastal
steelhead is not well understood, but has been attributed to differences in gonadal
maturation strategies, freshwater re-entry timing, migration distance, and total time spent
in freshwater. We provide an assessment of physiological nutritional factors between
inland and coastal steelhead kelts using measures of blood plasma. From 2009 to 2011,
steelhead from the Snake River subbasin were sampled at the Lower Granite Dam juvenile
bypass facility (N=1649) and multiple weir sites in tributaries of the Clearwater River
(N=272). For comparison, blood plasma was collected from kelts in the Situk River (N=37),
a coastal system in southeast Alaska in 2011. Plasma nutritional factors of cholesterol and
triglycerides were nearly three times higher in Situk River kelts than in Snake River kelts.
When detectable, values of plasma protein were similar between Situk and Snake River
kelts; however, plasma protein was below detection limits in 52% of Snake River kelts and
in only 32% of Situk River kelts. Our results suggest that coastal Situk River kelts have
greater nutritional and energetic reserves following spawning than inland steelhead kelts
from the Snake River subbasin.