Download Type of presentation preferred: Oral. Topic area from above list

Type of presentation preferred: Oral.
Topic area from above list: Steelhead life histories.
Abstract Title: Steelhead kelt reconditioning: Physiological insights and lessons learned.
Author(s) name(s) as they should appear in the program, affiliation, mailing address, phone
number and email address:
Lucius K. Caldwell ab1, Andrew L. Piercebc, Joseph W. Blodgettd, David E. Fastd, Douglas
R. Hatchc, James J. Naglerb
a
Cramer Fish Sciences; 600 NW Fariss Rd; Gresham, OR; 97031
b
Department of Biological Sciences; 875 Perimeter Drive, MS 3051; University of Idaho; Moscow, ID;
83844-3051
c
Columbia River Inter-Tribal Fish Commission; 700 NE Multnomah St. Suite 1200; Portland, OR; 97232
d
Yakama Nation Fisheries; P.O Box 151; Toppenish, WA; 98948
1
Corresponding author. Telphone: (503) 491-9577. Email: [email protected]
Name of presenter: Lucius K. Caldwell
Text of abstract in 300 words or less:
Steelhead are capable of repeat spawning; however, most do not. Those that survive spawning
are called kelts. Kelts either recover to spawn again the following year (consecutive spawners),
or delay rematuration for one or more years (skip-spawners). One strategy to increase returns of
steelhead in the Columbia River Basin (reconditioning) involves capturing post-spawned
steelhead during outmigration in spring, holding and feeding them in tanks during summer, and
releasing them in autumn, with the assumption that these fish will migrate upstream and spawn
again.
The goals of this study were threefold: 1) to monitor the reproductive status of steelhead kelts; 2)
to compare reproductive and energetic status of reconditioned kelts and in-river migrating
steelhead (IRMS); and 3) to compare parameters measured at release among Viable Salmonid
Population (VSP) segments.
We hypothesized that kelts would be bigger, with higher condition factor (k), higher muscle lipid
content, and higher plasma 17b-estradiol—the primary fish estrogen and an established marker
of reproductive development in O. mykiss—than IRMS. We combined plasma hormone assays,
physical measurements, and tracking data for steelhead in the reconditioning program at Prosser,
WA, to determine how early kelt rematuration can be detected, what parameters accurately
predict rematuration, and which physical and endocrine parameters differ among steelhead from
the different VSP segments within the YRB.
We found that rematuring kelts were longer and heavier at intake in spring; grew faster during
summer reconditioning; and were longer, heavier, fatter, and of higher condition factor, with
higher plasma 17b-estradiol and similar plasma vitellogenin concentrations at autumn release.
Modest differences in condition factor were observed among the VSPs, and rematuring
reconditioned kelts behaved congruently with repeat spawning in the Upper YRB. Thus,
reconditioning projects yield bigger and fatter fish, with higher circulating levels of estrogen and
similar circulating levels of vitellogenin compared to IRMS.