7766

• UCREFRP Catalog Number: 7766
• Author: Scholz, A. T., et al.
• Title: Notes on the Development and Measurement of Egg and Larval Thyroxine Concentration in Flannelmouth Suckers ‎(
• USFW Year: 1992.
• Copyright Material: NO

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ABSTRACT

Thyroxine concentrations [T 4] were measured in 540 flannelmouth
sucker (Catostomus latipinnis) eggs or larvae collected from the Green
RiVer, UT and reared at Ouray National Fish Hatchery, UT. One group of
eggs was fertilized on May 28, 1991 and a second group on June 10, 1991.
In the first group, 25 eggs or larvae were collected at daily intervals from
the time of fertilization until day 10 post-fertilization. In the second
group, eggs or larvae were collected at daily intervals from the time of
fertilization to 18 days post-fertilization, then at 7 day intervals until
38 days post-fertilization. Mean [T4] :t SEM for each day was determined
by radioimmunoassay. In the first group, [T 4] peaked at 18.6 :t 8.0 nglg
body weight at the time of hatch on day 6 post-fertilization, rising from
basal levels of 1.7 :t 0.2 to 4.2 :t 0.8 nglg body weight from day 1 to 5
post-fertilization. After decreasing to 5.9 :t 0.7 nglg body weight on days
7 to 9 post-fertilization, [T4] peaked again at 14.9 :f: 0.7 nglg body weight
at the time of swim-up on day 10 post-fertilization. In the second group,
[T4] peaked at 8.5 :t 5.1 nglg body weight at time of hatch on day 5 post-
fertilization, and again at 11.8 :f: 5.4 nglg body weight at the time of
swim-up on day 9 post-fertilization. [T4] in prehatch eggs ranged from
1.6 :t 0.4 to 2.5 ::f: 0.4 nglg body weight. [T4] in post swim-up fry
fluctuated between 2.6 :t 0.9 and 10.6 ::f: 2.8 on days 10 to 18 post-
fertilization before decreasing to 5.1 :f: 1.4 to 5.8 :f: 0.2 nglg body weight
on days 24 and 38.

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