February 15-18, 2009 Washington State Convention Center Seattle ...

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CORRELATION OF ULTRASOUND IMAGING WITH HISTOLOGICAL ASSESSMENT AND
CONDITION FACTORS IN THE DEVELOPMENTAL STAGING OF CHANNEL CATFISH
OVARIES
Douglas E. Kuenz*, Noel Novelo, Christopher Green and Terrence R. Tiersch
Aquaculture Research Station
Louisiana State University Agricultural Center
2410 Ben Hur Rd.
Baton Rouge, LA 70820 USA
dkuenz1@lsu.edu
Before, during, and after spawning season, multiple stages of gonad maturation can be found in populations of channel catfish.
The purpose of this study was to compare ultrasound imaging with histological assessment and several condition factors to
better define stages of gonadal maturation of female channel catfish. Fish were studied from April through July, 2008 in Baton
Rouge, Louisiana. In total 51 females were sampled before, during, and after the spawning season to ensure a wide range of
developmental stages for analysis.
An ultrasound image of the ovary was captured and classified from “Stage 1” (undeveloped) to “Stage 6” (atretic), with “Stage
5” being fully mature and ready to spawn. Females were selected randomly from each of the ultrasound groupings to ensure
representation of all stages in the histological and condition factor assessments. Attributes recorded were length, weight, girth,
gonad weight, liver weight and visceral fat weight, from which were calculated several indices including hepatosomatic index,
gonadosomatic index and condition factor (Table 1).
Photographs were used to record condition of fish, livers, and gonads. Sections were taken from the middle of the ovary to
represent the area viewed by ultrasound. These were fixed in 10% buffered formalin and stained with hematoxylin and eosin.
Oocyte maturation was classified from “Stage 1” (pre-vitellogenic) to “Stage 6” (atretic) with “Stage 5” representing readiness
to spawn.