7948

• UCREFRP Catalog Number: 7948
• Author: Martinez, A. M.
• Title: Observed Fin Ray Deformities Resulting from Handling Stress in the Intensive Culture of Razorback Suckers.
• USFW Year: 1995.
• USFW - Doc Type: \
• Copyright Material: NO

Anita M. Martinez 7
to be attributable to handling stress resulting from larval examinations. Diets HEG1 and
HEG1+ produced the highest survival (63% and 66% respectively), but the least growth
(15.8 and 15.6 mm SL respectively), while B-250 produced the greatest growth (18.2 mm
SL). Reduced larval density due to mortality did not appear to be responsible for the
increased growth of larvae fed B-250 because their siblings, maintained at a much greater
density in the same trough were also fed B-250 and displayed elevated growth (17.4 mm
SL) compared to those larvae fed HEG1 and HEG1+. Papoulias (1988) reported that
average growth in 6 feeding trials following 50 days of feeding live brine shrimp nauplii
(Anemia sa/ina) was 18.8 mm TL. This is comparable to growth of larvae fed B-250 in this
study. However, Tyus and Severson (1990) reported less growth (17.9 mm TL) for this diet
and believed ration was a factor limiting growth. Their ration began at 5% of body weight
per day but ranged from 0.9 to 2% of body weight per day at the completion of their study.
This study began at 10% of body weight per day and did not appear to limit growth.
Fin Ray Development and Deformities
A total of 680 larvae, 50-G3 larvae per diet per Lot, were examined fior the onset and
progression of fin and fin ray development and deformities. Principal caudal fin rays were
first observed on larvae as small as 10 mm SL but more commonly at 11 mm SL. This
coincides with the findings of Snyder and Muth (1990). The onset of fin ray formation in
all other fins occurred at a larger size, 14 mm SL for dorsal and anal fins, and 15 mm SL
for pelvic and pectoral fins. Though fin ray deformities were observed in all fins,