Type of Document Master's Thesis Author Schmitz, Mark Harvey URN etd-052599-174233 Title Comparative Growth of All-Female Versus Mixed Sex Yellow Perch (Perca flavescens) in Recirculating Aquaculture Systems Degree Master of Science Department Fisheries and Wildlife Sciences Advisory Committee
Advisor Name Title Libey, George S. Committee Chair Hallerman, Eric M. Committee Member Smith, Stephen A. Committee Member Keywords
- yellow perch
- Perca flavescens
- fish culture
Date of Defense 1999-05-20 Availability restricted AbstractNine, production-scale, recirculating aquaculture systems were utilized to
compare the growth parameters between all-female and mixed sex yellow perch stocks.
Each system was stocked with 455 fish m-3 and contained one of three different biofilter
types: a rotating biological contactor, a trickling filter or a bead filter. The all-female
fingerlings (S1) used were originally derived from Lake Mendota, Wisconsin. The
mixed-sex fingerlings (S2) used were originally derived from Lake Erie. Temperature
and photoperiod (23oC, 16H-L) were maintained at levels for optimal growth.
Absolute growth rates ranged from 0.27-0.48 g/day. Mean final density within
treatments was 42.8 kg/m3 and ranged from 37.2-50.2 kg/m3. The main effect of stock
did not have a significant effect on growth (p > .1). All-female treatments exhibited more
uniform growth. The main effect of filter type did have a significant effect on fish
growth (p < .01), with fish in tanks containing trickling filters exhibiting significantly
higher growth. Total feed conversion averaged 1.61 across all treatments and ranged
from 1.38-1.78. S1 treatments consumed a significantly higher percent body weight per
day than S2 treatments (p < .05).
Analysis of PIT tagged individuals revealed that the mean relative growth rate
was significantly higher in S2 individuals (513.9%) compared to S1 individuals (315.3%:
p < .01). S2 females (597.8%) grew 1.9 times faster than S1 females (315.3%: p < .01).
Within S2 individuals, females (597.8%) grew 1.5 times faster than males (395.2%: p <
.05). For all individuals, 33.6% of the variation in final weight was explained by the
variation in initial weight. Differences in the geographic strain or culture history of these
stocks may have had a larger overall effect on growth than sexual classification (all-
female or mixed sex).
Dress percentage of skin-on butterfly fillets was examined in 20 individuals per
stock and in six groups of 20 individuals per stock. Within S2 individuals, 73.7% were
female. Mean fillet yield was significantly greater in S1 individuals (47.6%) compared to
S2 individuals (43.0%: p < .01). Mean GSI in S1 individuals (1.01%) was significantly
higher than S2 individuals (0.54%: p < .05). Within S2 individuals, mean GSI was
significantly higher in females (0.70%) when compared to males (0.08%: p < .05). Fillet
yield was significantly greater in S1 groups (47.2%) compared to S2 groups (44.9%: p <
.01). Within each stock fillet yield increased with size.
The difference in fillet yield demonstrated between these stocks may be a result of
differences in strain of origin. The identification of superior yellow perch strains or
strain crosses with regard to growth rate and fillet percentage is of considerable
importance to the industry.
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