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

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EVALUATION OF WINTER FEEDING ON EXPERIMENTAL CHANNEL CATFISH
GROWOUT POND PLANKTON
Peter Perschbacher,* Gerald Ludwig and Adam Nanninga
Aquaculture/Fisheries Department
University of Arkansas at Pine Bluff
Pine Bluff, AR 71601 USA
pperschbacher@uaex.edu
Ten, 0.1-ha ponds at the UAPB Aquaculture Station were sampled weekly from Dec. 7-Feb. 22 (n=90) to test the effect of winter
feeding on phytoplankton and zooplankton. Five of the ponds were randomly assigned to each of two treatments: no feeding
and feeding based on recommended rates. Channel catfish sizes and numbers approximated a typical winter carryover scenario.
Chl. a (biomass) and variability was low and not significantly different (Table 1). Average combined algal natural units were
more than twice as high in fed ponds (P=0.02). Composition between treatments was not significantly different. Diatoms were
the most abundant group. Zooplankton did not differ. Off-flavor cyanobacteria were two species of Anabaena and Pseudanabaena
sp. These off-flavor algae were found on 7 of the 9 sampling dates in fed ponds and 9 of 9 in unfed ponds and occurrence
was significantly higher in unfed ponds (P=0.08) by 70%.
Thus, algae in fed ponds were smaller and off-flavor algae less common than in unfed ponds. Winter feeding of channel catfish
may benefit algal composition.
Table 1. Effect of winter feeding on plankton in experimental catfish production ponds (significance indicated by *).
Parameter fed unfed
Chl. a (ug/l) 82.5 + 56.2 81.2 + 53.5
Pheophytin a (ug/l) 35.9 40.9
Total algae (#/ml) 11,506 4,851*
Algal composition (%)
Diatom 63.5 57.7
Green 12.9 18.1
Euglenoid 15.4 13.8
Cyanobacteria 10.4 7.8
Off-flavor algae occurrence
(% of samples) 22.2 37.8*