Co-Authors:
Barki, A., Department of Aquaculture, Institute of Animal Science, Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Gur, N., Zemach Feedmill, Zemach 15133, Israel
Karplus, I., Department of Aquaculture, Institute of Animal Science, Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
Abstract:
Interspecific competition for food in polyculture is enhanced in intensive systems because the cultured species mostly depend on artificial feed. This study evaluated the effectiveness of spatially and temporally separating the feed for red hybrid tilapia and redclaw crayfish (Cherax quadricarinatus) as a means of decreasing interspecific competition and increasing the performance of each species in communal culture. The effects of the spatial and temporal separation of feed (i.e., feeding with sinking and floating pellets vs. sinking pellets only, and by day and night vs. day only, respectively) were tested in a 2×2 factorial design. Two 6-week experiments were conducted involving inverse fish-crayfish size relationships. Monocultures of each species were included as controls. No effects of the spatial and temporal separation of feed on the survival and growth of tilapia were found. However, tilapia grew better in duoculture than in monoculture. The performance of redclaw was generally better in monoculture than in duoculture with tilapia. The magnitude of the deleterious effect of tilapia on redclaw was size-dependent, as reflected in reduced survival, growth and foraging of small redclaw in the presence of relatively larger tilapia. There was a significant effect of the temporal separation of feed on the growth of small crayfish; feeding them at night increased their growth by 32%. The temporal separation of feed, in which redclaw were fed at night and tilapia during the day, proved to be an appropriate feeding strategy in their communal culture. © 2001 Elsevier Science B.V. All rights reserved.