Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Three Malaysian prawn (Macrobrachium rosenbergii)/channel catfish (Ictalurus punctatus) polyculture studies were conducted from May 1984 through October 1986. In the first study prawn stocking size and density on catfish and prawn production were examined. In 1984 catfish, x = 24 g, were stocked at 9,884/ha. Prawns, x = 0.04 g, were stocked at 4,942, 9,884 and 14,826/ha. After 144 days catfish average weights, survival and yields were $<$340 g, $<$78% and $<$2,000 kg/ha, respectively. Prawn weight, survival and yields ranged from 34-54 g, 47-61% and 165-344 kg/ha, respectively. In 1985 catfish, x = 33 g, were stocked at 7,410/ha and prawns, x = 0.15 and 0.70 g, were stocked at 1984 densities. After 137 days catfish average weight, survival and yields were 427 g, 86% and 2,726 kg/ha, respectively. Prawn weight, survival and yields ranged from 48-73 g, 41-88% and 110-471 kg/ha, respectively. Positive economic net returns were achieved with 0.15 g prawns stocked at 14,826/ha and 0.70 g prawns stocked at 9,884 or 14,826/ha. In a second study prawn bottom location preference and movement were determined in ponds. Males were more frequently observed in the deep ends of ponds and near the ponds' perimeters, and females were observed more frequently in the shallow ends and in the middles of ponds. Prawn movement did not differ between day and night, averaging 1.1 m/hr. Two-funnel crawfish traps and box traps with slit entrances, 12 and 24 hr set times, and white light and commercial crawfish bait attractants were evaluated for capturing prawns. Traps were not effective at capturing prawns regardless of set time or attractant. In the third study catfish and prawn mean lengths and weights from cast-netted and seined samples were compared to a complete population census taken after 48, 92 and 139 days of growth. Ponds were stocked with catfish at 7,410/ha and prawns at 1984 study levels. Cast-netted samples under-estimated and seined samples over-estimated catfish size. Cast-netted and seined sample prawn means did not differ from each other or population parameters. Catfish and prawn size variation increased over time. Catfish and prawn survival decreased during the first 48 days and then remained constant throughout the rest of the grow-out period.

Pages

152

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