Performance evaluation of concurrent rice-fish-prawn culture with and without cull harvesting

Abstract

This study was carried out in farmers' ¢elds for three experimental culture cycles to evaluate the performance of rice^¢sh^prawn culture. The treatments carried out were deepwater rice mono-cropping (R), and rice^¢sh^prawn culture with cull harvesting (R^FC) and without cull harvesting (R^F). Water pH and total alkalinity were signi¢cantly higher (Po0.05) in R^FC than in R^F, while the concentrations of total suspended solids, plankton and chlorophyll a were higher in R^F. Cull harvesting in R^FC had no marked in£uence on the concentrations of dissolved oxygen, NH 4 1 , nitrite, nitrate and phosphate compared with the R^F treatment. The signi¢cantly higher ¢sh and prawn yields (Po0.05) and specieswise faster individual growth performance in R^FC than in R^F were probably due to periodic cull harvesting, which minimized the competition for food and space as well as physiological stress at reduced density. The paddy yield and percentage increase in paddy yield over rice mono-crop was signi¢cantly higher (Po0.05) in R^FC (25%), followed by R^F (16.9%), probably due to lower chlorophyll a (36. 7 mg m À 3 ) and plankton density (1.4 Â 10 4 L À 1 ), which minimized the competition for nutrients with rice plants.The highest rice equivalent yield (38.5), output value^cultivation cost ratio (1.56) and enhanced net return (28%) in deepwater rice¢ sh culture were recorded when cull harvesting was practiced.

Effects of water exchange protocols on water quality, sedimentation rate and production performance ofPenaeus monodonin earthen ponds

“…Gradual increasing trend in nitrite, nitrate and ammonia were attributed to intermittent fertilization, increased levels of metabolites and decomposition of unutilized feed in the absence of water replenishment (Mohanty 2004;Mohanty, Thakur, Ghosh, Mohanty & Patil 2010). In general, the poor growth performance of cultured shrimp species takes place at pH < 6.5 (Mount 1973), while higher values of total alkalinity (>90 ppm) indicates a more productive eco-system (Mohanty et al 2009).…”

Impact of Water Resources Development and Technology Introductions on Livelihood of Farmers in Eastern India: A Case Study

“…Usually L. rohita grows faster than C. mrigala . However, in all the WHSs, bottom feeders ( C. mrigala ) registered better growth rates than the column feeder ( L. rohita ), probably due to their superior feed‐utilizing capability and their high degree of tolerance to fluctuations of dissolved oxygen and the rich detritus food web that was maintained through periodic manuring, liming and fertilization (Mohanty et al ., ). The sustainability of short‐duration aquaculture in WHSs referred to both ecological and economic sustainability, which is the capacity of the production system to produce a positive income in the long run.…”

Effects of feed restriction on compensatory growth performance of Indian major carps in a carp-prawn polyculture system: a response to growth depression

“…However, in all the treatments, bottom feeders ( C. mrigala ) registered better growth rates than the column feeder ( L. rohita ), probably due to their superior feed utilizing capability and their high degree of tolerance to fluctuations of DO and the rich detrital food web that was maintained through periodic manuring, liming and fertilization (Mohanty et al . ,b). Condition factor (Ponderal index) of fish and prawn was <1.0 (0.88–0.94) at the initial 3 weeks of rearing (monsoon phase) and improved thereafter (1.06–1.21) with gradual improvement in water quality (post‐monsoon).…”