Relative prawn production and benthic macroinvertebrate densities in unfed, organically fertilized, and fed pond systems

• Published in: Aquaculture Vol. 149; no. 3; pp. 227 - 242
• Main Authors: Tidwell, James H, Coyle, Shawn D, Webster, Carl D, Sedlacek, John D, Weston, Paul A, Knight, Wanda L, Hill, Sankie J, D'Abramo, Louis R, Daniels, William H, Fuller, Marty J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.03.1997; Elsevier Sequoia S.A
• Subjects: ALIMENTACION DE PECES; ALIMENTATION DES POISSONS; Aquaculture; Benthic macroinvertebrates; Diet; Diets; ESTANQUES; ETANG; FISH FEEDING; Invertebrates; MACROBRACHIUM ROSENBERGII; Organic fertilization; PONDS; RENDEMENT; RENDIMIENTO; Shellfish; Unfed ponds; YIELDS; Diets; Organic fertilization; Macrobrachium rosenbergii; Unfed ponds; Benthic macroinvertebrates
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/S0044-8486(96)01452-4

Relative prawn production rates in unfed, organically fertilized, and fed pond systems were evaluated. Populations of benthic macroinvertebrates that potentially serve as forage organisms in these systems were also evaluated and compared with ponds without prawns to evaluate forage preferences. Juvenile prawns (x̄ = 0.36 ± 0.02 g) were stocked into nine 0.04 ha ponds at a density of 39 520 ha −1. Prawns in three ponds were not fed, prawns in three ponds were fed a complete diet, and three ponds received organic fertilization. Three additional ponds (0.02 ha) served as controls (not stocked with prawns and received no nutrient input). Survival averaged 86%, overall, and was not significantly different among treatments. Average weights of prawns fed complete feed or raised in fertilized ponds (36 and 33 g, respectively) were not significantly different ( P > 0.05). Prawns in unfed ponds were significantly ( P ≤ 0.05) smaller (13 g). Average prawn yields in fed, fertilized, and unfed ponds (1261, 1056, 426 kg ha −1, respectively) were all significantly different ( P ≤ 0.05). In ponds receiving no nutrient input, macroinvertebrate densities were significantly higher ( P ≤ 0.05) in ponds without shrimp (controls) than in those stocked with shrimp. In ponds stocked with shrimp, macroinvertebrate densities in fed and fertilized treatments were significantly greater ( P ≤ 0.05) than in the unfed treatment, but not significantly different ( P > 0.05) from each other. Insect taxa showed a greater negative response to prawn predation than non-insects. Non-insect taxa demonstrated a more positive response to fertilizer and feed than insects. Although prawn production in organically fertilized ponds was surprisingly high (>1000 kg ha −1), economic analysis demonstrated higher net returns when prawns were fed a prepared diet, principally due to the production of greater numbers of large, high value prawns.