62 SEPTEMBER 2014 • WORLD AQUACULTURE • WWW.WAS.ORG Pond Renovation In most instances, a pond undergoing renovation must be dried after first removing water by draining, siphoning or pumping. If feasible, fish may be removed from ponds by seining and transferred to another pond(s). However, fish diseases may be transmitted when fish from different ponds are mixed. Fish populations may be eliminated completely by draining or by using a fish toxicant, such as rotenone (Wynne and Masser 2010). Depending on weather, up to one year may be required for completion of pond renovation. Typically a pond would be drained and drying would begin during a period of diminished rainfall, such as late spring or summer in temperate regions. Periodic disking of moist pond soils will reduce drying time by exposing deeper soils to the surface where they will dry faster. A bulldozer can be used to create rows or piles of basin soil that will also reduce drying time. Care should be taken not to damage the integrity of the ponds’ compacted clay lining while removing unwanted sediment and other debris. A damaged clay lining can lead to excessive pond seepage upon refilling and may be expensive to repair (Stone 1999). Tractor-drawn dirt pans and bulldozers may be used to transport moist soils to rebuild pond levees to a 3:1 or 4:1 inside slope. Layers of soil, 15 cm deep, should be spread on the levee and each layer compacted with a sheepsfoot roller or non-tracked equipment before adding another layer. Detailed information on rebuilding commercial aquaculture ponds is provided by Steeby et al. (1998). Following renovation, it is critical to stabilize exposed soils on the dam and in the watershed as soon as possible with appropriate seasonal grasses. Topsoil that was set aside during earthmoving may be used to cover such areas and promote rapid vegetative growth (Whitis 2002). Established grasses on the dam and throughout the watershed will prevent erosion when runoff occurs. The establishment of trees and other woody vegetation growth on pond dams and along the shoreline should be discouraged by periodic mowing. Large roots weaken the dam or cause large voids when trees or shrubs die and roots decay. Smaller trees should be removed from dams during renovation. Large, established trees can be left in place if their removal is expected to create significant structural damage. Repairs to a seeping dam or pond basin are typically made while the pond is drained and dry. Severely leaking ponds may need to be rebuilt, filled in with earth, or abandoned. If a pond is constructed on a poor site it should be abandoned in favor of a better location. A properly built pond may leak slightly, especially in the first year after construction. Accumulation of organic matter may help seal small seepage problems as the pond ages. Where soils are acidic, agricultural limestone should be spread and disked into the pond basin before flooding. Limestone is added to bring soil pH to near neutral. Adding agricultural limestone will help stabilize water pH and increase total alkalinity. When ponds are subsequently filled, this will enhance nutrient availability to the phytoplankton that form the base of the food chain. A pond with a total alkalinity of less than 20 mg/L as CaCO3 may benefit from the addition of agricultural limestone. A dry soil sample of pond mud collected from different locations throughout the pond basin can be sent to a soil testing laboratory for analysis. Wurts and Masser 2004 provide more information about pond liming. Notes Forrest Wynne, Aquaculture Extension Specialist, Kentucky State University, College of Food Science and Sustainable Systems, Division of Aquaculture. Graves County Extension Office, 251 Housman Street, Mayfield, KY 42066 Phone: 270-247-2334 email: forrest.wynne@kysu.edu References Avery, J.L. 2010. Site Selection of Levee-Type Fish Production Ponds. Southern Regional Aquaculture Center Publication No. 100. Mississippi State University, Mississippi State, Mississippi. Steeby, J.A. and J.L. Avery. 2002. Construction of Levee Ponds for Commercial Catfish Production. Southern Regional Aquaculture Center Publication No. 101. Mississippi State University, Mississippi State, Mississippi. Steeby, J.A., N. Stone, S. Killian and D.K. Carman. 1998. Repairing Fish Pond Levees. Southern Regional Aquaculture Center publication No. 104. Mississippi State University, Mississippi State, Mississippi. Stone, N. 1999. Renovating Leaky Ponds. Southern Regional Aquaculture Center Publication No. 105. Mississippi State University, Mississippi State, Mississippi. Whitis, G.N. 2002. Watershed Fish Production Ponds Guide to Site Selection and Construction. Southern Regional Aquaculture Center Publication No. 102. Mississippi State University, Mississippi State, Mississippi. Wurts, W.A. and M.P. Masser. 2013. Liming Ponds for Aquaculture. Southern Regional Aquaculture Center Publication No. 4100. Mississippi State University, Mississippi State, Mississippi. Wynne, F. and M.P. Masser. 2010. Removing Fish from Ponds with Rotenone. Southern Regional Aquaculture Center Publication No. 4101. Mississippi State University, Mississippi State, Mississippi. Depending on weather, up to one year may be required for completion of pond renovation. Typically a pond would be drained and drying would begin during a period of diminished rainfall, such as late spring or summer in temperate regions. Periodic disking of moist pond soils will reduce drying time by exposing deeper soils to the surface where they will dry faster. A bulldozer can be used to create rows or piles of basin soil that will also reduce drying time. Care should be taken not to damage the integrity of the ponds’ compacted clay lining while removing unwanted sediment and other debris. A damaged clay lining can lead to excessive pond seepage upon refilling and may be expensive to repair.
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