ARCHIVAL WEBSITE
You are viewing the archived website of Pond Dynamics / Aquaculture CRSP. When using this website, please understand that links may be broken and content may be out of date. You can view more information on the continuation of PD/A CRSP research archived at AquaFish Innovation Lab.
D. Southeast Asia

D. Southeast Asia


The Effects of Fertilization on Growth and Production of Nile Tilapia in Rain-Fed Ponds

Work Plan 7, Thailand Study 1

James Diana
School of Natural Resources and Environment
University of Michigan
Ann Arbor, Michigan, USA

C. Kwei Lin
Agricultural and Food Engineering Program
Asian Institute of Technology
Bangkok, Thailand

Abstract

The purpose of this study was to evaluate fertilization strategies for rain-fed ponds based on strategies developed for ponds with regular water inputs. Rain-fed ponds might be expected to have different fertilization schedules because the water depth changes with time and evaporation may concentrate nutrients and metabolites. Four experimental treatments were used: A) fertilization every two weeks with water replacement, B) fertilization every two weeks with no water replacement, C) fertilization once at the start of culture without water replacement, and D) fertilization irregularly when water nutrient levels declined without water replacement. Fertilization rates were similar to earlier optimal rates for CRSP ponds. Fish were stocked at 2 per m2 (1600 per pond) and cultured for 150 days. Growth, survival, and yield were determined, and water quality was evaluated throughout the experiment. Treatments A and B (regular fertilization with or without water replacement) resulted in the highest growth rates, with irregular fertilization yielding lower growth and one fertilization the lowest growth. Survival was not significantly different among treatments. Several water quality variables, particularly nitrogen levels, varied among treatments, with A and B having higher levels than the other treatments. Regularly fertilized ponds with or without water addition both showed significant accumulation of nutrients over time, but there was no difference between these treatments. Fertilization strategies developed for ponds with regulated water depth worked effectively for ponds with evaporation losses that were not replaced. This study used input additions on a per areal basis, which were lower (by about one-half) than inputs would be on a per volume basis since the guidelines were developed for 1 m deep ponds and the study ponds began with water depths at 2.5 m. Growth and yields were slightly reduced compared to experiments in other pond systems, probably due to slightly lower nutrient input rates.

A Finishing System for Large Tilapia

Work Plan 7, Thailand Study 3

James Diana
School of Natural Resources and Environment
University of Michigan
Ann Arbor, Michigan, USA

C. Kwei Lin and Yang Yi
Agricultural and Food Engineering Program
Asian Institute of Technology
Bangkok, Thailand

Abstract

The objective of this study was to evaluate caging densities and pond loading rates for tilapia caged and fed in semi-intensive ponds with small tilapia at large. Such a system could be an effective means to produce large tilapia efficiently, as well as produce smaller tilapia and keep culture facilities at a reasonable level. Caged tilapia were held at five densities; 16, 32, 64, 128, and 256 fish per m3 cage. Pond loading rates were 2 tilapia per m2 (626 fish per pond) and caged tilapia were loaded at two rates: 224 or 560 caged fish per pond. Growth, survival, and yield of tilapia in cages and in ponds were estimated over 90 days of culture. Growth rates of tilapia in cages were similar regardless of density, and average tilapia size at harvest was 700g. Survival differed significantly with cage density, with fish from 16-64 per cage showing no differences in mortality, while fish at higher densities had very high morality rates. Fish at large in the ponds showed similar growth and mortality rates to other culture systems, even though the only source of nutrients was through the unused feed, fecal matter, and excretory products of the caged fish. Water quality did not deteriorate within the ponds at either loading rate. Cage stocking densities of 64 fish per m3 were most reasonable for tilapia culture, and resulted in good survival and significant growth. The results on pond loading rates were not clear, since significant mortality occurred for some caged fish in the high loading ponds, yet it is unclear if the problem was a cage effect or a pond effect.

Stocking Density and Supplemental Feeding

Work Plan 6, Thailand Study 6

James Diana
School of Natural Resources and Environment
University of Michigan
Ann Arbor, Michigan, USA

C. Kwei Lin and Yang Yi
Agricultural and Food Engineering Program
Asian Institute of Technology
Bangkok, Thailand

Abstract

The purpose of this experiment was to determine the upper limits to tilapia production utilizing supplemental feeds. In order to test this, fish were stocked at 3, 6, and 9 fish per m2. These fish were supplementally fed to satiation during culture for 146 days. Growth, survival, yield, and water quality were evaluated during the experiment. Growth continued in a linear fashion throughout the experiment, and density dependent growth occurred with the lowest density having significantly higher growth rate than the intermediate density, and with the highest density having the lowest growth rate. Survival also differed significantly among treatments, with lowest survival at highest density. Feeding rate averaged 1.9 %BW/d and was not significantly different among treatments. Feed conversion rate averaged 0.89 and was also similar among treatments. Water quality was not significantly different among treatments, and did not deteriorate during culture. The highest growth rate and survival occurred in low density ponds, yet there was no measured deterioration in water quality even in higher density ponds. It is unclear whether the higher density ponds had behavioral differences among tilapia to result in lower growth and higher mortality, or whether water quality actually differed but was not measured with our sampling regime. At present, the best system seems to be culture at 3 fish per m2 with intensive feeding.

Carp/Tilapia Polyculture on Acid-Sulfate Soils

Work Plan 7, Thailand Study 5

James P. Szyper and Kevin D. Hopkins
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Abstract

CRSP research in Thailand has concentrated on the dynamics of Oreochromis niloticus monocultures. As Oreochromis niloticus is primarily a planktivore, the addition of the benthic detritivore Cyprinus carpio was hypothesized to lead to increased system productivity through the conversion of currently unutilized benthic matter into fish flesh.

A five-month experiment was conducted in earthen ponds of 200 m2 surface area at the Asian Institute of Technology. Fifteen ponds were allocated to five treatments: carp stocking densities of 0, 0.1, 0.3, 0.5, and 0.7 fish/m2, with three replicates, in three blocks which represented common carp of different sizes at stocking. Ponds were fertilized weekly with chicken manure, urea, and TSP.

Only preliminary results are available for this experiment. Tilapia growth was slow and uniform across blocks and treatments, likely because larger fish (>25 g/fish) had been erroneously selected from the batch to stock a different experiment before this experiment was stocked. Carp growth was extremely sensitive and inversely related to stocking density; carp of initial (pond mean) weights 11-40 g/fish grew to pond means 41-270 g/fish during five months.

Through the first half of the experiment, there was little indication of treatment-related differences in water quality except in measures of turbidity. Total suspended solids were markedly lower in ponds without carp. The parameters chosen for this experiment were appropriate to produce treatment-related differences in suspended solids and to reveal the density dependence of carp growth.

Diel Cycles of Temperature and Dissolved Oxygen Stratification in Deep Rain-fed Ponds

Work Plan 7, Thailand Study 7

James Szyper
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Abstract

In regions of large seasonal differences in rainfall, many farms have reservoir ponds. These can be used in addition for fish culture, but are often deeper (2-3 m) than those in which the CRSP fertilization protocols and other aspects of pond dynamics have been studied. The greater depth potentiates more severe density stratification than is common in shallower ponds, and therefore less often dissolved by convective overturn at night or by wind-induced mixing. This makes oxygen depletion of the hypolimnion more likely. This study attempted to describe and quantify diel cycles of temperature and DO stratification in the deep rain-fed ponds of current focus in the AIT Outreach activities, and to compare these patterns with those of shallower ponds typical of CRSP experiments.

Ponds of 800 m2 area and 2.5 m depth at the Huay Luang station were monitored during fish growth experiments; diel cycles of temperature and DO were recorded with an automated monitoring system. During sunny, dry season days, the pond had a slightly deeper mixed layer (at least 35 but much less than 75 cm) than is characteristic of ponds at the more sheltered AIT site. The bottom water below 2 m depth was almost completely isolated from the upper water, receiving only minimal transport of oxygen from above. During the rainy season, the isolation below 200 cm was maintained even through a dark rainy day. These assessment techniques showed that active mixing may be necessary to maintain deep ponds as suitable culture environments for some animal species; the techniques can be used to assess low-cost mixing strategies.

Carbon Dioxide Exchange between Pond Water and the Atmosphere

Work Plan 7, Thailand Study 8

James Szyper
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Abstract

Rates of exchange of dissolved oxygen and carbon dioxide between pond waters and the atmosphere are often significant components of a pond's budget for these materials. Oxygen exchange is routinely estimated in free water studies, but far less attention has been given to diffusion of carbon dioxide, which may, however, be significant. The objectives of this work were to quantify the rates of exchange of carbon dioxide between pond water and the atmosphere in fertile earthen ponds, and to elucidate major factors which determine these rates. An analysis of data from the University of Hawaii pond research facility in the U.S. was made, detailing the diel cycles of total carbon dioxide, the component species aqueous ("free") carbon dioxide, net changes in CO2 concentrations, and wind speed.

Total CO2 concentrations varied little during the day, but showed a perceptible dip during mid-day, reflecting photosynthetic uptake. Wind speeds at 0.5 m above water surface ranged from about 0.6 to 1.8 m/s, with the windiest periods concentrated into daylight hours. The free CO2 fraction of total CO2 (about 1% of the total) varies in parallel with total CO2, but accounted for only about 25% of the diel variation in the total CO2. Multiple regression analysis showed that the concentration of free CO2 and wind speed together accounted for 81% of the variation in the diffusion rates during this diel cycle. The net rates of change in CO2 concentration during the 30 minute sampling intervals contributed no significant effect to diffusion rates and did not add to the percentage of the diel variation in diffusion rates which was explained by the other two factors. Model prediction of diffusion rates thus requires only observed concentrations and wind speed, though photosynthetic demand can be the primary determinant of concentrations under some conditions.


Growth Comparison of Three Strains of Nile Tilapia in Fertilized Ponds

Work Plan 7, Thailand Study 9

Kevin Hopkins
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Eduardo Lopez
Freshwater Aquaculture Center,
Central Luzon State University, Philippines

James Szyper
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Abstract

Three strains of Oreochromis niloticus were grown in ponds fertilized with 4 kg N/ha/d plus 0.8 kg P/ha/d to compare growth performance. The FAC strain were descendants of O. niloticus imported to the Philippines in the 1970s and kept at the Freshwater Aquaculture Center (FAC). The Thai strain were descendants of fish imported from Thailand in the 1980s and maintained by the Bureau of Fisheries and Aquatic Resources and ICLARM. The Egypt-Swansea strain originated from fish collected from Lake Manzala in 1979. These fish were used to create a laboratory strain at University College of Swansea during the 1980s and were subsequently transferred to FAC in 1989. Extrapolated yields of the Thai and Egypt-Swansea strains were not significantly different from each other and averaged approximately 5,000 kg/ha/yr. The average extrapolated yield of the FAC strain was only 2,389 kg/ha/yr reflecting the probable introgression of O. mossambicus.

Additionally, the yield of Egypt-Swansea fish grown in ponds fertilized at 2 kg N/ha/d plus 0.4 kg P/ha/d was compared to yield of fish grown at 4 kg N/ha/d. No significant difference was observed.

Polyculture in Deep Ponds

Work Plan 7, Thailand Study 2

James Diana
School of Natural Resources and Environment
University of Michigan
Ann Arbor, Michigan, USA

C. Kwei Lin and Yang Yi
Agricultural and Food Engineering Program
Asian Institute of Technology
Bangkok, Thailand

Abstract

The objective of this study was to assess the effect of other fish species on the water quality and yield of tilapia and of all fish in deep, rain-fed ponds. The experimental design included three fish stocking treatments with four replicates per treatment. Sex-reversed Oreochromis niloticus were stocked at 2 fish/m2 into 12 earthen ponds at Udorn. Stocking occurred in late June 1995. They are to be cultured for five months, with a final harvest in late November 1995. Three treatments differed in stocking density of common carp Cyprinus carpio, with 0 carp in treatment 1,500 carp per hectare in treatment 2, and 1,000 carp per hectare in treatment 3. Carp were stocked at 500 g in size. All treatments will receive fertilizer application at the optimum frequency and rate, which is 70 kg/ha/wk of chicken manure, with sufficient urea and phosphorus added to provide 0.5 g/m2/d N and 0.125 g/m2/d P. Ponds were filled initially to 2.5 m, further water addition will only occur by rainfall. Standard protocols will be utilized for physical and chemical monitoring of ponds with the following exceptions. Diurnal sampling will be done every month at 4 depths (stratification can be quantified by top to bottom differentials in O2 or temperature). Secchi disk depth will also be measured in diurnal analyses. Evaporation rate will be measured weekly. Final comparisons will be made to determine if the addition of carp influenced the stratification or turbidity of these ponds, as well as the yield of tilapia.


Outreach Assistance

Work Plan 7, Thailand Study 4

C. Kwei Lin
Asian Institute of Technology
Bangkok, Thailand

James S. Diana
University of Michigan
Ann Arbor, Michigan, USA

Abstract

This study was initiated by holding two workshops with 10 fisheries officers from four provinces in Northeast Thailand, including Udorn, Nong Khai, Sakon Nakhon, Loei. Each provincial fisheries officer solicited four to six small-scale farmers from his or her province to participate in the high input green water scheme recommended by AIT-CRSP program. Biologists from Udorn station monitored the farmers activities.

Most farmers started their growout at the beginning of the rainy season in May and June 1995. There were complications getting production data because most farmers do not harvest their fish in one harvest; instead they catch fish in small numbers upon demand by local consumers or simply for their own consumption. In addition, the farmers mostly keep their fish until ponds dry out during the dry season. However, preliminary feedback from the farmers was very positive.

We will follow up to collect production data. We are planning to expand the number of farmers.


Effect of Pond Size

Work Plan 5, Thailand Study 9

James P. Szyper and Kevin D. Hopkins
College of Agriculture
University of Hawaii
Hilo, Hawaii, USA

Abstract

Extrapolation, particularly scaling upward the results of trials in small impoundments to production scale ponds, is a classical and unsolved problem in aquaculture. Our interest here was not in solving the lager problem, but rather to examine earthen ponds of available different sizes for potential effects on CRSP experimental results at the Asian Institute of Technology (AIT). A five month experiment was conducted in 11 earthen ponds of four different surface areas (approximately 200, 380, 610, and 1390 m2) with triplicate ponds of each size. Ponds were stocked with sex-reversed fingerlings of Nile tilapia (Oreochromis niloticus) at 2 fish per m2. Ponds were fertilized with chicken manure at 250 kg dry matter/ha/wk supplemented with urea and TSP to attain rates of 35 kg N/ha/wk and 7 kg P/ha/wk. Water sampling and analysis were performed according to standard protocols, with detailed water sampling/analyses conducted every month. Extrapolated yields ranged from 1,921 to 8,631 kg/ha/yr. Single-factor ANOVA showed no significant relationship between yield and pond size. This means that areal fish yields may be expected to increase as ponds become larger. However, extrapolation to pond sizes beyond the largest used here is unwarranted.