Production costs decreased in the polyculture
scenarios because culture cycles were shorter as a
result of greater tilapia weight gain over a shorter time
period. Gross income was higher from polyculture
largely due to the commercial value of the crayfish,
which is comparable to the price of freshwater prawn
and some marine shrimp species. Time horizon plays a
determinant role in the consolidation of rural aquaculture
companies, meaning it is vital and necessary to
research and propose alternative production strategies
that allow for rapid return of investment capital. All the
polyculture scenarios simulated here attained a yield
rate higher than the discount rate, which is required for
an investment's net present value to be positive.
Greater profits were obtained with medium crayfish
densities. The polyculture scenarios analyzed here
Table 3
Sensitivity analysis
33/0 33/10 33/20
Year Tilapia Tilapia Crayfish Tilapia Crayfish
Sale price
5 616.92 22.97 1.97 56.68 5.93
10 22.89 12.84 1.07 13.59 1.83
15 17.73 10.83 0.89 11.45 1.54
Feed cost
5 −346.45 −13.05 −0.36 −23.87 −1.12
10 −23.69 −7.28 −0.20 −7.78 −0.36
15 −9.87 −6.13 −0.17 −6.55 −0.31
Seed cost
5 −106.88 −4.78 −1.21 −8.61 −4.35
10 −4.23 −2.70 −0.68 −2.79 −1.41
15 −3.33 −2.28 −0.58 −2.37 −1.19
Percentage change in IRR versus a percentage unit increase in sale
price and main production costs
156 D. Ponce-Marbán et al. / Aquaculture 261 (2006) 151–159
meet the yield, risk and investment capital period
objectives of rural aquaculture companies in Yucatan,
Mexico.
The sensitivity analysis suggested that diversifying
Nile tilapia polyculture with high commercial value
species like Australian redclaw crayfish can attenuate
the risk implicit in the market. Model results encourage
field testing with mean densities in a pilot tilapia–
redclaw polyculture system in Yucatan, Mexico before
advising producers. Until such time, these simulations,
based on experimental data, suggest that a polyculture
strategy may be an option for increasing production,
mitigating risk in the tilapia market and improving
producer income.
Production costs decreased in the polyculturescenarios because culture cycles were shorter as aresult of greater tilapia weight gain over a shorter timeperiod. Gross income was higher from polyculturelargely due to the commercial value of the crayfish,which is comparable to the price of freshwater prawnand some marine shrimp species. Time horizon plays adeterminant role in the consolidation of rural aquaculturecompanies, meaning it is vital and necessary toresearch and propose alternative production strategiesthat allow for rapid return of investment capital. All thepolyculture scenarios simulated here attained a yieldrate higher than the discount rate, which is required foran investment's net present value to be positive.Greater profits were obtained with medium crayfishdensities. The polyculture scenarios analyzed hereTable 3Sensitivity analysis33/0 33/10 33/20Year Tilapia Tilapia Crayfish Tilapia CrayfishSale price5 616.92 22.97 1.97 56.68 5.9310 22.89 12.84 1.07 13.59 1.8315 17.73 10.83 0.89 11.45 1.54Feed cost5 −346.45 −13.05 −0.36 −23.87 −1.1210 −23.69 −7.28 −0.20 −7.78 −0.3615 −9.87 −6.13 −0.17 −6.55 −0.31Seed cost5 −106.88 −4.78 −1.21 −8.61 −4.3510 −4.23 −2.70 −0.68 −2.79 −1.4115 −3.33 −2.28 −0.58 −2.37 −1.19Percentage change in IRR versus a percentage unit increase in saleprice and main production costs156 D. Ponce-Marbán et al. / Aquaculture 261 (2006) 151–159meet the yield, risk and investment capital periodobjectives of rural aquaculture companies in Yucatan,Mexico.The sensitivity analysis suggested that diversifyingNile tilapia polyculture with high commercial valuespecies like Australian redclaw crayfish can attenuatethe risk implicit in the market. Model results encouragefield testing with mean densities in a pilot tilapia–redclaw polyculture system in Yucatan, Mexico beforeadvising producers. Until such time, these simulations,based on experimental data, suggest that a polyculturestrategy may be an option for increasing production,mitigating risk in the tilapia market and improvingproducer income.
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