Purdue University Graduate School
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posted on 2020-04-16, 13:02 authored by Roberto Manolio Valladao FloresRoberto Manolio Valladao Flores
The Brazilian aquaculture sector has experienced growth in recent decades, and economic data from the sector is needed to characterize the supply chain, the consumer markets and financial indicators of fish producing units. Reliable statistical data on the Brazilian aquaculture sector is also needed to aid in the research efforts toward the sector. This dissertation analyzes data collected from experiments, suppliers and consumers of tilapia and tambaqui, the two most important fish farming species in Brazil, in three essays.

The first essay aims to fill a gap in the literature by assessing the economic returns to lettuce and juvenile tilapia production in an aquaponics system. Experimental data that varied fish stocking density and feeding rate when co-producing fish and lettuce in Brazil is analyzed. Using different nonparametric efficiency testing methods, a set of undominated technologies in the form of input mix, is identified. In addition, sensitivity analysis is used to assess the ranges for prices over which the choice of technology is robust. Results from the technical efficiency analysis show that it is possible to get marketable lettuce in synchronization with the fish production cycle using a reduced level of feed. At observed average regional market prices (0.18 R$/tilapia fingerling, 2.8 R$/kg for fish feed, 20 R$/kg for juvenile fish and 1.70 R$/lettuce plant), the highest profit alternative in the experimental design is from an initial stocking density of 250 fingerlings per m3, feeding at the recommended rate, and harvesting on the 29th day. Sensitivity analysis indicates that the choice of best input combination is sensitive to only the prices of fish feed input and juvenile fish output. A complete financial analysis was based on this production strategy, and results indicate that a 10-year project is economically viable.

Consumer demand for tilapia and tambaqui product attributes is studied in the second essay. Seafood supply chains, from fish farmers to supermarkets selling direct to consumers, must understand consumer demand for product attributes to ensure production and availability of desired products. Consumers’ willingness to pay (WTP) for tilapia and tambaqui fillets was estimated taking consumer demographics into account for each of the five Brazilian regions. A random parameters logit model was used to analyze data from discrete choice experiments conducted in-person at supermarket seafood counters. On average, Brazilian fish consumers prefer tilapia to tambaqui, and fresh to frozen fillets. Stated preferences were found to be related to knowledge about fish. This study is the first known analysis of national seafood preferences considering factors such as product form, species, and familiarity with fish and fish products in Brazil.

In the third essay, a spatial analysis of the supply chain of tilapia and tambaqui is conducted with a focus on potential policy interventions and changes in the economic environment. The analysis is based on a partial equilibrium model of the sector and is the first comprehensive model of the aquaculture supply chain for Brazil. The demand component of the model is estimated econometrically using synthetic data based on the previous consumer choice experiment combined with secondary data on aggregate fish demand. The resulting demand system reflects asymmetric cross price impacts violating Samuelson’s integrability condition. Rather than imposing symmetry during estimation, the model is formulated as a complementary problem. The spatially disaggregated model is applied to the evaluation of the impact of factors such as governmental incentives (subsides of fish feed), international oil price shocks (changes in the cost of transportation), increases in consumers’ income (shifts in demand), and decreases in retailers’ margins on the regional pattern of tilapia and tambaqui production and final consumption. Changes in transportation costs, impacted by oil prices or road improvements had little impact on market outcomes. A 10% reduction on retailers’ gross margins decreased prices by 5.2% and increased quantity demanded by 5.4%, while an 8% reduction in fish feed costs due to tax cuts indicates, on average, 5.4% lower selling prices for farmers.




Degree Type

  • Doctor of Philosophy


  • Agricultural Economics

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Kwamena K. Quagrainie

Advisor/Supervisor/Committee co-chair

Paul V. Preckel

Additional Committee Member 2

Nicole O. Widmar

Additional Committee Member 3

Maria Célia Portella

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