Carole Engle, Ph.D.

Current Grad Student Research - (Click on Title for Abstract)

Umesh Bastola
•  Development of Mathematical Models of Catfish Production Characteristics 
•  Effect of Increased Frequency of Feeding of Channel Catfish on Growth, Yield, and Survival in Multiple-Batch Culture 
•  A Review of the Literature on Economically Critical Production Parameters of Channel Catfish Foodfish Production 

Pratikshya Sapkota Bastola
•  Developing a Mathematical Programming Model for Hybrid Striped Bass Fingerling Production
•  Risk Analysis of Hybrid Striped Bass Morone chrysops x Morone saxatilis Fingerling Production in Ponds and Tanks
•  Cost Analysis of Mobile Nursery System for Hybrid Striped Bass Morone chrysops x Morone saxatilis Fry

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Development of Mathematical Models of Catfish Production Characteristics.  (Umesh Bastola) - < | Back | >
    Studies conducted at UAPB have tested effects of different stocking and culture conditions on a variety of catfish production parameters. The major differences among these studies were in terms of stocking density, sizes of fish stocked, the cropping system used, and the duration of culture period. There has been little effort to combine data from these various studies to provide more complete answers to management questions. This study combines data from those multiple studies to develop comprehensive mathematical models of catfish production. Different functional forms will be evaluated to assess the relationship among key production parameters of catfish fingerling, stocker, and foodfish production. Thus developed models will be tested for their validity with data from commercial catfish farms in Arkansas . The models will specifically assist catfish farmers to select management options among different stocking rates and sizes, culture days, and stocking and feeding strategies to harvest fish in given size range to meet their production goals.  

Effect of Increased Frequency of Feeding of Channel Catfish on Growth, Yield, and Survival in Multiple-Batch Culture.  (Umesh Bastola) - < | Back | >
    Channel catfish have been shown to have poorer growth and survival in winter months. Previous work suggested that feeding catfish more frequently and at lower temperatures than published recommendations may improve outcomes of catfish over the winter. Twelve 0.25-acre ponds were stocked with 987 kg/ha market-sized fish (> 0.54 kg; mean weight 1 kg) and 2,960 kg/ha sub-marketable fish (mean weight 0.23 kg) in November 2008. Treatments consisted of the following with four replications each: (1) unfed; (2) fed daily; and (3) fed less than daily (Fed LTD) based on feed consumption - temperature relationships developed in previous work. 

    Fish in the Fed Daily treatment received feed for 90 days while those in LTD were fed for 62 days. Total feed fed was significantly higher in the Fed Daily treatment but the daily feeding rate (kg/ha/d for days fed) was significantly lower than in LTD. Gross yields, net yields, survival, and mean weight at harvest of both market-sized and sub-marketable fish did not differ significantly among treatments. Net yield, though negative, was nominally improved in the LTD treatment. Fish did not lose weight in the LTD treatment, in contrast to results with previous recommendations. Sub-marketable fish had better survival, yield, and weight gain than the market-sized fish in all treatment groups. A partial budget is under development to estimate the costs of holding market-sized fish over the winter. Increasing the frequency of feeding over the winter maintained the average weight of fish, but mortalities resulted in loss of overall yield.

A Review of the Literature on Economically Critical Production Parameters of Channel Catfish (Ictalurus punctatus) Foodfish Production.  (Umesh Bastola) - < | Back | >
    The catfish industry, the largest segment of aquaculture in the United States, has been facing a decline in the number of operations, total yield, and sales in recent years. This has resulted in a call for innovations to improve production efficiencies and lower costs of production. Investment costs, yields, and feed conversion ratio were identified as the economically critical production parameters that are under the control of an individual catfish farmer. Through review of the research literature, management parameters such as production systems, stocking density, size of fish at stocking, duration of culture, cropping systems, feeding strategies, and aeration have been found to significantly affect the economically critical parameters of investment costs, yields, and feed conversion ratio. Further researches to identify innovations that enhance productivity in an economically efficient manner are needed. Quantitative analyses that model the effects and relationships of the most important production parameters may be useful to provide guidance.

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Developing a Mathematical Programming Model for Hybrid Striped Bass Fingerling Production.  (Pratikshya Sapkota) - < | Back | >
    Year-round production of hybrid striped bass fingerlings has been limited by low survival during the late summer. The technology to produce fingerlings in indoor tanks in re-circulating system has been developed, providing a possible option of producing fingerlings year-round. However, enterprise budgets show that the cost of producing fingerlings in tanks is more expensive than in ponds. A whole-farm model that allows for effects of resource interactions and constraints across the farm should provide useful guidance on the economic trade-offs associated with hybrid striped bass fingerling production in tanks and in ponds. A mixed-integer linear programming model will be developed to identify the best production technology among currently available options to produce hybrid striped bass fingerlings year-round.  Different scenarios for farm sizes, levels of production and other sensitivities such as different survival rate will be run in the model. The model will demonstrate the most cost effective technology for producing hybrid striped bass fingerling across the year.  

Risk Analysis of Hybrid Striped Bass Morone chrysops x Morone saxatilis Fingerling Production in Ponds and Tanks.  (Pratikshya Sapkota) - < | Back | >
    Hybrid striped bass fingerling production is affected by fluctuating survival rates and prices of inputs that create economic risk and fluctuation in breakeven prices. Enterprise budgets developed for 15 pond and 17 tank production scenarios (various production scales and sizes of ponds and tanks) were used to conduct a risk analysis. Monte Carlo simulations were conducted with Crystal BallTM to generate probability distributions of breakeven prices (BEPs) of hybrid striped bass fingerling production.

    The risk analysis showed a greater than 50% certainty of BEPs being higher than those of the base enterprise budgets. This indicates a high level of economic risk associated with hybrid striped bass fingerling production in both ponds and tanks. Comparison of BEPs between ponds and tanks in the risk analysis showed that the probability of tank-produced fingerlings having a production cost less than that in ponds was 0%. This finding supports results of previous work that showed tank production costs of hybrid striped bass fingerlings to be higher than those in ponds. The greatest contributing factors to the risk levels estimated were: survival rate (accounted for 72-74%), costs of lime and interest rates for pond production and survival rate (accounted for 73-76%), prices of rotifer cysts and interest rates for tank production of hybrid striped bass fingerlings. Additional work will develop sensitivity analyses to evaluate the effects of recent dynamic changes in the market prices of inputs such as feeds and fertilizers. 

Cost Analysis of Mobile Nursery System for Hybrid Striped Bass Morone chrysops x Morone saxatilis Fry. (Pratikshya Sapkota) - < | Back | >
    Although hybrid striped bass broodstock can now be spawned year-round, year-round supply of fingerlings has been limited due to low survival of fry stocked in ponds in late summer. Hybrid striped bass fry are small (3-5 mm long), require live food (primarily small rotifers), and are susceptible to predation by insects and cyclopoid copepods. Hence, growth and survival of fry depend directly upon the number of zooplankton of appropriate size available in the system and the absence of predators. 

    A mobile nursery system was developed at the University of Arkansas at Pine Bluff. The system cultures fry under protected conditions by filtering out large zooplankton and providing fry with the appropriate size of live rotifers until they are large enough to escape predators in pond. The specific objective of this study was to estimate the investment and annual costs associated with such a mobile nursery system.

    Economic engineering techniques were used to estimate the investment cost, annual fixed cost and annual operating costs of the mobile nursery system. Annual fixed costs were estimated by adding annual interest rate on total investment to the annual depreciation cost. The major operating costs required to run this system included costs for electricity, labor, repairs and maintenance. The total investment cost for the primary system was computed to be $29,812. Annual fixed costs were $5,887 and composed 93% of total annual cost as compared to 7% for operating costs for one production cycle. Increasing the number of production cycles in a year from one to six resulted in decrease in annual fixed cost as a percent of total annual cost by 24%.The cost analysis will be extended to include larger scales and temperature controls. Sensitivity analyses will evaluate effects of varying unit costs of key inputs and effects of varying survival rates. 

Page last updated on Monday, October 18, 2010