Factors Affecting the Frequency of Oversized and Undersized Channel Catfish, Ictalurus punctatus, ? X Blue Catfish, I. furcatus, ? Hybrid Catfish at Food Fish Harvest and their Economic Impact
Type of DegreePhD Dissertation
Fisheries and Allied Aquacultures
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Hybrid catfish (channel catfish, Ictalurus punctatus, ♀ x blue catfish, I. furcatus, ♂) farming is a prime example of yield intensification but has witnessed growth variability problem. Investigating the causative factors of such problem and the economic impact analysis are critical to understand fish producer’s profitability related to the fish processor’s demand for specifically sized categories of fish (undersized, premium, and oversized). A comprehensive industry-wide fish sampling and survey were conducted in Mississippi, Arkansas, and Alabama from 2015 to 2017. In total, 164 culture units were sampled, which included single batch (N=25), multiple batch (N=16), split pond (N= 98) and in-pond raceway system (IPRS, N=25) of which, 4 raceways were from research settings and 21 from commercial settings. The causative factors of the undersized and oversized hybrid catfish were related to feeding and stocking management. Most of the variables under the feeding, and stocking management and few other operational variables significantly influenced the growth variability of hybrid catfish production. These included feed usage, feed conversion ratio (FCR), stocking density, individual weight of fingerling, number of fish harvest, graded fingerling, pond area, depth, aeration, and fingerling sources. The best management practices may vary from one production system to another, and the results for the IPRS were the most unique compared to the pond systems. For example, deep ponds reduced oversized fish percentage, but deep raceways increased the oversized fish frequency. Although, the factors affecting size distribution were not always exactly the same or of the same magnitude among the different production systems, some generalizations can be made regarding which variables such as high stocking rates, stocking of large fingerlings, everyday feeding, relatively high feeding rates, adequate length of culture, use of small ponds, utilization of more than 4 hp/ha (aeration rate) and harvest of large numbers of fish (presumed efficient harvest and grading), had the most impact. Comparative economic analyses were developed by using standard enterprise budgeting, partial budgeting and sensitivity analysis. Split pond systems were the most profitable enterprise compared to traditional systems (single and multiple batch) and IPRS (research). Split ponds had higher net returns ($8,578/ha), resulting from the highest availability of premium size fish (0.45-1.81 kg in weight and sales price = $2.46/kg). Current analyses also showed that variations in dockage rates for the price of undersized (sales price = $2.34/kg) and oversized fish (sales price = $2.08/kg), had a significant economic impact on net returns that resulted in revenue loss. This loss, in total, was $1,712/ha for undersized and oversized fish, regardless of the production system. Partial budget analyses showed that using 20 cm fingerlings was economically feasible, but it resulted in lesser net returns to operator's labor, and management compared to medium size fingerlings (18 cm). Sensitivity analyses also showed that split pond systems would give greater net returns compared to other production systems for all potential scenarios of decreasing dockage prices for undersized and oversized fish at the 25%, 50%, and 75% reductions to the base sales price.