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Farm‐Level Economic Impacts of Bolbophorus Infections of Channel Catfish
Author(s) -
Wise David J.,
Hanson Terrill R.,
Tucker Craig S.
Publication year - 2008
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1577/a07-089.1
Subject(s) - ictalurus , catfish , biology , fish farming , zoology , population , infection rate , fish <actinopterygii> , aquaculture , fish pond , veterinary medicine , toxicology , ecology , fishery , demography , medicine , surgery , sociology
The prevalence of infections by trematodes Bolbophorus sp. in populations of pond‐raised channel catfish Ictalurus punctatus was determined by sampling 64 ponds on a farm in northwestern Mississippi. Of the 40 food fish ponds sampled, 23 (58%) contained trematode‐infected fish; 7 pond populations were categorized as having light infections (1–33% infection rates), 5 as having moderate infections (34–66% infection rates), and 11 as having severe infections (≥67% infection rates). Only 3 of the 24 fingerling ponds contained fish infected with Bolbophorus trematodes, and the infection rates were light. Feed consumption and estimated fish production in food fish ponds differed significantly among the four categories of within‐population infection rate, and feed consumption and fish production decreased as infection rates increased. Relative to the production in uninfected populations, estimated fish production was reduced by 14, 35, and 40% in populations with light, moderate, and severe infections, respectively. Estimated catfish receipts and actual feed costs were used in a generalized enterprise budget format to calculate income above variable costs and net returns for each infection‐rate category. The estimated net return to land for uninfected food fish populations was US$1,526/ha. Lower fish production in infected populations resulted in decreased incomes. The net return to land was $592/ha for the light‐infection‐rate category, a 61% reduction from that achieved in uninfected populations. Production receipts from food fish ponds in the moderate‐ and severe‐infection‐rate categories did not cover the costs of production, and the net returns to land were −$781/ha for moderately infected populations and −$1,123/ha for severely infected populations. This study shows that trematode infections reduce fish production and farm economic returns and that the impacts increase as infection rates increase. However, even light and moderate infections—which may go unnoticed by farmers—can seriously affect farm profitability.