Cultures of Streptomyces tendae grown on Actinomyces medium containing clomazone contained less geosmin 48 h after inoculation than untreated controls, suggesting a possible inhibition of reactions prior to sesquiterpenoid biosynthesis. However, exposure to clomazone increased geosmin accumulation in S. tendae cultures grown on Hickey-Tresner medium and in cultures of the fungus Penicillium expansum. Additionally, clomazone increased accumulation of a sesquiterpenoid tentatively identified as a eudesmol in S. tendae, indicating possible point(s) of inhibition subsequent to sesquiterpenoid biosynthesis. Geosmin biosynthesis was induced by transferring cultures of S. tendae inoculated on Actinomyces medium to Hickey-Tresner medium 24 h after inoculation. When harvested at 48 h, geosmin biosynthesis-induced-cultures exposed to clomazone contained more geosmin than untreated controls, indicating that response of a single taxon to clomazone can be rapidly altered by changing medium composition.

Cost, returns, and economies of scale for small, medium and large catfish farms with recirculating ponds are presented for the upper Texas coast. Internal rates of return are 0.150, 0.183 and 0.219, respectively. Total investment is higher than farms with static ponds but investment per unit production capacity is 7 percent to 16 percent lower. Average total cost per pound is between $0,565 and $0,541, (11 percent-20 percent lower than farms using current technology). These results have implications for regional comparative advantage of catfish production as well as incentive for adoption of new technology in conventional ponds.

Off-flavor in catfish restricts farm marketings 10 to 45% depending on the season. The economic impact on society of this imposed supply restriction depends, in part, on the elasticity of demand for catfish. Econometric estimates based on disaggregated processing plant data indicate an elastic demand at the processor level but an inelastic demand at the farm level. Short-run social welfare gains from the elimination of off-flavor are estimated to equal 12.0% of farm revenues ($10.0 million in 1983). The inelastic demand for catfish at the farm level, however, means that most of the societal gains will accrue to individuals beyond the farm gate. Thus, an economic justification exists for public sector funding of off-flavor research.