A survey of chlorine use among alabama's channel catfish farmers

摘要

A survey was conducted among 205 catfish producers from 31 counties in the state of Alabama to determine the extent of chlorine use and the effects of chlorine on fish production. Of the 59 farmers returning the questionnaire, 22 of them revealed that they used chlorine. Most (36.6%) of the farmers said they received information on the use of chlorine from other farmers; 13.6% said they received their information from the extension service; and 18.2% said they received theirs from a former government employee, now a private consultant. Rates of application varied from 0.1 ppm to 7.4 ppm. Farmers used chlorine for the disinfection of ponds, for the reduction of diseases and phytoplankton, and for insect and predator control. Two main methods for applying chlorine were used: 54.5% broadcast the chlorine (applying it randomly from a boat); 36.4% applied from the shoreline, while only 4.5% used the "hotspot method" (application of chlorine to specific areas with excessive algal bloom). There were no significant differences (P > 0.05) in yields and mortality between farmers who used and those who did not use chlorine. The method and rates of application did not affect yields or fish losses. The use of chlorine increased variable cost of production and reduced net returns.