VARIABLES ASSOCIATED WITH THE USE OF CHEMOTHERAPEUTIC-AGENTS ON TROUTFARMS IN ONTARIO, CANADA

This study investigated whether certain farm-level variables were rela ted to the use of chemotherapeutic treatments by Ontario, Canada trout producers, Several treatment outcomes were examined in each of two fi sh-size categories (10 cm or less and over 10 cm), including: (1) the likelihood of initiating any treatment; (2) the frequency of treatment initiation; (3) the likelihood of using any preventive treatments; (4 ) the likelihood of initiating more than half of all treatment regimen s for preventive reasons. Data were obtained by personally interviewin g 62 farmers who in total marketed 91% of the farmed trout produced in Ontario in 1990. Producers with more years of fish farming experience or those with no more than one full-time equivalent person working wi th the fish were less likely to have initiated treatment in either siz e category than were those with less experience or more workers. In ad dition, farmers producing fewer fish or those running specialized hatc heries or vertically integrated operations were less likely to have ev er treated fish that were 10 cm or less in size than were those with l arger farms or growout-only operations. Treatment frequency increased significantly if farmers had used preventive treatments. Also, among f armers who did treat 10 cm or smaller fish, those with more years of f arming experience tended to initiate fewer treatments. Farmers with ha tcheries or vertically integrated farms were less likely to have initi ated any preventive treatments in 10 cm or smaller fish than were thos e with growout-only operations, Members of the Ontario Aquaculture Ass ociation were less likely than non-members to have initiated more than half of their treatment regimens in 10 cm or smaller fish for prevent ive reasons. Farmers who had lower water flows per 10 cm or over fish tended to rely more heavily on preventive treatments in this size grou p of fish than did those with higher flows per fish.