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Harmful infections by ectoparasites of the genus Argulus occur repeatedly in freshwater fish farming operations where the management has largely been ineffective. Preventative methods and regular monitoring are rarely applied, so that chemical interventions become necessary. According to the Integrated Pest Management (IPM) approach, a sustainable management or control program for a parasite should be based on knowledge of the ecology of the parasite along with adoption of several prevention and control methods, the application of which is dependent upon the prevailing infection level. The application of multiple management tactics is especially important because parasites can develop resistance to chemical treatments. We took a step towards sustainable management of Argulus populations and tested the effect of several types of treatments on survival of A. coregoni at different stages in its life cycle. Parasite juveniles and adults were highly sensitive to potassium permanganate treatments (0.01 g l -1), which lead to 100% mortality, whereas treatments with formalin (0.6 ml l ) or malachite-green/formalin were not effective. Mechanical treatment by shaking infected fish in a hand net was an effective means of detaching parasites from the fish, and resulted in > 80% decreases in parasite numbers. Compared to eggs in control treatments, both drying over a minimum period of 24 h and formalin treatments (120 ml l ), did not significantly affect the viability of eggs. Based on the present results and previously published papers, we present an initial framework showing how A. coregoni populations could be managed effectively. KEY WORDS: Integrated pest management · IPM · Control · Prevention · Parasite · Argulus coregoni · Fish louse Resale or republication not permitted without written consent of the publisherDis Aquat Org 82: [67][68][69][70][71][72][73][74][75][76][77] 2008 sive or both, and do not always prevent economic losses. The majority of management protocols have relied on the use of chemicals either as oral medications or bath treatments (e.g. Costello 1993Costello , 2006. For example, the in-feed medication SLICE ® (emamectin benzoate; Schering-Plough Animal Health) has been used to control many crustaceans, e.g. Lepeoptheirus salmonis in seawater aquaculture, Salmincola edwardsii and Argulus coregoni in freshwater aquaculture (Stone et al. 2000, Duston & Cusack 2002, Hakalahti et al. 2004a. Alternative methods are, for example, fallowing farm sites between stockings (Bron et al. 1993), use of cleaner fishes (Treasurer 2002) and removal of specific life-cycle stages from the parasite populations (Gault et al. 2002, Hakalahti et al. 2004b). The emergence of reduced sensitivity to chemical treatments with increased doses applied to control parasites, however, has lead to concerns about the sustainability of the industry (e.g. Jones et al. 1992), and consequently to the adoption of the Integrated Pest Management (IPM) concept into aquaculture (e.g. Sommerville 1998, Mordue (Luntz) & Pike 2002)....

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