including C. clemensi and C. rogercresseyi, can cause deadly infestations of both farm-grown and wild salmon. Sea lice migrate and latch onto the skin of wild salmon during free-swimming, planktonic nauplii and copepodid larval stages, which can persist for several days. Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice. When exposed in river estuaries containing large numbers of open-net farms, mathematical models have suggested that many young wild salmon may be infected Adult salmon may survive otherwise critical numbers of sea lice, but small, thin-skinned juvenile salmon migrating to sea are highly vulnerable. Sea trout populations in recent years may have seriously declined due to infestation by sea lice, and Krkosek et al. have claimed that on the Pacific coast of Canada the louse-induced mortality of pink salmon in some regions is over 80%. A few studies indicated no long-term damage to fish stocks in some locations, and a population decline in wild salmon that occurred in 2002 was caused by "something other than sea lice". However, the repeated epizootics of lice on wild fish have only occurred in areas with salmon farms in Ireland, Britain (Scotland), Norway, Canada (British Columbia), and Chile. Field sampling of copepodids, and hydrographic and population models, show how L. salmonis from farms can cause mass infestations of seaward-migrating salmonids, and this effect can occur up to from the farms. Several scientific studies have suggested that caged, farmed salmon harbour lice to a degree that can destroy surrounding wild salmon populations. Other studies have shown that lice from farmed fish have relatively no effect on wild fish if good husbandry and adequate control measures are carried out (see section: Control on salmon farms). Further studies to establish wild-farmed fish interactions are ongoing, particularly in Canada, Britain (Scotland), Ireland, and Norway. A reference manual with protocol and guidelines for studying wild/cultured fish interactions with sea lice has been published. Fish farming Control on salmon farms This has been reviewed by Pike & Wadsworth, McVicar, and Costello. Integrated pest management programs for sea lice are instituted or recommended in a number of countries, including Canada, Norway, Scotland, and Ireland. Identification of epidemiological factors as potential risk factors for sea lice abundance with effective sea lice monitoring programs have been shown to effectively reduce sea lice levels on salmon farms. Natural predators Cleaner fish, including five species of wrasse (Labridae),