Last year, increased resistance to sea lice treatments such as the pyrethroids cypermethrin and deltamethrin, as well as emamectine, was observed.
Pyrethroid use still increased from 2008 to 2009, although use of emamectine reduced significantly. Older sea lice treatments are being used again due to resistance problems, e.g. azametiphos, diflubenzuron and teflubenzuron. Hydrogen peroxide, which has not been used since 1997, was also used again in 2009, mainly under controlled conditions in wellboats.
The increase in antibacterial sales from 2008-2009 was marginal and, when seen in relation to the biomass of bred fish, the usage is very low.
Prescription-based statistics from the Norwegian Food Safety Authority for 2000-2008 show that antibacterials have been increasingly used in the treatment of newer breeding fish species, especially cod. For this period, the increase in the use in cod was positively correlated to the increase in biomass of cod produced. Data for sales per fish species for 2009 are not yet available.
Anthelmintics have shown an annual reduction in sales since 2004 and fungicides are back to 2008 levels.
