Sea lice in Iceland: assessing the status and current implications for aquaculture and wild salmonids

This is the first in-depth study which quantifies lice infestation levels on wild and farmed salmonids in a fjord system in Iceland (Arnarfjorour, Westfjords) and gives a baseline for the assessment of sea lice infestation within Icelandic fjords. The prevalence, abundances and intensities of sea lice infestation observed in this study were low and below the estimated thresholds for negative impacts of sea lice on their hosts. However, greater infestation levels occurred in 2 study sites located close to aquaculture farms, suggesting that farms were contributing to sea lice infestation. We infer that if production were to remain at the level in operation during this study, the threat of sea lice epidemics will be low. However, if salmonid aquaculture develops and production is expanded within the fjord, the risk of sea lice epidemics will increase, raising the need for environmental monitoring and coastal zone management.