Nearby farms are a source of lice for wild salmonids: a reply to Jansen et al. (2016)
Jansen et al. (2016; Aquacult Environ Interact 8:349350) question the regression analysis presented in Serra Llinares et al. (2014; Aquacult Environ Interact 5:116) which corre lates lice abundances on farmed and wild fish. Jansen et al. (2016) argue that the correlation might not reflect a cause effect relationship but be instead a mere artifact of the spatio temporal covari ance in lice abundance on farmed and wild fish driven by temperature. In this Reply Comment we revisit the analysis presented in Serra Llinares et al. (2014) and further re analyze our data follow ing the statistical approach used by Helland et al. (2015; Aquacult Environ Interact 7:267280) to rule out the potential confounding effect of temperature. We conclude that Jansen et al. (2016) were correct in conveying part of the observed correlation to the effect of temperature; however, there is solid evidence of a significant influence of lice originating from nearby farms on the observed lice abundances on wild fish, even after the effect of temperature is accounted for.