Management actions in relation to the controversy about salmon lice infections in fish farms as a hazard to wild salmonid populations

Risk analysis provides a logical strategy for the identification of hazards in an area of concern leading to their management. This approach has rarely been used for research studies on the possible links between salmon lice in fish farms and variations in wild salmonid populations. Although correlation has been found between some data sets, a series of international meetings of experts has not been able to establish cause-effect relationships between lice on farms and the current low level of salmonid stocks in Europe and eastern Canada. Research in this area is currently in progress in western Canada. Views on the meaning of the correlations found have become highly polarized in both the scientific and non-scientific communities, with the same data often being interpreted in different ways. Farm lice levels are being managed by industry codes and by official strategies in Europe, but these programmes have not so far resulted in associated benefit to the size of wild salmonid stocks. The large array of factors that cause variations in both the size of fish stocks and the level of fish diseases is frequently overlooked. Using a risk analysis approach, the key contributory factors may be identified and appropriate remedial management actions designed to meet achievable objectives. Regular assessment of the effectiveness of the measures introduced would then be possible.