Research Document - 2014/060

Monitoring for sea lice on wild salmon in western and eastern Canada

By Stewart Johnson and Simon Jones

Abstract

Well-designed and executed, systematic surveillance programs are necessary to obtain sea lice infection data from wild fish populations.  These data are necessary to inform decision makers with respect to the occurrence of sea lice parasitism within the wild population and the extent of bi-directional interactions of sea lice between the wild and farmed populations.  This section builds upon the peer-reviewed “Protocols and Guidelines for the study of interactions between salmonids and sea lice” that were developed by the BC Salmon Forum in 2006 (Appendix 1).  Various methods that are available for use in sea lice survey work are reviewed and an indication of their advantages and disadvantages is provided.  As well, aspects of the biology of sea lice, salmon and non-salmonid hosts and the environmental factors that need to be considered when planning sea lice surveys are also reviewed.  It is extremely challenging to design sea lice monitoring programs that take into consideration: ecological and behavioural differences between species of sea lice, ecological and behavioural differences between host species or hosts of different ages, the complex interactions between sea lice and salmon, the inherent natural variability of large ecosystems and the complex interactions which occur between hosts, sea lice, and environmental factors.  Furthermore, it is very unlikely that a single survey design or set of methods will be optimal for all situations under which monitoring of sea lice on wild fish may be conducted.  Surveys need to be designed and methods selected based on the goals of the monitoring program keeping in mind logistic and financial constraints.  Limitations posed by survey design or the methods used need to be carefully considered during interpretation of data and clearly communicated during reporting.

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