It must be Spring time, as Argyll Fisheries Trust has started its 2013 programme of sweep netting for sea trout as they migrate from the rivers to the coastal area.  We have been netting for sea trout since 2001 to monitor the numbers of sea lice found on the lice.

Sea lice are naturally occurring parasites of wild salmon and sea trout, however in areas with salmon fish farms sometimes a massive increase in abundance of lice can be found, and that is when sea lice become a problem to wild salmonids. 

The focus of our monitoring has changed over the years.  Initially we were looking to establish a link between high numbers of sea lice on sea trout and the presence of fish farms.  We are satisfied that such a link exists, and now, with the assistance of Marine Scotland Science, we are trying to establish up to what distance fish farms can have a harmful effect on wild salmon and sea trout.  The best estimate just now is 31 km.

The sweep netting is part of the RAFTS Managing Interactions with Aquaculture Project (MIAP).  More information about this project and reports to download can be found here http://www.rafts.org.uk/aquaculture/

Laying out the net

The bay near Dunstaffnage

A lovely sea trout

This poor soul had 165 sea lice on him.  Not nice!

Source: Argyll Fisheries Trust – 2013 Sweep netting for sea trout