REDUCED LICE INFESTATION IN SALMON HELD IN MODIFIED SEA CAGES: THE USE OF 'SNORKELS' TO MANIPULATE SWIMMING DEPTH

摘要

The world-wide salmon aquaculture production in sea cages provides millions of hosts for parasites. Consequently, the abundance of sea lice has been drastically elevated, and the spread from aquaculture farms to surrounding systems are considered a global problem for the conservation of wild salmonids. Furthermore, sea lice infestation may impose poor welfare to the caged individuals and burden production management, while chemicals used to treat the fish pollute the environment. The economic cost ofsea lice to the salmonid farming industry was calculated in 2008 to range of ?0.1-0.2 kg~(-1) fish produced annually (Costello 2009).