Sea louse control in Scotland, past and present

Methods for farming the Atlantic salmon (Salmo salar L) in Scotland were developed at the Unilever Research Laboratory facility at Lochailort on the west coast of Scotland in the late 1960s. By the spring of 1972 a fledgling commercial company had been set up and Marine Harvest, as it was known, received its first year class of smolts at Lochailort. Sea lice (Lepeophtheirus salmonis Krøyer) from passing wild fish infected the smolts but did not cause any significant damage until the summer of 1976 when intervention was required. The Scottish industry has since grown to become a vital source of employment for fragile rural economies and produced about 130,000 tonnes of salmon in 2000. This paper gives an overview of how fish welfare has been maintained by the development of treatments and management strategies aimed at minimising the impact of sea lice.