Lice infestations are one of the biggest problems in salmon aquaculture today costing the producer up to C$300/ tonne produced each year in losses and treatments. In recent years alternative methods of sea lice control, to complement therapeutant use, have become more popular as there are concerns over tolerance to therapeutants and the possibility of effects on non-target organisms. Northern Europe has begun using cleaner fish from the wrasse family to assist in controlling lice and two species in particular, the Goldsinny wrasse (Ctenolabrus rupestris) and the Balian wrasse (Labrus bergylta) have been identified as possible candidates.
In Atlantic Canada, the cunner Tautogolabrus adspersus (Walbaum), a northern member of the primarily tropical Labridae family, is a common fish with a wide range along the western North Atlantic coast from South Carolina, USA, to Newfoundland, Canada (Scott and Scott 1988; Bigelow and Schroeder 1953).
Cunners are common in shallow inshore waters near sheltered rock substrates, seaweed beds, wharves, wrecks, and reefs. Like other wrasses, cunners use these habitats as a shelter or cover for protection during their evening quiescence and during their over-wintering torpor (Dew 1976). Because of its relative abundance, ease of capture, scan-and pick feeding behaviour, as well as its dualistic spawning tendency it has received attention as the best candidate to serve as a Cleaner Fish for the Canadian Atlantic salmon industry. Little is known, however, about its efficacy in cleaning lice from salmon or its adaptivity to captive culture conditions.
This study is designed to investigate the utility of the cunner to control sea lice on Atlantic salmon. The first phase has established a good survival rate, with evidence of adaptation to captive culture conditions. Future work will include study of optimum tank habitats, including the construction of artificial shelter structures, spawning and larval rearing.