Investigation of behavioural interactions between lumpfish ( Cyclopterus lumpus ) and goldsinny wrasse ( Ctenolabrus rupestris ) under controlled conditions

A series of studies were undertaken to determine the behavioural interactions between three different size classes (110, 70 and 32 g) of lumpfish, Cyclopterus lumpus L., and one size class (30 g) of goldsinny wrasse, Ctenolabrus rupestris L. The study attempted to determine whether goldsinny wrasse could coexist with juvenile lumpfish in an attempt to enhance lice grazing potential of Atlantic salmon by using both species simultaneously. The results indicate that both lumpfish and goldsinny exhibit quite a limited and similar palette of behavioural traits. Size-dependent dominance behaviour of lumpfish against goldsinny wrasse was found. When large (110 g) lumpfish were reared together with small goldsinny wrasse (30 g), aggression towards goldsinny was seen in 15 % of the time, whilst for 70 and 32 g lumpfish, aggressive behaviour against goldsinny accounted for only 6 % of all observations.