Caligus rogercresseyi is an important parasite of a wide range of wild and farmed fish, and is widely distributed along the coasts of Chile, Peru and southern Argentina. Infestation of C. rogercresseyi on farmed salmonids is associated with severe economic losses in Chile due to reduced fish quality, cost of chemical treatments and association with outbreaks of other diseases (see Risk Statement). For original description of this species, see Boxshall and Bravo (2000).
Type host: Oncorhynchus mykiss (Rainbow trout)
Other recorded hosts: Elginops maclovinus (Rock cod), Odonthestes regia (Chilean silverside), Paralichthys microps, Salmo salar (Atlantic salmon), Salmo trutta (Brown trout),…
The life cycle of C. rogercresseyi was described by González and Carvajal (2003) from lab-reared rainbow trout. As for other Caligus species, the C. rogercresseyi life cycles comprises 8 stages: two naupliar, one copepodid, four chalimus and the adult stage.
Diagnostic features of the adult female. Genital complex about 1.1 times longer than wide, without posterolateral lobes, and about 1.2 times longer than abdomen; abdomen about 2.6 times longer than wide, 2-segmented. No posteromedial process present on basal segment of antenna. Post-antennal process reduced. No additional process between post-antennal process and base of antenna. Maxilla typical, with a smooth posterior margin. Maxilliped with large process on myxal margin. Maxillule simple, no postmaxillary process. Sternal furca with parallel or divergent pointed tines. Posterior margin of leg 1 distal exopodal segment with normal plumose setae; seta 4 about same length as longest spine and shorter than segment; spines 2 and 3 bifid. Outer margin of second endopodal segment of leg 2 ornamented with fine spinules. Spine on first segment of leg 3 exopod slightly curved, overlaying but just shorter than second segment; apron without armature or distinct ornamentation. Leg 4, 4-segmented; distal exopodal segment with 3 spines (3 distal, 1 lateral).
Caligus rogercresseyi is a major pathogen in the salmon industry in Chile, with an estimated economic impact in excess of $200 million (USD) (Bustos, 2007). Atlantic salmon (S. salar) and rainbow trout (O. mykiss) are reportedly the most susceptible hosts to this parasite (Bravo, 2003). Infestation with C. rogercresseyi has also been associated with outbreaks of other diseases, e.g. Piscirickettsiosis or amoebic gill disease (AGD) (Bustos et al. 2010).