Interactions of caligid ectoparasites and juvenile gadids on Georges Bank

Abstract

The role of the ectoparasite Caligus sp. (Copepoda: Caligidae) in the northeast Georges Bank cod-haddock ecosystem was examined. Vertical distribution of free-living Caligus elongatus adults and host-parasite relationships of juvenile Caligus sp. and juvenile gadids are described at 2 locations with contrasting oceanographic properties, one thermally stratified and the other well-mixed. Gadus morhua had both greater prevalence and number of Caligus sp. ectoparasites than did haddock, Melanogrammus aeglefinus , at both locations. Preferred sites of attachment on the host also differed. Free-living C. elongatus were demonstrated to be a significant component of fishes' diet, particularly for cod