Quantification of the Interaction Between a Parasitic Copepod, Caligus klawei Shiino, on its Fish Host, the Northern Anchovy (Engraulis mordax Girard), from Inner Cabrillo Beach, San Pedro, California, USA; with the Discovery of the Chalimus Stages of this Copepod and a Description of the Male

Infections of Northern Anchovies (Engraulis mordax) with the parasitic copepod Caligus klawei are reported from inspection of 1,256 anchovies collected at Inner Cabrillo Beach, San Pedro, CA during multiple collecting trips from 2014-2016. The overall prevalence of infection across all samples was 31.6%. The overall intensity of infection was 1.19. No significant correlation between the standard length of the host and prevalence or intensity was observed. Thirty-five of the 556 copepod specimens collected were in a chalimus developmental stage. This study constitutes the first record of developmental stages of C. klawei and their infection of E. mordax, the only recorded host for this species of copepod. Prior to this study, it was hypothesized that a possible intermediate host other than E. mordax may exist for the developmental stages of C. klawei. This current observation weakens the previous theory of an intermediate host and provides strong support that E. mordax is the sole host of C. klawei throughout its life cycle. A description of the male is also given herein for the first time, based on specimens collected, with a comparison of sexually dimorphic features