Parasite prevalence and intensity in Mugil cephalus (Pisces : Mugilidae), from Colorado River, Baja California, Mexico

The parasitic prevalence and mean intensity in the striped muller. Mugil ce phalus, was seasonally determined during an annual cycle (February 1994 to February 1995) in the confluence of the Colorado and Hardy rivers, Baja Cal ifornia. Mexico. Two species of parasites were identified, a nematode, Cont racaecum multipapillatum (von Drasche, 1882) (Ascaridida: Anisakidae), and a copepod, Ergasilus versicolor Wilson, 1911 (Poecilostomatoida: Ergasilida e). The larvae of C. multipnpillatum, which were represented by two size cl asses (A and B stages), had prevalences of 30% and 14.5%, respectively; whi le A. versicolor had a prevalence of 72.7%. The mean intensity of C. muitip apillatum was 6.18 and 2.37 individuals per infected fish for A and B stage s, respectively; and for A. versicolor, it was of 4.01, The number of paras ites (taxa combined) increased with the size of fish (p= 0.22. p= 0.02), bu t it was independent of the host's condition factor (K-SL).