We found numerous cases of multiple species 

 myxozoan infections in the gallbladder, particu- 

 larly in individuals >35 cm. Twenty-two percent 

 of all infections were comprised of two species, 

 5.1^ of three, and 1.29£- of four. The occurrence of 

 myxozoans in Deretrema cholaeum-infected 

 gallbladders occurred less frequently than ex- 

 pected (y 2 = 123.3, P < 0.0001). 



The species of parasites infecting olive rockfish 

 by host length and age is shown in Table 4. 

 Sebastes serranoides harbors a maximum number 

 of parasite species between 31 and 40 cm or 4 and 

 10 yr of age [compared with 3-6 yr in S. alutus and 

 S. caurinus (Sekerak 1975)]. Of the five species of 

 parasites found in the smallest size class, four 

 exhibited direct life cycles, whereas in fish of 20 cm 

 (1-2 yr old) 6 of 11 species had indirect life cycles. In 

 the largest class (41-50 cm), slightly less than half 



(15 of 34) of the species had indirect life cycles. By 

 20 cm, representatives of all the parasite groups, 

 with the exception of microsporida, were found in 

 olive rockfish. The prevalence rates of six parasite 

 species and one parasite group increased signifi- 

 cantly with increasing host length (Fig. 2). Seven 

 species or species groups showed significant an- 

 nual changes in prevalence (Fig. 3). 



Discussion 



Of the seven parasite species showing increas- 

 ing prevalence with increasing host length, six 

 (Lepeophtheirus sp., Neobenedenia girellae, Micro- 

 cotyle sebastis, Holobomolochus spinulus, Henne- 

 guya sebasta, and the gallbladder myxozoans) had 

 direct life cycles and one (Hysterothylacium adun- 

 cum) had an indirect cycle. A change in diet to- 



TABLE 4. — Parasite species infecting five size classes of olive rockfish off Diablo Cove, Calif. See Table 1 for number of specimens 



per size class. 



533 



