TABLE 1. — The number of olive rockfish taken per month per 

 size class, April 1975-February 1976. 



Thirty-six parasite species were recovered from 

 olive rockfish (Table 2). Five species were found in 

 <1% of the individuals examined. These inciden- 

 tal parasites were an unidentified microsporidan 

 and the copepods Neobrachiella robusta, Chon- 

 dracanthus pinguis, Naobranchia occidentalis , 

 and Sarcotaces arcticus. Found in <10% of the 

 hosts were Davisia reginae, Kudoa clupeidae, Lep- 

 totheca longipes, and L. macrospora (Myxozoa); 

 Trochopus marginata (Monogenea); Aporocotyle 

 macfarlani, Lecithaster gibbosus, Lecithochirium 

 exodicum, Parahemiurus merus, and Tubulovesi- 

 cula lindbergi (Digenea); Anisakis sp. and Phoca- 

 nema sp. (Nematoda); Caligus sp. and Clavella 

 parva (Copepoda); and Rhabinorhynchidae gen. sp. 

 (Acanthocephala). 



Larval cestodes were the most commonly en- 

 countered parasites, infecting 98% of all individu- 

 als >20 cm in length. Larval Contracaecum sp. 

 were found in 62% and cysticanths of immature 

 Corynosoma sp. in 18% of fishes >20 cm. 



Of parasites which use Sebastes serranoides as a 

 final host, Microcotyle sebastis had the highest 

 prevalence, occurring on more than 90% of hosts 

 >20 cm. It was most prevalent on the filaments of 

 the first gill arch (Table 3), declining in number 

 through successive arches (x 2 = 108.1, P < 0.001). 

 No significant differences in infection intensities 

 were noted between left and right arches. 



Other commonly encountered ectoparasites 

 were Holobomolochus spinulus, Neobenedenia 

 girellae, and Lepeophtheirus sp. Adult metazoan 

 endoparasites were not abundant, though three, 

 Deretrema cholaeum, Opechona sebastodis, and 

 Hysterothylacium aduncum, were often found in 

 larger fish. 



Three myxozoans, Henneguya sebasta, Lep- 

 totheca in for mis, and Zschokkella ilishae, were 

 found in more than 10% of hosts. Henneguya 

 sebasta was found in 93% of hosts >35 cm. Nine 



percent of H. sebasta infections were sufficiently 

 severe to virtually occlude the bulbous arteriosus. 

 Although no histological sections were made, no 

 evidence of gross pathogenic effects were noted, as 

 these heavily infected individuals were of an age 

 and weight indistinguishable statistically (analy- 

 sis of variance) from lightly or non-infected indi- 

 viduals. 



TABLE 2. — Parasites recovered from olive rockfish, Sebastes 

 serranoides, off Diablo Cove, Calif. *denotes first host records. 



Parasite 



Location 



Protozoa (Myxozoa) 

 Ceralomyxa sebasta 

 Davisia reginae 

 Henneguya sebasta 



'Kudoa clupeidae 



Leptotheca informis 



Leptotheca longipes 



Leptotheca macrospora 



Myxidium incurvatum 



Zschokkella ilishae 

 'Protozoa (Microsporida) 

 Monogenea 



'Microcotyle sebastis 



'Neobenedenia girellae 



'Trochopus marginata 

 Digenea 



'Aporocotyle macfarlani 



'Deretrema cholaeum 



'Lecithaster gibbosus 



'Lecithochirium exodicum 



'Opechona sebastodis 



'Parahemiurus merus 



'Podocotyle sp. 



'Tubulovesicula lindbergi 

 Cestoda 



"Tetraphyllidea (immature) 

 Nematoda 



Anisakis sp. (immature) 



'Contracaecum sp. (immature) 



'Hysterothylacium 



( =Thynnascans) aduncum 



Phocanema sp. (immature) 

 Copepoda 



'Neobrachiella robusta 



Caligus sp. 



'Chondracanthus pinguis 



'Clavella parva 



Holobomolochus spinulus 



'Lepeophtheirus sp. 

 'Naobranchia occidentalis 

 'Sarcotaces arcticus 

 Acanthocephala 

 'Corynosoma sp (immature) 

 "Echinorhynchus gadi 

 "Rhabdinorhynchidae gen. sp. 



Gallbladder 

 Urinary bladder 

 Bulbus arteriosus, 



gallbladder (rarely) 

 Muscle 

 Gallbladder 

 Gallbladder 

 Gallbladder 

 Gallbladder 

 Gallbladder 

 Urinary bladder 



Gills 



Skin, mouth 



Gills 



Afferent branchial arteries 



Gallbladder 



Stomach 



Stomach 



Intestine 



Stomach 



Stomach 



Stomach 



Viscera 



Viscera 

 Viscera 



Stomach, intestine 

 Muscle 



Gills 



Skin, gills 



Gills 



Dorsal and anal fin rays 



Gills, inner surface of 



gill opercula 

 Skin, gills 

 Gills 

 Body cavity near anus 



Viscera 



Intestine 



Intestine 



TABLE 3. — Position and number of 

 Microcotyle sebastis on 32 olive rock- 

 fish, Sebastes serranoides, off Diablo 

 Cove, Calif. 



532 



