O100r 

 P 90 

 ft 80 

 u! 70 

 ? 60 

 t- 50 

 5 40 

 O 30 

 £ 20 

 Q- 10 



OlOOr 



£ 90 

 O 80 

 £ 70 

 Z 60 

 H 50 

 Z 40 

 O 30 

 gj 20 

 Q- 10 



O.100 

 uj 90 

 O 80 

 £ 70 

 Z 60 

 t- 50 

 g 40 

 O 30 



£ 20F 



o. 10 



H. aduncum 



M J 



MJJASONDJF 

 MONTH 



Lepeophtheirus sp. 



\ 



/"' 



 



MJJASONDJF 

 MONTH 



q100 

 UJ 90 

 O 80 

 £ 70 

 Z 60 

 . 50 

 Z 40 

 S 30 

 a. 20 



q. TO 



100r 

 90 

 80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 



Q100 

 l= 90 

 ft 80 

 £ 70 

 - 60 

 \- 50 

 £ 40 

 O30 

 S 20 

 °- 10 



D. choleum 



\y 



y 



^__ i___^ 



AMJJASONDJF 

 MONTH 



Myxozoa sp. 



X 



M J J A S N 

 MONTH 



Hemiundae 



D J 



/ 



\ 



MJJASONDJ 

 MONTH 



M J J A S O 

 MONTH 



FIGURE 3. — The relationships between month of capture and percent prevalence of infection by seven parasite species from olive 

 rockfish taken off Diablo Cove, Calif. All relationships show significant differences at P =s 0.05. See Table 1 for the number of 

 specimens per month. 



movements and reproduction to coincide with that 

 period when their hosts may be at closest proxim- 

 ity with each other. This phenomenon was ob- 

 served between the Monogenea, Dactylogyrus vas- 

 tator and Mazocraes alosae, and their respective 

 hosts, Cyprinus carpio and Alosa sapidissima 

 (Kennedy 1975). 



Parasites with maximum prevalence during 

 other periods all had indirect life cycles. The 

 hemiurid trematode infections peaked in autumn, 

 Opechona sebastodis in summer, and Hys- 



terothylacium aduncum was most abundant in 

 April and August. Seasonality among hemiurids 

 has been reported by Shotter (1973) in whiting, 

 Odontogadus merlangus, of the Irish Sea and in 

 staghorn sculpin, Leptocottus armatus, from Ore- 

 gon by Burreson and Olson (1974). In both cases 

 infections were greatest in late summer or early 

 fall. 



The infection patterns we observed may reflect 

 differences in the oceanographic conditions off 

 central California. Water conditions in this region 



535 



