macarovi, and Rhadinorhynchus cololabis in- 

 fections found on and in Pacific saury captured 

 off the Oregon, Washington, and British Colum- 

 bia coasts during August-September 1970-71. 

 Incidence of infestation and numbers of scars 

 resulting from previous copepod infestations 

 are presented by geographical areas and 

 correlated to size, age, and possible racial 

 composition of the host species. Sex ratio and 

 length data are included for R. cololabis re- 

 covered from saury; a second definitive host 

 infected by this acanthocephalan is reported. 



FISHERY BULLETIN: VOL. 71, NO. 4 



RESULTS 



Two copepods, Pennella sp. and Caligus 

 macarovi, and the acanthocephalan Rhadiuo- 

 rhy)ichus cololabis made up the major macro- 

 parasitic fauna of the eastern Pacific saury. 

 Other than an occasional nematode located in 

 the body cavity, additional metazoan parasites 

 were not detected. 



Incidence and intensity of infection of para- 

 sites recovered on and in saury throughout the 

 study are presented by sample in Table 1. 



MATERIALS AND METHODS 



A total of 4,396 saury sampled from 13 indi- 

 vidual fish schools captured in offshore waters 

 along the Pacific coast of North America between 

 lat. 44°01'N and lat. 49°16'N were involved in 

 this study. Fish were captured with a modified 

 purse seine-artificial light attraction system 

 (Ellis and Hughes, 1971). Random samples 

 were collected and frozen for processing at shore- 

 side facilities. In the laboratory, fish samples 

 were examined for copepod parasites and scars 

 from previous copepod infestations. Simul- 

 taneously, host length, weight, sex, maturity, 

 and age indicators were collected. Digestive 

 tracts from 20 saury randomly subsampled from 

 12 of the 13 samples were placed in 10% 

 Formalin'^ and later examined for metazoan 

 parasites with the aid of a dissecting microscope 

 (7 X — 50 X). Each R. cololabis was measured 

 (trunk length) to the nearest 0.5 mm, and its 

 sex determined by dissection and examination 

 of the posterior portion. Females were generally 

 swollen with bipolar eggs, and the uterus was 

 easily distinguished from cement glands in the 

 males. Host age was determined from scales. 

 Patterns of growth displayed on the scales were 

 used to identify the two hypothesized spawning 

 groups, spring- and autumn-born fish. 



Specimens were photographed in a circum- 

 illuminated lightbox, using standard techniques 

 and materials. 



^ Reference to trade names does not imply endorsement 

 by the National Marine Fisheries Service, NOAA. 



Peuuela sp. 



An adult fish heavily parasitized by this large 

 copepod is shown in Figure 1. In addition to 

 three mature females (one with broken egg 

 strings), two juveniles are shown — one posterior 

 to the pectoral fin and the other posterior to the 

 pelvic fin and above the anal finlets. Figure 2 

 shows an entire mature female (A), with a juve- 

 nile (B), after removal from the host. The exter- 

 nal portion of this parasite usually protruded 

 from the host at some point below the darkly 

 colored dorsal surface but above the lateral line; 

 and the head was usually lodged in or adjacent to 

 the host's heart or major blood vessels. The 

 tissue invading portion ends where the trunk 

 diameter increases notably. Infected hosts 

 weighed as much as 17% less than uninfected 

 hosts of equal length, and extensive destruction 

 of host tissue occurred during degeneration of 

 the parasite. 



Pennella sp. was frequently encountered in 

 each of the six samples collected in 1970 but 

 was detected in only one of seven samples 

 collected in 1971. Incidence of infection for 

 schools sampled in 1970 ranged from 17.0 to 

 21.6% (mean 18.4% )offOregon and 11.5 to 18.4% 

 (mean 14.5% ) off Washington. Multiple infec- 

 tions were common. Only 2.1% of one school 

 was infected in 1971 and no multiple infections 

 were detected. 



The 1970 data showed a trend toward increas- 

 ing incidence of infection with increasing host 

 size. To determine whether this noted increase 

 was a function of increasing host age, length, 

 or both, Washington and Oregon Pennella sp. 

 data were analyzed by host age groups, length 



944 



