10 



> 

 o 



z 



LU 



D 



o 



LU 



OTTER TRAWL 

 N =38 



10 u 



n n 





D Juveniles 

 E3 dd on Fish 

 □ Unattached dd 

 ^ no on Fish 

 H Unattached ^ <J> 



nn 



3.4 



6.6 



9.8 



t 

 13.0 16.2 19.4 



SCUBA 

 N = 85 



5- n 



6.6 9.8 13.0 16.2 

 ISOPOD LENGTH (mm) 



19.4 



M.A. Thesis, San .lose State Univ., San Jose, Calif. 

 MONTALENTI, G. 



1941. Studi sull' ermafroditismo dei Cimotoidi. — I. 

 Emetka audouinii (M, Edw.) e Anilocra physodes (L.). 

 Publ. Stn. Zool. Napoli 18:337-394. 



Gary R. Robinson 



Department of Biological Sciences 

 I diversity of ( 'alifornia 



Santa Barbara, Calif. 



Present address: Charles Darwin Research Station 



Santa Cruz lata ml, Galapagos 



Casilla 58-39, Guayaquil, Ecuador 



Figure 2.— Comparison of size-frequency histograms for the 

 gill parasite, Lironeca vulgaris, from sanddab hosts collected 

 by otter trawl and scuba divers. Size distributions of isopods 

 were significantly different between the two samples (Kolmo- 

 gorov-Smirnov test, P<0.05). Small male isopods were notably 

 absent and several isopods were unattached to sanddab hosts in 

 the otter trawl sample. 



lations on C. stigmaeus and C. sordidus. This bias 

 is caused by the abandonment of hosts, particu- 

 larly by small male isopods. Shorter trawling 

 times may reduce the amount of bias. However, 

 when accuracy is desired, scuba is the preferred 

 sampling method. 



Acknowledgments 



S. Anderson, D. Richardson, B. Harman, and 

 S. Karl Kindly provided diving and trawling 

 assistance. A. Kuris, R. Warner, G. Wellington, 

 B. Victor, and M. Schildhaeur provided valuable 

 comments on the manuscript. 



Literature Cited 



Brusca, R. C. 



1978. Studies on the cy mothoid fish symbionts of the east- 

 ern Pacific (Crustacea: Cymothoidae). II. Systematics 

 and biology of Lironeca vulgaris Stimpson 1857. Occas. 

 Pap. Allan Hancock Found., New Ser. 2:1-19. 



1981. A monograph on the Isopoda Cymothoidae (Crus- 

 tacea) of the eastern Pacific. Zool. J. Linn. Soc. Lond. 

 73:117-199. 

 Keusink, C. 



1979. Biology and natural history of the fish parasite 

 Lironeca vulgaris (Crustacea: Isopoda: Cymothoidae). 



909 



