the populations of other pinniped species at the 

 Farallones were usually near their annual low 

 (Ainley et al. footnote 3), which indicates even 

 further that elephant seals were the usual prey 

 of sharks. Rather exceptional were the high num- 

 bers of California sea lions present in the fall 1978 

 (Huber et al."*). Sharks and shark incidents were 

 seen often then but we could identify few of the 

 pinniped prey. One incident definitely involved 

 a sea lion but most others occurred in areas 

 frequented by elephant seals and not by sea lions. 

 Several elephant seals arrived at the Farallones 

 for the breeding season bearing shark-bite 

 wounds, some fresh and some healed. The his- 

 tories of these animals are noteworthy, particu- 

 larly since their being severely wounded may 

 have affected their reproductive performance. 

 Twenty-four breeding attempts by females identi- 

 fiable as individuals were available for analysis. 

 In 10 attempts, females arrived with fresh wounds. 

 In only one (10% ) did she successfully rear a pup by 

 herself, three lost their pups, three received help 

 from other cows (i.e., they shared suckling), and 

 three apparently did not pup. In 1977 three newly 

 wounded cows disappeared (not even present dur- 

 ing spring molt) after leaving the island with 

 healed wounds. In 14 pupping attempts by known 

 females with no wounds (but wounded in a later 

 year) or with old, healed wounds, all but two 



"Huber, H. R., D. G. Ainley, S. H. Morrell, R. R. LeValley and 

 C. S. Strong. 1978. Studies of marine mammals at the 

 Farallon Islands, California, 1977-78. Final report, Marine 

 Mammal Commission (Contract No. MM7AC025), Wash., D.C., 

 available Natl. Tech. Inf. Serv., Springfield, VA 22151 as 

 PB 80-111602, 50 p. 



Figure 2. — Annual cycles in monthly mean sea-surface tem- 

 perature, elephant seal numbers and number of shark/pinniped 

 interactions in the Farallon Islands, central California, vicinity, 

 1970-78. Seal numbers are from Ainley et al. (text footnote 3) and 

 Huber et al. (text footnote 4). 



(86%) successfully raised a pup without help. The 

 difference is significantly different from the 10 

 attempts mentioned above {t = 3.3, P< 0.001). 

 Since many of the freshly wounded females were 

 probably pupping for their first time, it could have 

 been lack of experience that resulted in their poor 

 record rather than being wounded. Two females, 

 however, without wounds raised their first pups 

 successfully but the next season, each with a fresh 

 wound, they either allowed another cow to help in 

 suckling or failed to pup successfully. In addition, 

 of 11 females pupping for their first time in 1977 

 and not having shark-bite wounds, 7 (64%) were 

 successful, and only 1 allowed its pup to be nursed 

 by another female. Thus females with fresh, 

 severe shark-bite wounds were less successful in 

 pupping than others. Perhaps the energy and 

 tissue-building resources needed to heal a severe 

 wound were taken from those required in the 

 rearing of a pup. None of the 6 females with fresh 

 shark wounds in the 1977 breeding season was 

 observed to copulate; among other females 99 

 (77%) were observed in copulation. 



Two male elephant seals have also hauled out at 

 the Farallones, bearing shark-bite wounds. One 

 first visited in December 1972 as a subadult bull 

 (probably about 5 yr old) and had an old shark-bite 

 wound. He returned each season through the 1976 

 breeding season. Another was first seen in 1972 as 

 a young adult (Le Boeuf et al. 1974) and was the 

 alpha bull in the breeding hierarchy during 1972, 

 1973, and 1974. In 1975 he arrived for the fourth 

 year, was initially the alpha bull, but was de- 

 throned before the end of the breeding season. In 

 1976 he appeared on the island with two fresh 

 shark wounds. Thereafter he visited the breeding 

 colony intermittently, but was not part of the 

 hierarchy of breeding bulls. 



Discussion 



It is obvious that the frequency of shark attacks 

 on pinnipeds and other shark observations have 

 been increasing at the South Farallon Islands 

 (Table 1). We are convinced this is not an artifact 

 of increasing observer awareness for a number of 

 reasons, because a flock of 50-1- gulls hovering for 

 10-15 min above a large, blood-red patch of water 

 within 50 m of shore is not easy to miss, particu- 

 larly from such a small island; and daily censuses 

 have been conducted consistently since 1970. 



Since the seasonal occurrence of some sharks 

 is related to water temperatures (e.g., O'Gower 



943 



