NOTE Long: Predation by Carchaiodon carchanas on Kogia breviceps 



539 



Figure 1 



Left lateral view of bite scars from a white shark Carcharodon carcharias on the anterior caudal peduncle of 

 a live 1.8 m juvenile male pygmy sperm whale Kogia breviceps. Dorsal scars correspond to the upper jaw of the 

 shark, and ventral scars correspond to the lower jaw. 



violently to inflict a fatal initial bite. The bite marks 

 on the ventral surface of the whale were deeper than 

 the dorsal set of scars, and the deepest scars were on 

 the upper left and lower right, indicating initial pene- 

 tration with the lower teeth, biting down of the upper 

 jaw, and a roll to the left as the shark attacked the 

 whale. The initial bite was relatively superficial and 

 apparently unsuccessful, since the whale survived the 

 attack. The bite-and-spit attack behavior of the white 

 shark (McCosker 1985, Tricas and McCosker 1984) may 

 have allowed the whale to escape any further injury 

 by the same shark. 



Many white shark attacks are made while the prey 

 is floating or swimming at the surface, and the shark 

 usually attacks from below or behind (McCosker 1985). 

 Pygmy sperm whales have been observed floating 

 quietly on the surface of the ocean with the tail hang- 

 ing low in the water (Caldwell and Caldwell 1989). This 

 'basking' behavior seen in Kogia may facilitate easier 

 attack by predators. 



Although shark predation on smaller odontocetes is 

 apparently rare, white sharks are known to attack and 

 eat living dolphins (Arnold 1972, Corkeron et al. 1987). 

 White sharks are also known to eat marine mammals 

 as large as adult male elephant seals. Le Boeuf et al. 

 (1982), documented remains of a 3m-long male ele- 



phant seal that may have weighed over 600 kg taken 

 from the stomach of a 4.7m white shark. Thus, a 1.8m, 

 82 kg whale is within the size range of white shark prey. 



Based on calculations by Randall (1973), the width 

 of the bite marks on the pygmy sperm whale (roughly 

 25 cm wide) and the relative spacing between individual 

 tooth scars indicate a 4-5 m shark made them. Pratt 

 et al. (1982) recorded white sharks 4-5m-long feeding 

 on the carcass of a dead fin whale Balaenoptera phy sa- 

 ins, and Le Boeuf et al. (1982) examined seven white 

 sharks ranging in length from 2.4 to 5.5 m and recorded 

 pinniped remains in each of their stomachs. Therefore, 

 medium and large white sharks attack and consume 

 marine mammals their size or smaller, and scavenge 

 on cetacean carcasses larger than themselves (Klimley 

 1985, McCosker 1985, Pratt et al. 1982). 



This is the first report of an attack on a Kogia, and 

 on any cetacean in the northeast Pacific by a white 

 shark. It is one of the few records of a shark attack 

 on a live cetacean, other than a porpoise or dolphin. 

 In a recent review, Caldwell and Caldwell (1989) list 

 no known predators for Kogia; this observation impli- 

 cates white sharks as a predator. 



Although such predation has not previously been 

 reported, the ranges of white sharks and Kogia overlap 

 in the coastal areas of eastern and western North 



