Two Shark Incidents at Eniwetok Atoll, Marshall Islands 1 
E. S. Hobson , 2 F. Mautin , 3 and E. S. Reese 2 
The two shark incidents described in this 
paper can be be considered as unprovoked shark 
attacks (Gilbert et al. I960: 324). The impor- 
tance of documenting these incidents is that they 
were observed by persons with some experience 
in the study of animal behavior. The great need 
of precise and detailed observational informa- 
tion on shark attacks has been stressed in recent 
reports on the subject (Coppleson, 1938: ix; 
Gilbert et al, I960: 323; Tester, I960: 181). 
It is the belief of the authors that well-docu- 
mented reports of shark incidents will contrib- 
ute significantly to a clearer understanding of 
the stimulus situations in which shark attacks 
on man can be expected. 
The authors wish to thank Dr. Albert L. 
Tester, who read the manuscript and whose Of- 
fice of Naval Research contract Nonr-2756(00) 
Project NR 104503 enabled Mr. Hobson and 
Mr. Mautin to participate in the shark research 
program at the Eniwetok Marine Biological Lab- 
oratory, and the Atomic Energy Commission, 
whose support enabled Dr. Reese to work at the 
laboratory. The authors are also indebted to Dr. 
R. W. Hiatt, director of the laboratory, who 
made the facilities available. 
FIRST INCIDENT 
At noon on September 1, I960, Hobson, 
Mautin, and Reese were engaged in spear fish- 
ing activities on a reef about 25 ft. below the 
surface and approximately 200 yd. from shore 
on the lagoon side of Parry Island, Eniwetok 
Atoll, Marshall Islands. Dr. Richard A. Booloo- 
tian of the University of California was in a 
16-ft. skiff powered by a 35-hp. outboard motor 
which was idling nearby. The sea was calm, 
there was very little wind, and the sky was clear. 
Underwater visibility was in excess of 100 ft. 
1 Contribution no. 158, Hawaii Marine Laboratory. 
Manuscript received November 9, I960. 
2 Department of Zoology and Entomology, Univer- 
sity of Hawaii. 
3 781 5th Avenue, New York City. 
Table 1 indicates the nature of the equipment 
that was being used. The spatial relationship of 
the divers to one another and to the skiff above 
the reef at the start and the end of the encounter 
is shown in Figure 1. 
Hobson speared a 25-lb. grouper ( Plectro - 
pomus sp.), which swam, trailing the spear, 
beneath a large coral boulder (rock 1, Fig. 1). 
Almost immediately three grey sharks ( Car- 
charhinus menisorrah, Fig. 2), approximately 
5-7 ft. in length, appeared from the deep water 
of the lagoon and began to circle the rock. Hob- 
son observed ( 1 ) the sharks were swimming in 
an excited manner, and ( 2 ) they paid no atten- 
tion to him floating quietly on the surface. Sud- 
denly the grouper broke cover and dashed to a 
second large coral boulder (rock 2, Fig. 1). The 
three sharks immediately followed and began to 
circle the second rock. 
Reese, who was directly above rock 2, no- 
ticed the sharks and was also impressed with the 
excited appearance of their swimming. Mean- 
while, Hobson swam towards rock 2 to inform 
Mautin and Reese of the speared fish and the 
excited sharks in the area. At about this time 
Mautin observed the sharks and noted their ex- 
cited state. All three began to swim toward the 
skiff, making a conscious effort not to produce 
an undue amount of commotion on the surface. 
There were now four or five sharks swimming 
in an excited manner on the reef below. Mautin, 
who was unarmed and farthest from the boat, 
was swimming strongly in an effort to join the 
others. Both Hobson and Reese observed that 
Mautin’s swim-fins were breaking the surface of 
the water resulting in clouds of bubbles being 
carried beneath the surface at each down stroke. 
The following sequence of events was very 
rapid. Almost simultaneously with the above ob- 
servation, Mautin had reached a position almost 
above rock 2 ( see Fig. 1 ) . Suddenly one of the 
sharks rose from the bottom and swam very fast 
in a direct line towards Mautin. Mautin saw the 
approaching shark and rolled on his right side 
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