Fisheries Science 62(5), 830-831 (1996)

Short Paper

A Fatal Shark Attack in Aichi Prefecture, Japan,

with Other Confirmed Attack Cases in Japanese Waters

Kazuhiro Nakaya

Laboratory of Marine Zoology, Faculty of Fisheries, Hokkaido University,

Minato-cho, Hakodate, Hokkaido 041, Japan

(Received September 11, 1995)

Key words: shark attacks, white shark, Carcharodon carcharias, Aichi Prefecture, Japanese

waters

A fatal shark attack on a shell diver occurred in Aichi Prefecture, middle Japan on April 9, 1995, and a detailed investigation of the victim's wet suit was made at the re

quest of Nagoya Maritime Safety Office. The regulator and the harness, which were discovered about one month later at the attack site, were also sent to the author for detailed inspection. The present paper reports the results of the investigation of the wet suit and diving gears in the Aichi case, disscusses the identity of the attacking shark species, and also records other cases supplemental to the Japanese shark attack list.1)

A 47 year old professional diver, Mr. Shintaro Hara, was engaged in fishing for the bivalve Panopea japonica (Japanese name: Namigai, Shiro-mirugai) on April 9, 1995 off the west end of Atsumi Peninsula in Aichi Prefecture. He wore SCUBA and a black wet suit, and carried a lamp and a nozzle of a water-jet hose for digging the shell from sand bottom. His wife was tendering on the boat above him, supporting her husband's underwater work. According to interviews, at first the position of bubbles from the diver began to move around unusually on one side of the tendering boat, and then the bloody water came up with the bubbles. The shark soon came up to the surface with the victim in the jaws, shook its head violently, severing the body on the right side, and disappeared. The body was left afloat and it was pulled aboard the boat by colleagues. The air tank and weight belt were not on the victim's body. Mr. Hara was transported immediately to the hospital, but apparently he had been killed instantly. An autopsy was performed by Mr. Seiji Itoh, a coroner of Gamagouri Maritime Safety Office, and he reported that the right half of the pectoral region, including the right arm, was severed and missing from the shoulder to the waist, and the detail results of the autopsy were sent to the author for identification of the attacking shark species.

The victim wore black inner and outer rubber wet suits. The right side of the trunk and the right arm of the inner and outer jackets were missing below the base of the neck and the upper right corner of the pants was also cut away

(Fig. IA). Many tooth marks were found along the cut margin of the suit (white dots in Fig. 1A). Fine notches were discovered along the cut margin of the suit, and fine streaks were left on the sectioned surfaces (Fig. IC). The tooth marks were confined on the right half of the jacket

Fig. 1. Diving gears used by the victim in Aichi case.

A, wet suits (left: inner suit, right: outer suit), white dots show

tooth marks; B, harness; C, enlargement of a tooth mark on wet suit; D, sectioned surface of air hose.

and pants, and no tooth mark or scratch was found on the other parts of the suits. Various measurements were taken on the remaining part of the wet suits and tooth marks. Maximum diameter of the missing part of the wet suit was 46 cm from neck to the lateral side of the abdomen. The width of the jaws estimated by the distribution of tooth marks was roughly 40 cm. The distances between neighboring tooth marks ranged from 18.5 mm to 62 mm, mostly between 35 mm and 50 mm.

Although the air tank and the weight belt were missing at the time of the accident, they were subsequently recovered from the nearby bottom on May 4, 1995. Mrs. Etsuko Hara, the victim's wife, sent me the harness and the

Nakaya 831

Table 1. Recent shark attacks in Japan

*1 Shark attack case number of International Shark Attack File, Florida Museum of Natural History, Gainesville, Florida, 32611-2035, U.S.A.*2 Present report,

regulator. The right side of the hard plastic harness received eight narrow, sharp and long cuts, 1.6 mm wide, 7 to 34 mm long and about 10 mm deep (Fig. 1B). Fine clear streaks were observed on the cut surfaces, and the width of one streak averaged 0.8 mm. The right shoulder belt was cut off at the shoulder and waist, and the middle part of the belt is missing. The waist belt received a deep cut on the left side of the buckle, and was cut off at the right side of the harness. Other parts of the harness and the left shoulder belt received no damage. The two hoses on the regulator leading to the mouth piece and the depth gauge were cut off at about 18 cm from the regulator, and had received some additional scratches. The air hose was cut obliquely, with many parallel fine streaks on the surface (Fig. 1D).

There were about 80 fishing boats nearby when the acci

dent happened. According to Mr. Sadao Hara (pers.

comm.), the shark reappeared at the same place 15 or 20

minutes after the accident, and hovered under the stern of

Mr. Sadao Hara•Œs fishing boat for about half a minute. He

described it as a huge dark colored shark without any pat

terns, and estimated the shark about 6 meters in total

length, in comparison with his boat size. After the attack,

fishermen attempted to capture the attacking shark, but no

large shark was caught from the nearby waters.

According to the Nagoya Maritime Safety Office, the at

tack happened at 10:15 a.m. at a depth of 25 meters on the

sandy bottom about 1 km offshore in Atsumi-cho (34°

35.6•ŒN, 137°01.6•ŒE). The weather condition was cloudy,

but the sea was calm. The surface water temperature was

reported about 13•Ž at the attack site. The oceanic and

weather conditions of the day at the nearest oceanographic

observation station (34°40.3•ŒN, 137°06.0•ŒE), which is lo

cated about 10 km N.W. from the attack site, were as fol

lows: air temperature 12.2•Ž, water temperature and salin

ity 11.4•Ž and 32.3%o at surface, and 11.8•Ž and 32.5%o at

bottom (14 m deep).

The distribution of the tooth marks left on the wet suit appeared to show the arched arrangement of the teeth on the jaws . The width of the jaw was estimated at least 40 cm, suggesting a huge shark species. Fine notches and streaks were found on the surface of cuts on the wet suit, harness and breathing tube, and these indicate that the attacking shark has serrated teeth on jaws. Collier2) dis-

cussed the relationship of dentition and the wound charac

teristics, and concluded that the serrated teeth of white

shark mostly give rise to long, narrow, razor-like cuts,

while the more rounded unserrated teeth as those in bonito

shark produce circular punctures with ragged edges. The

cuts on the wet suit were sharp, and the very narrow long

cuts were left on the plastic harness. The water tempera

ture was between 11 •Ž and 13 •Ž. These facts are very simi

lar to those seen in the Matsuyama case, in which a white

shark was involved, and it is most reasonably inferred that

the attacking species was a white shark Carcharodon car

charias in this case as well. The white shark is a cool water

species, usually appearing in the waters of 11 •Ž to 24•Ž,3)

with the coldest record for the species at 7•Ž.4) Nakaya5) in

vestigated the occurrence of white shark around Japan,

and suggested that the white shark is likely to stay in the

waters of southern Japan, including waters of Aichi

Prefecture, throughout the year. Verbal evidence given by

Mr. Sadao Hara also support the above conclusion of at

tacking species. The width of jaws, estimated about 40 cm,

equates to a 5.2 m white shark caught in Hokkaido which

had a mouth width of this size.4)

Present Aichi case and other confirmed shark attack cases are summarized in Table 1. See Nakaya1) for other shark attacks occurred in the Japanese waters.

Acknowledgments Dr. G. H. Burgess (Florida Museum of Natural History, University of Florida, U.S.A.) read the manuscript. Mrs. Etsu

ko Hara (Atsumi-cho, Aichi Prefecture) gave me permission to examine the harness and the regulator of her husband. Mr. Sadao Hara (Atsumi

cho, Aichi Prefecture), Dr. Masahiro Kohama (lejima Medical Health Center, Okinawa), Dr. Yasutetsu Araki (Okinawa Prefectural Health In

stitute), and Nagoya and Gamagouri Maritime Safety Offices were helpful in obtaining the information about the shark and the accidents. The oceanographic data and various information were supplied by Aichi Fish

eries Experimental Station.

References

1) K. Nakaya: Japan. J. Ichthyol., 40, 35-42 (1993).

2) R. S. Collier: Environrn. Biol. Fish., 33, 319-325 (1992).

3) J. 0. Casey and H. L. Pratt, Jr.: Mem. South Calif. Acad. Sci., 9, 214 (1985).

4) H. Nakano and K. Nakaya: Japan. J. Ichthyol., 33, 414-416 (1987).

5) K. Nakaya: Fisheries Sci., 60, 515-518 (1994).