A Fatal Attack by a White Shark in Japan and a Review of Shark Attacks in Japanese Waters

Abstract

On March 8, 1992, a male professional diver was collecting the pen shell Atrina pectinata, Japanese name Tairagigai, at a depth of 22 m about 2.3 km offshore of Matsuyama, Ehime Prefecture, Japan. At about 15: 20 he was attacked by a large shark, and only a severely damaged diving suit and helmet were recovered. The right half of the trunk and right leg of the suit were torn off. A rescue rope and a rubber radio cable, both of which connected the diver to a support boat were severed, but the diver's air tube remained intact. The diver's body was not recovered, nor was a shark captured that might have perpetrated the attack, despite extensive fishing efforts by local fishermen. A small piece of a broken shark tooth was recovered from the rubber surrounding the neck of the diving suit. The tooth fragment contained two large serrations of about 0.85mm in width. The suit's steel shoulder protector had a single hole (6mm×3mm), penetrated by a shark tooth. The edge of the hole showed regular minute undulations, and the cut surfaces on the rubber and the cable had minute parallel streaks, both apparently made by the serrations of shark teeth. Tracing of the scratches and cuts on the shoulder protector and back part of the diving suit made it possible to estimate a jaw size of about 40cm in width, suggesting a very large shark. The water temperature was low about 11.6°C, at 20m depth at a nearby locality. These facts support the contention that the shark involved in this incident was a white shark of about 5m in total length. Shark attacks in Japanese waters were investigated, and at least sixteen shark attacks on people and boats were recognized.