Shark Info Logo

Shark Info   (02-15-1999)



Shark Accidents or Shark Attacks ? 2/2

Shark Info

  Main article:

Which shark species are really dangerous?

Dr. E. K. Ritter

  Article 1:


Marie Levine

  Fact Sheet:

Biology of the Megamouth Shark

Dr. J. F. Morrissey


By Marie Levine

The "Global Shark Attack File" (GSAF) is one of the few large databanks which tries to fight the internationally propagated misunderstanding of the shark's alleged bloodthirsty behavior. In order for them to demystify the shark and its "JAWS image" they must gather and publish as much precise data as possible on shark attacks. The databank is maintained by the "Shark Research Institute" (SRI) seated in Princeton, New Jersey, USA. The GSAF documents more than 2,500 accidents experienced by divers, surfers, swimmers and fishermen and is based on information gathered by a network of assistants who investigate shark attacks globally. Although the GSAF also includes accidents dating back to the year 1501, today's attacks are investigated as thoroughly as possible.

The research method employed by the GSAF to compile current shark accident reports is described below:

Field Research

Whenever possible the victim's wounds are photographed prior to being operated on. This normally takes place in the operating or preparation room and is performed by medical personnel or by GSAF employees. Such photos are absolutely essential to enable reconstruction of the accident sequence and to determine which shark species was involved. Assistants and doctors are also asked to look for teeth fragments of the shark and finally to measure the wound, including the distance between the individual teeth impressions - additional factors which can simplify this search.

As soon as possible after the incident, GSAF employees contact and interview the victim. The victim's perceptions on environmental conditions, the shark's behavior and possible factors which could have favored the accident are then recorded in an initial questionnaire. Since many victims of such attacks suffer from lapse of memory regarding the accident - similar to the victims of car accidents and other traumatic experiences - a second interview is performed at a later time, but not before the first emotional trauma has been overcome, and before all participants in the accidents have been interviewed and the respective data analyzed. All persons involved in the accident - such as, for example, witnesses, medics, rescue swimmers, policemen, shore and medical personnel - are visited and interviewed.

All environmental data at the accident scene is registered - e.g., water temperature, visibility, tides, salt content of the water and current. The scene itself is photographed and those environmental factors found at the time of the accident which may be connected to the accident itself are noted. In this regard, dolphins, seals or other sea mammals can play an important role next to any observed unusual activities of fish and birds, and even anglers are considered vital witnesses because they can supply information on ocean conditions at the time of the accident. Investigations do not, however, end here.

The possibility of finding waste water from water purification plants is also explored and if appropriate noted, as well as the proximity of rivers and canals and their water level. Furthermore, data on prevailing weather conditions about one week prior to the day of the accident is gathered at local weather stations, while underwater photographs often document the accident scene.
In addition, a list of all objects found in the vicinity of the accident is compiled, including surf boards marked with shark teeth indentations, or wetsuits and bathing suits. Such objects are handled very carefully and are returned to the victim upon completion of the investigations. In some cases the SRI was allowed to keep surf boards which have been damaged by teeth bites for training purposes. In the rare case that a shark is successfully captured, it is examined for anatomical, physiological and biological abnormalities.

Data Evaluation

Final evaluation comprises an analysis of weather, oceanographic and environmental data. The medical evaluation describes the extent of the wounds and the treatment proved to the victim by the rescue squad and doctors (in fatal accidents this data is normally included in the autopsy or inquiry report). Explanations can be given by the responsible doctor. Additional investigations must be approved by the victim. Such consent is also included in the GSAF's questionnaire.
The species and size of the shark are determined on the basis of the victim's wounds.


Sometimes the shark bites through objects during the incident and as a result leaves parts of its teeth or jaw embedded in them. An evaluation of these objects includes measuring the length, width and diameter as well as the extent and position of the bites. In this connection, the distance between the centers of these bite impressions and the gaps between the teeth are also measured.


With surfboards, paddle skis or body boards the color and pattern of the top and bottom sides, the color and position of the skeg and the color of the foot line are registered. The board is photographed, with closeups made of the area bitten which is marked with a tape measure or a forensic teeth sample. A light source positioned behind the board can reveal details of the bite.

Large teeth parts in the wound or on the surfboard can be located with x-rays, however, the possibility still exists that small fragments may be overlooked. The xeroradiography is thus used to explicitly locate teeth fragments measuring less than 1 mm (similar to mammographies). Long exposure times and less power can result in very high resolutions so that differences between objects with a minimum thickness can be made visible.

Only at this point will the board be searched for teeth fragments. Knowing the form of the teeth indentations is very helpful in identifying the type of shark. The points marking the highest bite indentations can also be determined due to the compression of the foam core material which reduces the permeability of x-rays. This procedure requires longer exposure times than a mammography yet has no harmful effects on inanimate objects. After some experimentation we discovered that best results are achieved with a minimum of radiation (30 kvp) and exposure time (200-240 mAs).


Xeroradiography of a surfboard showing teeth impressions of a white shark, with arrows in the photo pointing to triangle impressions of the teeth.

© Shark Info / GSAF

Finally, the length, width and depth of the teeth marks are measured using a blunt probe (a pointed probe would penetate the teeth marks and result in misleading measurements).


As with surfboards, the color, pattern and thickness of wetsuits are also photographed. In this case, determining the width of the shark bite may cause some problems since the leg may have been twisted during the attack. If part of the leg is stretched, one might falsely assume that it was a large shark. Measuring the distance between the centers of the individual teeth impressions, the gaps between the teeth and the bite curve are useless if control measurements are not performed simultaneously on a test person of the same height, weight and stature. This person must put on the wetsuit, the gloves or booties and assume the same position as the accident victim.

Rescue swimmers, rescue teams and hospital personnel must be questioned about damage to the wetsuit (exception: normal wear and tear). In many cases the wetsuit is not removed by the rescue workers since it serves as a compression bandage, with clips being placed over the wound area. Such clips can tear the suit and these tears may resemble superficial bites. (With automobile accidents the victim is not necessarily removed from the car, but instead the car is removed from the victim. With shark accidents the procedure is similar: The suit is cut away from the victim, and obviously such damage to the suit can easily be mistaken for tears stemming from the shark!) Many oceanographic research stations maintain collections of shark teeth which are catalogued according to species, total length, weight and sex. As soon as the jaw is measured (e.g. based on surfboard markings) and the distance between the imprint points and species of shark are known, it becomes possible to draw conclusions on the size and weight of the shark.


This is the last phase of every investigation. Accident results are recorded in standardized form in order to make it easier for scientists to identify general factors and shark behavioral patterns, as follows:

  1. Place and date of the accident (longtitude and latitude, distance to reference points, e.g. places).
  2. Name and body description of the victim, including clothes and jewelry, as well as any equipment used by the victim, including harpoons and surfboards.
  3. General data on weather, water and environmental factors at the time of the accident. Also noted is the distance to the shore, the time of the accident, water depth and the victim's position. This information is supplemented by sketches of the accident scene with details on the shore, canals and rock formations.
  4. Narrative description of the accident sequence, also including the victim's subjective impressions and reports from witnesses.
  5. Medical description of the wounds by the doctor who treated the victim either in the Trauma Center or in the operating room. Any damage to surfboards or other objects which have been chewed up is also described. Sketches on the location and extent of the victim's wounds as well as close-up photographs of the bite and wounds are added to the description.
  6. Description of first aid measures taken and medical care, including any administered antibiotica.
  7. Description of the sequence of events surrounding the accident investigation. Discussion and analysis of this data, sketches or bite damage as reference for special descriptions.
  8. Conclusions
  9. Appendix. This section includes: names, addresses and telephone numbers of the victim and of all persons involved in the investigation; slides in archived form; mounted photographs which are protected with plastic foil, ready for archiving; and negatives in nonacid envelopes. Also enclosed are photocopies of all medical reports, meteorological and oceanographic data, completed questionnaires, media reports and any further information on the accident (even if it appears unimportant when making the report).

(9039 characters)

* Marie Levine Marie Levine is Head of the Shark Research Institute in Princeton and is responsible for the Global Shark Attack File.

May be published only by indicating the source: Shark Info / Marie Levine



last change: 06-04-2016 11:48