How severe are most shark attacks?

Shark attacks occur very infrequently, especially considering how much time so many people spend in the sea. Nonetheless they tend to make headline news regardless of their severity – whether simply a scratch or tragically fatal – as papers are quick to thrive off the public fear and intrigue.

Despite this general fascination with shark attacks, there has been no convention for the classification of how severe injuries sustained from a shark attack really are, with most available information simply stating whether or not they were fatal. Now, however, researchers at the University of Florida have formulated a five point scale to grade the severity of shark bites, similar to that used for categorising burns. The scale, termed the Shark-Induced Trauma (SIT) Scale, has been established after reviewing 96 cases that had complete medical records and it assigns scores to clinical findings (such as blood pressure, location and depth of injury, damage to the organs and death) in order to designate a value between 1 and 5.

In this manner higher values on the scale are assigned to more severe bite injuries. Lead researcher Dr. Ashley Lentz clarifies that, for instance, an abrasion to an extremity would simply score a 1 on the SIT scale, whilst a large bite to the thigh that severs the femoral artery and is subsequently life threatening would score a 5. From the study Dr. Lentz was able to show that the majority of attack victims only sustained very minor injuries:

The designation of 41.7% of shark attacks as level 1 on the SIT scale, with only 8.3% scoring 5, clearly shows that the majority of shark induced injuries are not at all severe. For example in Florida, dubbed by press as the ‘shark attack capital of the world’, shark attacks that only result in small lacerations account for more than 90% of injuries. The findings of Dr. Lentz et al. support and build upon general data records that show only a small proportion of shark attacks prove fatal: between 2002 and 2007 there was an annual average of 63.1 attacks, of which 3.8 per year were fatal.

Researchers have welcomed the scale saying that it will help medical personnel to better assess patient risk and administer the most appropriate treatment. In addition it will also allow the evaluation of trends in attack severity, and make it easier to communicate to the public how severe an attack actually was.

Understandably we have a predisposition to fear the unseen and potentially dangerous, but hopefully the research by Dr. Lentz and her team will help put the frequency and severity of attacks on people by sharks into an objective perspective.

If you’re interested in learning more about shark attacks and what might cause them, be sure to read Sam’s article ‘Why do white sharks bite people?‘.