In the event of a shark attack, it’s crucial to determine which species of shark is responsible so authorities can take appropriate action. A new study suggests that first responders can use readily available medical gauze to obtain this information.
Typically, investigators rely heavily on eyewitness accounts and bite mark characteristics to determine which shark species was involved in an attack. Accounts can be very subjective and influenced by the trauma of the incident, but bite marks can be distorted by factors such as bite force, bite angle, and the material bitten.
This is where “transfer DNA” comes into play.
When a shark bites an object, such as a surfboard, kayak, or paddle board, it often leaves traces of its genetic material in the bite marks. Trained researchers can then use forensic-grade swabs to collect this material for later DNA analysis to see which species of shark bit it.
This information is vital to security efforts, as not all species attack humans for the same reasons. Additionally, some species are likely to simply be passing through the area, while others may be permanent residents. And if shark-hunting measures are implemented, it would be a shame if the wrong species were targeted.
Unfortunately, neither forensic researchers nor specialized swab samples are typically available at the time and place of an attack. By the time bite marks on a surfboard or similar can be professionally analyzed, genetic material may have been washed away. However, it is often is Immediately after a shark attack, a first aid kit is found at the scene.
A team of scientists led by Dr. Belinda Martin from Flinders University in Australia set out to see if the plain medical gauze included in such kits could be used by people like lifeguards to collect transferable DNA. The researchers began by examining a surfboarder who had been bitten in an attack during a surfboard race in Australia.
Flinders University
In this particular case, not only were there traces of DNA at the bite edge, but a relatively large piece of shark tissue was also left behind. Both forensic swab samples And Pieces of standard medical gauze were used to collect trace material and subsequently analyzed.
Both DNA collection methods were found to identify the culprit as a great white shark, and this was confirmed by more precise analysis of the larger tissue sample. Definitely It happened There is a possibility of misidentification in this case, as the shark tooth found on the deck of the boat from which the surfboard was recovered belonged to a different species.
In two subsequent attacks – one on a surfer and one on a surfboarder – the collection of transferred DNA from bites on both boards on gauze was again sufficient to identify the attacker as a great white. In one of these cases, the gauze was not analysed until 33 days after the attack (although it had been stored in a sealed container).
Flinders University
“We have shown that the use of gauze swabs, which are widely available and accessible, is a simple and effective alternative to forensic-grade sterile cotton swabs,” says study co-author Dr Michael Doane from Flinders. “We therefore encourage the use of gauze as a DNA collection tool by first responders, including surf lifeguards, police and paramedics.”
A paper on the research, which also involved scientists from the New South Wales Department of Primary Industries and the Queensland Department of Agriculture and Fisheries, was recently published in the journal Forensic Sciences International: Genetics.
Source: Flinders University