An understanding of shark movements and behaviour, however, is important to better understand the risk of encounters with sharks. Our research does not relate directly to shark attacks.
Sharks are a part of healthy marine ecosystems and being bitten by a shark is a real yet very unlikely danger of entering the sea.
The presence of sharks close to shore is normal and not new behaviour.
Our power to observe the sea has greatly increased due to technology allowing for sharks to be followed, aerial patrols as well as the rapid rise in sharing of mobile phone camera photos and experiences via the Internet.
The more we observe the more we see and this is especially true for sharks.
While it may give the impression that sharks have rapidly increased in numbers, it is the ability to see and report them that has substantially increased.
Teasing out real increases or decreases in shark populations from our increasing ability to observe white sharks is the focus of our research.
The presence of sharks is not always a good indicator of attack risk
Encounters with white sharks do not always lead to an attack.
In fact, there are many more sightings of white sharks by divers and other water users throughout Australian waters during which an aggressive interaction did not occur, than there are in which the safety of the person was threatened.
There are some popular bathing areas in Australia where white sharks are common yet these areas do not have a high rate of attack and on some beaches there have been no attacks despite frequent encounters.
The reasons why some encounters lead to an attack are unclear, but similar behaviours have been observed in terrestrial top-order predators such as 'big cats'.
Like other top order predators, white sharks do not continuously feed. They punctuate periods of predatory behaviour with lengthy periods of just swimming.
The presence of a large shark at any place frequented by people should always be taken seriously as the sharks can present a threat.
In most cases, however, encounters do not lead to an attack.
For these reasons too, the number of attacks, and how this varies from year to year, is a poor indicator of the number of sharks in the population.