Why do shark accidents happen?
We were all naturally very keen to hear what caused Erich's shark accident and why deadly shark accidents happen when we can see that the animals are reasonable and non-aggressive. First of all, you have to see that the shark in itself is not dangerous. It’s the same with a sleeping dog. But if the shark feels threatened it can become dangerous, just as the dog would bite if you suddenly touched it from behind.
Of course we cannot repeat the entire content of the lectures here, but I would like to mention a few key points: Poor underwater visibility, nearby estuaries, sand banks and edges of quay walls with large accumulations of fish, all these can lead to dangerous situations.
Erich showed us a few Google aerial photographs of regions where shark accidents had happened. After explaining the first few pictures, we were soon able to guess correctly in the following ones where the accident might have happened. The frequency of accidents near sandbanks surprised us, but this is where the shallow water means that sharks find themselves in a stressful situation. Imagine the sharks are surrounded by a three-dimensional spherical "comfort zone". If this is impinged upon by the water surface, their stress level increases. Sandbanks with their shallow water provide a high nutritional density, but reduce the sharks’ "comfort zone" to a minimum.
The lecture on the prevention of shark accidents was very entertaining. Erich has been trying to explain to the US Navy for years that their ditching manual contains instructions that are counterproductive! It tells pilots to clap their hands on the water surface to frighten away the sharks. In one video an aerial view clearly shows the sharks turning round immediately to swim towards the person who has disturbed the water surface by clapping their hands.
Erich was also able to disprove the commonly held theory that sharks confuse surfers with seals. Although sharks may not be the most intelligent animals on this planet, they have in the course of evolution learned what their prey really looks like. An attempt with a sound playing device, hanging in the water, and a surfboard a few meters away with a paddling doll clearly showed the sharks ignoring the "surfer" and with over 90% consistency biting the sound-producing object. So it’s not the silhouette of the "fat surfer", but a certain audio frequency which awakens the sharks’ curiosity. Erich was able to find out that a surfboard lying on the water surface produces “rattling” noises on the water surface that sound like injured fish. Sharks recognise the sounds as possible prey, but not the silhouette. So they try to find out what it is. If sharks had hands to feel with, there would not be a single dangerous incident with surfers.
Many millions of people invade the habitat of sharks every year. Yes, there are accidents and about five people die on average each year as a result of a shark accident. About 500 people die each year from defective toasters. But who is afraid of toasters?