Shark Deterrent! How Close Is Too Close?

sharktrooth batman shark repellent batspray

Earlier this month, some scientists published a paper on the effectiveness of electrical field deterrents on Great White Sharks:

How Close is too Close? The Effect of a Non-Lethal Electric Shark Deterrent on White Shark Behaviour

Ryan M. Kempster, Channing A. Egeberg , Nathan S. Hart, Laura Ryan, Lucille Chapuis, Caroline C. Kerr, Carl Schmidt, Charlie Huveneers, Enrico Gennari, Kara E. Yopak, Jessica J. Meeuwig, Shaun P. Collin

ABSTRACT:

Sharks play a vital role in the health of marine ecosystems, but the potential threat that sharks pose to humans is a reminder of our vulnerability when entering the ocean. Personal shark deterrents are being marketed as the solution to mitigate the threat that sharks pose. However, the effectiveness claims of many personal deterrents are based on our knowledge of shark sensory biology rather than robust testing of the devices themselves, as most have not been subjected to independent scientific studies. Therefore, there is a clear need for thorough testing of commercially available shark deterrents to provide the public with recommendations of their effectiveness. Using a modified stereo-camera system, we quantified behavioural interactions between white sharks (Carcharodon carcharias) and a baited target in the presence of a commercially available, personal electric shark deterrent (Shark Shield Freedom7). The stereo-camera system enabled an accurate assessment of the behavioural responses of C. carcharias when encountering a non-lethal electric field many times stronger than what they would naturally experience. Upon their first observed encounter, all C. carcharias were repelled at a mean (± std. error) proximity of 131 (± 10.3) cm, which corresponded to a mean voltage gradient of 9.7 (± 0.9) V/m. With each subsequent encounter, their proximity decreased by an average of 11.6 cm, which corresponded to an increase in tolerance to the electric field by an average of 2.6 (± 0.5) V/m per encounter. Despite the increase in tolerance, sharks continued to be deterred from interacting for the duration of each trial when in the presence of an active Shark Shield. Furthermore, the findings provide no support to the theory that electric deterrents attract sharks. The results of this study provide quantitative evidence of the effectiveness of a non-lethal electric shark deterrent, its influence on the behaviour of C. carcharias, and an accurate method for testing other shark deterrent technologies.

Recently, another product hit the market – the Sharkbanz. Sharkbanz is based on electro-magnetic field disruption as a deterrent and some guys in Australia put it to the test and filmed the results:

Sharktrooth’s opinion:

Some of these products do seem to have an initial benefit, which may buy you enough time to get out of the water if a shark is displaying aggressive behaviour towards you. In that respect – they could turn out to be lifesavers. However, due to the fairly rapid increase in tolerance from the animals, Sharktrooth believes that the best items to equip yourself with before entering the water with sharks are knowledge and respect.

sharktrooth

Just for fun – here is the iconic scene from Batman in 1966 (skip to 3 minutes in if you just want to see the battle with the shark):

 

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