Evidence that sharks attack undersea fibre-optic cables, mistaking them for fish

The Guardian reports, 14th August 2014: “Google is going to great lengths to reinforce some of the world’s undersea data cables after a series of shark bites, a product manager has revealed. The fibre optic cables, which carry internet traffic around the world, are protected by a series of layers to protect against impact and from movement that could break the glass fibres. Showing underwater surveillance video of a shark biting a cable, a cloud product manager said that Google is working with partner companies on cables across the Pacific to reinforce them with a Kevlar-like matting to prevent damage.

Older copper cables have not seen the same problem, and it has been speculated that sharks are attracted to the magnetic field created by the high voltage carried through the cables, which resembles those created by fish.

Sharks attack undersea cables causing internet disruption.
Photograph: Kevin Weng/Reuters

Fibre optic cables carry data across continents, in this case across the Pacific, and are the backbone of the internet. Each cable is made of many individual optical fibres, which are delicate but can transmit data at up to around 1 Gigabit per second or around 100 times faster than copper cables.

Most cables have shielding to specifically prevent electrical transmission outside of the protective layers, although whether this shielding prevents all electrical and magnetic fields from expanding beyond the cable is unknown.

Google is likely not the only company that suffers from shark bites and has to spend large amounts to protect their undersea infrastructure. Routes across the Atlantic require more than 50 repairs a year, broken by a range of things including fishing trawlers, anchors, earthquakes and water pressure at depth.

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