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Low-cost transponders could stop ‘ghost nets’ from wreaking havoc on marine life

Image credit: DT

Researchers have developed cheap, acoustic tags that can be attached to fishing gear in order to reduce the prevalence of wildlife-harming ‘ghost nets’.

Lost fishing gear, known as ghost nets, are a threat to many forms of oceans life. They have been found choking coral reefs, damaging marine habitats and entangling fish, marine mammals and seabirds.

They are also a danger to boats, catching in the propellers and are a key source of plastic pollution, gradually breaking up and disintegrating to add to the growing volume of microplastics in the ocean.

Now, Newcastle University researchers have developed matchbox-sized transponders that allow fisherman to retrieve their lost gear.

Prototype transponder

Costing as little as £100, the transponders will have very low power consumption, meaning the battery could last for months in the water. With nets sometimes costing thousands of pounds, the new tech is poised to be a “win-win” for both fishermen and the environment.

When the transponders come within range of a tracking signal, they emit a low volume ‘ping’ that allows fisherman to locate their nets. The noise is only made when the tracking signal is detected, in order to minimise the audible disruption to sea life.

Once located, fishermen can either try to recover the nets themselves or the fisheries authorities could be brought in to use underwater robotic technology to collect the marine litter in hard-to-reach places.

They could also be used by divers to tag litter they see in the ocean, so it can be retrieved later.

Jeff Neasham, senior lecturer in the School of Engineering, said: “We want to achieve a win-win scenario where modest investment by fishermen can be more than paid back by avoiding the loss of valuable assets, while also significantly reducing a major source of plastic pollution in the marine environment.

“These devices don’t sit there and transmit continuously, making a racket all the time; they sit and listen and they only talk if a unit on the surfaces accesses them to talk.

“We are not creating a big environmental problem with noise emissions - they will only talk if someone is in range searching for them.”

Underwater acoustic transponders and modems have historically been large and expensive technology costing up to £15,000, which limits their use to high-value applications, for example in the oil and gas industry.

Furthermore, many devices emit high power in transmission (up to 100 Watts), which has environmental implications for large scale use, or consume significant power when listening which requires large battery packs for long deployment.

These cheaper devices are able to send data reliably up to 3km range at a rate of 500 bits per second which is able to support many applications in underwater data gathering, diver messaging and asset tracking.

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