A computer rendering of how fish might travel through SafetyNet's escape rings.
An early prototype of the SafetyNet escape rings.
A prototype ring, lighting up within the trawler net.
What it does
The SafetyNet is a new trawling system that could help decrease catching and the subsequent discarding of juvenile and endangered fish. By exploiting fish behavioral habits and physiology the trawl separates different species and ages of fish. The goal is to use SafetyNet devices in conjunction with legislation to help tackle the issues of bycatch and discarding.
A BBC article alerted me to some of the issues around overfishing and I wanted to find out more. I discovered that 40% of the global population are dependent on fish as their protein source, and yet commercial fisheries are struggling to fish sustainably. Half of fish caught in the North Sea, many of them juveniles, are thrown back dead, leading to diminishing stocks. This is a global problem which needs to be solved in order to guarantee a reliable food supply for future generations.
How it works
Several working prototypes have been created - both battery powered and energy harvesting - and the rings will soon be trialled in conjunction with a UK government body. Particular attention has been paid to finding materials and processes that can withstand the rough nature of the fishing industry and chemical attack of a marine environment. I have aimed to keep manufacturing cost and complexity to a minimum, making them affordable for fishermen. Strength, performance at 25 atmospheres pressure and different methods of power generation have all been subject to rigorous testing and iteration. Rings weigh under 100g, are 20mm thick, and able to stand compression from a full trawl under towing conditions. Fishermen have been consulted at every stage from inception to prototype, and their feedback has helped make the Escape Rings what they are in terms of usability and fitness for purpose. The goal has always been to create a product that would actually be used and their support has helped immensely.
Escape Ring devices form a part of this system, and are currently the focus of the development work. The rings tackle the problem of holes in a net closing up during trawling when under tension. Many small fish are unable to escape, or are severely injured in the process. Escape Rings hold the meshes open, and a simple light ring acts as an emergency exit sign. The lights make the rings more visible and also stimulate fish escape reactions, guiding them out. All electronic devices are powered by a tested on-board energy harvesting system, meaning that once fishermen fit the devices to their nets they never have to think about them again. When trawls reach the end of their working life, the Escape Rings can be removed and fitted to the new one. The Rings are available in a range of sizes.
How it is different
While many projects exist or are being developed which tackle the problem of overfishing, SafetyNet is unusual in that it can be retrofitted to trawl nets. It is also the only solution which uses Escape Ring technology.
SafetyNet has evolved from a degree project to a start-up business. I will continue to develop SafetyNet: refining prototypes and approaching fishing companies with a view to carrying out further research. I hope that SafetyNet will, once finalised, be fitted to all trawl nets.