The most visually noticeable aspect of the SafetyNet is the series of illuminated escape rings that allow smaller fish to swim out of the net.
Watson says, “The rings deal with the issue of the meshes in the net closing up, which happens when the net is under tension. The rings fit into the meshes and hold them open, basically acting as a really strong scaffold. The illuminated part of the ring attracts the fish’s curiosity and when they go to investigate they can feel the flow of the water through the holes so they know how they can get out.”
The illuminated part of the ring attracts the fish’s curiosity
The rings harvest energy from the motion of the trawler to create the electricity needed for the LEDs that light the rings.
Another ingenious design concept, which is inspired by the differing behaviours of fish species, is to divide the net into two halves. Watson says, “If you imagine the front of the net as an oval shape, almost like a big mouth, when the fish are in front of that, because of their different behavioural reactions, they will move to different parts of the oval. Some will swim down, some will swim up and some will hover around the middle.”
Though still in prototype stages, the plan is to create different mesh sizes for each half of the net. Watson continues, “Above the dividing line you might have a very fine mesh net, which leads the fish back to the retention area and below that dividing line you might have a very wide open mesh which will retain nothing, so all the fish that swim to that section can escape.”
People who I’ve been trying to get in touch with for a year are now contacting me
Cod, which are an endangered species, respond to a threat by swimming downwards. This means they will enter the lower half of the net and escape while non-endangered Haddock and Whiting, which naturally swim upwards when stressed, will get caught in the top half. The net has also been designed to float one meter off the ground so that the seabed isn’t damaged. This also reduces friction which means less power is consumed when dragging the nets.
As well as providing capital for SafetyNet, the Dyson award has also dramatically raised the project’s profile.
Watson says, “The publicity around it has meant that people are getting in touch with me. For example, people from fishery research institutes have contacted me saying they have trawler facilities that we can use to test our nets. There have been people who I’ve been trying to get in touch with for a year who are now contacting me.”
SafetyNet has been designed to be affordable so that fishing companies will be more inclined to buy the product. “If it isn’t affordable it isn’t going to get used. One of the main things is that the rings actually retrofit onto existing nets. You can buy a set of these and stick them onto the net you already have. We are also using the most straightforward and bog standard manufacturing processes possible to keep the costs down.”
With luck SafteyNet, with its illuminated rings, will become a common sight in our seas and will help put a stop to the rapidly depleting stocks of endangered fish.
For more information go to SafetyNet and the James Dyson Award.