Can clever nets make fishing sustainable?

The pressure is on for fishing trawlers to reduce the harm they do to the oceans. Their deep-sea nets catch too many of the wrong fish. Much of their catch is waste, which costs them money and reduces biodiversity. ‘SafetyNet‘ can help spare young fish and endangered species from the nets. As a result, they can grow to adulthood and breed to keep their numbers healthy.


Image: Flickr/the boatman

The fishing industry is in crisis. Centuries of trawl fishing have pushed many species to the brink of extinction. Deep-sea trawl nets destroy delicate marine ecologies.


Image: Flickr/dyamosquito

Not all the fish caught in trawler nets can be sold. Some species are protected by law and young fish are too small. These are thrown back in the sea; sadly most of them die.


Image: SafetyNet

The SafetyNet combines several engineering ideas to limit the catch to larger fish and stop damage to the ocean floor.


Video: SafetyNet

The escape rings attach easily to gaps in the net, keeping them open. This means small, young fish stand a better chance of growing up to breed.


Video: SafetyNet

The rings light up to attract the young fish towards them. These lights can be powered by battery or even by the net’s own movement.


Image: Flickr/Skytruth

A system of weights and floats hold the trawl net a metre off the seabed. This causes far less damage and makes the net easier to drag through the water.

Image: Flickr/Dave Wilson Cumbria

Less drag means the boat doesn’t have to use as much fuel, so its CO2 emissions are lower too.

dying fishImage: Flickr/Derek Keats

The SafetyNet also uses the way fish react when they sense danger to avoid catching endangered species. Cod swim downwards – so a separator panel in the bottom of the SafetyNet has a larger mesh for them to escape through.

net underwaterImage: SafetyNet

The escape rings, weights and floats, and separator panels in the SafetyNet should work together to make trawl fishing far more sustainable. Trawlers will test the SafetyNet at sea soon.

carving of fishermenImage: Flickr/D H Wright

Let’s hope it works as planned and helps to keep fish numbers healthy. And that less of the trawlers’ catch is wasted.


drDan Watson ( far left) is the freelance designer who created the SafetyNet. He graduated from Glasgow University in product design engineering and Imperial College London in innovation design engineering. David (immediate left) asked him how his net works and how it could reduce the environmental impact of fishing.


What’s the problem with current fishing practice?

‘Many fishermen use big trawl nets to capture large numbers of fish at once. The nets aren’t as selective as they need to be, so they catch many different sizes and species of fish. A lot of fish that shouldn’t end up in the net – they’re too small or the wrong species. They get thrown back, often dead.’

 

 


Why are you interested in this problem?

‘Lots of people in Scotland make their living from fishing. If we manage our fishing badly, it could be catastrophic for them and for our environment. I really enjoy problem-solving, and this is a problem I was in the right place at the right time to try and address.’

 

 

What is your new innovation for trawl nets?

‘I’ve modified the design of a traditional trawler net to create the SafetyNet. The new design should reduce damage to the seabed and allow small, or endangered, fish to get out. My most significant modification is the escape ring.’

 

 

What do the escape rings do?

‘When trawl nets are pulled through the water, holes in the net become distorted and smaller, so little fish can’t get out. Escape rings are installed in the net to provide escape routes for small fish. They have built-in lights to help the fish notice the exits.’

 

 

 

Do you know if the escape ring works?

‘Yes, in theory! It is based on research about fish behaviour and how nets distort under trawling conditions. So far my prototypes have been working correctly. We plan to test the system in the ocean, so I can be sure it helps small fish escape in real situations.’

 

 

Will it solve our over-fishing problems?

‘If the theory is sound and escape rings are installed widely, more young fish will survive to breeding age to keep stocks healthy. However, fishing is a complex issue and there is no single change that will make it sustainable. I think we need to proactively manage our fisheries and take only our fair share.’

 


Can ideas such as the SafetyNet make fishing more sustainable? I asked some experts for their views…

 

Lekelia (Kiki) Jenkins, Marine environment researcher

‘For years I’ve thought there’s a lack of trained engineers working on new marine conservation technology. Uniting engineers with fishers could help tackle some complex problems in the fishing industry. Engineering schools should embrace fisheries problems as worthy pursuits for their students. The SafetyNet system is an example of how useful this collaboration can be.’

 

Zaina, Fisherwoman from Charlottesville, Tobago

‘In some parts of the world local fishing trawlers might well be poachers. They don’t care about regulations and restrictions. Poachers are quite happy to use fish they don’t want as cat and dog food! However, I think conscious-minded fisherfolk would use the SafetyNet if it is hard wearing and if it is not too expensive to maintain.’

 

The Department for Environment, Food and Rural Affairs

‘In the UK we’re committed to stopping unwanted dead fish from being discarded. It’s a clear waste of natural resource and money for the fishing industry. We really want to see the development of new equipment to reduce this waste. When properly tested the SafetyNet could help fishing vessels to fish more selectively.’

 

Aniol Esteban, Environmental economist

‘Using technology and innovation to reduce the harmful effects of trawler fishing is a welcome move. But all this technology will not lead to healthy fish stocks if we keep fishing more than the sea can give us. SafetyNet might make trawling less harmful, but it will still be very far from being an environmentally friendly fishing technique.’


(Rohan amendment: My two cents on this topic is that if you care about fish stocks and related environmental/ecological issues just don’t eat fish! Pretty simple?)

This article was originally published as an interactive document in the Antenna gallery at the Science Museum.

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