Fish are evolving to escape modern fishing techniques. This is what it means

Huge, coordinated groups of fish swimming together – or schooling – to evade predators is a sight familiar to many lovers of nature programmes.

But this incredible display could now be dead in the water, according to a new study that says modern industrial fishing could be causing fish to change their behaviour. They may be growing anti-social to survive – and the consequences could be far reaching.

Modern fishing techniques involve using drones and planes to spot larger schools from above, so huge trawler nets and walls of netting called purse seines can capture schools in their entirety.

But in areas where these mass-capture practices are employed, fish may be swimming in smaller, harder-to-detect groups, according to a scientific model simulating schooling behaviour.

“Humans have become the dominant predator in many marine systems, with modern fishing gear developed to specifically target groups of schooling species,” write the authors of the study published in Proceedings of the Royal Society B.

“Therefore, ironically, behavioural strategies which evolved to avoid non-human predators may now actually make certain fish more vulnerable to predation by humans.”

The impact of solitary fish

Not only does this suggest fish – so often just defined by stock numbers or profit margins – are capable of adapting their behaviour to avoid capture, it also has consequences for the people that catch them.

Fishing supports the livelihoods of millions across the globe – the seafood sector is worth $362 billion and it generates income for 800 million people.

As fish move to smaller schools, the resources required to capture them will increase, impacting the profitability of the industry.

But along with making it more tricky for humans to catch huge swathes of fish quickly and efficiently, it will also alter the eating patterns of predators that rely on fish swimming in schools, such as whales, dolphins and sharks.

The paper’s authors believe the trend is reversible, but say that achieving this would require fishing practices to be scaled back to a much lower level.

Overfishing remains a stark and urgent issue. The number of overfished stocks has tripled in half a century, according to the WWF, and “bycatch” – sea creatures caught but not wanted – means billions of fish and other marine animals are lost, exacerbating the disruption of marine ecosystems.

Furthermore, many fisheries in developing countries lack the resources to be sustainable, while illegal fishing is believed to be worth $36.4 billion a year.

Rethinking the ocean

Overfishing is just one of the threats to ocean ecosystems, with others including climate change and pollution.

To assist in finding solutions to these issues, the World Economic Forum’s UpLink platform, which aims to crowdsource innovations to help meet the UN’s Sustainable Development Goals (SDGs), has launched its second ideas sprint.

UpLink’s Ocean Solutions Sprint 2 is welcoming submissions on four main topics: Restorative aquaculture (farming of fish, shellfish and seaweed); protecting and restoring coral reefs; investing in nature-based solutions to climate change; and technology supporting Marine Protected Areas.