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How to sustainably boost fish yields to feed a growing population

How to sustainably boost fish yields to feed a growing population
30 Dec
Food systems will need to change as the global population grows. With reform, could fishing and aquaculture step up to the challenge?

As Earth’s population grows, future food systems will need to adapt. Scaling up crop and meat production both come with challenges, including lack of space and declining soil quality. Seafood – a dietary option rich in omega-3, iodine, vitamin D, calcium and zinc – could be a different kettle of fish. 

The UN’s Food and Agriculture Organisation (FAO) estimates that total fish production will expand from 179 million tonnes in 2018 to 204 million tonnes in 2030. A team of 22 global experts has recently sought to demonstrate that, with reform, the productivity of our seas could sustainably increase beyond even that.

As it stands, seafood provides 3.3 billion people with roughly 20 per cent of their average intake of animal protein. ‘Seafood hasn’t really been an integral part of the future food system narrative though,’ says Stefan Gelcich, associate professor at Pontifical Catholic University of Chile and one of the authors of the new report. ‘We wanted to ask whether the seas have more sustainable potential.’ To do this, the team amassed a huge data set, breaking down the ocean into pixels programmed with economic and ecological factors unique to each region. They used this powerful ‘bioeconomic’ model to estimate the sustainable yield from wild fisheries and mariculture – where fish and shellfish are farmed at sea – under a range of management scenarios.

The model estimates that wild fisheries can sustainably achieve a 16 per cent bump in catch by 2050, while mariculture can generate a two- to four-fold increase in finfish yields. ‘About half of the world’s fisheries have become well managed over the last few decades. The other half have been overfished, with fishermen spending more time chasing fewer fish. The net result is the balancing effect in catch that we’ve seen since the 1990s,’ says another author, Christopher Costello, professor of environmental and resource economics at the University of California, Santa Barbara. ‘If done right, there is potential for sustainable growth in every sector of ocean food production.’  

The team carved out a blueprint that could see this vision become reality. First, since 80 per cent of the seafood we eat still comes from wild fisheries, the authors urge governments to reform poorly managed ‘open access’ zones. ‘In these waters, fishing pressure increases as product prices rise, creating an unsustainable supply curve,’ says Costello. Acknowledging that monitoring fisheries through stock assessments and quotas can be expensive, the team included scenarios where such reforms are first focused on fisheries in which future profits outweigh the associated cost of reforms. Marine protected areas (MPAs) could also come into play. Though not considered by the authors, other researchers have highlighted their potential. A recent study led by Reniel Cabral at the University of California demonstrated that expanding ocean networks of MPAs by five per cent could increase future catch by 20 per cent through ‘spillover’ of fish from MPAs into wild fisheries.

Mariculture montenegroAquaculture farms off the coast of Montenegro

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When it comes to mariculture, the authors argue that the industry needs to tighten up lax regulation that has resulted in poor environmental stewardship, disease and even fisheries collapse. ‘There are a lot of horror stories out there about the state of mariculture. Now we’re starting to focus on the role of coupled small-scale fisheries and mariculture, which opens up a whole new avenue for innovation and improvement,’ says Gelcich.  

Currently, three quarters of mariculture requires fishmeal and fish oil derived from wild fisheries, further exacerbating demand and contributing to unsustainable practices. Alternative feeds, using microbial ingredients, insects or algae, could decouple mariculture production from wild fisheries. This is already the case for Atlantic salmon, where fish-based feeds have dropped from 90 per cent in the 1990s to 25 per cent today. 

With reforms, say the authors, wild fisheries and mariculture could sustainably achieve an 18–44 per cent increase in live catch production per decade. ‘We have enough knowledge now to help governments design sustainable transformations for a more prosperous and sustainable ocean,’ says Costello. 

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