Aquaculture could reduce environmental impact of land farming

A study conducted by scientists at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS) in California, US, has revealed that the amount of farming land required to support future protein needs is substantially higher when not coupled with fish farming.

The UN Food and Agriculture Organisation (FAO) estimated that current global livestock production will grow by an average of 52% by 2050, in order to feed the nearly 10 billion people that scientists predict will inhabit the planet.

The research team estimated that seafood can help feed the future global population while reducing the environmental impact caused by land farming.

NCEAS postdoctoral researcher Halley Froehlich said: “While aquaculture can add some pressure because ultimately it is a food production system, our study demonstrates the relative amount is minuscule compared to terrestrially farmed animals.

“Aquaculture is not going to be the main strain on future crop feed and land use. It is—and will likely continue to be—terrestrial livestock.”

Aquaculture is unique in that it partly depends on cropland farming to provide feed for the fish. To understand the extent of this, researchers examined how much land would be required to grow seven of the most common crops used to feed terrestrial livestock and for aquatic farming in 2050 and found that by replacing the added terrestrial production with aquaculture 729 million to 747 million hectares of land would be saved, a geographical area equivalent to twice the size of India.

The team discovered that land savings would be the same when substituting in completely marine-based aquaculture, or a mix or marine-based and freshwater farming. Land would be conserved because fish and other types of seafood convert feed to biomass for human consumption at a more efficient rate than traditional land animals.

A cow requires around 6lb to 30lb of feed for 1lb of biomass meant for human consumption. Most farmed fish only need 1lb to 2lb of feed. The reduced amount of feed required will lead to significant reductions in cropland use.

Froehlich stressed that the study does not reveal that aquaculture is a solution for sustainable food production, but evidence is building towards the potential of aquatic farming to reduce environmental damage through land use.

“Aquaculture does not have to be this massive burden on land or in the water, especially if farms are sited strategically and there are incentives for management that move it toward sustainable siting and feed practices,” she said.

NCEAS director and co-author Ben Halpern added that he hopes the study gives consumers a stronger motive to eat more fish.

He said: “What you eat has an impact, but we understand shifting diets can be difficult. We hope that awareness of how much land can be spared with a fish-rich diet helps individuals make the change. Similarly, we hope our results put more ‘fish on the bones’ of policy arguments to make more systematic changes.”

This study is the first of its kind to focus on aquaculture as a future food system, the fastest growing food sector, and sheds light on the potential role of fish farming in conservation and food security.