Protecting fish biodiversity is a win-win solution for human nutrition and sustainable fisheries, finds a new study. The research, published in Nature Sustainability, unearthed some interesting findings including that biodiverse fisheries tend to contain smaller, more nutrient-dense fish that are also more resilient to fishing pressures and climate change. 

“More biodiversity means more opportunities to make better decisions for nutrition and ecosystems,” says the paper’s lead author Sebastian Heilpern, a postdoctoral fellow in the College of Veterinary Medicine at Cornell University, and lead author on the new research.

In their paper, Heilpern and colleagues set out to map the diversity and nutritional makeup of thousands of fish species worldwide. They looked at the fish species in over 290 countries and territories. Their search included sharks and rays and incorporated 30,000 fish species overall. Then they looked at the levels of protein, fatty acids, calcium, iron and zinc provided by each one, and ranked fish accordingly for their nutritional value.

From this data, an interesting picture of fish diversity and its benefits began to emerge. Firstly, it revealed that in regions with a greater array of fish species, it is possible to meet the recommended dietary allowance with less fish. Put another way, “biodiversity reduces the harvest intensity required” to provide essential nutrients, the paper explains. Furthermore, greater biodiversity creates greater ‘nutritional redundancy’ among fish, meaning that there aren’t just one or two but several highly-nutritious species, so these fish could be interchanged with one another to get the same nutritional benefit. 

In a striking example, the researchers compare the species-rich waters of the Micronesian island of Kiribati, to the less productive seas around Iceland. In Kiribati, the category of ‘most nutritious fish’ includes 30 species, while in Iceland it includes just 13. Also, in Kiribati fisheries could provide 50% of the total recommended dietary allowance with just 128 grams of fish per day, whereas in Iceland more than triple that amount would be needed to meet the same nutritional target. 

There are also clear sustainability benefits threaded through this nutritional reality. If less fish is needed in terms of biomass to reach nutritional outcomes, that can take pressure off wild stocks. Similarly, being able to draw from a wider pool of high-quality species to meet nutritional demands could ease fishing pressure on one or two species, and reduce the risk of overfishing, the study says. 

Finally, the paper revealed another feature that shows how intertwined nutrition and sustainability are with biodiversity. As the researchers found, in more biodiverse regions, nutritional needs can be met with less fish, in part because these regions contain more individual species of highly-nutritious fish. What they also discovered is that those species tend to be smaller (which explains the lower biomass needed to reach nutritional targets), faster-growing, and better able to survive in a wide range of temperatures. 

In other words, the most nutritionally-beneficial fish are likely to also be more resilient to fishing and climate pressures.

Protecting and restoring biodiversity, therefore, is a linchpin of nutrition and sustainability, the study finds. These results are important especially for highly-biodiverse regions, says Heilpern. “It turns out that people in places that have higher biodiversity are also more reliant on fisheries. So the opportunities afforded by biodiversity are highest where they are most needed.”

Going forward, Heilpern says he hopes that the concept of “many species of small fish” will become a guiding principle in food security and conservation policies, because biodiversity is deeply intertwined with our nutritional future. “Food systems are changing biodiversity, but also…biodiversity is a central ingredient for healthy and sustainable food systems,” he says. 

Heilpern et. al. “Leveraging biodiversity to maximize nutrition and resilience of global fisheries.” Nature Sustainability. 2025.

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