The primary goal of the model was to solve a complex optimization problem. As Heilpern explains, the researchers wanted to determine which combinations of fish could most efficiently meet human dietary needs. "We can then ask, out of all these combinations of potential options of species, which ones could we select and how much of each, in a way that would provide us with sufficient nutrition to meet a person’s diet [needs] with the lowest amount of fish biomass," he said.
The results of the modeling were revealing. When fisheries are managed and harvested with biodiversity in mind, the optimal diet shifts toward species that possess specific biological traits. Interestingly, these traits often align with greater ecological resilience. The model showed that a nutritionally optimal diet that utilizes the lowest quantity of fish biomass tends to favor species that are smaller and positioned lower on the food chain. These species are not only nutrient-dense when combined correctly, but they are also better equipped to withstand the "anthropogenic pressures" currently reshaping the world’s oceans, such as overexploitation and the escalating impacts of climate change.
Smaller species, such as sardines and anchovies, serve as prime examples of this resilience. Because they grow at significantly faster rates than larger, predatory fish like tuna or swordfish, their populations can rebound more quickly from fishing pressure. Furthermore, these smaller species often exhibit a higher tolerance for a wider range of water temperatures. In an era of warming oceans and frequent climate shocks, such as marine heatwaves, this thermal flexibility makes them a more reliable and stable food source than their larger, more specialized counterparts.
The study also highlights the concept of "functional redundancy" in biodiverse systems. In a highly diverse fishery, many different small species may contain similar levels of nutrients. This means that if one species’ population fluctuates or declines due to environmental changes, there are numerous potential alternatives that can be substituted without compromising the nutritional intake of the human population. This diversity acts as a safety net, ensuring that the food system remains robust even in the face of ecological instability.
Geographically, the study underscores a stark contrast between different regions of the world. Tropical coastal countries emerged as the primary hotspots for biodiverse fisheries. The researchers identified the Coral Triangle in the Pacific Ocean, as well as the coastal waters of Australia, India, and the vast networks of the Amazon, as areas where the natural variety of fish offers the greatest potential for optimized nutrition. In these regions, the sheer number of available species provides a wealth of opportunities to create highly efficient, nutrient-rich diets that support both people and nature.
