To satisfy the seafood needs of billions of people, offering them access to a more biodiverse array of fish creates opportunities to mix-and-match species to obtain better nutrition from smaller portions of fish.
The right combination of certain species can provide up to 60% more nutrients than if someone ate the same quantity of even a highly nutritious species, according to a global analysis of fisheries published May 27 in Nature Sustainability.
Wild fish harvests have stagnated for decades as many fisheries have been depleted by a growing global demand for seafood, which makes the need to maximize nutrition from limited fish stocks even more urgent.
"This research hopefully highlights the importance of biodiversity, not just because of a moral quandary that we're causing a mass extinction on Earth, but also because biodiversity can lead to better outcomes for fishery sustainability," said first author Sebastian Heilpern '10, a Schmidt AI in Science Postdoctoral Fellow in the College of Veterinary Medicine (CVM).
In the study, Heilpern and colleagues began by identifying a list of fish species that people are known to consume. "There are 30,000 species of fish on the planet, and we eat a subset of that, and so coming up with that list was not trivial," Heilpern said.
Once a list was created, Heilpern cross-checked it with existing nutrient content data for each species. From there, they determined the fish species that are found in every country or territory on Earth.
The biogeographic and nutrient data was then fed into a computer model (called a constrained optimization model).
"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," Heilpern said.
The model revealed that when fisheries are more biodiverse, an optimal diet that uses the lowest quantity of fish skews towards species with traits that can give them greater resilience to anthropogenic pressures like overexploitation and climate change. Such species tend to be smaller, lower on the food chain, and can be substituted with a wider range of other small species that contain similar levels of nutrients, thereby providing people with many potential alternatives.
Smaller species, like sardines, tend to be more ecologically resilient because they grow at faster rates than larger species. Additionally, optimal species are able to tolerate wider temperature ranges, making them more resilient to climate shocks.
The investigation showed that tropical coastal countries tend to have the most biodiverse fisheries, including countries in the Coral Triangle in the Pacific Ocean (from the Philippines to Singapore to the Solomon Islands), Australia, India and the Amazon. The U.S. has good biodiversity, though Americans tend to consume a select few species; only 10 species account for up to 90% of fish that Americans eat, depending on the year.
In order to promote biodiversity at the consumer level, the authors suggest that people try eating a wider breadth of smaller species. At a regional level, marine protected areas, where fishing is banned, have proven very effective at protecting biodiversity and increasing fisheries productivity. In places like the Amazon, fisheries co-managed by both specialists and local communities improve biodiversity and catches.
Study co-authors include Kathryn Fiorella, associate professor in the Department of Public and Ecosystem Health (CVM); Franz Simon, a visiting fellow in the Department of Natural Resources and the Environment in the College of Agriculture and Life Sciences (CALS); Peter McIntyre, associate professor in the departments of Ecology and Evolutionary Biology and Natural Resources and the Environment (CALS); Alex Flecker, professor of ecology and evolutionary biology (CALS); and Carla Gomes, Ronald C. and Antonia V. Nielsen Professor of Computing and Information Science (Bowers College of Computing and Information Science). Suresh Sethi, a fisheries ecologist at Brooklyn College, is also a co-author.
The study was funded by the Schmidt Sciences programs, Cornell University, the National Science Foundation, the National Institute of Food and Agriculture, the Air Force Office of Scientific Research, and the David and Lucile Packard Foundation.
