A new study by University of California, Santa Barbara marine scientists led by Professor Rebecca Gentry, along with researchers from the Nature Conservancy, the National Oceanic and Atmospheric Administration, and the University of California, Los Angeles (UCLA), shows considerable potential for aquaculture to develop around the globe.
Fish farming is now the fastest-growing food sector in the world, and is frequently cited as having the potential to address future global food security issues. In their study, the researchers estimated that 15 billion metric tons (MT) of finfish could be grown globally per year, which is 100 times more than current world seafood consumption.
The results of their study, “Mapping the global potential for marine aquaculture,” published in the journal Nature Ecology and Evolution on 14 August, demonstrates the oceans’ vast potential to support aquaculture, director of the UCLA Institute of the Environment and Sustainability and report co-author Peter Kareiva said.
“We need to find more protein for our growing population, and we have pretty much tapped out wild fish as protein sources,” he said. “This study shows that farming fish in the ocean could play a huge role in feeding people without degrading our ocean or overfishing wild species.”
Both fish and bivalve aquaculture have potential for expansion in what the researchers termed “hot spots” – particularly in warm, tropical regions.
Indonesia, for example, was found to have one of the highest production potentials for fish and bivalves. Developing just one percent of Indonesia’s suitable ocean area could produce more than 24 million MT of fish per year. If this was used entirely for domestic consumption, it would increase seafood consumption per capita six-fold.
In total, more than 11.4 million square kilometres of the ocean were considered to be suitable for fish production and more than 1.5 million square kilometres were deemed viable for bivalves.
“There is a lot of space suitable for aquaculture, but that is not what’s going to limit its development,” Gentry said. “It’s going to be other things such as governance and economics.”
A gap between science, policy, and local socioeconomic conditions appears to be a common problem limiting aquaculture expansion. Further challenges lie in developing sustainable feeds, and in understanding how large-scale ocean farming systems interact with ecosystems and human well-being, according to the report.
The research project was among the first global assessments of the potential for marine aquaculture. To date, little has been published about the extent, location, and productivity of potential growing areas across the globe, with most of the research focused on specific species or specific regions.
This study found that if fish farming were developed in only the most productive areas, the oceans could theoretically produce the same amount of seafood currently caught from wild fisheries, but in less than one percent of the total ocean surface. By comparison, this is a combined area the size of Lake Michigan, or Belgium and the Netherlands combined.
“There are only a couple of countries producing the vast majority of what’s being produced right now in the oceans,” Gentry said. “We show that aquaculture could actually be spread a lot more across the world, and every coastal country has this opportunity.”
The researchers first divided up the ocean into a grid, excluding areas that were too deep or already given over to other marine use such as oil extraction, marine parks, or shipping lanes. They then used an innovative approach to map the biological production potential for 120 marine fish and 60 bivalve species, using known physiological and tolerance factors and growth rates of the species, along with environmental data to make their predictions.
They were pleased to find that following the application of substantial constraints based on existing ocean use and limitations, vast areas suitable for aquaculture production could still be identified in nearly every coastal region. These areas offer opportunities to develop new, sustainable marine farming industries in line with local economic, environmental and social objectives.
Most aquaculture currently takes place on land, in freshwater or in nearshore marine waters. However, problems such as high resource use, pollution and habitat destruction have created a negative reputation in many countries and pose challenges for continued expansion. Open-ocean aquaculture would offer advantages over more traditional fish farming methods, such as fewer spatial conflicts and a higher nutrient assimilation capacity.
However, the development of open-ocean farming technology is still at an early stage and the report recommends making adaptive management and careful research an essential element of sustainable marine aquaculture expansion. Integrating best-practice farming guidelines with spatially integrated assessments and indicators of ocean health and utilization could help guide marine aquaculture towards sustainable expansion.
Interestingly, countries found to have the highest potential are not currently producing large quantities of marine aquaculture. Likewise, the species showing the most promise for open-ocean aquaculture are not the same as those currently being farmed.
Countries such as Chile, China, and Norway currently produce large volumes of marine finfish, while Australia, India, Argentina, Kenya, Pacific island nations, and Indonesia (amongst others) were considered to have the most promising potential for growth. Some of these are also experiencing fast rises in population growth, making the need for increased protein a more urgent issue.
Image courtesy of Jeff Milisen, ©Kampachi Farms, LLC
